What is the human brain made of? I read an article that stated that the human brain contains 60% fat. Is this fatty tissue structural building material? Or does it just serve as an energy source for the mitochondria?

Since our body are also made out of 70% water, is there also a water in our brain?

And the most important question I want to ask is: what percentage of the brain is actually a neuron?

The brain has a lot of a fatty substance called myelin. It wraps around nerve fibers and enhances the speed of electrical communication between neurons (source: Brain Facts), and increases transmission efficiency (Fig. 1). It is produced by supporting cells in the brain called oligodendrocytes. Myelin is really just many wraps of membrane, and since neurons have long axons and dendrites, too, they also have a lot more membrane than if they were just spherical cells - all of this membrane is "fat" called phospholipid.

Now on to your questions -

  Is this fatty tissue structural building material? Or does it just serve as an energy source for the mitochondria?

Myelin and cell membranes are the most abundant fatty substances in the brain - they are structural fatty substances found around cells and neuronal axons, respectively, and they are not fuel.

  [I]s there also a water in our brain?

Every cell contains water, as nearly all biochemical reactions take place in a watery solution. An early report found the water content of neurons to be 55% (Saubermann & Scheid, 1985)

  [W]hat percentage of the brain is actually a neuron?

Scientific American performed a review on this and settles on a ratio of neurons : glia cells of 1:1 (although numbers of 10:1 have been reported). Glia are the brain's supportive cells and include the oligodendrocytes as mentioned above that produce the myelin (Jabr, 2012).

Fig. 1. Schematic showing a myelin sheath around an axon. source: WebMD

References
 - Jabr, Sci Am (2012), June 2012
 - Saubermann & Scheid, J Neurochem (1985); 44(3): 825-34


What makes words (entities) positive or negative? I am conducting a lexicon study asking people to classify words as being positive, negative, or neutral. It seems to be a very natural ability for us to perform such classifications.

The next step is for me to understand what makes a word (or an entity behind it in general) positive. There could be a variety of reasons:

(usefulness) highly effective, useful;
(budget) reasonable price, discount;
(comfort) cozy, comfortable shoes;
(joy) tasty pie, pleasant sleep;
(emotion) incredible adventure, happiness;
...

(Naturally some words could fall into more than one category.)

I am looking for some research on the topic to learn from.  Please advise.

The classification of affect as positive (as in "good") or negative (as in "bad") is called valence.

There is a large body of research regarding word valence, owing to interest from corporate communications and public messages, for example as delivered through social media.  To further address demand, Bradley & Lang (1999) developed a database of dictionary words and their valence scores, that is available for download.  More recently, such databases have been developed for dozens of languages, and the English database has been greatly expanded as well.  These databases often feature multiple dimensions of affect, but if you are not interested in them, then just look at valence and ignore the rest.

With such databases in hand, it is possible to test how different factors predict word valence.  Many hypotheses have been tested, such as word length, conjugations, age of acquisition, etc.  A comprehensive review by Warriner et al (2013) lists a few more examples of correlations with lexical properties, such as smell, color, and motion:

  Most correlations that emotional ratings show with other semantic
  properties are weak to moderate, with the exception of correlations
  with variables that directly tap into emotional states.

Of particular note, and extensively studied in this field, are concreteness, imageability, context availability, and familiarity.  Familiarity for example, is a term that has to do with how well known and how common words are - common words tend to be rated more positively than uncommon ones.  This has to do with the mere-exposure effect, and more generally, processing fluency (a.k.a. "cognitive ease"):

  Fluency and familiarity have been shown to lead to the mere exposure
  effect. Research has found that repetition of a stimulus can lead to
  fluent processing which leads to a feeling of liking. ... Later
  research observed that high perceptual fluency increases the
  experience of positive affect.

Another good list of databases and research on concreteness, imageability, context availability, and familiarity can be found in Riegel et al (2015).  As I said, it's a big field, but hopefully this gets you started.


Are there any long term cognitive impairments from prolonged period reduced sleep? What are the consequences of chronic lack of sleep? For example, insomniacs are known to sleep less than normal sleeping individuals.

I am wondering if there are any long term cognitive impairments from reducing sleep time to, say 4h instead of the normally recommended 8 hours in the long run, say for a year or so?

Wikipedia has some good information on this issue. Search for:

Effects of sleep deprivation on cognitive performance

In summary, 'yes', sleep deprivation can have a multitude of negative consequences on your cognitive abilities, like weakening your ability to handle complex cognitive tasks.


How to make diagnosis of these symptoms using Pet scan, fMRI, and EEG? The symptoms are muscle weakness, slow reaction time, visual perception issues, seizures, hearing loss, weight gain, general sense of pain and delusions. Using the above scanning techniques, a doctor concluded that there are problems in emission of neurotransmitters and secretion of hormones as well as myelin sheath of some neurons, occipital lobe, and temporal lobe. Could you tell me how the doctor used the scanning tools to reach to his conclusion? I totally have no idea how the doctor learned that there's problem in emission of neurotransmitter by using scanning techniques.

T2 weighted MRI scans can reveal white matter lesions, so that may explain the detection of demyelination.

Of course, that's not fMRI...


Looking for a paper: AI in human host I am searching for a paper where participants were confronted with a (female) person, who gave answers according to a computer algorithm. She had an earpiece that gave her the answers and was trained to simultaneously listen and speak.

Some participants thought that she was acting a bit off, but none recognized that they are talking to a computer. I think the aim of the study was some sort of turing test.

Hope anyone can help me find it. I don't know how to look for it anymore...

Finally!

I found a news article explaining the Echoborg.
The research was done in 2015 by Kevin Corti and Alex Gillespi at the London School of Economics and Political Science. Published at Frontiers of Psychology: https://doi.org/10.3389/fpsyg.2015.00634


Research software for conducting a task between card sorting and sketch map drawing I'm doing research in Spatial Cognition and am looking for software which will allow me to conduct the following task:

Participants will walk around a space and sit down to a computer task afterwards. There'd be a 2d architectural layout of the space visited by participants presented in the centre of the screen. On the side of the screen, the participants will see randomly scattered image stimuli, representing objects they have seen inside the space. I want them to be able to either drag&drop the images to their assumed locations in the architectural layout, or to click/select an image and click on the place inside the layout where they think they saw a given object. I want to record the final location and the sequence of operations.

I looked at card sorting tools from HCI, but these seem to be too restrictive (won't allow to change background image for example), so I thought someone in this group could hear of psychological software capable of running this sort of task.

I think a good option would be to use a general purpose language. For example, I once used Visual Basic to program a task that allowed for dragging elements around a display. The IDE for Visual Studio makes it easier to create GUIs. You could readily include a background image and so forth. You could also record location of visual elements and each action that a user takes.


Neurologic coherence between numbers and colors? I came across a magic trick on YouTube that made me curious (starting from 10m15s). Maybe it has something to do with synesthesia? But let me first describe the trick in short.

It involves two persons. One from the audience and of course the magician itself. The magician holds a card with a pyramide of numbers on it, like this:

    5
   5 5
  5 5 5
 5 5 5 5
5 5 5 5 5

Then the magician asks the person to read out loud the numbers several times (five, fifty five, ...). The magician informs the person beforehand, that he is going to ask a question later on. And that he wants the person to answer it right away.

Then after a minute or so, the magician asks: "Think of a vegetable and tell me it's name". According to this trick there is a 70% chance that the person answers carrot. And the second most given answer is tomato.

Now, why is that? The magician explains this with a neurological coherence between numbers and colors. Would that be some form of mild synesthesia that a lot of perople have? So that (statistically seen) the neurological representation of number is similar to the perception of a specific color?

Please bear with me, I am total laymen on this topics!

In some sense yes, we all have some mild synesthesia and tend to associate some shapes with some colors/names etc. There is a famous experiment from Ramachandran showing that when asked to identify 2 shapes, one called "bouba" and the other one "kiki", almost everybody reports the rounder shape as "bouba" and the sharper one as "kiki". It's unclear why, it's a classical chicken or egg problem. It could suggest that language reflects to some extent the visual appearance of objects. Or that from experience we match the visual appearance of objects with sounds they are (randomly) often associated with. In any case, if one takes the time to conduct polls and measure how often a stimulus is associated with another stimulus one can, at least in some situations, predict to a fairly large degree what people will think.

https://en.wikipedia.org/wiki/Bouba/kiki_effect


Bias distrusting area of expertise while implicitly trusting other domains? I've run across descriptions of this bias before, but cannot find it right now...  I checked Wikipedia's list of cognitive biases to no avail.
Basically, people working in some domain and having expertise in it, naturally tend to notice the problems in that area, such as incompetence of other people working in their field, bad policies and poor management decision making, etc, resulting in a disproportionate distrust of their own field of expertise.  For example, healthcare workers are more likely to be vaccine hesitant because they distrust their own industry more than most due to personal experience with incompetence, mismanagement, politics, and corruption within their field.
However, this distrust does not carry over to other domains.  So for example, watching a movie that portrays something you have domain knowledge in, you will quickly notice the inaccuracies and misrepresentation, but portrayals of domains outside your expertise will naturally be believable and perceived as accurate.  Similarly, reading news stories about topics that you have expertise in, you will notice inaccuracies and bias immediately, but fail to recognize that the same level of inaccuracy and bias must exist in domains outside your area of expertise, implicitly treating such news stories as accurately reported.
What is this bias called?

I found what I was looking for.  It's called the Gell-Mann Amnesia effect:

... You open the newspaper to an article on some subject you know
well. ... you read with exasperation or amusement the multiple errors
in a story, and then turn the page to national or international
affairs, and read as if the rest of the newspaper was somehow more
accurate about Palestine than the baloney you just read. You turn the
page, and forget what you know.

That quote is attributed to Michael Crichton, who named the effect after his physicist friend Murray Gell-Mann, who discovered it.
This effect is not studied in psychology as far as I can tell, so it may not be real, but having a name for it helps learn at least that much.


Why clothes' color is different than it appeared in stores? This is my first time askin on Cog Sci board, not sure this is a right place to ask but I think it's something relates to Psychology and Cognitive Science.

So yesterday I bought a shirt that looked very nice on my with its grayish color. I brought it back home and tried it again but I was surprised that the color was not as grayish as I had seen in the store, but rather bluish. Thought I picked up the wrong one so I asked my roommate but he said that it had happened to him once before that the color didn't turn out to be exactly the same as he had seen in store.

I'm interested in that phenomena but don't really have enough knowledge in that field to search for a right term or word. So can you please explain that phenomena in short and which field/term should I dig into in order to explore it more?

Thank you

It's difficult to say why this happened in your particular situation, but one contributing factor may be that color perception is relative. How a particular color is perceived depends on the surrounding colors. The best way to demonstrate this is through an optical illusion:

It looks like there are two different color hearts, but all of the hearts are exactly the same color. The illusion is created because the "green" hearts are striped with orange lines, and the "blue" hearts are striped with purple lines. Since color processing is relative, the different stripes cause us to perceive the underlying color very differently.This illusion comes from Akiyoshi Kitaoka's website, where there are several more examples.


What are a digital dementia and a pseudo debility? I'm a fan of Psychology.

I'd like to know what "pseudo debility" is. Unfortunately, I don't know what it means in English. This is my free translation from Russian.

I've encountered the terms "pseudo debility" and "digital dementia" on resources that popularize science. But I still haven't found a generally accepted definition.

This "pseudo debility" is the simplification and flattening of delirium in the modern world. In the past, delirium was more saturated, unique and striking imagination.

I'd like to know:

What is it?
Who invented and studied it?

Links

Цифровое слабоумие: кто на самом деле глупеет от гаджетов?
Псевдодебильность и слабоумие общества. Андрей Курпатов на QWERTY
The video above refers to such authors as Manfred Spitzer and Theo Compernolle
Digitale Demenz is a book by Manfred Spitzer

"Digital dementia" seems to be (from de.wiki link) an idiosyncratic (and pejorative) term used to describe a high dependence on portable electronics like smartphones, notebooks. See e.g.

"Why Smartphone Dependence Is Ravaging a Generation" obviously from an alarmist proponent of this phenomenon, or "Mobile phone overuse" on Wikipedia for a more neutral perspective.
the more general term seems to be "overuse of technology". Calling it "dementia" probably relates to an influential article (discussed in the previous link) titled "Is Google Making us Stupid?". Another pejorative term is "digital zombie".

From the absence of sources you provided, I don't know what "pseudo debility" might be, but based on your def "simplification and flattening of delirium in the modern world" it doesn't sound terribly related to "digital dementia" in the sense used by Manfred Spitzer.


What would the effect on psychology experiments be if we found out that one person sees blue if another sees red? Suppose we conducted an experiment that found that the color red makes people depressed and the color blue makes people happy.

Now suppose we found out that when looking at a red object, person A sees red but person B perceives blue.

Would the conclusions of the experiment still apply?

My take would be that the results would still apply, just that they apply to different definitions and it would be just a matter of semantics.

While the sensation of color is well defined, the perception of color is indeed shrouded in ambiguity (Brainard, 2001). There are no colors, just electromagnetic radiations that oscillate in different frequencies in the frequency domain. Our brains interpret those various wavelengths as color.

Now on to your experiment: if you find a statistical difference and you later find out that a group of people perceive the color blue as red and vice versa, the first thing you want to do is control for that population and take them out from the data set. Then you can compare the 'true seers' with the 'reversed seers' and see if they are statistically different in their emotional response. If yes, you'd better split them and analyze them separately. If not, a pooled analysis is fine, perhaps you can add the normal or inverse perception as a co-factor, dependent on the exact analysis.

But then, perhaps, the most important question here is - how would you find out what a person actually perceives?

Reference
- Brainard, Int. Encyclopedia Social & Behavioral
Sciences, Smelser & Baltes (eds.), Pergamon Press, Amsterdam


Comparative functional neuroanatomy: humans & octopodes Cephalopod brains are toroidal (high surface area to volume ratios!), with the esophagus passing through the, uh, donut hole; octopodes are very intelligent, particularly spatially.

Where can I find more information on the functional and anatomical comparisons between human and cephalopod brains, and its consequences for the cognitive abilities of both?  Specifically questions like

How does the functional neuroanatomy of the cephalopod compare to
human functional neuroanatomy?
How does cortical organization (both    perpendicular to the surface
and across the surface) between    cephalopods and humans compare?
How do human spatial cognitive abilities differ from those of the octopus?  (Somewhat akin to how the pigeon's object recognition capabilities are less dependent on canonical views of familiar objects than the human system.)

Bonus points for answer materials that are aimed at those with a knowledge of other neural systems, particularly human.

You could start with Hochner's papers, like this one:

Hochner, B., Shomrat, T., & Fiorito, G. (2006). The octopus: a model for a comparative analysis of the evolution of learning and memory mechanisms. The Biological Bulletin, 210(3), 308-317. http://www.biolbull.org/content/210/3/308.full

As far as I know, he is a world expert.


Does getting any job (no matter how demeaning) builds up one's character? A certain blogger claims that

  [if you] Work a shitty job, it builds character [nonetheless].

I'm curious if there are any academic studies relating to this issue. Of course one needs to consider the definition of job carefully in this case: does prostitution count for instance (it's legal in some countries), or does drug dealing, i.e. are we talking about income, legal income or just doing work; what if it's unpaid work, e.g. volunteering? It would be really nice if some study went to such extents to distinguish between these in relation to the outcome..., but I'll settle for more generic descriptions of "job".

Also one would have consider what exactly "build character" translates into (psychologically speaking)... enhancing self-esteem, or something else I haven't thought of just yet. But I'll leave this aspect fairly open as well.

I suppose much depends on what one means by "building character"; if it's increasing self-esteem, then the answer is probably no, as you've already pointed out.  But I don't think that's what most people mean by building character.  So what is it?  Certainly you'll learn something from having a demeaning job, because you'll learn something from just about anything; also, it is likely to lower your expectations, so you might be more excited about any given other job and value the money you earn more (see for example this article).  So it's probably possible to adjust the definition of "building character" until it's mostly true.  But after twisting the definition too far, it's unclear that "building character" is a desirable thing to do, so it doesn't offer much in the way of advice for life.

Incidentally, it has been argued that most work in the US is actually fulfilling.


Doing PCA and ICA analysis on EEG data with 24 channels I am very new to this type of neuroscience research and I am trying to do some automatic artifact detection. I am having trouble understanding how I should work with my data. I have data recorded from 20 electrodes on my EEG. The outputs are all in microVolts and are recordings for only one person doing eye blinking during the recording. My question is, now that I have the data from the 20 electrodes, how would I do PCA or ICA analysis on them? Like should I apply sklearn (from python) PCA or ICA option to the whole matrix, meaning to the whole data of the 20 electrodes, at once or should I apply these options to the measurements from one electrodes at a time and then combine them?

Thanks so much for your help and let me know if more specificity in the question is needed.

First of all, I would recommend working with a domain specific (EEG) and established analysis package of your choice. You mentioned python, so I would advise you to check out MNE-Python. There is a tutorial regarding eyeblink detection/correction/rejection from EEG data that you could work through.

To answer your general question, ICA and PCA are typically done on the complete data matrix, i.e., each row of the data matrix is a channel and each column is a sampled timepoint (values in microvolts).


Why some people feel their skin itching when they're told about insects and no insects happen to be nearby? Sometimes when people talk in public about cockroaches, for example, it happens for some people to feel the skin itching and yet, no cockroaches were there. Is there a name for this phenomenon?

The name you are looking for is Formication.

  Formication is the medical term for a sensation that exactly resembles that of small insects crawling on (or under) the skin. It is one specific form of a set of sensations known as paresthesias, which also include the more common prickling, tingling sensation known as "pins and needles". Formication is a well documented symptom, which has numerous possible causes.


How is doing a manipulation check different from doing the analysis on the main dependent variable? How is doing a so-called manipulation check (i.e. checking to see whether the different groups actually differ for different levels of the independent variable) different from doing - as a main analysis - e.g., an ANOVA to see if the independent variable has had an effect on the dependent variable? From reading papers, it seems people just do manipulation checks prior to the main analyses.

It depends on what you mean by manipulation check.

Manipulation check to filter participants: A manipulation check is usually done to verify that some experimental manipulation has had some preliminary effect. For example, in one of my studies I asked people to answer a personality test (a) honestly, (b) as an ideal worker, and (c) as the worst possible worker. I asked each participant how they intended to answer the personality test. The manipulation check was there to verify that they had understood the instructions. In this case, the manipulation check was used to potentially exclude participants who failed to pass the manipulation check.

Manipulation check to verify group-level effect: Of course, you could perform such manipulation checks on an entire group using group comparison tools such as ANOVA for a numeric variable or chi-square for a categorical outcome. For example, in some psychological studies, the experimenter may attempt to manipulate mood as baseline manipulation. Thus, they may want to get check whether the group that has been made to experience negative affect does on average experience more negative affect. In that case an ANOVA makes sense.

Checking approximate group equivalence:: A third case is where you are merely checking whether the groups are the same at baseline and that has more to do with how participants were allocated to groups. It doesn't sound like you are talking about this case.

Using manipulation check outcome as covariate: In general, manipulation checks are typically reported prior to conducting main analyses. In this sense, they are a bit like assumption tests. They verify that some experimental manipulation has worked and that you can now proceed to examine the effects of substantive interest. That said, you could do a range of other analyses where the outcome measure in the manipulation check is included in your analysis of the substantive outcome. For example, if you were studying task performance in two groups, one with a positive mood induction and one with a negative mood induction, you could run an ANCOVA where condition was your independent variable, measured mood (i.e., the manipulation check variable) was your covariate, and task performance was your dependent variable.


Terminology for when a person starts to like something they previously didn't like due to exposure from a friend What is the term for when a person starts to like something they previously didn't like due to exposure from a friend? What is the term for such phenomenon in social psychology?

For example, I don't like soccer, but since my friend likes and watches a lot of soccer, I also start to like it.

I think the most obvious match to what you are talking about in terms of social psychology terminology is cognitive dissonance theory. This theory covers a lot of phenomena, but in relation to friendship an attitude formation, it suggests that we will tend to like what our friends like in order to achieve a state of belief consistency.

From a more sociological perspective, you could look into homophily. This is the idea that "birds of a feather flock together". But in addition to people being attracted to those similar to them, there is also a process by which such an effect emerges over time.

In general there many mechanisms that could describe the process of starting to like something because your friends like it.

mere-exposure effect: Merely experiencing something can help you to like something.
Persuasion, learning, etc: In general, a friend may help you to appreciate something. If its sport, they may explain the rules and communicate the finer points of strategy. If its music, the friend may explain the history of the style, the meaning of the lyrics, or the emotional importance of the music.
Positive associations: Spending time with a friend whose company you enjoy will help to create positive associations with other things you do with them.
Social norms: Spending time with your friend may create social norms that the things that they do are normal and appropriate.


Super polymath feasibility: Is it possible to have the highest intellectual ability in every area? Could a single individual have the abilities of Gauss in mathematics, play soccer like Messi, write like Dostoyevsky, play chess like Carlsen, have ideas in physics comparable to those of Einstein, have the talent of Mozart in music, and so on for every area?

Since this have never happened, maybe there are limitations to how talented a person can be, or time limitations for a single individual to develop all of them. What does neuroscience have to say about it?

Note: I got this question from Sigma Society (in Portuguese). I've found nothing more about it, maybe because it's too speculative.

I'm inclined to see it as more a matter of statistics. Since you're asking a question of rank, the possibility depends on the population. For an extreme example, if you were the last man on earth, you'd be your own super polymath by default! Given a population of $N>7\rm B$, competition is of course much fiercer. Since the chance of being #1 in any skill is infinitesimal to begin with, the chance of being #1 in multiple skills is several times more infinitesimal. Granted, these are not independent probabilities; there is evidence of a general factor of intelligence.

Nonetheless, math, soccer, creative writing, chess, physics, and music all involve somewhat different kinds of intelligence; quantitative, kinesthetic, verbal, strategic, spatial, and musical intelligences may all be partially independent. Furthermore, none of these are purely intuitive for anyone. Culture-dependent conventions influence each to at least limited extents. Therefore experience comes into play, and some amount of practice may be necessary to express ability in any of these domains. The more separate domains a person of any innate ability attempts to master through practice is the thinner the person's time for each will be spread, which further reduces one's competitiveness versus specialists.

In issues of rank, sometimes very small practical differences separate the performances of competitors; you need only watch a few minutes of the Olympics to see this principle demonstrated. You may also disagree with scoring systems in the Olympics if you watch a little longer. This indicates another problem with high-level competition: ability measurement becomes less reliable at extremes. See a related question: How can psychometry measure the very high IQ's in adults? Taking this into account, we now face the dual challenge of first producing an incredibly improbable individual with maximally extraordinary abilities, then having identified this individual (itself not a trivial task), performing accurate assessments demonstrating her/his superiority over all others. Again, from a statistical standpoint, odds aren't good.


What is the support for a global personality factor? The Big 5 is a popular framework for describing major factors of individual differences in personality. More recently, I've been hearing people talking about the utility of conceptualising personality in terms of a single factor of personality. The idea might be to map the Big 5 on to one global factor with high conscientiousness, agreeableness, extraversion, and openness combined with low neuroticism.

Questions

How has such a global factor been conceptualised?
How much variance is typically explained by this factor relative to other factor models such as the Big 5 using personality test items?
To what extent  does such a global factor reflect true personality variance versus social desirability bias or an artefact of questionnaire item measurement?
What are the major authors or references advocating the global personality factor?

Digman (1997) performed higher order factor analysis on several Big 5 intercorrelation matrices and proposed that the Big 5 could be partially explained in terms of two higher order factors: Alpha (Agreeableness, Conscientiousness, Emotional Stability) and Beta (Extraversion, Openness).

Musek (2007) presented evidence for a Big 1 factor of personality. Musek and others observe that while the Big 5 factor structure was based on orthogonal rotations, Big 5 scales based on items tend to intercorrelate. With regards to interpretation, Musek states that "[it seems plausible therefore to assume that, beyond the connections with semantic factors and social desirability, The Big One is substantially related to the basic dimensions of emotionality (affect), personal well-being, and self-esteem."

To empirically test the Big 1, Musek presented results from three datasets. Results showed that (a) the first factor of a factor analysis of the Big 5 explained approximately 40 to 50 percent of the variance (b) a reasonable amount of variance in test items was explained by the first factor, (c) several confirmatory factor analytic models indicating reasonable fit for a hierarchical model of the Big 5 that includes the two higher order factors proposed by Digman subsumed under a global personality factor.

van der Linden et al 2010 extend the work of Musek (2007) by presenting a meta-analysis of Big 5 intercorrelation matrices
 in order to assess the evidence for a General Factor of Personality.
Table 2 shows the meta-analytic average scale intercorrelations for the big 5 measures included in the meta-analysis. It shows how across a wide range of measures and measurement procedures, the Big 5 scales moderately intercorrelate. The average absolute unadjusted correlations between the Big Five was 0.23.

They then show how across a range of Big 5 measures, measurement procedures, and samples that a single factor accounts for between 42 and 78 percent of variance in the Big 5 scale scores.

With regards to interpretation the van der Linden et al present various views on what the factor represents including views that see it as a statistical or measurement artefact and views that see it as a meaningful construct. One interpretation is that it is a general goodness of character factor or perhaps a social adjustment factor.
The authors conclude with the following:

  The existence of a higher-order GFP does not invalidate the clinical,
  vocational, or theoretical importance of lower-order factors. It is an
  empirical and practical question as to which level provides the best
  predictor for a given criterion. Since the personality facets that
  exist below the Big Five factors lie closest to the behavior
  expressed, they are often more diagnostic or better predictors than
  higher order traits (Sackett & Lievens, 2008).

Concluding thoughts: It seems that there is a meaningful higher level factor. While it may reflect social desirability, such a characteristic may reflect as much true variance in social desirability as it does a response style. As an aside, I have noticed that in experiments where people are asked to persent themselves in a positive way for a job, the big 5 intercorrelations increase dramatically. In broad terms the global factor of personality also reflects broadly the sign of meta-analytic correlations of Big 5 with job performance (i.e., positive correlations for extraversion, openness, emotional stability, etc.).

I have pondered to what extent measures of the Big 5 are unnecessarily loaded to see various poles as socially desirable. For example, a quick look at this IPIP measure of the Big 5 shows quite clearly how positive aspects of for example introversion are lacking (e.g., the item is "I have little to say" rather than something like "I  enjoy my own company") and negative aspects of extraversion are lacking (e.g., the item is "I am the life of the party" rather than "I like to dominate social situations").

I'd also like to see more item-level analyses and the relative support for the Global personality factor.

Clearly, a lot of detail is lost in the reduction from the Big 5 to the Big 1, but it also seems to reflect a useful summary of personality for some predictive purposes.

References

Digman, J. M. (1997). Higher-order factors of the Big Five. Journal of Personality and Social Psychology, 73, 1246–1256.
Musek, J. (2007). A general factor of personality: Evidence for the Big One in the
Five-Factor Model. Journal of Research in Personality, 41, 1213–1233.
van der Linden, D., te Nijenhuis, J., & Bakker, A. B. (2010). The general factor of personality: A meta-analysis of Big Five intercorrelations and a criterion-related validity study. Journal of Research in Personality, 44(3), 315-327. PDF
Sackett, P. R., & Lievens, F. (2008). Personnel selection. Annual Review of Psychology,
59, 1–32.


Does the scarcity of female programmers, suggest that men are more intelligent than women? Developing software is simultaneously artistic and scientific, which accounts for its appeal for some of the smartest and intuitive people on the planet

There is a generally observable and most likely a statistically provable scarcity of women in the programmer community.

Would it be right to conclude from this that men are generally more intelligent than women? If so, what's the cause of this? And if not, why?

The short answer: No, sex differences in professions is not a good basis for judging the intelligence of males and females.
I would like to address some of the assumptions and misconceptions in the question. First, I would like to deconstruct the question, and then answer it.
Deconstructing the question
One of the earlier titles of the question was "Are men more intelligent than women?". It starts with the observation that there are more males who work in areas related to mathematics and programming, therefore males are more intelligent.
I think this is a common bias in humans. People know a lot about their area of expertise and then judge others by their lack of understanding of what they are experts in. To take a stereotypical example, perhaps a female clinical psychologist, doctor,  or lawyer may wonder why so many males are mathematicians and programmers. She might think that this is because they lack the intelligence to function effectively in domains that require strong interpersonal skills. I am not defending this point of view either. I merely intend to highlight that to judge others by your own standards of what represents intelligence is problematic.
Answering the question
Have a read of page 91 of "Intelligence: Knowns and Unknowns", which represents the position of a large reputable APA task force of leading intelligence researchers. Summarising a huge literature, males tend to perform much better on visual-spatial intelligence test items such as mental rotation and tracking moving objects. Females often perform better on verbal abilities such as synonym generation and verbal fluency. Overall, there is minimal difference in full-scale IQ.
You could also have a read of Hide's (2005) summary of meta-analytic sex differences across a wide range of cognitive tests.

Here, the author advances a very different view, the gender
similarities hypothesis, which holds that males and females are
similar on most, but not all, psychological variables.

However, this only addresses mean differences, and there is certainly much greater differences within sexes than between.
References

Neisser, U., Boodoo, G., Bouchard Jr, T. J., Boykin, A. W., Brody, N., Ceci, S. J., ... & Urbina, S. (1996). Intelligence: Knowns and unknowns. American psychologist, 51(2), 77. PDF
Hyde, J. S. (2005). The gender similarities hypothesis. American psychologist, 60(6), 581. PDF


The psychology of nymphomania So this is a question that requires maturity and discretion.  I present it as an authentic point of research for a class I am taking.  I understand the basic principles of mania, psychomania, and manic episodes.  However one thing that pops into question are possible explanations for nymphomania.  To the scientific community I ask:

Is the condition of nymphomania coupled as a symptom of mania?
Or is it some kind of hormonal/biochemical imbalance that presents itself as it's own issue?
Or is it just some addiction to the hormones released via copulation?

I am not referring to women or men with high sex drive, clearly nymphomania is in it's own class.  I personally have postulated to my class that it is something that is coupled together with mania, or as a symptom of bipolar/mood disorder in patients that are not well controlled on their medications.  My professor then instructed me to post it up here to gather knowledge and present it to my class at some point.  Any thoughts and/or opinions must be clean and professional, any nasty/vulgar language will be reported.

::: It seems like you're trying to get to the root cause as either organic or functional? Maybe a bit of both. They jury will forever be out thus we have the stress-diathesis model for comfort. Here is some interesting discussion on the norm-referencing in assessment of manic behavior such as hypersexuality and the implications of various factors like gender. OOhh - this is a good one too actually- a very large study on the whole range of abnormal sexual activity.

In working with individuals who are hypersexualized, i've found that it's learned, it's reactive attachment gone awry...co-occurring borderline meets cyclic dysthmia.... it's never just hormone or just addiction. I have not looked at extreme cases really, though...


Why some papers suggest that losses and gains are coded by the same mechanism while other suggest that distinct circuits anticipate gain and loss? In this paper, it states that "Consistent with neuroimaging evidence suggesting that distinct circuits anticipate gain and loss,..."
However in this paper, it states "..., these results are consistent with the conclusion that losses and gains are coded by the same mechanism rather than by two separate mechanisms."

Both papers are from reputable journals and well-cited. So why are there these two contradictory statements? Is it because the papers are in different contexts? (The statements themselves seem to be general statement though.)

Because we still don't know exactly how the brain works. That's why we do research. If these authors knew the answer ahead of time, neither of them would have done the study.

These are research papers, they are showing findings that are consistent with different models. Maybe the real model is somewhere in between, maybe there are context-dependencies, maybe one measure was more sensitive than the other for a particular result, maybe statistical thresholds caused one paper to emphasize one circuit and another to emphasize another.

There are other mediating effects like arousal and salience that can bias results; responses may not be linear so the degree of effect may be important.

Brain regions can excite or inhibit other regions and those connections can be reciprocal, so it is often not clear if decreases in one area are causing or caused by increases in another.

There are more recent papers like Bartra et al 2013 (citation below) that have tried to compare these different studies, so that's a good place to start for further reading, but you will find that they still do not have a clear answer.

Bartra, O., McGuire, J. T., & Kable, J. W. (2013). The valuation system: a coordinate-based meta-analysis of BOLD fMRI experiments examining neural correlates of subjective value. Neuroimage, 76, 412-427.


Mental illness developing in midlife There is much research about personality development and childhood. The onset of many mental disorders and illnesses, will occur in early adulthood. Studies are done to link certain childhood personality traits with the manifestation of the illness in adulthood.  Conversely, there is much research into the onset of aged onset dementia, Alzheimer's and the like.

With the exception of the Mid Life Crisis, I have not seen much research on the onset of mental disorders or mental illness in  adults during midlife, or approx. 35-50 years. What studies are there investigating major personality changes later in a person's life?
An example could be the percentage of new diagnoses of "a particular illness" for 35-50 year old age group.

I am not interested in an ongoing illness that was diagnosed as a younger adult and is  still occurring during this age group. I am interested in the  first time onset of an illness in an individual during these years.

I am not a professional, but it is my understanding that it is common for major depression to not show up in adults until the age of 30 to 60 years old; see for example, Table 2 of Lifetime Prevalence and Age-of-Onset Distributions of DSM-IV Disorders in the National Comorbidity Survey Replication, Mood Disorders - Major Depressive Disorder.  Overall, the most likely age group for any disorder to present itself is the years 30-44.

The beginning of the paper states: "Little is known about lifetime prevalence or age of onset of DSM-IV disorders".  The study included 9282 participants.


Innate personality tests: do they exist? If not, why? A personality is developed by innate factors and by the things that happen in your life, but how would your personality be if you either had received the same amount of positive and negative stimuli from those, or if your stimuli from those influences had always been neutral? How would you be?

I'd like to know if tests of innate personality exist, and if not, why not. I think this could be helpful in some psychological treatments. If a person has depression, I think that the treatment should be different if that person has an innate tendency to be depressive, as opposed to if he or she is depressive because a lot of things have made him or her depressive. I think these types of tests would be worth trying to develop, though they might be difficult to do. Thanks for your time.

A useful model for topics like this comes from McCrae and Costa (1999):

There's quite a lot more going on here than is pertinent to your question, but note that influences originate from biological bases on the top left, and from external influences on the upper right. Everything else is modeled as an effect of mediated, dynamic processes between these two...except basic tendencies. McCrae and Costa's theory claims that "basic tendencies" such as the Big Five are in fact those aspects of innate personality you'd probably want to test: truly innate, and separable from external influences. However, McCrae and Costa (2003) themselves had to back off of this claim somewhat and present a more qualified model, so the goal remains elusive by practically all accounts.

Behavioral genetics is making a lot of progress in sorting out what's definitionally innate, but there's a lot of progress left to make. Half of the progress is in discovering the complexities that explain why simpler theories don't work as often as we'd like. Dealing with those complexities is another matter in itself. I agree that tests of genetic factors that influence behavior are very valuable, and far too few at present, but we're definitely working on it.

Another approach that's making a lot of progress on the experiential side is cross-cultural psychology. The story is much the same as with behavioral genetics: our access to the methods for investigating these influences is growing rapidly, hence so are our understandings of both the questions and answers. Ask again in another decade and we'll have much more to tell you than we do right now.

@Ana raises a great point that complicates matters quite a bit: gene-environment interaction. So much of who we're born as determines how we interact with our parents, and whether we choose to be like them or different. Choices of identity thus reflect both our genetic heritage and our environmental interactions. Genetic influences even affect whether we experience given stimuli as positive or negative, and then go on to influence how we choose to react. Over time, it becomes very difficult to separate environmental influences from innate influences, because our choices shape who we are, and our identities become innate in many ways too. Another useful term in this vein of theory is reciprocal determinism, which refers to this sort of bidirectional causality we see between innate and environmental factors in development.

In my limited experience teaching on these topics, I've found some particular examples of reciprocal determinism especially illustrative of both the complexity of the problem and the degree of progress we've made. Two worth offering here are as follows:

Monoamine oxidase A (MAO-A) is sensitive to genetic variation that decreases its concentration in the body. MAO-A deficiency increases stress vulnerability (or diathesis: see another answer of mine for another example of the diathesis-stress model) in terms of the likelihood of aggressive maladaptation (Brunner, Nelen, Breakefield, Ropers, & van Oost, 1993). In children born with the gene that leads to MAO-A deficiency, a stressful environment such as one involving child abuse will be very likely to cause antisocial behavior in those children later in their lives, whereas children without MAO-A deficiencies tend to withstand such stressful environments better (Caspi et al., 2002). Furthermore, aggressive tendencies are much more similar regardless of MAO-A levels when childhood environments aren't so stressful. Thus one could test for the relevant gene to identify an innate vulnerability to aggressive maladaptation, but whether a person with genetic risk would see that risk realized would remain to be determined by the environment.
Genetic variation may also determine the environment at a cultural level to some extent. This is where the worlds of behavioral genetics and cross-cultural psychology play very well together. An example of why we really need tons of research in both and cross-pollination between their respective theories arises in the "A118G single nucleotide polymorphism of the mu-opioid receptor gene (OPRM1)," which, first of all, relates to pain sensitivity (Fillingim et al., 2005). The global cultural relevance emerges clearly in this figure (Way & Lieberman, 2010):

Bear in mind that this is correlational evidence though; hence it's also worth considering whether cultures in these areas could've selected certain alleles like A118G over the course of history. A great many factors powerfully influence cultures besides genes, after all (Diamond, 1998; see for a book review Venkatachalam, 2001).
The 5-HTTLPR gene may relate to innate tendencies toward anxiety, but doesn't seem to relate consistently (Ebstein, 2006). Culture may have something to do with this (Chiao & Blizinsky, 2009):

Top left: collectivism (vs. individualism), from low in yellow to high in red
Top right: frequency of the anxiety-prone allele of 5-HTTLPR
Bottom left and right: prevalence of anxiety and mood disorders, respectively

These maps demonstrate that despite the much higher genetic vulnerability to anxiety in China vs. USA (top right), anxiety and mood disorders appear to have much lower prevalences there than here (speaking as an American myself; see the bottom two maps). Chiao and Blizinsky argue that the higher genetic vulnerability to anxiety in China might've led to a collectivist culture there through a coevolutionary process of cultural adaptation to an ethnically linked genetic predisposition. It's an interesting argument that these innate factors could actually lead to such a strong compensatory shift in culture that the innate influence would be not only dwarfed, but reversed. As to whether that's a falsifiable theory, on the other hand...You'd probably want to read and judge for yourself; I get a little fuzzy on the details here. I suppose I make a decent example of how hard it is to keep up with theoretical advances like these though.

Aside from all that, understanding how personality develops is tricky enough already without trying to separate genetic from environmental factors. There's a rich history of debate on the degree to which stable personalities even exist, and the general consensus now is that they do, but reaching this conclusion took a lot of work (see the person–situation debate), much of which is far from settled in the details. Personality does change over time, but subtly, and with resistance – a useful simile is that personality sets like plaster over time (Srivastava, John, Gosling, & Potter, 2003).

References

- Brunner, H. G., Nelen, M., Breakefield, X. O., Ropers, H. H., & Van Oost, B. A. (1993). Abnormal behavior associated with a point mutation in the structural gene for monoamine oxidase A. Science, 262(5133), 578–580. Retrieved from http://www.bioforensics.com/conference07/DNA_and_behavior/Abnormal_behavior.pdf.
- Caspi, A., McClay, J., Moffitt, T. E., Mill, J., Martin, J., Craig, I. W., Taylor, A., & Poulton, R. (2002). Role of genotype in the cycle of violence in maltreated children. Science, 297(5582), 851–854. Retrieved from http://www.crassh.cam.ac.uk/uploads/documents/Caspi1.pdf.
- Chiao, J. Y., & Blizinsky, K. D. (2010). Culture–gene coevolution of individualism–collectivism and the serotonin transporter gene. Proceedings of the Royal Society B: Biological Sciences, 277(1681), 529–537. Retrieved from http://rspb.royalsocietypublishing.org/content/277/1681/529.full.html.
- Diamond, J. M. (1998). Guns, germs and steel: A short history of everybody for the last 13,000 years. Random House.
- Ebstein, R. P. (2006). The molecular genetic architecture of human personality: beyond self-report questionnaires. Molecular Psychiatry, 11(5): 427–445. Retrieved from www.nature.com/mp/journal/v11/n5/full/4001814a.html.
- Fillingim, R. B., Kaplan, L., Staud, R., Ness, T. J., Glover, T. L., Campbell, C. M., ... & Wallace, M. R. (2005). The A118G single nucleotide polymorphism of the μ-opioid receptor gene (OPRM1) is associated with pressure pain sensitivity in humans. The Journal of Pain, 6(3), 159–167.
- McCrae, R. R., & Costa Jr, P. T. (1999). A five-factor theory of personality. Handbook of Personality: Theory and Research, 2, 139–153.
- McCrae, R. R., & Costa, P. T. (2003). Personality in adulthood: A five-factor theory perspective. Guilford Press.
- Srivastava, S., John, O. P., Gosling, S. D., & Potter, J. (2003). Development of personality in early and middle adulthood: set like plaster or persistent change? Journal of Personality and Social Psychology, 84(5), 1041–1053. Retrieved from http://j.b5z.net/i/u/2043019/i/PersonalityDevelopmentInAdults.pdf.
- Venkatachalam, S. (2001). Guns, germs and steel: A short history of everybody for the last 13,000 years. Resonance, 84–88. Retrieved from http://www.ias.ac.in/resonance/Volumes/06/01/0084-0088.pdf.
- Way, B. M., & Lieberman, M. D. (2010). Is there a genetic contribution to cultural differences? Collectivism, individualism and genetic markers of social sensitivity. Social Cognitive and Affective Neuroscience, 5(2–3), 203–211. Retrieved from http://www.replicatedtypo.com/science/genetic-components-and-cultural-differences-the-social-sensitivity-hypothesis/1620/.


How to calculate IQ score based on raw score and adjust for age? I am having a hard time grasping how IQ scores are calculated. I think it has something to do with their age score ratio multiplied by 100.

Say I have a test that holds 30 questions. How would I generate from that test an IQ score?
Would each question be worth 1 point? Then I would divide by age and multiply by 100?

So if someone got 26 questions correct and they were 18 it would be

26 / 18 = 1.44
1.44 * 100 = 144

Is this the general way of doing things?

I have researched the internet with no definitive answer to this even on wikipedia.

IQ scores in general: An IQ score is a normative score. The norm group is typically defined as the general population, and where the respondent is a child, the norm group is defined in terms of the general population of children of that same age. IQ scores typically have a mean of 100 and a standard deviation of 15.

In order to get an estimate of performance on the test of a norm group, it is necessary to get a sample from that population. Large and unbiased samples from the population are preferred.

Before discussing how to get IQ scores for children, let's focus on adults where there is no age adjustment. Assume we get a sample of 1,000 adult participants that is hopefully representative of a given adult population and we administer the intelligence test to the participants. We score the test and we then get a set of raw test scores. The most common scoring system is one point per correct question, but many other systems are possible including penalising for incorrect answers, weighting some questions more than others, and so on. Once you have raw scores, there are now several options for creating a norm table that converts raw scores into IQ scores. The simplest approach is to get the raw mean and standard deviation, convert to z-scores, and then convert to IQ units:

$$\begin{array}{c} {z_i}{\rm{ \;=\; }}\frac{{{\rm{x}}_i}{\rm{ \;-\; }}{{\rm{MEAN}}}}{{\rm{SD}}}\\ {\rm{IQ}_i}{\rm{ \;= 100 }} +{\rm{ }}{z_i}{} \times {\rm{ 15}} \end{array}$$

Where MEAN is the mean of the normative sample, SD is the SD of the normative sample, $x_i$ is the the score of respondent $i$, $z_i$ is respondent $i$'s z-score, and $\rm{IQ}_i$ is participant $i$'s IQ score.

Angoff (1984, the text is available online for free from ETS) calls this the linear transformation (standard scores) approach. There are more advanced methods which you can read about in Angoff (1984) such as percentile-derived linear scale, percentile rank scale, normalised scale.

Age adjustments: Angoff (1984) also discusses how to construct age equivalent norms.

In summary, if you want to get IQ scores for children, then your aim is to estimate the distribution of raw test scores in the general population for each age group of interest. There are various ways of doing this. The simplest approach is to get large samples of children at each year age of interest, and get means and standard deviations, and use them as above as appropriate. A more sophisticated approach involves smoothing the data to get an estimate of the systematic changes in both the mean and the standard deviation with age. Such a smoothed model can also be applied to get more fine grained estimates of a child who is say not exactly 10 years old, but rather 10 years and 5 months. There are many variations on this approach, and there are many issues to consider regarding the applicability of the same intelligence test to adults and children, especially as you get towards early childhood.

See also this earlier question about Raven's Matrices and age adjusted norms.

References

Angoff, W. (1984). Scales, norms, and equivalent scores. Educational Measurement: Origins, Theories, and Explications, 2, 121. PDF


Is there a place where I can find inconsistent images? I would like to find some images in which there are logical inconsistencies. I want to use them for practicing my attention towards those kinds of logical errors (so that I could more easily spot them in my dreams, I am not sure if this works, but I just want to test.). I remember back in the high school someone showed me a picture where one is supposed to find such logical inconsistencies and picture included shadows facing wrong directions, things affected by winds in different directions etc.

The University of Adelaide has a lot of information concerning inconsistent images:

http://www.hss.adelaide.edu.au/philosophy/inconsistent-images/

There are also a few of those on this page:

http://www.hss.adelaide.edu.au/philosophy/inconsistent-images/galleries/#sl


cleanIAT function in R IAT package Has anyone used cleanIAT (function in IAT package) to compute D-scores for their IAT data? Have you noticed any discrepancies between your D-scores and those of colleagues that used another program (e.g., SPSS) to clean the same data? Can anyone describe each column in cleanIAT s output?

While the manual says:

  "Outputs a dataframe that must be saved to an object. The variable IAT is the
  calculated D-Score for each individual. SUBEXCL notes any exclusion
  criteria, with 0 being inclusion data, 1 for exclusion due to fast
  response, and 2 for exclusion due to missing blocks. C indicates
  standard deviation for combined blocks (correct trial only), while A
  indicates standard deviations for combined blocks (all trials). M
  (mean), E (percent error), N (number of trials used), and F (percent
  fast responses), are reported for each block included in the original
  dataframe."

There are a number of columns that are in the output that aren't explained in the documentation. For example, there are three IAT scores (3 D-scores?). And there are 2 S scores and 2 C scores.

I'd like to start an ongoing discussion about this because the package isn't mentioned at all in forums and "cleanIAT" gives zero results in Google Scholar.

So I'm the author of the IAT package in R. It's based on the original scoring algorithm outlined in this publication. Because the scoring algorithm is based on a standard 7-block IAT, the score IAT1 corresponds to the D score relative to the difference between blocks 6 and 3, while IAT2 corresponds to the D score relative to blocks 7 and 4. IAT is then simply the mean of IAT1 and IAT2, and represents the overall D-score of the test. In a simple applied example, you might use this variable as the outcome in a simple t-test to see if there is an effect of some treatment group versus a control group.

One thing to keep in mind when using the IATData loaded with the package is that there are order effects due to randomization of whether participants received stereotype congruent sorting first or stereotype incongruent sorting first. Thus, the D score needs to be calculated separately between these two groups, otherwise the D score would be flipped for half of the participants (see the example in ?cleanIAT to see what I mean).

As for discrepancies, I never tested against SPSS code, but it was designed to replicate the SAS macro used by the Nosek lab exactly.

Finally, a faster version using dplyr is available for download off of my github if you're interested:

library(devtools)
install_github("dpmartin42/IAT")


Can repetitive sports-related head injuries make a person senile many years later? Would repetitive football injuries to the cranium show up decades later, causing symptoms resembling mild retardation, OCD, etc.? What is the best way to determine this in terms of imaging, testing, etc.?

yes, here is a nice paper which shows evidence : http://www.nature.com/srep/2013/131017/srep02972/full/srep02972.html

from the paper :
" a report commissioned by the National Football League (NFL), showed that retired players between the ages of 30–49 were 20 times more likely, at a rate of 1.9%, to receive a diagnosis of dementia, Alzheimer's disease (AD), or other memory-related impairments11. Over the age of 50, the proportion diagnosed with one of the above rose to 6.1%, compared with only 1.2% In the general population11. Overall, neurodegenerative mortality of NFL alumni is 3 times greater than that of the general population, with AD and amyotrophic lateral sclerosis (ALS) estimated at 4 times as high '


How effective is cognitive behavioral therapy for anxiety disorders? How effective have cognitive behavioral therapy type techniques been shown and proven to work for anxiety based on published literature?

Citations please.

Meta-analyses are usually pretty accurate, as they essentially bring together the data from many studies that investigate the same topic of interest together and use statistical methods to effectively get the most conclusive answer possible, throughout all of the studies assessed, just HOW effective is a certain treatment?

For your specific question, there's one in particular that strongly supports CBT for anxiety.  It looks at 71 different studies (that's a ton).  It also investigates it's effectiveness in a variety of different environments and versions of it's therapy.
 It was even published only last month.

  Clin Psychol Rev. 2013 Jul 20;33(8):954-964. doi:
  10.1016/j.cpr.2013.07.003.

  A meta-analysis of nonrandomized effectiveness studies on outpatient cognitive behavioral
  therapy for adult anxiety disorders. Hans E, Hiller W. Source
  Department of Clinical Psychology, Johannes Gutenberg University
  Mainz, Germany. Electronic address: hans@uni-mainz.de. Abstract
  OBJECTIVE: The primary aim of this study was to assess the overall
  effectiveness of individual and group outpatient cognitive behavioral
  therapy (CBT) for adults with a primary anxiety disorder in routine
  clinical practice. METHOD: We conducted a random effects meta-analysis
  of 71 nonrandomized effectiveness studies on outpatient individual and
  group CBT for adult anxiety disorders. Standardized mean gain effect
  sizes pre- to posttreatment, and posttreatment to follow-up are
  reported for disorder-specific symptoms, depression, and general
  anxiety. The mean dropout from CBT is reported. RESULTS: Outpatient
  CBT was effective in reducing disorder-specific symptoms in completer
  (d=0.90-1.91) and intention-to-treat samples (d=0.67-1.45). Moderate
  to large (d=0.54-1.09) and small to large effect sizes (d=0.42-0.97)
  were found for depressive and general anxiety symptoms posttreatment.
  Across all anxiety disorders, the weighted mean dropout rate was
  15.06%. Posttreatment gains for disorder-specific anxiety were maintained 12months after completion of therapy. CONCLUSIONS: ****CBT for
  adult anxiety disorders is very effective and widely accepted in
  routine practice settings.**** However, the methodological and reporting
  quality of nonrandomized effectiveness studies must be improved. ©
  2013.

Across 71 studies, the conclusion used the word "very effective," which is very rare to see in any study in the conclusions section, especially a meta-analysis,  the weighted mean dropout rate across all different types of its application was only 15.06%, AND gains were generally maintained for 12 months (maybe more, I don't have full text) after beginning therapy.

The only caveat they mention is that the methodology and reporting quality must be improved, but I feel that's a general trait that almost all studies need improvement in.
Plus when you investigate SEVENTY-ONE (71) studies, statistical laws start to take over anyway.

Based on this, I'd have to say that there is very, very strong evidence that Cognitive Behavioral Therapy is an effective treatment for anxiety disorders.

In my opinion, and as an analogy, it's almost just as if not more proven than using aspirin or acetaminophen to relieve a simple headache.  It just works according to the literature, which, if you have that many studies then "routine clinical analysis" really does become reality.  More and more clinical psychologists are switching over to this method or attempting to make some sort of derivative of it.


Cognitive Effects of studying for the LSAT? Is this study/article scientifically valid.

http://news.berkeley.edu/2012/08/22/intense-prep-for-law-school-admissions-test-alters-brain-structure/

The study you refer to shows that a measure of brain white matter connectivity, called diffusion tensor imaging (DTI) shows increases in structural connectivity between brain areas that have been previously implicated in reasoning and other brain functions.

The news article goes on to make additional claims, not made in the paper, that this result means studying for the LSAT improves reasoning overall. The study itself does not make that claim, and they did not test reasoning besides measuring LSAT performance. Therefore, you cannot conclude from this work that studying for the LSAT improves performance on anything besides the LSAT, only that studying is sufficient to make detectable changes in brain structure.

I would certainly say it is plausible that studying one set of tasks, like studying for the LSAT, would cause improvement in related skills (certainly this assumption is the basis of a whole lot of pedagogy), but that certainly doesn't mean it is the best way to improve or that it is special compared to other types of study.

Note also that the participants in the study were involved in a particular training program and the results may not generalize to other forms of LSAT preparation.

As a side note, it is always important to read original research articles before taking news at face value. Even the researchers quoted in a news article may not approve of how exactly they were quoted. The news process is subject to sensationalization and the qualifying language that scientists frequently use may not reach the final edits.

Mackey, A. P., Whitaker, K. J., & Bunge, S. A. (2012). Experience-dependent plasticity in white matter microstructure: reasoning training alters structural connectivity. Frontiers in neuroanatomy, 6, 32.


Can we change a particular addiction into another addiction? My current knowledge about dopamine and serotonin came from a series of articles and web pages, a few videos also.

As per my knowledge and readings I know that addiction is about reward, a person’s brain releases a chemical called dopamine when a person do addictive task and hence he feels momentarily good. But doing too much of it damages the receptors and hence the person cannot feel happy anymore by doing that addictive act but he keeps on doing it in hope of that reward.

Now, if we treat that person so that his receptors gets healed a little and then we start giving him some medicine which releases dopamine in right amount and hence converting that person’s addition from that previous addictive task to the medicines ( well I believe this is what psychiatrist actually do, because a person who goes to a psychiatrist always ends up taking medicines whole of his life) . If it’s all about feeling good and the release of dopamine then it seems completely logical to treat it by medicines and some self control. Then, my question, finally, is Is it possible to cure addiction by converting it into another addiction?

I talked to some professionals and they said that it’s not wise to substitute a behavioural addiction with a substance addiction, but I cannot see any difference because both of these have same effect on the brain i.e. release of a chemical.

I know that there lies many many minute and significant details which I have failed to look over but I expect that the researchers, well educated and even self-learner’s will get the gist of what I have said.

Thank you.

Intro and Bill
For this answer, I am going to refer to a fictional person named Bill.  You can skip to the next header if you wish, but here is a brief rundown on Bill.
Bill has always been a gambler.  He started when his older brother used to sneak him into the pub to play on the fruit machines.  Now, 15 years on, he has progressed from machines to horses, and over the last few years, to online betting.
Bill had a good job in the city, but was made redundant 6 months ago due to cutbacks.  He was not too worried about finding more work in a hurry, as he had some savings.  Now, those are gone, and his online betting has increased so much that this month he was unable to make the mortgage payment.  That is when his wife discovered that the joint credit card was up to its limit and that there was no money left at all.
Bill loves his wife and winces when he describes the day she found out, and how frightened for the future and how betrayed she was.  He desperately needs to pay back the money he owes her and some money he now owes to friends.  He just cannot see how, unless he can get that one big win.  Bill describes how he can study form and then will just ‘know’ that he has a winner.  As soon as that happens, the feeling of anticipation and excitement just grows, and the feeling is better than almost anything in the world.  Yes of course he must stop gambling, but never having that feeling again is going to be hard.
Important - Addiction as opposed to Habit
Addiction issues likely to arise are wide and varied.  There are 2 types of addiction — Substance Addictions, and Process Addictions (Alavi, et al. 2012); and they can be anything from Risk Taking (“Adrenaline Junkie”) behaviours, Alcohol, Drugs or Food Addictions to Work, Shopping or Travel Addictions.
Although the demarcation can be blurry (Eddy, 1957) The difference between addictions and habits are that habits are generally unconscious actions and they do not take over your life.  Addictions on the other hand are generally conscious actions which affects the person and their family with the fact that the person has become reliant on the actions to “live their life” (Byrd, 2016).
Addictions can impact the person’s wheel of wellness [self-care] (Crowell, 1998; Myers, et al. 2011; Myers & Sweeney, 2005) and there can be severe emotional and/or other psychological disturbances if the actions are not followed.
Addictions can start in many different ways.  Addictions, or Self-Defeating Behaviours, operate within the following 3-step cycle.

Usually, but not every time, it starts with something which the person has found deeply uncomfortable in an emotional sense which leads to the feeling of need to relieve the discomfort.
This then leads to avoidance, distraction or escape from the emotional pain, in this case through the addictive behaviour, and
the addictive behaviour then leads to guilt for having done it, which is another uncomfortable (negative) feeling or emotion to add to the list from the start, and the process continues from the beginning (at number 1) again.

In the case of drug or alcohol abuse without an initial deeply uncomfortable emotional feeling, it could start with a heavy night of use which creates an elevated sense of feeling.  This can lead to feelings of guilt and other negative feelings, and so the cycle continues from there.
Alternatively, the seeking to regain those feelings in “that next high” can lead to feelings of inadequacy and/or despair which then takes you onto the negative feelings part of the cycle.
Can we change a particular addiction into another addiction?
Prolonged use of certain alcoholic drinks or certain drugs can lead to a situation where it would take so much more of the substance to get the “high” that you may then seek alternative (stronger) substances (Skinner & Allen, 1982).  With alcohol for example, you may move from beer to spirits.  With process addictions, it could lead to substance habit(s) followed by addiction.
Counselling such as Cognitive Behaviour Therapy may be used to challenge certain stages of the cycle of Self-Defeating Behaviours and therefore break that cycle and put an end to it.
If we apply what I have said so far to Risk Taking as an addiction, it can be classed as a substance addiction as it involves the elevation of adrenaline in the body, or it can be classed as a process addiction as it involves taking risks.  However, if you take Bill as an example, you can deduce that the addiction is a process addiction as it doesn’t involve intoxication from a substance related addiction per se, however, at certain times, there can be adrenaline involved and at some other times there can be other feel good hormones involved such as dopamine and serotonin.
How does this apply to Bill?
If we apply what I have said so far to Risk Taking as an addiction, it can be classed as a substance addiction as it involves the elevation of adrenaline in the body, or it can be classed as a process addiction as it involves taking risks.  However, if you take Bill as an example, you can deduce that the addiction is a process addiction as it doesn’t involve intoxication from a substance related addiction per se, however, at certain times, there can be adrenaline involved and at some other times there can be other feel good hormones involved such as dopamine and serotonin.
To summarise what Bill’s problem is, he has a gambling addiction which seems to have started 15 years ago.  His wife discovered the problem once she saw that their joint credit card is maxed out.
At the height of the chase to gain winnings, adrenaline will be rushing through his body giving feelings of excitement, and when there are wins, dopamine will affect the reward centres of his brain whilst serotonin provides some relaxation counteracting the adrenaline.
Bill sees himself as always been a gambler and it started with his brother taking him to the pub to play on fruit machines.  Now he is gambling through online betting.  Looking at Bill’s history, the problem has escalated through the years and he is at the point where he needs help to stop.
How long that takes will be down to the hard work Bill is prepared to undertake, and it is generally believed that it takes around 21 days to stop a habit — just as it does to start one — although it is not necessarily that clear cut (Lally, et al., 2010).
The problem has been exacerbated by a combination of:

the increase of access to gambling through online gambling sites,
the fact that he was made redundant 6 months ago, and
he wished to become a “professional gambler” to profit from his savings.

How could we help Bill?
First, we need to get Bill to examine why he looked for help.  He said that having that feeling of anticipation and excitement is better than almost anything in the world and never having it again is going to be hard.
Bill winces when he describes the day his wife found out.  Has he only come due to the fact that he was caught with the problem and needs to pay his friends and credit card back?  If that is the case, once he has paid them back, will he go back to his old habits?
Bill’s Goal
Once he has done this, the last part of the combination of problems which exacerbate things (the wish to be a professional gambler) will make things a little more difficult to start with, and therefore this would need to be looked at first as it will affect his ability to look at what is known as self-exclusion schemes. (GambleAware, n.d.(a))
What does it mean to be a professional gambler?  What about the problem of “House Edge” (GambleAware, n.d.(b))
References
Alavi, S. S., Ferdosi, M., Jannatifard, F., Eslami, M., Alaghemandan, H., & Setare, M. (2012). Behavioral Addiction versus Substance Addiction: Correspondence of Psychiatric and Psychological Views. International journal of preventive medicine, 3(4), 290–294. pmcid: PMC3354400
Byrd, N. (2016). Addiction vs. Habit: Recognizing the dangers. Retrieved from: https://byrdnick.com/archives/9951/addiction-vs-habit-infographic
Crowell, D. M. (1998). Care for the case manager: balancing your wheel of life. Journal of case management, 7(3), 112-116. PMID: 10703376
Eddy, N. B. (1957). Addiction-producing versus habit-forming: Guest Editorial. Journal of the American Medical Association, 163(17), 1622-1623. doi: 10.1001/jama.1957.02970520056015
GambleAware, n.d.(a). Self-Exclusion. Retrieved from: https://www.begambleaware.org/stay-in-control/what-is-self-exclusion/
GambleAware, n.d.(b). Gambling Words and Phrases Explained. Retrieved from: https://www.begambleaware.org/understanding-gambling/gambling-words-and-phrases-explained/
Lally, P., van Jaarsveld, C. H. M., Potts, H. W. W. & Wardle, J. (2010). How are habits formed: Modelling habit formation in the real world. European Journal of Social Psychology, 40(6), p. 998—1009. doi: 10.1002/ejsp.674
Myers, J. E., & Sweeney, T. J. (2005). The indivisible self: An evidence-based model of wellness. Journal of Individual Psychology, 61(3), 234-244. Free PDF: https://libres.uncg.edu/ir/uncg/f/J_Myers_Indivisible_2004.pdf
Myers, J. E., Sweeney, T. J., & Witmer, J. M. (2011). The wheel of wellness counseling for wellness: A holistic model for treatment planning. Journal of Counseling & Development, 78(3), 251-266. doi: j.1556-6676.2000.tb01906.x
Skinner, H. A., & Allen, B. A. (1982). Alcohol dependence syndrome: Measurement and validation. Journal of Abnormal Psychology, 91(3), 199–209. doi: 10.1037/0021-843X.91.3.199


Synchronization of perception of sensory information I am not an expert (actually I am not even psychologist/neuroscientist or anything like it).My question is:

Since light and sound comes to, respectively, our eyes and ears at different times and "visual input" and "sound input" take different times to be processed (and as far as I know, even some traits of vision - like color, motion, shape - take different time to be processed), how does our brain gives rise to the counscious experience of simultaneity (in the case of actual simultaneity, of course)?

How do we experience this synchronization of stimulus (which, of course, can include others senses, like touch and proprioception)? What would be a time line of that? Because it makes a bit confuse. Aren't we experiencing reality in real time (except for the fact that stimulus take time to get to our senses)?

Short answer
The brain actively integrates and synchronizes sensory inputs, up to the point that it actually delays one modality to match it with another.

Background
Your question is all about intersensory asynchrony and sensory integration.

A well-known example where the two stimulus modalities you mention in your question (light and sound) are perceived as separate, while they are in fact coming from the same event, is a thunder heard after lightning. This is caused by the fact that sound travels at a speed much slower than light, and hence a thunder can lag lightning by seconds (Fig. 1).

source: NASA

In many instances, however, a multimodal perception is actually perceived as being synchronous, while they are in fact offset in time due to differences in physical characteristics of the stimuli. Take the storm as an example - when it is far away, the thunder is perceptually dissociated from the lightning, because the sound lags the light by seconds. But when the thunderstorm is close enough, the auditory crack and visual lightning are perceived as synchronous, while in fact they are still offset because of the sound travelling so much slower than light.

So why does the brain sync perceptions into 1 event, and sometimes not? This has to do with the window of integration. Vroomen and Keetels (2010) conclude in their review on this topic that a stimulus asynchrony in the case of auditory beeps and visual flashes can be between 25 and 50 ms and still be perceived as coming from the same event.

The window of integration between more complex stimuli can be much greater. For example, the window for speech and visual information can be as large as 203 ms. Such large windows of integration point toward higher processes playing a role in the brain. Only temporal lags below 20 msec are expected to go unnoticed because of hard-wired limitations on the resolution power of the individual senses.

Hence, Vroomen and Keetels (2010) argue there must be higher processes at work in the brain that actively synchronize percepts that are offset in time, but seem to belong to one and the same event. One such mechanism is referred to as temporal ventriloquism, which means that a perceptual modality is actively shifted in time to match it with another modality. This effect is most pronounced in visual stimuli. Visual perceptions are in fact actively adjusted in time to match a sound or tactile stimulus. Likely visual percepts are shifted preferably by the brain, because the visual system is the slowest of all the senses.

Reference
Vroomen & Keetels, Att Percept Psychophys 2010; 72(4): 871-84


Are there peer-reviewed psychology or neuroscience journal articles that include the raw data (data set)? I am hoping to carry out a pedagogical analysis of some peer reviewed papers, preferably on topics in cognitive science.

This would be easier with the raw data its self, in additional to the results section of the paper.

Check out Psychological Science articles with the "Open Data Badge".  There's also the Journal of Open Psychology Data.


What does hemispatial neglect vision look like? I need to know more about hemispatial neglect, in order to compose a picture of what it would look like to someone who has this issue.

Is there any resources for finding more about their actual vision?  I have seen the very popular picture on the internet of a patient who has the illness, and then draws a clock and a house:

But, I am trying to compose a real world image, as a person who has this illness, and I feel like just leaving half of the page empty is incorrect.  I would think that they would see a full picture, it would just not include the left hand side.

I think this is an interesting, but difficult question to answer.

Hemispatial neglect patients do not typically have problem with visual pathways per se. Wikipedia suggests that the disorder is most closely linked to damage of the temporo-parietal junction and posterior parietal cortex, areas associated with attention. Thus, the sensation (e.g. on the retina, and in early visual pathways) should be similar in patients and non-patients.

Let me make an analogy to the inattentional blindness literature. You may have seen a famous video by Daniel Simons and Christopher Charis. If you haven't, go watch it now before continuing... (I'll wait.)

Now how would you paint a picture of how that video 'looks' to someone? Does that picture include a gorilla? It seems even normal perception has blindspots. In fact, much of our perception is not strictly bottom-up, but is a mixture between bottom-up and top-down processes.

I would argue comparing a hemispatial neglect patient to a control is (very loosely) like comparing someone watching the inattentional blindness video for the first time to someone who has seen it before.

One might argue that hemispatial neglect patients do not 'see' things any differently than us, only that they 'perceive' it differently. So you could possibly create a caricature of how these patients 'see' the world, but it would be just that: a caricature.

One thing for certain is that hemispatial neglect patients do not 'perceive' that half of their visual field is missing (e.g. leaving half the page blank). When prompted, these patients typically do not report that anything is out of the ordinary.

All that being said, this is not my area of expertise, so please feel free to post a better answer if you think this analogy is misleading...


Can one reasonably guess the gender of a person from their writing/speech contents? Is it possible to reasonably guess the gender of a person from a random sample of their writing (text, not handwriting)?

How about from the contents of their speech (not including their voice, of course)?

While you are probably better to ask your question over at the AI Stack Exchange for more practical answers on how to accomplish the task, I would also suggest you could take a look into the topics on Wikipedia for Sociolinguistics, and also Language and gender for the underlying theories as to why Machine learning models are able to make guesses/predictions with upwards of 80% accuracy in trained models such as the following.

Machine Learning Models of Text Categorization by Author Gender Using Topic-independent Features (86% accuracy - Russian corpus)
Investigating the Role of Emotion-Based Features in Author Gender Classification of Text (80% accuracy)
Gender Attribution: Tracing Stylometric Evidence Beyond Topic and Genre (85% accuracy)

So to fully answer your question

  Can one reasonably guess the gender of a person from their writing/speech contents?

What is a 'reasonable guess' is not something I can define and is something you would wan't to think seriously about before using the predictions for anything of import to those you are labelling! However it would seem you can make a significantly better than random guess.


Is there a technical term for someone being burnt out on something they enjoy? What I mean is like how one might tire of a typical everyday activity they enjoy if they indulge in it too much, like how if you listen to your favorite album too many times you eventually won't be able to enjoy it anymore. I guess this would also be analogous to how addicts develop a tolerance to their drug of choice.

I figure it is an interesting phenomenon that must have a very large affect on our behavior patterns so there must be a technical term for it. I wanted to know so I can look into any research there has been on it.

There is no specific term for this entire phenomenon because there is more than one psychological theory playing a role in your overindulgence or "binge". Fatigue from repetitiveness, durability bias, and habituation all play a huge role in determining how long you can listen to a certain song before its gets repetitive and boring.
On the other hand, tolerance from substance abuse has its own special term: Drug Habituation.
You would be best off searching scholarly journals using the keywords fatigue and habituation.

Further Reading:

https://en.wikipedia.org/wiki/Habituation
http://changingminds.org/explanations/theories/durability_bias.htm


Will some people ever be able to make our dreams visible on a screen? There are many SF-films in which dreams of people can be seen by others on a TV-screen. Don't you have to put so many information gathering devices in a person's brain for this to accomplish, that dream can't enter your brain anymore?

As @AaronWeinberg stated in the comments, just like many other technologies within Science Fiction, the Science Fiction of viewing dreams on screen has started to become Science Fact.

Rebecca Morelle, a science reporter for the BBC World Service wrote an article about researchers in Japan who used MRI scans to reveal the images that people were seeing as they entered into an early stage of sleep.

From the articles I have seen, it looks like the research has been led by Professor Yukiyasu Kamitani, from the ATR Computational Neuroscience Laboratories, in Kyoto.  It seems that the research started in 2005 with an article titled Decoding the visual and subjective contents of the human brain (Kamitani & Tong, 2005) followed by the article Neural Code Converter for Visual Image Representation (Yamada, et al. 2011), follwed then by Decoding visual experience from the human brain (Kamitani, 2012) and then the source of the first linked article Neural Decoding of Visual Imagery During Sleep (Horikawa, et al. 2013)

The results of the first study within the 2005 article demonstrated that

  fMRI activity patterns in early visual areas, including primary visual cortex (V1), contain detailed orientation information that can reliably predict subjective perception.

The 2011 article says

  [T]he neural code converter may provide a basis for brain-to-brain communication of visual images.

The 2012 article says

  Despite the wide-spread use of human neuroimaging, its potential to read out, or "decode", mental contents from brain activity has not been fully explored. In this talk, I present methods for decoding visual representations from fMRI activity patterns based on machine learning techniques.

and the final article in 2013 says

  Our findings demonstrate that specific visual experience during sleep is represented by brain activity patterns shared by stimulus perception, providing a means to uncover subjective contents of dreaming using objective neural measurement.

References

Horikawa, T., et al. (2013) Neural Decoding of Visual Imagery During Sleep. Science 340(6132): pp. 639—642DOI: 10.1126/science.1234330

Kamitani, Y. & Tong, F. (2005) Decoding the visual and subjective contents of the human brain. Nature Neuroscience 8(5): pp. 679—685
DOI: 10.1038/nn1444

Kamitani, Y. (2012) Decoding visual experience from the human brain. Proceeding MM '12 (Proceedings of the 20th ACM international conference on Multimedia). New York:Association for Computing Machinery pp. 5—6 DOI: 10.1145/2393347.2393353

Yamada, K., et al. (2011) Neural Code Converter for Visual Image Representation. 2011 International Workshop on Pattern Recognition in NeuroImaging: pp. 37—40DOI: 10.1109/PRNI.2011.13


Do non-human primates exhibit the Kiki/Bouba effect? After understanding that cats cannot experience the Kiki/Bouba effect, I wonder if smart non-human primates can experience it. There is evidence suggesting that Chimpanzees associate high pitch with high luminance, and low pitch with low luminance.. However, the kiki/bouba effect is a more complicated phenomenon.

So do chimps experience it, even at a lower level, or is the Kiki/Bouba effect limited to human beings only?

Short answer
As far as I can see, testing the existence of the kiki/bouba effect in primates is technically impossible, because of their lack of speech and/or potential bias due to training effects inherently necessary for animal behavioral experiments.

Background
The reasoning in that other question was basically as follows:

  Cats [read: non-human animals] don't have that kind of repertoire of phonemes. So regardless the > similarity in some brain areas [of animals other than modern day humans], I dare to say a bouba/kiki or
  baluba/takete effect can never be found in cats [or any other non-human animals].

Hence - along those lines the answer to your question is 'no', as the bouba/kiki effect can simply not be tested in its current form in non-human animals, because the latter are not capable of uttering the words bouba or kiki. An interesting note on this are parrots and related species that are capable of reproducing human speech. However, they simply imitate the sounds, just like other species of birds imitate the sounds of ringtones and the likes. That, however, does not mean they associate those words or sounds with the meaning they have to us.

Further, as suggested in that previous answer; synesthesia and cross-modal associations can certainly not be ruled out by any means.

An interesting side track on your question would be the question wether there are cross-cultural differences within the human species. For example, folks speaking languages unrelated to Western languages, like the tonal language Chinese Mandarin, may produce a different outcome in the same bouba/kiki test.

The comment from ArnonWeinberg is an interesting one - why not train an animal to point at one of the two graphs when hearing bouba or kiki? Well, the issue here is that the animal needs training; the trick with the bouba/kiki effect is that naive people assign the same pointy structure to the work kiki and the blobby image to bouba. If one would train an animal the trainer needs to reward (or punish) the animal when it responds in a satisfactory way. That means the experimenter's influence on the animal's response will be paramount for the outcome of the experiment. In turn, a trained animal will respond the way it was taught, which is not the intention of this experiment.


What is the optimal contrast ratio for best readability? I have asked the same question half a year ago on Graphic Design but received no useful answer.

According to the W3C (and another question on this site), the contrast ratio between body text and text background should be at least 7:1 for good legibility. Google takes this up in their typography guidelines, but they also maintain that

  Text with too much contrast can also be hard to read.

Unfortunately, they don't state what "too much contrast" exactly is, and I was unable to find anything definite on the web.

What is the optimal contrast ratio for best readability – that is, neither too little nor too much contrast – for subjects with normal vision ?

Short answer
Higher contrast increases readability.

Background
In a series of papers under the umbrella "Psychophysics of Reading" (link is to first paper in the series of five) the authors investigate parameters that affect readability in normally sighted folks, as well as people with impaired vision. These studies seem particularly relevant to your question.

The authors investigated reading rates as an outcome measure for readability. In paper V of the series (Legge et al., 2007) they tested the dependence of letter size and contrast (black-and-white) on reading rate. Rates were highest (about 350 words/min) for letters ranging in size from 0.25° to 2° visual angle. Within this range, reading rates proved to be tolerant to contrast reduction. For 1° letters, reading rate decreased by less than a factor of two for a tenfold reduction in contrast. The results were very similar for white-on-black and black-on-white text. Reading rate declined more rapidly for very small (<0.25°) and very large (>2°) letters with lower contrast.

Based on these findings, the intuitive answer to your question is, the larger the contrast, the better. I've never heard of decreasing contrast enhancing reading abilities, barred under some very specific conditions of ultra-low vision, regardless of Google's statements on this. Your first reference clearly supports 'higher contrast is better', without the presence of a sort of optimum.

Reference
- Legge et al, Vis Res (1985); 25(2): 239–52