question: Why after putting my hand under hot water do I flinch first and then feel the pain seconds later?
comment: Flinching is a natural instinct to avoid touching the hot thing first. It bypasses the conscious part of your brain and the part responsible for the actual "feeling" of the pain to keep your hand safe. You feel it a bit later when the rest of your brain catches up.
passages: The hunting reaction is one out of four possible responses to immersion of the finger in cold water. The other responses observed in the fingers after immersion in cold water are a continuous state of vasoconstriction, slow steady and continuous rewarming and a proportional control form in which the blood vessel diameter remains constant after an initial phase of vasoconstriction. However, the vast majority of the vascular responses to immersion of the finger in cold water can be classified as the hunting reaction.
   Many illusions in vision are caused by adaptation, the prolonged exposure to a previous stimulus. In such cases, the perception of a subsequent stimulus is altered. This phenomenon is sometimes referred to as a contingent after-effect. Similarly, adaptation can cause such illusions in the sense of touch.
  
  BULLET::::- If one hand is immersed in cold water and the other in hot for a minute or so, and then both hands are placed in lukewarm water, the lukewarm water will feel hot to the hand previously immersed in cold water, and cold to the hand previously immersed in hot water.
   The physiological response of surprise falls under the category of the startle response. The main function of surprise or the startle response is to interrupt an ongoing action and reorient attention to a new, possibly significant event. There is an automatic redirection of focus to the new stimuli and, for a brief moment, this causes tenseness in the muscles, especially the neck muscles. Studies show that this response happens extremely fast, with information (in this case a loud noise) reaching the pons within 3 to 8 ms and the full startle reflex occurring in less than two tenths of a second.
   The unprotected human body responds to cold water immersion in a progression from a stress situation to hypothermia and death, at a rate depending on time and water temperature. Hypothermia is not the major problem in the early stages of exposure as other stresses are more immediately life-threatening.
   First, nociception is required. This is the ability to detect noxious stimuli which evoke a reflex response that rapidly moves the entire animal, or the affected part of its body, away from the source of the stimulus. The concept of nociception does not imply any adverse, subjective "feeling" – it is a reflex action. An example would be the rapid withdrawal of a finger that has touched something hot – the withdrawal occurs before any sensation of pain is actually experienced.
   Cold shock response
  
  Cold shock response is the physiological response of organisms to sudden cold, especially cold water.
   Section::::Research findings.:Peripheral nervous system.
  
  Section::::Research findings.:Peripheral nervous system.:Receptors.
  
  Crayfish ("Procambarus clarkii") respond quickly and strongly to high temperatures, however, they show no response to low temperature stimuli, or, when stimulated with capsaicin or isothiocyanate (both are irritants to mammals). Noxious high temperatures are considered to be a potentially ecologically relevant noxious stimulus for crayfish that can be detected by sensory neurons, which may be specialized nociceptors.
   Scalding is a serious concern with any water heater. Human skin burns quickly at high temperature, in less than 5 seconds at , but much slower at — it takes a full minute for a second degree burn. Older people and children often receive serious scalds due to disabilities or slow reaction times. In the United States and elsewhere it is common practice to put a tempering valve on the outlet of the water heater. The result of mixing hot and cold water via a tempering valve is referred to as "tempered water".
   Reflexes are a vital part of our everyday activities. We have all experienced how fast and automatic these responses to environmental interactions can be. They can protect us from potentially dangerous situations such as touching a hot stove or stepping on a tack. There are also reflex pathways involved in more dynamic activities such as walking and running, helping to ensure a smooth gait and allowing us to respond quickly to obstacles or unexpected perturbations or disturbances.
   Taking advantage of the cooling properties of water may help attenuate the consequences of heat sensitivity. In a study done by White et al. (2000), exercise pre-cooling via lower body immersion in water of 16–17 °C for 30 minutes allowed heat sensitive individuals with MS to exercise in greater comfort and with fewer side effects by minimizing body temperature increases during exercise. Hydrotherapy exercise in moderately cool water of 27–29 °C water can also be advantageous to individuals with MS. Temperatures lower than 27 °C are not recommended because of the increased risk of invoking spasticity.
  
  Section::::History.
   Flinching is showing a strong negative physical reaction to a proposal. Common examples of flinching are gasping for air, or a visible expression of surprise or shock. The flinch can be done consciously or unconsciously. The flinch signals to the opposite party that you think the offer or proposal is absurd in hopes the other party will lower their aspirations. Seeing a physical reaction is more believable than hearing someone saying, "I'm shocked."
  
  Good Guy/Bad Guy:
   During attacks in infants, the child often looks startled or terrified and can scream inconsolably. These attacks can be precipitated by injections, defecation, wiping of the perineum, eating, or the consumption of oral medication. When attacks occur due to such precipitation, pain and flushing are often present in the area of attack precipitation, though symptoms may also be diffuse in nature.
   Section::::Gunfight.
  
  Section::::Gunfight.:The first encounter.
   BULLET::::3. A causal link between the breach and the psychiatric illness, i.e. the nervous shock was the direct consequence of the defendant's breach of duty;
  
  BULLET::::4. The nervous shock was not too remote a consequence of the breach.
   Temperature and pain are thought to be represented as “feelings” of coolness/warmness and pleasantness/unpleasantness in the brain. These sensory and affective characteristics of thermoregulation may motivate certain behavioral responses depending on the state of the body (for example, moving away from a source of heat to a cooler space). Such perturbations in the internal homeostatic environment of an organism are thought to be key aspects of a motivational process giving rise to emotional states, and have been proposed to be represented principally by the insular cortex as feelings. These feelings then influence drives when the anterior cingulate cortex is activated.
   First, nociception is required. This is the ability to detect noxious stimuli which evoke a reflex response that rapidly moves the entire animal, or the affected part of its body, away from the source of the stimulus. The concept of nociception does not imply any adverse, subjective "feeling" – it is a reflex action. An example in humans would be the rapid withdrawal of a finger that has touched something hot – the withdrawal occurs before any sensation of pain is actually experienced.
   Hypothermia from exposure to cold water is not as sudden as is often believed. A person who survives the initial minute of trauma (after falling into icy water), can survive for at least thirty minutes provided they don't drown. However, the ability to perform useful work (for example to save oneself) declines substantially after ten minutes (as the body protectively cuts off blood flow to "non-essential" muscles).
  
  Section::::Physiological response.
  
  The physiological response results in temporary breathlessness and vasoconstriction.
  
  Section::::Conditioning against cold shock.
   Hot-cold empathy gap is also dependent on the person's memory of visceral experience. As such, it is very common to underestimate visceral state due to restrictive memory. In general, people are more likely to underestimate the effect of pain in a cold state as compared to those in the hot state.
  
  Section::::Memory.:The experiment.
  
  Nordgren, van der Pligt and van Harreveld (2006) assessed the impact of pain on the subjects performance on a memory test. In the assessment process, participants were questioned how pain and other factors affected their performance.
  
  Section::::Memory.:The result of experiment.
   A painful facial expression is one way in which the experience of pain is communicated from one individual to another. One study aimed to measure test subject’s related brain activity and facial muscle activity when they watched video clips of a variety of facial expressions including neutral emotion, joy, fear, and pain. The study found that when a subject is shown a painful facial expression, their late positive potential (LPP) is increased during the time period of 600–1000ms after the initial exposure of the stimulus. This increase in LPP for painful facial expressions was higher than the increase caused by other emotional expressions. 
   Section::::Determinants of reaction time.:Affordance.
  
  Also important to S–R compatibility is the type of stimulus; familiar objects tend to invite specific responses. As one example, if an object is perceived as more easily (or more typically) manipulable with one hand than the other, any response requiring use of the other hand will tend to have a long reaction time.
  
  Section::::Determinants of reaction time.:Affordance.:Evidence.
   Section::::Physiological responses.
   First mentioned in the 6th-century "Lex Salica", the ordeal of hot water required the accused to dip his hand in a kettle or pot of boiling water (sometimes oil or lead was used instead) and retrieve a stone. The assessment of the injury and the consequences of a miracle or lack of one followed a similar procedure to that described above. An early (non-judicial) example of the test was described by Gregory of Tours in the late 6th century. He describes how a Catholic saint, Hyacinth, bested an Arian rival by plucking a stone from a boiling cauldron. Gregory said that it took Hyacinth about an hour to complete the task (because the waters were bubbling so ferociously), but he was pleased to record that when the heretic tried, he had the skin boiled off up to his elbow.
   Particularly in the case of fish, it has been hypothesized that the differences in escape response are due to the evolution of neural circuits over time. This can be witnessed by observing the difference in the extent of stage 1 behaviour, and the distinct muscle activity in stage 2 of the C-start or fast-start response.
   BULLET::::- 54 "thalamitai" or "thalamioi" in the lowest row, ("thalamos" means "hold"). Their position was certainly the most uncomfortable, being underneath their colleagues and also exposed to the water entering through the oarholes, despite the use of the "askōma", a leather sleeve through which the oar emerged.
   The common brown shrimp "Crangon crangon" and the prawns "Palaemon serratue" and "Palaemon elegana" all exhibit a nociceptive sensitivity to both hot and cold temperatures. Both thermal sensitivity levels and nociceptive thresholds change with changes in acclimation temperature.
  
  Section::::Research findings.:Peripheral nervous system.:Nerve fibres.
  
  Crayfish have peripheral nerve fibres which are responsive to noxious stimuli.
  