question: If person A is pulling on something stuck, does it help at all for person B to pull on person A?
comment: person A's grip is a limiting factor. If it helps, it wouldn't be much, since people can usually pull harder than their own grip anyway. Plus people arent designed to be pulled on so person B could injury person A.
passages: The type of apparatus used in cooperative pulling experiments can vary. Researcher Meredith Crawford, who invented the experimental paradigm in 1937, used a mechanism consisting of two ropes attached to a rolling platform that was too heavy to be pulled by a single chimpanzee. The standard apparatus is one in which a single string or rope is threaded through loops on a movable platform. If only one participant pulls the string, it comes loose and the platform can no longer be retrieved. Only by pulling together in coordination can the participants be successful; success by chance is highly unlikely. Some researchers have designed apparatus that involve handles instead of ropes.
   Section::::Findings.:Birds.:Keas.
   Most animals that passed solo training were successful in spontaneously cooperating to obtain food (22 out of 26). More than half the pairs that chose to cooperate were juvenile-adult pairs. More than two monkeys pulling was never observed; stealing food from a partner was rare. After a first successful cooperation, they were more likely to pull when a partner was directly available, but this was not always the case. Molesti and Majolo did not rule out that pulling while no one held or pulled the other end of the rope was simply a signal to actively recruit a potential partner.
   The researchers provided 24 three-year-old children with some basic training in pulling food rewards towards themselves; in pairs using a loose-string setup, and solo training in which the two ends of a rope were tied together. They then tested the children in an apparatus choice set-up. On one side was the loose end of a rope that threaded through the apparatus to the other child. On the other side were two ends of a rope that when pulled would pull a platform towards both the child and its partner. Both the joint-operator platform and the solo-operated platform were holding two food dishes, all containing the same amounts of food. That is, from a partner's perspective, on one side the child had to pull to get food; on the other the partner could get food without any effort. The children chose the joint-operated board in 78% of trials.
   The cooperative pulling paradigm is an experimental design in which two or more individuals, typically but not necessarily animals, can pull rewards towards themselves via an apparatus they can not successfully operate alone. The cooperative pulling paradigm is the most popular paradigm for testing cooperation in animals.
  
  Section::::Method.:Apparatus.
   Rewards can be food split equally over two bowls in front of each animal, or in one bowl only. The type of food can vary from lots of small pieces to one big lump (e.g., slices of an apple vs. a whole apple). In combination with the apparatus choice, the reward for the joint-task apparatus is often twice as big as the reward for the solo apparatus. Another variation is a modified apparatus where one partner gets food before the other, requiring the first one to keep pulling despite already having received the reward.
  
  Section::::Method.:Conditions.:Visibility.
   Section::::Findings.:Other mammals.:Otters.
   The type of apparatus used in cooperative pulling experiments can vary. Researcher Meredith Crawford, who invented the experimental paradigm in 1937 while at the Yerkes National Primate Research Center, used an apparatus consisting of two ropes attached to a box that was too heavy to be pulled by a single chimpanzee. The standard apparatus is used in the loose-string task, designed by Hirata in 2003, in which a single string or rope is threaded through loops on a movable platform. If only one participant pulls the string, it comes loose and the platform can no longer be retrieved. Only by pulling together in coordination can the participants be successful; success by chance is highly unlikely. Some researchers have designed apparatus that involve handles instead of ropes. De Waal and Brosnan have argued that complex electronically-mediated devices are not conducive to arrive at findings regarding cooperation. This is in contrast to mechanical pulling devices, in which the animals can see and feel their pull having immediate effect. String-pulling tasks have advantages in terms of ecological validity for animals that pull branches with food towards themselves. Tasks in which participants have different roles in collaboration, such as for example, one pulls a handle and the other one needs to insert a stick, are considered outside the cooperative pulling paradigm.
   Section::::Findings.:Birds.
  
  Section::::Findings.:Birds.:Rooks.
   Greenberg, Hamann, Warneken, and Tomasello used a modified apparatus that required two captive chimpanzees to pull, but delivered food to one ape first. They found that in many trials the apes who already had received a reward from joint effort kept pulling to help their partner obtain their food.
  
  These partners did not need to gesture to solicit help, suggesting there was an understanding of what was wanted and needed.
  
  Section::::Findings.:Primates.:Bonobos.
   Section::::Findings.:Other mammals.:Dolphins.
   show, for nonhuman primates, unusually high levels of social tolerance around food. Early experiments to prove their ability to cooperate were unsuccessful. These tests involved capuchins having to pull handles or press levers in complex devices that the animals did not understand. They did not pull the handle more often when a partner was pulling; both novices and experienced participants kept pulling even in situations where success was impossible. Visalberghi, Quarantotti, and Tranchida concluded that there was no evidence of an appreciation of the role played by the partner.
   Head pull
  
  Head pull is an Inuit game where two people lie belly-down on the ground, pull each other’s heads, and try to move the opponent across a line. The game is played with a loop placed around the competitors’ heads as they face each other. The loop is placed above the ears, and the game becomes more difficult the higher the loop is placed. The winner is the one who first pulls their opponent across the line, or if the loop slips off their opponent’s head.
   In the 1960s, National Football League (NFL) coach Vince Lombardi of the Green Bay Packers utilized the Packers sweep play in which guards Jerry Kramer and Fuzzy Thurston rapidly pulled out from their normal positions and led blocking for the running back (typically Paul Hornung or Jim Taylor) going around the end. It was an integral part of an offense that won five NFL titles in seven years.
   Section::::Findings.:Other mammals.
  
  Section::::Findings.:Other mammals.:Hyenas.
   Section::::Findings.:Other mammals.:Dogs.
   Coué noted that young children always applied his method perfectly, as they lacked the willpower that remained present among adults. When he instructed a child by saying "clasp your hands" and then "you can't pull them apart" the child would thus immediately follow his instructions and be unable to unclasp their hands.
  
  Section::::The Coué method.:Self-conflict.
   Since the guard is free of responsibility for play-side outside runs and far-side counter plays, pulling is generally a unique responsibility for guards.
  
  Section::::Tackles.
  
  While tackles can also pull, this strategy is generally less common as they are too far away to pull to the opposite side of the formation (for counter plays) and have the responsibility of blocking the outside defender (generally the defensive end) for outside runs.
  
  Section::::History.
  
  John Heisman is credited with first pulling guards. Vanderbilt's Dan McGugin soon followed.
  
  Section::::History.:Trap block.
   A 2005 episode of "Naturally, Sadie", "Survival of the Stupidest" featured Sadie and Hal entering a contest where they must keep their hand on a Jeep Grand Cherokee in which the last one touching it wins. 
  
  A 2006 episode of the TV show "Malcolm in the Middle", features Hal and Lois entering a contest to keep their hand on a truck, in which the last one touching it wins the truck.
   Three of the four keas were successful at a significant rate: they chose to wait when they had to and immediately pulled when the task could be done alone. However, when the researchers modified the set-up and coiled up the string end of the delayed partner, no bird was successful at discriminating between a duo platform with both ends of string available to both keas and a duo platform with the partner's string coiled out of reach.
   Rekers, Haun, and Tomasello tested the cooperation abilities and preferences of humans ("Homo sapiens") and compared them to chimpanzees.
   Section::::Findings.:Primates.:Orangutans.
  
  Orangutans ("Pongo pygmaeus") are tool-using apes that are mostly solitary. Chalmeau, Lardeux, Brandibas, and Gallo tested the cooperative capabilities of a pair of orangutans, using a device with handles. Only through simultaneous pulling could the pair retrieve a food reward. Without any training the orangutans succeeded in the first session. Over the course of 30 sessions, the apes succeeded more quickly, having learned to coordinate. Across trials the researchers found an increase in a sequence of actions that suggested understanding of cooperation: first looking at the partner; then if the partner holds or pulls the handle, starting to pull.
   Section::::Findings.:Birds.:Ravens.
   Theoretical considerations aside, in real world use the mechanical advantage of the trucker's hitch is significantly less than the ideal case due to the effects of friction. Friction has been reported to reduce the mechanical advantage from 3 to 1, to well less than 2 to 1 in many cases. One advantage of the friction within the trucker's hitch, compared to a hypothetical pulley-based system, is that it allows the hitch to be held taut with less force while the working end is secured.
  
  Section::::Cultural references.
   De Waal and Berger used the cooperative pulling paradigm to investigate animal economics. They compared the behavior when both transparent bowls were loaded with food to when just one was loaded, and with a solo task where the partner was only an observer and unable to help. They found that captive capuchin monkeys were willing to pull even if their bowl was empty and it was uncertain if their partner would share food. In 90% of cases the owner of the food did indeed share the food. Food was shared more often if the partner actually worked for it than just being an observer.
  
raw_presuppositions: Person B could help by puling on Person A.
raw_corrections: Person A's grip is the limiting factor, not their pulling strength. Their strengths would add, but grip does not increase. 