I may have, or only wish to have, a relationship, without turning my back to pursue the conversation. This occurs even though there is nothing visual to hide and the act of turning gives me away. Perhaps this is a case of reducing cognitive dissonance—and cognitive load—by not having to watch one woman watch you while you pretend not to talk to another woman.
In ravens, the pilferers avoid searching for known caches when in the presence of those who cache but will go immediately to the caches in the presence of a noncaching bird (that is unlikely to defend). In addition, they actively search away from the cache in the presence of the cacher, as if hiding their intentions. In one experiment, when ravens were introduced into an area where food was hidden, a subordinate male quickly developed the ability to find food, which the most dominant quickly learned to parasitize. This in turn led the subordinate to first search in areas where no food was present, to lure the dominant away, at which point the subordinate moved quickly to the food itself.
Mantis shrimps are hard-shelled and their claws dangerous for seven weeks out of eight. On the eighth week, they are molting, and their body and claws are soft; they are unable to attack others and are vulnerable to attack by them. When encountered at this time, they greatly increase their rate of claw threats, sometimes combined with insincere lunges at the opponent. About half the time, this scares off their opponent. The other half, the soft-shelled shrimp runs for its life. The week before a mantis shrimp becomes soft-shelled, it increases its rate of claw threats but also increases the rate at which these threats are followed by actual attack, as if signaling that threats will be backed up by aggressive action just before the time when they will not.
In fiddler crabs, the male typically has a large claw used to fight and threaten other males and to court females. Should he lose this claw, he regenerates one very similar in appearance but less effective than the original. The size of the first claw does indeed correlate (independent of body size) with claw strength as well as ability to resist being pulled from one’s burrow, but the size of the replacement claw does not, and males can’t distinguish between the two kinds of claws in an opponent.
In primates, hiding information from others may take very active forms. For example, in both chimpanzees and gorillas, individuals will cover their faces in an apparent attempt to hide a facial expression. Gorillas in zoos have been seen to cover “play faces” (facial expressions meant to invite play) with one or both hands, and these covered faces are less likely to elicit play than uncovered play faces. Of course, a play face hidden in this fashion is hardly undetectable and may easily become a secondary signal. Chimpanzees will hide objects behind their backs that they are about to throw. They will also throw an object to one side of a tree to frighten another chimp into moving to the opposite side, where his opponent awaits him.
DECEPTION AS AN EVOLUTIONARY GAME
An important part of understanding deception is to understand it mathematically as an evolutionary game, with multiple players pursuing multiple strategies with various degrees of conscious and unconscious deception (in a fine-grained mixture). Contrast this with the problem of cooperation. Cooperation has been well modeled as a simple prisoner’s dilemma. Cooperation by both parties benefits each, while defections hurt both, but each is better off if he defects while the other cooperates. Cheating is favored in single encounters, but cooperation may emerge much of the time, if players are permitted to respond to their partner’s previous moves. This theoretical space is well explored.
The simplest application of game theory to deception would be to treat it as a classical prisoner’s dilemma. Two individuals can tell each other the truth (both cooperate), lie (both defect), or one of each. But this cannot work. One problem is that a critical new variable becomes important—who believes whom? If you lie and I believe you, I suffer. If you lie and I disbelieve you, you are likely to suffer. By contrast, in the prisoner’s dilemma, each individual knows after each reciprocal play how the other played (cooperate or defect), and a simple reciprocal rule can operate under the humblest of conditions—cooperate initially, then do what your partner did on the previous move (tit for tat). But with deception,