Humans intentionally deceive each other as to their thoughts and intentions. Nearly all societies have both sanctioned and unacceptable forms of deception. The ability of great apes to intentionally deceive one another is not well defined. Some propose that apes do intentionally deceive each other (specifically captive chimpanzees with regard to the localization of desirable food or objects), while others feel that deception is solely a human trait. Chimpanzees have so far not been shown to be able to hold false beliefs.
Deception occurs ubiquitously among organisms (including viruses, bacteria, plants, and animals) and facilitates feeding, mating, threat evasion, and other advantages (Trivers 2011). Intentional (or tactical) deception is more specific, and may be defined as the purposeful presentation of false information in order to manipulate others and gain an advantage (Byrne, Whiten 1992). Deception is universally recognized among human societies, many of which directly address the issue of deception using ethical and/or legal frameworks. Rules against deception like tax evasion or counterfeiting are designed to prevent cheating behavior that undermines social stability. Although intentional deception appears to be present in the great apes, there is significant debate about whether such behavior employs theory of mind.
Recorded evidence for human deception far exceeds the case reports for other great apes. In frequency, scope, and sophistication of deception, we appear to be unrivaled as a species. Our ability to purposefully manipulate another’s mental state may be specific to our species. Nonetheless, efforts to identify cognitive prerequisites and examples of deception in captive and wild great ape communities continue. Based on current evidence, intentional deception appears widely among primates and differs fundamentally from camouflaging behavior exhibited by other taxa. The distinction between deception in humans and other primates remains controversial. Intentional deception is often cited as evidence for theory of mind among the great apes. In short, successful intentional deception provides evidence that an animal recognizes and manipulates consciousness/mental states in others (Premack and Woodruff 1978). Recently, Daniel Povinelli has challenged the relevance of these experiments, arguing that intentional deception requires behavioral abstraction, but not reasoning from mental states. In other words, primates may learn how their behavior affects the behavior of others without recognizing that another mind is involved. Citing experiments using blindfolded handlers, Povinelli observes that chimpanzees employ food-begging behavior regardless of whether the handler can see them or not. Povinelli argues that reasoning about another’s mental state is a unique, human development that is built on top of the basic primate model of predictive behavioral abstraction. If this is the case, then experiments that use primate behavior as evidence for theory of mind engage in “folk psychology.” In these studies, researchers fallaciously assume that primates engage in behavioral responses because they use the same mental reasoning that we employ (Povinelli, 2003).
Deception is a human universal. Whether active deception for tangible benefit, concealment of feelings, or self-deception, all humans appear to engage in some level of intentional deception that works on an understanding of behavior and mental status in others.
Humans experience sophisticated, reciprocal self-awareness that builds on top of primate behavioral abstraction. This awareness may place increased demand for self-deception on the human brain. The benefit of successful deception can be weighed against the cost of increased cognitive load, and individuals with exceptional unconscious/self-deceptive abilities may have enjoyed a significant benefit in resource acquisition, mating, and coping with manifest adversities (Trivers 2011).
An alternative hypothesis suggests that the conflict between trust and deception is an important selective pressure that manifests as a difference between human speech and gesture-call systems in other primates. In this model, the benefits of decepetion far outweigh costs, requiring members of a community to actively defend against deception. This defense against deception selects for signals whose veracity can be immediately confirmed. Displaced reference, metaphor, and combinatorial signals are all ruled out in favor of deception resistance, leading to a limited, literal, and direct series of signals. Human beings are outliers, then, because of exceptional trust that supports the development of complex language. This development in turn allows for more sophisticated deception. Despite social rules that forbid dishonesty (including moral and legal codes), deception is ubiquitous amongst humans. The practice may even be embraced when it saves another individual from embarassment. Human cooperation and trust despite rampant, recognized deception may be a defining characteristic of our species. Humans may also be unique because they leverage deception for group benefit. While primate deception appears to be largely selfish, humans use collective deception to build group identity through shared mythology, symbolism, and ritual (Knight 1998).
As a species that may depend on self-deception for functionality in the face of perceived mortality, we may find that psychiatric illness, criminality, and treachery finds root in a species specific coping mechanism for the burden of awareness. Intentional deception in the context of confirmed theory of mind may make humans an ideal model for studying the function of deception in living primates. In turn, these studies may allow us to determine how the solace and advantages provided by deception stack against societal instability that results.
Using studies conducted on captive chimpanzees at Arnhem, Frans de Waal concluded that primates utilize intentional deception, concealing true conditions and projecting false images. He argues that, in animals that learn the effects of communication, voluntary signal production can lead to social manipulation for one’s benefit. Krebs, Dawkins, and Smith debate whether communication emerged from attempts to manipulate others or cooperate. Regardless, the short-term advantage to the individual must be balanced against long-term group stability. In essence, once deception predominates, communication becomes impossible. While many types of animals possess “species-typical” behaviors that camouflage their condition, de Waal argues that intentional deception that comes from an understanding of signal meaning should display much greater diversity (de Waal, 1992). For example, false injury display among ground-nesting birds was described by Swarth, Grimes, and Allen in 1935-1936. The behavior is attributed to efforts to decoy predators away from vulnerable nests. De Waal argues that intended deception requires much more sophisticated cognition, including a sense of self, an understanding of signal meaning to others, and the motivation to manipulate. Menzel’s work in the 1970’s appears to elucidate these elements in chimpanzees. In a series of experiments, Menzel observed that subordinate chimpanzees with knowledge about food location will lead other subordinates to the cache, but lead the group away when a dominant male is present. (Menzel, 1974). The experiments appear to demonstrate intentionality, manipulation, and flexibility that are consistent with purposeful deception. Efforts to quantify episodes of deception by Byrne and Whiten reveals species-specific differences, with chimpanzees engaging in frequent intentional deception relative to other great apes like gorillas. Surprisingly, strepsirhines do not appear to engage in such behavior at all (Byne and Whiten, 1992). Research continues, and recent work by Wheeler identifies the use of false predator warning calls by capuchins in order to secure more food than other group members.
A recent paper identifies innovations in stone-throwing behavior by a chimpanzee at Furuvik Zoo in Sweden. The chimpanzee, named Santino, has been observed collecting stones and caching them in seemingly strategic locations. He later uses these caches, throwing stones at zoo visitors during dominance displays. Wary visitors have learned to back out of range when Santino acts aggressively. According to observations made by Osvarth and Karvonen in 2010, Santino has recently started hiding his stone supplies under hay piles and behind logs. He has also started throwing stones without engaging in aggressive displays. The authors argue that Santino is innovating, concealing his ammunition and intentions to deceive his targets (Osvath, 2012). This conclusion is keeping with De Waal's argument that intentional deception should produce diverse strategies in response to new challenges.
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