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Human Communication as a Primate Heritage

Instructor: Anne Zeller

Lecture Five: Deception in Humans and Animals

Current understanding of deceptive behaviour has developed over the last 150 years, from the idea that it represents a rational intended will to deceive another, to an understanding that there are many levels of deceptive behaviour and it is widespread in living forms. In particular, it has become clear that deception is a specialized aspect of communication which has a set of forms in which it can occur, and characteristics which are usually present if it is successful. Basically deception can be described as a long line of increasingly complex behaviours which are based on evolutionary, morphological or psychological developments. The words humans use to describe behaviours are often shorthand indicators reflecting similarity in outcome of such behaviour rather than similarity of causative agency. This is why the effect of crypsis or camouflage colouring in insects can be called deception although there is no choice of intentionality on the part of the butterfly to deceive its predators. However, this deception will act to increase the fitness of the individual and its gene line, thus making such deception a vital part of the animal's life. The same goes for coat colour changes in arctic ptarmigan and hare whose colour shifts with the seasons in an effort to deceive their predators.

Other levels of deceptive behaviour seen in animals include strategies which have some level of choice in timing of initiation, usually in response to the receiver's behaviour. These include activities such as "broken wing" displays in birds to lead predators from the nest, bluff displays in stomatopods, and deceptive flash patterns in fireflies in which females try to lure non-species males close enough to eat by sending the male's species mating flash pattern. Male fireflies also can show several flash patterns to thwart this behaviour in an effort to keep the females from catching them. As these examples indicate the deception involved may be initiated by the presence of an appropriate receiver, but operates on a class of receivers in particular situations with a very limited set of responses. These responses do not seem particularly modifiable and the main variability in their occurrence is in when they are used and their frequency rather than in what behaviour occurs and how it is done. For higher levels of deception, the developmental history of an action rather than just the action itself needs to be taken into account when characterizing its nature. For example, a child who has just learned the word fire, may repeat it many times with no external referent, yet no one would accuse the child of trying to deceive them that it was in danger of being burned. In another situation a child may awake from a dream calling out about fire, and perhaps really feeling in danger, but this is not classed as deception either, even if the child maintains that it was being burned thus confusing dream and reality. However, a situation in which a child repeatedly calls out 'fire' with no referent and then uses the resultant confusion to its own advantage, or merely enjoying the commotion, would be considered to engage in deception, particularly if the activity was repeated. Thus the same action can be interpreted in different ways depending on the developmental stage of the child and the surrounding circumstances.

Mitchell (1986) has organized these varying situations into a hierarchy of four levels which allows the categorization of behaviour between those which have the effect of deceiving and those which have the intention to deceive. Level one refers to situations in which the acts of the receivers have no influence on the acts of the sender in one lifetime (although there may be evolutionary consequences). These situations can be called a 'mime' when appearance is calculated to deceive the receiver such as in camouflaged butterflies. Level two occurs when the receiver's actions influence the occurrence of the behaviour and perhaps its intensity, but not its form. An example is the injury feigning of birds leading predators away from the nest. Level three occurs in situations in which a particular behaviour has worked before and in similar circumstances is tried again, relying on trial and error, instrumental or observational learning. Animals acting in this way can be considered to be acting with intention because previously so doing has brought about a particular result without the animal actually having an explicit intent to deceive. For example a dog holding up a foot and whining which was effective in getting attention when the foot was sore, may repeat this behaviour when nothing is wrong with the result of getting petting and attention. The same kind of thing can occur when one monkey presents to another after an antagonistic interaction. The roots of this behaviour may have been to encourage positive sexual contact rather than aggression, but the behaviour has become ritualized over time into a signal that means something else, but is still effective in reducing aggression. Level four deception occurs in situations when the sender corrects its actions to match the receiver's behaviour in such a way as to encourage desired acts or beliefs of a receiver. In other words, the sender is manipulating the receiver's understanding of a situation. It is at this level that intentional deception of the type most frequently attributed to adult humans occurs.

These patterns of modifying the receiver's behaviour can occur either by withholding information (inhibition) or by providing wrong information (false message). In humans, with their communication emphasis on verbal skills providing false information is at least as frequent (if not more so) than inhibition. In non-humans, inhibition is much more common except at the first and second levels indicated above where the false messages are pre-set.

However, these levels of self awareness and intentionality are currently matters open to considerable discussion where primates are concerned. Kathleen Gibson reported (1994) on her 10 year observation of a home raised capuchin monkey named Andy that his frequency and level of deception were quite low. He would use an alarm bark to get attention when there was nothing evident to cause the alarm, but this might easily be a level three trial and error type of behaviour in which the activity elicits the desired response without Andy actually having an intention to deceive. His other patterns involve redirecting attention or exhibiting aggressive gestures. He would play with his owner and be looking elsewhere when one hand would sneak into a pocket or try to grab her watch or glasses. He was sometimes in contact with chimpanzees who he would groom with and inhibit facial expressions of aggression until they came quite close when he would bite them very hard. This also happened sometimes with humans. These are activities which are difficult to determine exact motivations for. Perhaps he was really grooming in a friendly manner and had a sudden change of motivation, but no instigating actions to prompt the change in motivations were observed.

Franz de Waal (1986) discussed a series of deception mechanisms which he observed in a group of captive chimpanzees in a large outdoor enclosure over a period of years. This list includes behaviours he classified as, hiding while engaging in ilicit activity, ignoring another, feigning interests in something else, withholding information, feigning emotion, signal correction, and falsification. Many of these headings can be used to classify behaviours seen in gorillas and orangutans also. De Waal's major example of hiding while engaging in elicit activity had to do with sexual encounters between estrus female chimpanzees and low ranking males. The high ranking male would inevitably interfere with such encounters if he saw them so these males and females would quietly and one at a time disappear from view behind some rocks or bushes in the enclosure. That the activity was clandestine is supported by the fact that the females would inhibit their usual copulation calls which occurred uniformly in open matings with high ranking males. Also, on one occasion a sub-adult male who saw such a covert mating in progress rushed over to the leader male, barking and grabbed his arm to lead him over to the consorting couple in the bushes. In other words, the ilicit couple hid their behaviour, suppressed their usual calls, and the behaviour is recognized as being subject to sanctions by others of the group. Ignoring another sometimes occurs when monkeys or apes pretend they haven't seen a threat by a more dominant individual. They may remain seated, look up into the sky, or away from the other and not respond to even repeated threats. However, monkeys doing this usually orient their heads so that their peripheral vision covers the sender and their bodies are usually tense. A skilled human observer can usually tell if the receiver truly has not seen the threat or is only pretending. Sometimes the sender will actually grab the receiver's head and turn it to face the threat, which is then received at close quarters. The advantage of apparently not receiving such a threat is that if the sender gives up and doesn't pursue the issue you are free to continue as you were before. Feigning interest in something else, or ignoring a motivation close at hand has been seen several times when an animal has seen a food item that no one else has noticed, but there are others in the vicinity who would take it if it were openly retrieved. De Waal observed this in a situation where grapefruit was buried in the enclosure and one young male walked across the area. He didn't stop or look around but three hours later when the big chimps were asleep in the sun he came right back to the place, dug up and ate the grapefruit. In other cases chimpanzees have been seen staring at something or even approaching a door and alarm barking at something but when the others rushed to see what it was the first one doubled back and got the preferred item that the others were monopolizing. Chimpanzees can also act in ways that may be an effort to disguise what they are truly feeling. This has been noted above for the capuchin who groomed others until they came close enough to be bitten. Chimpanzees have been seen to make reconciliation gestures after a conflict only to attack again when the other approached in an unsuspecting way. Also one of De Waal's adult male chimpanzees used to begin to play with youngsters when he was being threatened by other males. That he was not truly unconcerned was revealed by his frequent quick glances at the threatening male and his occasional yelps and his hugging his play partners. Yelps and reassurance hugs are not characteristic of play sessions.

The ability to suppress information by redirecting attention or appropriate calls or facial gestures might be considered indicative of irrationality or confusion by chimpanzees, but the argument that it is intended to mislead is supported by observations of chimpanzees actually turning away from aggressive interactions until his own signs of fear (teeth baring) had disappeared, or actually using his hands to push his lips back over his teeth again so as not to demonstrate fear. Another circumstance of signal hiding occurs when males hide the evidence of an erect penis from a higher ranking male by bending up their knees or shielding it with a hand until the higher ranked male leaves. In some cases they actually orient themselves so that estrus females can see the sexual invitations, but it is hidden from higher ranking males when would attack them if they saw it.

Falsification can occur in a number of ways from simple to complex. One simple example is one chimp holding a weapon behind his back as he runs up to another one, ready to attack. Also, especially in captivity, chimpanzees will sit for many minutes with mouths full of water, waiting to spit until an unwary human comes within range. More complex incidents include one male chimpanzee chasing a female behind a tree. She dodged out one way and he threw a brick at her. She jumped back but he had already gone the other way, anticipating her response and thus caught her. Since he did not wait to see her reaction to his projectile this represents a multistage planning of action and response.

Such levels of action are also reported for signing chimpanzees as well as Koko and Chanteck, the signing gorilla and orangutan respectively. All of them have used various verbal claims in an effort to mislead their handlers and get out of lessons or into forbidden activities. The most frequent is the use of the request to go to the bathroom, instead of doing lessons. When taken to the toilet usually they spend a long time with no result, or take the opportunity to try to escape or get into things in the bathroom-like powder or toilet paper. In other cases signing apes may hide things and claim not to know where they are (Nim chimp cited from Terrace 1979 in Miles 1986), but under pressure lead the observer to them. With signing apes use of purely verbal responses sometimes make it difficult to distinguish between errors and lies, unless non-verbal indicators are also present, or there is a video record of the ape actually doing the forbidden activity. Of course situations in which signing apes claim to be innocent of wrongdoing may be ways of attempting to avoid punishment rather than real efforts to deceive, especially if these episodes were observed.

Incidents of these types vary in frequency and complexity as well as in interpretation. In some cases a level 3 explanation of trial and error or observational learning can be advanced as explanations for feigning a mood, or feigning interest in an outside object or concealing facial gestures indicative of their moods until another approaches. On the other hand, some of these situations such as the young male who waited to dig up the grapefruit were first incidents of such behaviour and give every evidence of level 4 deception. Much of the non-human primate deception occurs through withholding information, but providing wrong information (false messages) does occur especially in the signing apes. One good example of false messages in non-signing forms was the old male who played with youngsters while being threatened. His seeming unconcern did result in other threatening males backing down on some occasions.

What primates actually think is going on or intend to happen in these situations is still open to experimental evidence and interpretation. Levels of ape self awareness are currently being investigated because for highly intentional deceit involving the belief systems of others some level of awareness of self and awareness of other must be present. The human level of self awareness is such that we usually know what we are doing, whether concealing or manipulating information, and usually we even know that others will know what we are doing is intentional if we make a slip or do not present a convincing enough case. In some situations we realize that others know what we are doing in any case, whether or not they choose to act on it. These levels of knowledge are characteristic of humans and can lead to very complex levels of deceit.

Humans also have a pervasive and complex form of behaviour called 'self deception' in which people will believe things contrary to the evidence around them which they make every effort to ignore. In some cases when they eventually accept their self deceit they may say "I knew it all along", but for various reasons (emotional, financial, etc.) refused to accept the implications of the evidence until it became overwhelming or the consequences of self deceit become too great. In many cases people operate at some level of self deceit all their lives and this may be evident to an observer who either has access to the information, or who can interpret the strain and fatigue that such self deceit frequently costs.

Some levels of misinformation or deceit are institutionalized in human society and accepted in their contexts. These include things like play acting, social lies, games and some levels of tricks and exaggerations. These aspects of deceit become less socially acceptable as the scale and consequences are more severe. Practical jokes are one level of deceptive trick (or magic acts) but financial trickery or serious stock market infractions are viewed in a less lenient light. Bluff in sports is considered quite acceptable and part of strategy, as it is in military encounters, but in corporate dealings it can shade from a 'sharp' business practice into illegal situations. Wishful thinking is a more personal level of deception, which may range from children's fantasy games to an adult's avoidance of reality. To actually label these activities 'deception' in the reprehensible sense of the term requires information about the intentions of the sender, his beliefs about the world, insight into the circumstances surrounding the situation and a clear idea of how to distinguish between lying and someone making an honest mistake. All of these activities are engaged in by children and adults alike, more or less successfully. Serious intentional deception is more likely to be a problem and to be more subtle with the use of language. The most important aspect of successful deception is that it should be plausible. There should be enough corroborating evidence from various channels to make it easy to accept. One important source of support is to make the deceit fall in line with what the receiver wants to happen because they are much more likely to accept it. Playing games is usually a training ground for the detection of deception in humans (Mawby + Mitchell 1984). Bluff is institutionalized in many sports. when planning to feint in baseball, football, hockey, etc. the player will look one way—say right—nod right, lift right foot, but is not committed to going until the weight is shifted, which may be to the left. Vision is usually the first act in a sequence so the observer is trained to look at the eyes first, because they may glance left, and motion of hands and feet often precede that of the body. The deceiver may unknowingly leak information through the eyes, mouth and hands for example, how the fingers curl around a baseball which gives the responder cues that the body orientation may be a false lead. Boxers often use a head movement to draw another's attention to the head, then hit the body. The goal of opponents is to force the other to commit to an action before you do, and perhaps to control the options they have open. Once this learning of what to watch for has occurred it can be used in every day life to look for possible deceit in interactants. First watch the eyes, then lips, head, hands and body. Often skilled deceivers control these areas well but do not control lower legs and feet because they are frequently ignored, so if skilled deception is suspected look for foot movements and lower body orientation. Another aspect is pupil size since lying is often an effort which may result in minor pupil dilation. Coherence of story, voice patterns, emphasis, pitch, loudness and body movements are important in assessing truth in fact to face interactions. Still limbs, gaze avoidance, and over pronounced mouth movements may be indicators of untruth. The most important aspect of this discussion to me is to remember that there are many levels of deceptive behaviour with differing costs and benefits for different senders and receivers. Also, it is important to remember that there are cultural differences in markers for deceit among humans.


Gibson, K.R. 1994. "Tool Use, Imitation and Deception in a Captive Cebus Monkey. " In: Language and Intelligence in Monkeys and Apes. ed. Sue Taylor and Kathleen Gibson. Cambridge U. Press. Cambridge, pp. 205-218.

Mawby, R. and Mitchell R. 1984. "Feints and Ruses: An analysis of deception in sports." In: Deception. ed. Robert Mitchell and Nicholas Thompson. Suny Press. Albany pp. 313-321.

Miles, H.L. 1984. "How can I tell a lie? Apes Language and the Problem of Deception." In: Deception. ed. Robert Mitchell and Nicholas Thompson. Suny Press. Albany. pp. 245-266.

Mitchell, R.W. 1984. "A framework for discussing deception." In: Deception. ed. Robert Mitchell and Nicholas Thompson. Suny Press. Albany. pp. 3-40. de Waal, F. 1984. "Deception in the Natural Communication of Chimpanzees." In: Deception. ed. Robert Mitchell and Nicholas Thompson. Suny Press. Albany. pp. 221-244.

copyright 1999 Anne Zeller
Send comments or question to Anne Zeller: azeller@artspas.watstar.uwaterloo.ca
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