Primate cognition

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The chimpanzee Bobe painting in 1967 Bobe majom fest - 1967 - vehir.hu.jpg
The chimpanzee Böbe painting in 1967

Primate cognition is the study of the intellectual and behavioral skills of non-human primates, particularly in the fields of psychology, behavioral biology, primatology, and anthropology. [1]

Contents

Primates are capable of high levels of cognition; some make tools and use them to acquire foods and for social displays; [2] [3] some have sophisticated hunting strategies requiring cooperation, influence and rank; [4] they are status conscious, manipulative and capable of deception; [5] they can recognise kin and conspecifics; [6] [7] they can learn to use symbols and understand aspects of human language including some relational syntax, concepts of number and numerical sequence. [8] [9] [10]

Studies in primate cognition

Theory of mind

Theory of mind (also known as mental state attribution, mentalizing, or mindreading) can be defined as the "ability to track the unobservable mental states, like desires and beliefs, that guide others' actions". [11] Premack and Woodruff's 1978 article "Does the chimpanzee have a theory of mind?" sparked a contentious issue because of the problem of inferring from animal behavior the existence of thinking, of the existence of a concept of self or self-awareness, or of particular thoughts. [12]

Non-human research still has a major place in this field, however, and is especially useful in illuminating which nonverbal behaviors signify components of theory of mind, and in pointing to possible stepping points in the evolution of what many claim to be a uniquely human aspect of social cognition. [13] [14] [15] While it is difficult to study human-like theory of mind and mental states in species which we do not yet describe as "minded" at all, and about whose potential mental states we have an incomplete understanding, researchers can focus on simpler components of more complex capabilities.

For example, many researchers focus on animals' understanding of intention, gaze, perspective, or knowledge (or rather, what another being has seen). Part of the difficulty in this line of research is that observed phenomena can often be explained as simple stimulus-response learning, since mental states can often be inferred based on observed behavioural cues. [11] Recently, most non-human theory of mind research has focused on monkeys and great apes, who are of most interest in the study of the evolution of human social cognition. Research can be categorized in to three subsections of theory of mind: attribution of intentions, attribution of knowledge (and perception), and attribution of belief.

  1. Attribution of intentions. Research on chimpanzees, capuchin monkeys, and Tonkean macaques (Macaca tokeana) has provided evidence that they are sensitive to the goals and intentions of others and are able to differentiate between when an experimenter is unable to give them food versus when the experimenter is just unwilling to. [16] [17]
  2. Attribution of knowledge (and perception). Hare et al. (2001) demonstrates that chimpanzees are aware of what other individuals know. They can also understand what another perceives, and they selectively choose food that is not visible to their competitor. [18]
  3. Attribution of belief. A false-belief test is a comprehensive test used to test for an individual's theory of mind. Understanding language is a key component to being able to understand the directions for the false-belief test, and researchers have had to get creative to utilize this test in the research of non-human primates' theory of mind. Recent technology has enabled researchers to closely resemble the false-belief task without needing to use language. In Krupenye et al. (2016), an advanced eye-tracking technology was used to test for false-belief understanding in apes. The findings of this experiment showed that apes understood and accurately anticipated the behavior of an individual who held a false belief. [19]

There has been some controversy over the interpretation of evidence purporting to show theory of mind ability—or inability—in animals. Part of this debate has involved whether animals are really able to associate cognitive abilities with another individual, or if they are just able to read and understand behavior. [20] [21] Povinelli et al. (1990) points out that most evidence in support of great ape theory of mind involves naturalistic settings to which the apes have already adapted through past learning. Their "reinterpretation hypothesis" explains away evidence supporting attribution of mental states to others in chimpanzees as merely evidence of risk-based learning; that is, the chimpanzees learn through experience that certain behaviors in other chimpanzees have a probability of leading to certain responses, without necessarily attributing knowledge or other intentional states to those other chimpanzees. They have proposed testing theory of mind abilities in great apes in novel, and not naturalistic settings. [22] Experimenters since then, such as demonstrated in Krupenye et al. (2016), have gone to extensive lengths to control for behavioral cues by placing the apes in novel settings as suggested by Povinelli and colleagues. Research has shown that there is substantial evidence for some non-human primates to track the mental state, like desires and beliefs, of other individuals that cannot be deduced to a response of learned behavioural cues. [19]

Communication in the wild

For most of the 20th century, scientists who studied primates thought of vocalizations as physical responses to emotions and external stimuli. [23] The first observations of primate vocalizations representing and referring to events in the exterior world were observed in vervet monkeys in 1967. [24] Calls with specific intent, such as alarm calls or mating calls has been observed in many orders of animals, including primates. Researchers began to study vervet monkey vocalizations in more depth as a result of this finding. In the seminal study on vervet monkeys, researchers played recordings of three different types of vocalizations they use as alarm calls for leopards, eagles, and pythons. Vervet monkeys in this study responded to each call accordingly: going up trees for leopard calls, searching for predators in the sky for eagle calls, and looking down for snake calls. [25] This indicated a clear communication that there is a predator nearby and what kind of predator it is, eliciting a specific response. The use of recorded sounds, as opposed to observations in the wild, gave researchers insight into the fact that these calls contain meaning about the external world. [26] This study also produced evidence that suggests vervet monkeys improve in their ability to classify different predators and produce alarm calls for each predator as they get older. Further research into this phenomenon has discovered that infant vervet monkeys produce alarm calls for a wider variety of species than adults. Adults only use alarm calls for leopards, eagles, and pythons while infants produce alarm calls for land mammals, birds, and snakes respectively. Data suggests that infants learn how to use and respond to alarm calls by watching their parents. [27]

A different species of monkeys, the wild Campbell's monkeys have also been known to produce a sequence of vocalization that require a specific order to elicit a specific behaviour in other monkeys. Changing the order of the sounds changes the resulting behaviour, or meaning, of the call. Diana monkeys were studied in a habituation-dishabituation experiment that demonstrated the ability to attend to the semantic content of calls rather than simply to acoustic nature. Primates have also been observed responding to alarm calls of other species. Crested Guinea fowl, a ground-dwelling fowl, produce a single type of alarm call for all predators it detects. Diana monkeys have been observed to respond to the most likely reason for the call, typically a human or leopard, based on the situation and respond according to that. If they deem a leopard is the more likely predator in the vicinity they will produce their own leopard-specific alarm call but if they think it is a human, they will remain silent and hidden.

The ability for non-human primates to understand call systems that belong to a different species of monkey happens but to a limited extent. In this case Diana monkeys and Campbell's monkeys often form mixed species groups but they seem only to respond to each other's danger related calls. [28]

Tool use

Tool use by a gorilla Gorrila tool use-Efi.jpg
Tool use by a gorilla

There are many reports of primates making or using tools, both in the wild or when captive. Chimpanzees, gorillas, orangutans, capuchin monkeys, baboons, and mandrills have all been reported as using tools. The use of tools by primates is varied and includes hunting (mammals, invertebrates, [29] fish), collecting honey, [30] processing food (nuts, fruits, vegetables and seeds), collecting water, weapons and shelter.

Tool making is much rarer, but has been documented in orangutans, [31] bonobos and bearded capuchin monkeys. Research in 2007 shows that chimpanzees in the Fongoli savannah sharpen sticks to use as spears when hunting, considered the first evidence of systematic use of weapons in a species other than humans. [32] [33] Captive gorillas have made a variety of tools. [34] In the wild, mandrills have been observed to clean their ears with modified tools. Scientists filmed a large male mandrill at Chester Zoo (UK) stripping down a twig, apparently to make it narrower, and then using the modified stick to scrape dirt from underneath its toenails. [35] [36]

There is some more recent controversy over whether tool use represents a higher level of physical cognition, although this contradicts a long held tradition of tool use as conferring the highest status in the animal world. One study suggests that primates could use tools due to environmental or motivational clues, rather than an understanding of folk physics or a capacity for future planning. [37]

Problem solving

In 1913, Wolfgang Köhler started writing a book on problem solving titled The Mentality of Apes (1917). In this research, Köhler observed the manner in which chimpanzees solve problems, such as that of retrieving bananas when positioned out of reach. He found that they stacked wooden crates to use as makeshift ladders in order to retrieve the food. If the bananas were placed on the ground outside of the cage, they used sticks to lengthen the reach of their arms.

Köhler concluded that the chimps had not arrived at these methods through trial-and-error (which American psychologist Edward Thorndike had claimed to be the basis of all animal learning, through his law of effect), but rather that they had experienced an insight (sometimes known as the Eureka effect or an "aha" experience), in which, having realized the answer, they then proceeded to carry it out in a way that was, in Köhler's words, "unwaveringly purposeful."

Asking questions and giving negative answers

According to numerous published studies, apes are able to answer human questions, and the vocabulary of the acculturated apes contains question words. [38] [39] [40] [41] [42]

Despite these abilities, the published research literature did not include instances of apes asking questions themselves; in human-primate conversations, questions were exclusively asked by humans. Ann and David Premack designed a methodology to teach apes to ask questions in the 1970s: "In principle, interrogation can be taught either by removing an element from a familiar situation in the animal's world or by removing the element from a language that maps the animal's world. It is probable that one can induce questions by purposefully removing key elements from a familiar situation. Suppose a chimpanzee received its daily ration of food at a specific time and place, and then one day the food was not there. A chimpanzee trained in the interrogative might inquire 'Where is my food?' or, in Sarah's case, 'My food is?' Sarah was never put in a situation that might induce such interrogation because for our purposes it was easier to teach Sarah to answer questions". [43]

A decade later, the Premacks wrote: "Though [Sarah] understood the question, she did not herself ask any questions—unlike the child who asks interminable questions, such as What that? Who making noise? When Daddy come home? Me go Granny's house? Where puppy? Toy? Sarah never delayed the departure of her trainer after her lessons by asking where the trainer was going, when she was returning, or anything else". [44]

Joseph Jordania suggested that the ability to ask questions could be the crucial cognitive threshold between human and other ape mental abilities. [45] Jordania suggested that asking questions is not a matter of the ability to use syntactic structures, that it is primarily a matter of cognitive ability.

g factor of intelligence in primates

The general factor of intelligence, or g factor, is a psychometric construct that summarizes the correlations observed between an individual's scores on various measures of cognitive abilities. First described in humans, the g factor has since been identified in a number of nonhuman species. [46]

Primates in particular have been the focus of g research due to their close taxonomic links to humans. A principal component analysis run in a meta-analysis of 4,000 primate behaviour papers including 62 species found that 47% of the individual variance in cognitive ability tests was accounted for by a single factor, controlling for socio-ecological variables. [46] This value fits within the accepted range of the influence of g on IQ. [47]

However, there is some debate as to the influence of g on all primates equally. A 2012 study identifying individual chimpanzees that consistently performed highly on cognitive tasks found clusters of abilities instead of a general factor of intelligence. [48] This study used individual-based data and claim that their results are not directly comparable to previous studies using group data that have found evidence for g. Further research is required to identify the exact nature of g in primates.

See also

Related Research Articles

<span class="mw-page-title-main">Primate</span> Order of mammals

Primates is an order of mammals, which is further divided into the strepsirrhines, which include lemurs, galagos, and lorisids; and the haplorhines, which include tarsiers and simians. Primates arose 85–55 million years ago first from small terrestrial mammals, which adapted for life in tropical forests: many primate characteristics represent adaptations to the challenging environment among tree tops, including large brain sizes, binocular vision, color vision, vocalizations, shoulder girdles allowing a large degree of movement in the upper limbs, and opposable thumbs that enable better grasping and dexterity. Primates range in size from Madame Berthe's mouse lemur, which weighs 30 g (1 oz), to the eastern gorilla, weighing over 200 kg (440 lb). There are 376–524 species of living primates, depending on which classification is used. New primate species continue to be discovered: over 25 species were described in the 2000s, 36 in the 2010s, and six in the 2020s.

<span class="mw-page-title-main">Ape</span> Branch of primates

Apes are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia, which together with its sister group Cercopithecidae form the catarrhine clade, cladistically making them monkeys. Apes do not have tails due to a mutation of the TBXT gene. In traditional and non-scientific use, the term ape can include tailless primates taxonomically considered Cercopithecidae, and is thus not equivalent to the scientific taxon Hominoidea. There are two extant branches of the superfamily Hominoidea: the gibbons, or lesser apes; and the hominids, or great apes.

<span class="mw-page-title-main">Animal cognition</span> Intelligence of non-human animals

Animal cognition encompasses the mental capacities of non-human animals, including insect cognition. The study of animal conditioning and learning used in this field was developed from comparative psychology. It has also been strongly influenced by research in ethology, behavioral ecology, and evolutionary psychology; the alternative name cognitive ethology is sometimes used. Many behaviors associated with the term animal intelligence are also subsumed within animal cognition.

<span class="mw-page-title-main">Animal language</span> Complex animal communication

Animal languages are forms of communication between animals that show similarities to human language. Animals communicate through a variety of signs, such as sounds and movements. Signing among animals may be considered a form of language if the inventory of signs is large enough. The signs are relatively arbitrary, and the animals seem to produce them with a degree of volition.

<span class="mw-page-title-main">Great ape language</span> Efforts to teach nonhuman primates to communicate with humans

Great ape language research historically involved attempts to teach chimpanzees, bonobos, gorillas and orangutans to communicate using imitative human speech, sign language, physical tokens and computerized lexigrams. These studies were controversial, with debate focused on the definition of language, the welfare of test subjects, and the anthropocentric nature of this line of inquiry.

<span class="mw-page-title-main">Mirror test</span> Animal self-awareness test

The mirror test—sometimes called the mark test, mirror self-recognition (MSR) test, red spot technique, or rouge test—is a behavioral technique developed in 1970 by American psychologist Gordon Gallup Jr. as an attempt to determine whether an animal possesses the ability of visual self-recognition. The MSR test is the traditional method for attempting to measure physiological and cognitive self-awareness. However, agreement has been reached that animals can be self-aware in ways not measured by the mirror test, such as distinguishing between their own and others' songs and scents, and being aware of their own bodies, while humans have abnormally good vision, and thus intelligence that is highly visual.

The Mind of an Ape is a 1983 book by David Premack and his wife Ann James Premack. The authors argue that it is possible to teach language to (non-human) great apes. They write: "We now know that someone who comprehends speech must know language, even if he or she cannot produce it."

<span class="mw-page-title-main">Tufted capuchin</span> Species of New World monkey

The tufted capuchin, also known as brown capuchin, black-capped capuchin, or pin monkey, is a New World primate from South America and the Caribbean islands of Trinidad and Margarita. As traditionally defined, it is one of the most widespread primates in the Neotropics, but it has recently been recommended considering the black-striped, black and golden-bellied capuchins as separate species in a new genus, thereby effectively limiting the tufted capuchin to the Amazon basin and nearby regions. However, the large-headed capuchin (S. a. macrocephalus), previously defined as a distinct species, has been reclassified as a subspecies of the tufted capuchin, expanding its range east to Peru and Ecuador and south to Bolivia.

<span class="mw-page-title-main">Tool use by non-humans</span>

Tool use by non-humans is a phenomenon in which a non-human animal uses any kind of tool in order to achieve a goal such as acquiring food and water, grooming, combat, defence, communication, recreation or construction. Originally thought to be a skill possessed only by humans, some tool use requires a sophisticated level of cognition. There is considerable discussion about the definition of what constitutes a tool and therefore which behaviours can be considered true examples of tool use. A wide range of animals, including mammals, birds, fish, cephalopods, and insects, are considered to use tools.

<span class="mw-page-title-main">Hominidae</span> Family of primates

The Hominidae, whose members are known as the great apes or hominids, are a taxonomic family of primates that includes eight extant species in four genera: Pongo ; Gorilla ; Pan ; and Homo, of which only modern humans remain.

Anne E. Russon is a Canadian psychologist and primatologist. She is a researcher and Professor of Psychology at Glendon College, York University, Toronto, Ontario, Canada whose research focuses on learning and intelligence in ex-captive Bornean orangutans. Russon is widely published in the fields of primate behavior and ecology, is executive director of the Borneo Orangutan Society of Canada, and is the author of several popular press books dealing with Great Apes including Orangutans: Wizards of the Rainforest, Reaching into Thought: The Minds of the Great Apes, and The Evolution of Thought: Evolution of Great Ape Intelligence.

<span class="mw-page-title-main">Josep Call</span> Spanish psychologist and primatologist

Josep Call is a Spanish comparative psychologist specializing in primate cognition.

Social learning refers to learning that is facilitated by observation of, or interaction with, another animal or its products. Social learning has been observed in a variety of animal taxa, such as insects, fish, birds, reptiles, amphibians and mammals.

David Andrew Whiten, known as Andrew Whiten is a British zoologist and psychologist, Professor of Evolutionary and Developmental Psychology, and Professor Wardlaw Emeritus at University of St Andrews in Scotland. He is known for his research in social cognition, specifically on social learning, tradition and the evolution of culture, social Machiavellian intelligence, autism and imitation, as well as the behavioral ecology of sociality. In 1996, Whiten and his colleagues invented an artificial fruit that allowed to study learning in apes and humans.

Theory of mind in animals is an extension to non-human animals of the philosophical and psychological concept of theory of mind (ToM), sometimes known as mentalisation or mind-reading. It involves an inquiry into whether non-human animals have the ability to attribute mental states to themselves and others, including recognition that others have mental states that are different from their own. To investigate this issue experimentally, researchers place non-human animals in situations where their resulting behavior can be interpreted as supporting ToM or not.

<span class="mw-page-title-main">Pointing</span> Gesture

Pointing is a gesture specifying a direction from a person's body, usually indicating a location, person, event, thing or idea. It typically is formed by extending the arm, hand, and index finger, although it may be functionally similar to other hand gestures. Types of pointing may be subdivided according to the intention of the person, as well as by the linguistic function it serves.

<span class="mw-page-title-main">Brian Hare</span> American anthropologist (born 1976)

Brian Hare is a professor of evolutionary anthropology at Duke University. He researches the evolution of cognition by studying both humans, our close relatives the primates, and species whose cognition converged with our own. He founded and co-directs the Duke Canine Cognition Center.

The evolution of cognition is the process by which life on Earth has gone from organisms with little to no cognitive function to a greatly varying display of cognitive function that we see in organisms today. Animal cognition is largely studied by observing behavior, which makes studying extinct species difficult. The definition of cognition varies by discipline; psychologists tend define cognition by human behaviors, while ethologists have widely varying definitions. Ethological definitions of cognition range from only considering cognition in animals to be behaviors exhibited in humans, while others consider anything action involving a nervous system to be cognitive.

Jessica C. Flack is a data scientist, evolutionary biologist, and professor at the Santa Fe Institute.

Primate archaeology is a field of research established in 2008 that combines research interests and foci from primatology and archaeology. The main aim of primate archaeology is to study behavior of extant and extinct primates and the associated material records. The discipline attempts to move beyond archaeology's anthropocentric perspective by placing the focus on both past and present primate tool use.

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