A persistent methodological problem in primate social cognition research has been how to determine experimentally whether primates represent the internal goals of other agents or just the external goals of their actions. This is an instance of Daniel Povinelli’s more general challenge that no experimental protocol currently used in the field is capable of distinguishing genuine mindreading animals from their complementary behavior-reading counterparts. We argue that current methods used to test for internal-goal attribution in primates do not solve (...) Povinelli’s problem. To overcome the problem, a new type of experimental approach is needed, one which is supported by an alternative theoretical account of animal mindreading, called the appearance-reality mindreading (ARM) theory. We provide an outline of the ARM theory and show how it can be used to design a novel way to test for internal-goal attribution in chimpanzees. Unlike protocols currently in use, the experimental design presented here has the power, in principle and in practice, to distinguish genuine mindreading chimpanzees from those who predict others’ behavior solely on the basis of behavioral/environmental cues. Our solution to Povinelli’s problem has important consequences for a similar debate in developmental psychology over when preverbal infants should be credited with the ability to attribute internal goals. If what we argue for here in the case of nonhuman primates is sound, then the clearest tests for internal-goal attribution in infants will be those that test for attributions of discrepant or ‘false’ perceptions. (shrink)
Since the BBS article in which Premack and Woodruff (1978) asked “Does the chimpanzee have a theory of mind?,” it has been repeatedly claimed that there is observational and experimental evidence that apes have mental state concepts, such as “want” and “know.” Unlike research on the development of theory of mind in childhood, however, no substantial progress has been made through this work with nonhuman primates. A survey of empirical studies of imitation, self-recognition, social relationships, deception, role-taking, and perspective-taking (...) suggests that in every case where nonhuman primate behavior has been interpreted as a sign of theory of mind, it could instead have occurred by chance or as a product of nonmentalistic processes such as associative learning or inferences based on nonmental categories. Arguments to the effect that, in spite of this, the theory of mind hypothesis should be accepted because it is more parsimonious than alternatives or because it is supported by convergent evidence are not compelling. Such arguments are based on unsupportable assumptions about the role of parsimony in science and either ignore the requirement that convergent evidence proceed from independent assumptions, or fail to show that it supports the theory of mind hypothesis over nonmentalist alternatives. Progress in research on theory of mind requires experimental procedures that can distinguish the theory of mind hypothesis from nonmentalist alternatives. A procedure that may have this potential is proposed. It uses conditional discrimination training and transfer tests to determine whether chimpanzees have the concept “see.” Commentators are invited to identify flaws in the procedure and to suggest alternatives. Key Words: apes; associative learning; concepts; convergence; deception; evolution of intelligence; folk psychology; imitation; mental state attribution; monkeys; parsimony; perspective-taking; primates; role-taking; self-recognition; social cognition; social intelligence; theory of mind. (shrink)
Two substantive comments are made. The first is methodological, and concerns Heyes's proposals for a critical test for theory of mind. The second is theoretical, and concerns the appropriateness of asking questions about theory of mind in nonhuman primates. Although Heyes warns against the apparent simplicity of the theory of mind hypothesis, she underplays the linguistic implications.
Heyes argues that nonhuman primates are unable to imitate, recognize themselves in mirrors, and take another's perspective, and that none of these capabilities are evidence for theory of mind. First, her evaluation of the evidence, especially for imitation and mirror self-recognition, is inaccurate. Second, she neglects to address the important developmental evidence that these capabilities are necessary precursors in the development of theory of mind.
Recent studies with human infants and nonhuman primates reveal that posture interacts with the expression and stability of handedness. Converging results demonstrate that quadrupedal locomotion hinders the expression of handedness, whereas bipedal posture enhances preferred hand use. From an evolutionary perspective, these findings suggest that right-handedness may have emerged first, following the adoption of bipedal locomotion, with speech emerging later.
Gurven suggests that the tolerated scrounging model has limited relevance for explaining patterns of food transfers in human populations. However, this conclusion is based on a restricted interpretation of the tolerated scrounging model proposed originally by Blurton Jones (1987). Examples of food transfers in nonhuman primates illustrate that the assumptions of Gurven's tolerated scrounging model are open to question.
The radical nub of Byrne & Russon's argument is that passive priming effects can produce much of the evidence of higher-order cognition in nonhuman primates. In support of their position we review evidence of similar behavioral priming effects n humans. However, that evidence further suggests that even program-level imitative behavior can be produced through priming.
Given Heyes's construal of “theory of mind,” there is still no convincing evidence of theory of mind in human primates, much less nonhuman. Rather than making unfounded assumptions about what underlies human social competence, one should ask what mechanisms other primates have and then inquire whether more sophisticated elaborations of those might not account for much of human competence.
The highly recommended transposition of the dynamic system approach for tackling the question of apes' linguistic abilities has clearly not led to a demonstration that these primates have acquired language. Fundamental differences related to functional modalities – namely, use of the declarative and the form of engagement between mother and infant – can be observed in the way humans and apes use their communicatory systems.
The scientific, ethical, and policy issues raised by research involving the engraftment of human neural stem cells into the brains of nonhuman primates are explored by an interdisciplinary working group in this Policy Forum. The authors consider the possibility that this research might alter the cognitive capacities of recipient great apes and monkeys, with potential significance for their moral status.
Research on mirror self-recognition where animals are observed for mirror-guided self-directed behaviour has predominated the empirical approach to self-awareness in nonhuman primates. The ability to direct behaviour to previously unseen parts of the body such as the inside of the mouth, or grooming the eye by aid of mirrors has been interpreted as recognition of self and evidence of a self-concept. Three decades of research has revealed that contrary to monkeys, most great apes (humans, common chimpanzees, pygmy chimpanzees and (...) orangutans but not the gorilla) have convincingly displayed the capacity to recognize self by mirrors. The putative discontinuity in phylogeny of the ability suggests the existence of a so-called cognitive gap between great apes and the rest of the animal kingdom. However, methodological and theoretical inconsistencies regarding the empirical approach prevail. For instance, the observation of self-directed behaviour might not be as straightforward as it seems. In addition, the interpretation of mirror self-recognition as an index of self-awareness is challenged by alternative explanations, raising doubt about some assumptions behind mirror self-recognition. To evaluate the significance of the test in discussions of the concept of self this paper presents and analyses some major arguments raised on the mirror task. (shrink)
Study of “theory of mind” in nonhuman primates is hampered both by the lack of rigorous methodology that Heyes stresses and by our lack of knowledge of the cognitive neuroscience of nonhuman primate conceptual structure. Recent advances in this field indicate that progress can be made by first asking simpler research questions.
Primate vocal communication is very different from human language. Differences are most pronounced in call production. Differences in production have been overemphasized, however, and distracted attention from the information that primates acquire when they hear vocalizations. In perception and cognition, continuities with language are more apparent. We suggest that natural selection has favored nonhuman primates who, upon hearing vocalizations, form mental representations of other individuals, their relationships, and their motives. This social knowledge constitutes a discrete, combinatorial system that (...) shares several features with language. It is probably a general primate characteristic whose appearance pre-dates the evolution of spoken language in our hominid ancestors. The prior evolution of social cognition created individuals who were preadapted to develop language. Several features thought to be unique to languageâlike discrete combinatorics and the encoding of propositional informationâwere not introduced by language. They arose, instead, because understanding social life and predicting othersâ behavior requires a particular style of thinking. (shrink)
This commentary focuses on the importance of auditory object processing for producing and comprehending human language, the relative lack of development of this capability in nonhuman primates, and the consequent need for hominid neurobiological evolution to enhance this capability in making the transition from protosign to protospeech to language.
Primate research suggests that affiliation is a highly complex construct. Studies of primate affiliation demonstrate the need to distinguish between various affiliative behaviors, consider relationships as emergent properties of these behaviors, define affiliation in the context of general environmental responsiveness, and address developmental changes in affiliation across the lifespan.
The article analyzes the neural and functional grounding of language skills as well as their emergence in hominid evolution, hypothesizing stages leading from abilities known to exist in monkeys and apes and presumed to exist in our hominid ancestors right through to modern spoken and signed languages. The starting point is the observation that both premotor area F5 in monkeys and Broca's area in humans contain a “mirror system” active for both execution and observation of manual actions, and that F5 (...) and Broca's area are homologous brain regions. This grounded the mirror system hypothesis of Rizzolatti and Arbib (1998) which offers the mirror system for grasping as a key neural “missing link” between the abilities of our nonhuman ancestors of 20 million years ago and modern human language, with manual gestures rather than a system for vocal communication providing the initial seed for this evolutionary process. The present article, however, goes “beyond the mirror” to offer hypotheses on evolutionary changes within and outside the mirror systems which may have occurred to equip Homo sapiens with a language-ready brain. Crucial to the early stages of this progression is the mirror system for grasping and its extension to permit imitation. Imitation is seen as evolving via a so-called simple system such as that found in chimpanzees (which allows imitation of complex “object-oriented” sequences but only as the result of extensive practice) to a so-called complex system found in humans (which allows rapid imitation even of complex sequences, under appropriate conditions) which supports pantomime. This is hypothesized to have provided the substrate for the development of protosign, a combinatorially open repertoire of manual gestures, which then provides the scaffolding for the emergence of protospeech (which thus owes little to nonhuman vocalizations), with protosign and protospeech then developing in an expanding spiral. It is argued that these stages involve biological evolution of both brain and body. By contrast, it is argued that the progression from protosign and protospeech to languages with full-blown syntax and compositional semantics was a historical phenomenon in the development of Homo sapiens, involving few if any further biological changes. Key Words: gestures; hominids; language evolution; mirror system; neurolinguistics; primates; protolanguage; sign language; speech; vocalization. (shrink)
Research on human infants, adult nonhuman primates, and children and adults in diverse cultures provides converging evidence for four systems at the foundations of human knowledge. These systems are domain specific and serve to represent both entities in the perceptible world (inanimate manipulable objects and animate agents) and entities that are more abstract (numbers and geometrical forms). Human cognition may be based, as well, on a fifth system for representing social partners and for categorizing the social world into groups. (...) Research on infants and children may contribute both to understanding of these systems and to attempts to overcome misconceptions that they may foster. (shrink)
The charge that anthropomorphizing nonhuman animals is a fallacy is itself largely misguided and mythic. Anthropomorphism in the study of animal behavior is placed in its original, theological context. Having set the historical stage, I then discuss its relationship to a number of other, related issues: the role of anecdotal evidence, the taxonomy of related anthropomorphic claims, its relationship to the attribution of psychological states in general, and the nature of the charge of anthropomorphism as a categorical claim. I then (...) argue that the categorical reading of anthropomorphism cannot work and that it misrepresents what is being claimed when one claims that traits are shared between humans and nonhumans. We should think of such claims not as anthropomorphic per se– because that implies the trait is intrinsically human and only derivatively nonhuman. Instead, traits shared with mammals are mammalomorphic, for example, or primatomorphic when shared by primates. (shrink)
The close kinship between humans, chimpanzees, gorillas, and orangutans is a central theme among participants in the debate about human treatment of the other apes. Empathy is probably the single most important determinant of actual human moral behavior, including the treatment of nonhuman animals. Given the applied nature of questions about the treatment of captive apes, it is entirely appropriate that the close relationship between us should be highlighted. But the role that relatedness should play in ethical theory is less (...) clear. To the extent that legal and regulatory challenges to keeping apes in captivity are likely to be based on principles of theory, it is important to understand what roles evolutionary theory can play in deriving such principles. The development of ethically correct policies for captivity of animals will depend on taking into account both species-specific and individual differences in the ways that individuals perceive and conceptualize the spaces in which they live, and the choices with which they are presented. A fully evolutionary approach to cognition, a cognitive ethology, that is not just limited to the great apes or to primates is the best hope we have for understanding such perceptions and conceptions. (shrink)
Evidence from many species suggests that social, developmental, and cognitive variables are important influences on aggression. Few direct activational or organizational effects of hormones on aggression and dominance are found in nonhuman primates. Female aggression and dominance are relatively frequent and occur with low testosterone levels. Social, cultural, and developmental mechanisms have more important influences on dominance and aggression than hormones.
The claim of consistent hemispheric specialisations across classes of chordates is undermined by the absence of population-based directional asymmetry of paw/hand use in rodents and primates. No homologue of the cerebral torque from right frontal to left occipital has been established in a nonhuman species. The null hypothesis that the torque is the sapiens-specific neural basis of language has not been disproved.
Abstract In this paper I examine two claims that support the thesis that chimpanzees are substantive epistemic subjects. First, I defend the claim that chimpanzees are evidence gatherers (broadly construed to include the capacity to gather and use evidence). In the course of showing that this claim is probably true I will also show that, in being evidence gatherers, chimpanzees engage in a recognizable epistemic activity. Second, I defend the claim that chimpanzees achieve a degree of epistemic success while engaging (...) in epistemic activity. Typically humans qualify as substantive epistemic subjects. Again, typically, knowledge plays an integral role in intentional human behaviour. As a consequence of defending the claims that chimpanzees are evidence gatherers and achieve a degree of epistemic success while engaging in such epistemic activities, I will also have shown how knowledge plays an integral role in intentional chimpanzee behaviour. The importance of these arguments does not wholly reside in the significance of knowledge explaining some chimpanzee behaviour. Treatments of animal knowledge in the literature tend to go in one of two directions: either the treatment embraces reliabilism and so construes animal knowledge as reliably produced true beliefs (or, if not beliefs, the relevant analogue for non-linguistic animals), or it embraces an anthropocentric stance that treats animals as knowers only when they find themselves behaving in circumstances that, were it true of humans, would imply the presence of causally efficacious knowledge. What I offer here is another way of understanding non-linguistic animals, in this case chimpanzees, as knowers. (shrink)
Neural correlates exist for a basic component of logical formulae, PREDICATE(x). Vision and audition research in primates and humans shows two independent neural pathways; one locates objects in body-centered space, the other attributes properties, such as colour, to objects. In vision these are the dorsal and ventral pathways. In audition, similarly separable “where” and “what” pathways exist. PREDICATE(x) is a schematic representation of the brain's integration of the two processes of delivery by the senses of the location of an (...) arbitrary referent object, mapped in parietal cortex, and analysis of the properties of the referent by perceptual subsystems. The brain computes actions using a few “deictic” variables pointing to objects. Parallels exist between such nonlinguistic variables and linguistic deictic devices. Indexicality and reference have linguistic and nonlinguistic (e.g., visual) versions, sharing the concept of attention. The individual variables of logical formulae are interpreted as corresponding to these mental variables. In computing action, the deictic variables are linked with “semantic” information about the objects, corresponding to logical predicates. Mental scene descriptions are necessary for practical tasks of primates, and preexist language phylogenetically. The type of scene descriptions used by nonhuman primates would be reused for more complex cognitive, ultimately linguistic, purposes. The provision by the brain's sensory/perceptual systems of about four variables for temporary assignment to objects, and the separate processes of perceptual categorization of the objects so identified, constitute a pre-adaptive platform on which an early system for the linguistic description of scenes developed. Key Words: argument; attention; deictic; dorsal; logic; neural; object; predicate; reference; ventral. (shrink)
This commentary criticizes nonverbal methods of assessing theory-of-mind on the basis of prior training of the critical response because they would encourage simple, nonmentalistic, associative solutions even in subjects with mentalistic capacities. I propose instead a new experimental paradigm based upon the use of spontaneous responses in less artificial situations. This method has already provided positive evidence of some level of ToM understanding in nonhuman primates.
We cannot solve questions about imitative learning without knowing what motivates animals to copy others. Imitative capacities can be expected to be most pronounced in relation to situations and models of great social significance. Experimental research on nonhuman primates has thus far made little effort to present such situations and models.
A theory of how concept formation begins is presented that accounts for conceptual activity in the first year of life, shows how increasing conceptual complexity comes about, and predicts the order in which new types of information accrue to the conceptual system. In a compromise between nativist and empiricist views, it offers a single domain-general mechanism that redescribes attended spatiotemporal information into an iconic form. The outputs of this mechanism consist of types of spatial information that we know infants attend (...) to in the first months of life. These primitives form the initial basis of concept formation, allow explicit preverbal thought, such as recall, inferences, and simple mental problem solving, and support early language learning. The theory details how spatial concepts become associated with bodily feelings of force and trying. It also explains why concepts of emotions, sensory concepts such as color, and theory of mind concepts are necessarily later acquisitions because they lack contact with spatial descriptions to interpret unstructured internal experiences. Finally, commonalities between the concepts of preverbal infants and nonhuman primates are discussed. (shrink)
We argue that lateralities are not merely a result of phylogenetic processes but reflect probability functions that are influenced by task characteristics and extended practice. We support our argument by empirical findings on lateral biases in early infancy in general, and footedness in particular, and on hand preferences in nonhuman primates.
Heyes’s skepticism about theory of mind (ToM) in nonhuman primates exploits the idea of a strong and unified theory of mind in humans based on an unanalyzed category of mental state. It also exploits narrow debates about crucial observations and experiments while neglecting wider evolutionary trends. I argue against both exploitations.
La evidencia comparativa reciente sugiere que algunas especies no humanas sienten empatía hacia otros congéneres, la cual es una capacidad necesaria para la presencia y evolución de la moralidad. Por otro lado, la Hipótesis del Cerebro Social plantea relaciones entre la evolución de la neocorteza cerebral en primates y el tamaño de sus grupos sociales. Este artículo vincula estas ideas al señalar que: (i) la empatía y la moralidad son subproductos de la expansión de la neocorteza cerebral, y (ii) (...) la función de tales capacidades es facilitar la cooperación entre individuos, aumentando su cohesión social. Recent comparative evidence suggests that some nonhuman species feel empathy towards fellow group members and empathy is a necessary capacity for the presence and evolution of morality. On the other hand, the Social Brain Hypothesis suggests relationships between the evolution of brain's neocortex in primates and the size of their social groups. This paper links these ideas by suggesting that (i) empathy and morality are by-products of the expansión of brain's neocortex, and that (ii) the function of such capacities is to facilitate cooperation between individuals, increasing their social cohesion. (shrink)
The study of animal behavior, and particularly avian behavior, has advanced significantly in the past 50 years. In the early 1960s, both ethologists and psychologists were likely to see birds as simple automatons, incapable of complex cognitive processing. Indeed, the term “avian cognition“ was considered an oxymoron. Avian social interaction was also seen as based on rigid, if sometimes complicated, patterns. The possible effect of social interaction on cognition, or vice versa, was therefore something almost never discussed. Two paradigm shifts—one (...) concerning animal cognition and one concerning social interaction—began to change perceptions in, respectively, the early 1970s and 1980s, but only more recently have researchers actively investigated how these two areas intersect in the study of avian behavior. The fruits of such intersection can be seen in the various papers for this special issue. I provide some brief background material before addressing the striking findings of current projects. In some cases, researchers have adapted early classic methods and in other cases have devised new paradigms, but in all instances have demonstrated avian capacities that were once thought to be the exclusive domain of humans or at least nonhuman primates. Keywords: avian cognition; avian social learning; avian observational learning; avian communication. (shrink)
Biodefense and emerging infectious disease animal research aims to avoid or ameliorate human disease, suffering, and death arising, or potentially arising, from natural outbreaks or intentional deployment of some of the world’s most dreaded pathogens. Top priority research goals include finding vaccines to prevent, diagnostic tools to detect, and medicines for smallpox, plague, ebola, anthrax, tularemia, and viral hemorrhagic fevers, among many other pathogens (National Institute of Allergy and Infectious Diseases [NIAID] priority pathogens). To this end, increased funding for conducting (...) research, developing research facilities, and purchasing (stockpiling) developed vaccines, diagnostic tools, and therapeutics .. (shrink)
The quest for a ``theory of nonhuman minds'''' to assessclaims about the moral status of animals is misguided. Misframedquestions about animal minds facilitate the appropriation ofanimal welfare by the animal user industry. When misframed, thesequestions shift the burden of proof unreasonably to animalwelfare regulators. An illustrative instance of misframing can befound in the US National Research Council''s 1998 publication thatreports professional efforts to define the psychologicalwell-being of nonhuman primates, a condition that the US 1985animal welfare act requires users of (...)primates to promote. Thereport claims that ``psychological well-being'''' is a hypotheticalconstruct whose validity can only be determined by a theory thatdefines its properties and links it to observed data. Thisconception is used to contest common knowledge about animalwelfare by treating psychological well-being as a mentalcondition whose properties are difficult to discover. Thisframework limits regulatory efforts to treat animal subjects lessoppressively and serves the interests of the user industry.A more liberatory framework can be constructed by recognizing thecontested nature of welfare norms, where competing conceptions ofanimal welfare have implications about norm-setting authority, asit does in other regulatory contexts, e.g., food safety. Properlyconceptualized welfare should include both the avoidance ofdistressful circumstances and the relationship between ananimal''s capacities to engage in enjoyable activities and itsopportunities to exercise these capacities. This conception ofanimal welfare avoids appropriation by scientific experts. (shrink)
The target article argued that there is currently no reliable evidence of theory of mind in nonhuman primates and proposed research methods for future use in this field. Some commentators judged the research proposals to be too chauvinist (in danger of falsely denying that primates attribute mental states), but a majority judged them to be too liberal (in danger of falsely affirming theory of mind in primates). The most valuable comments from both camps exemplified “experimental thought,” the (...) obverse of “thought experiments,” and recommended specific alterations and alternatives to the studies I proposed. This Response evaluates these recommendations and presents a revised version of the proposals that appear in the target article. Other valuable commentary cast doubt on the assumption that people have a theory of mind, aired the possibility that language may be a prerequisite for either possession or detection of a theory of mind, questioned the notion of critical experiments, and emphasized the distinction between attribution of sight and belief. In addition to commenting on these issues, I respond to objections to my interpretation of existing research on self-recognition, imitation, and deception. (shrink)
Harry Harlow is credited with the discovery of learning set, a process whereby problem solving becomes essentially complete in a single trial of training. Harlow described that process as one that freed his primates from arduous trial-and-error learning. The capacity of the learner to acquire learning sets was in positive association with the complexity and maturation of their brains. It is here argued that Harlow's successful conveyance of learning-set phenomena is of historic significance to the philosophy of psychology. Learning (...) set is said to reflect the affirmation or rejection of hypotheses. Hypotheses are generated by the learner's brain, not its muscles. Thus, learning-set research served to advance the perspective that even nonhuman primates think and that their thinking reflects the active processing of information accrued from efforts to solve problems. Their learning processes are not simply the strengthening of some motor responses over others. Hence, learning-set research served to advance studies of animals as rational agents. This trend is serving to supplant the radical-behavioristic models, formulated earlier this century, with models predicated on rational processes for animals' complex learning and behavior. (shrink)
Merging the information from different senses is essential for successful interaction with real-life situations. Indeed, sensory integration can reduce perceptual ambiguity, speed reactions, or change the qualitative sensory experience. It is widely held that integration occurs at later processing stages and mostly in higher association cortices; however, recent studies suggest that sensory convergence can occur in primary sensory cortex. A good model for early convergence proved to be the auditory cortex, which can be modulated by visual and tactile stimulation; however, (...) given the large number and small size of auditory fields, neither human imaging nor microelectrode recordings have systematically identified which fields are susceptible to multisensory influences. To reconcile findings from human imaging with anatomical knowledge from nonhuman primates, we exploited high-resolution imaging (functional magnetic resonance imaging) of the macaque monkey to study the modulation of auditory processing by visual stimulation. Using a functional parcellation of auditory cortex, we localized modulations to individual fields. Our results demonstrate that both primary (core) and nonprimary (belt) auditory fields can be activated by the mere presentation of visual scenes. Audiovisual convergence was restricted to caudal fields [prominently the core field (primary auditory cortex) and belt fields (caudomedial field, caudolateral field, and mediomedial field)] and continued in the auditory parabelt and the superior temporal sulcus. The same fields exhibited enhancement of auditory activation by visual stimulation and showed stronger enhancement for less effective stimuli, two characteristics of sensory integration. Together, these findings reveal multisensory modulation of auditory processing prominently in caudal fields but also at the lowest stages of auditory cortical processing. (shrink)
We aim to show that far-related primates like humans and the capuchin monkeys show interesting correspondences in terms of artifact characterization and categorization. We investigate this issue by using a philosophically-inspired definition of physical artifact which, developed for human artifacts, turns out to be applicable for cross-species comparison. In this approach an artifact is created when an entity is intentionally selected and some capacities attributed to it (often characterizing a purpose). Behavioral studies suggest that this notion of artifact is (...) not specific to the human kind. On the basis of the results of a series of field observations and experiments on wild capuchin monkeys that routinely use stone hammers and anvils, we show that the notions of intentional selection and attributed capacity appear to be at play in capuchins as well. The study also suggests that functional criteria and contextualization play a fundamental role in terms of artifact recognition and categorization in nonhuman primates. (shrink)
Heyes's (1998) skepticism about theory of mind (ToM) in nonhuman primates exploits the idea of a strong and unified theory of mind in humans based on an unanalyzed category of mental state. It also exploits narrow debates about crucial observations and experiments while neglecting wider evolutionary trends. I argue against both exploitations.
The proposition that selective advantages of linguistic skills have contributed to shifts in ontogenetic landmarks of human life histories in early Homo sapiens is weakened by neglecting alternative mechanisms of life history evolution. Moreover, arguments about biological continuity through sweeping comparisons with nonhuman primates do not support various assumptions of this scenario.
Tomasello et al. have not characterized the motivation underlying shared intentionality, and we hope to encourage research on this topic by offering comparative paradigms and specific empirical questions. Although we agree that nonhuman primates differ greatly from us in terms of shared intentionality, we caution against concluding that they lack all aspects of it before other empirical tools have been exhausted. In addition, identifying the conditions in which humans spontaneously engage in shared intentionality, and the conditions in which we (...) fail, will more fully characterize this ability. (shrink)
In the social world, multiple sensory channels are used concurrently to facilitate communication. Among human and nonhuman pri- mates, faces and voices are the primary means of transmitting social signals (Adolphs, 2003; Ghazanfar and Santos, 2004). Primates recognize the correspondence between species-specific facial and vocal expressions (Massaro, 1998; Ghazanfar and Logothetis, 2003; Izumi and Kojima, 2004), and these visual and auditory channels can be integrated into unified percepts to enhance detection and discrimination. Where and how such communication signals are (...) integrated at the neural level are poorly understood. In particular, it is unclear what role “unimodal” sensory areas, such as the auditory cortex, may play. We recorded local field potential activity, the signal that best correlates with human imaging and event-related potential signals, in both the core and lateral belt regions of the auditory cortex in awake behaving rhesus monkeys while they viewed vocalizing conspecifics. We demonstrate unequivocally that the primate auditory cortex integrates facial and vocal signals through enhancement and suppression of field potentials in both the core and lateral belt regions. The majority of these multisensory responses were specific to face/voice integration, and the lateral belt region shows a greater frequency of multisensory integration than the core region. These multisensory processes in the auditory cortex likely occur via recip- rocal interactions with the superior temporal sulcus. (shrink)
This commentary deals with the relation between human language and nonverbal signals used by nonhuman primates. It suggests that human language could have developed through the interaction of procedural learning with a preexisting system for socio-affective communication. The introduction of “content” into existing “frames” requires a neurobiologically plausible learning mechanism.
Heyes discounts findings of imitation and self recognition in nonhuman primates based on flimsy speculation and then indicates that even positive findings would not provide evidence of theory of mind. Her proposed experiment is unlikely to work, however, because, even if the animals have a theory of mind, a number of assumptions, not directly related to theory of mind, must be made about their reasoning ability.
Fast and frugal heuristics function accurately and swiftly over a wide range of decision making processes. The performance of these algorithms in the social domain would be an object for research. The use of simple algorithms to investigate social decision-making could prove fruitful in studies of nonhuman primates as well as humans.
Byrne & Russon provide illustrative examples of imitative abilities in nonhuman primates. The convincing aspects of the examples are not, however, their hierarchical or structured nature: Such organization may be inevitable and hence, does not require explanation via imitation. Rather, examples of imitation are derived from reproduction of behaviors and sequences that, from the organism's perspective, are arbitrary.
Dienes & Perner (D&P) link explicit knowledge of facts to predication. But predication is basically a linguistic notion. Their approach therefore makes it difficult to attribute knowledge of facts to non- language-users, such as animals. The explicit/implicit distinction, as D&P formulate it, is accordingly of little use for exploring the cognitive capacities of nonhuman primates – despite the increasing evidence for sophisticated social awareness among apes, implying mental representations of events in which participants are clearly distinguished. A revised formulation, (...) less biased toward syntax as it happens to have evolved in humans, could avoid this drawback. (shrink)
Recent studies in human and nonhuman primates demonstrate that auditory objects, including speech sounds, are identified in anterior superior temporal cortex projecting directly to inferior frontal regions and not along a posterior pathway, as classically assumed. By contrast, the role of posterior temporal regions in speech and language remains largely unexplained, although a concept of vocal gestures may be helpful.
Knowledge of one's own states of mind is one of the varieties of self-knowledge. Do any nonhuman animals have the capacity for this variety of self-knowledge? The question is open to empirical inquiry, which is most often conducted with primate subjects. Research with a bottlenose dolphin gives some evidence for the capacity in a nonprimate taxon. I describe the research and evaluate the metacognitive interpretation of the dolphin's behaviour. The research exhibits some of the difficulties attached to the task of (...) eliciting behaviour that both attracts a higher-order interpretation while also resisting deflationary, lower-order interpretations. Lloyd Morgan's Canon, which prohibits inflationary interpretations of animal behaviour, has influenced many animal psychologists. There is one defensible version of the Canon, the version that warns specifically against unnecessary intentional ascent. The Canon on this interpretation seems at first to tell against a metacognitive interpretation of the data collected in the dolphin study. However, the model of metacognition that is in play in the dolphin studies is a functional model, one that does not implicate intentional ascent. I explore some interpretations of the dolphin's behaviour as metacognitive, in this sense. While this species of metacognitive interpretation breaks the connection with the more familiar theory of mind research using animal subjects, the interpretation also points in an interesting way towards issues concerning consciousness in dolphins. (shrink)
Human language is a peculiar primate communication tool because of its large neocortical substrate, comparable to the structural substrates of cognitive systems. Although monkey calls and human language rely on different structures, neural substrate for human language emotional coding, prosody, and intonation is already part of nonhuman primate vocalization circuitry. Motherese could be an aspect of language at the crossing or at the origin of communicative and cognitive content.
An evolutionary model of crying requires consideration of nonhuman primate data. Chimpanzees do not have colic. Although they have a peak of fussiness at 6 weeks with a decline by 12 weeks whether raised by biological mothers or in a human nursery, their crying is always consolable. Colic may be a by-product of delayed rates of brain development; that is, neoteny.
We applaud the spirit of MacNeilage's attempts to better explain the evolution and cortical control of speech by drawing on the vast literature in nonhuman primate neurobiology. However, he oversimplifies motor cortical fields and their known individual functions to such an extent that he undermines the value of his effort. In particular, MacNeilage has lumped together the functional characteristics across multiple mesial and lateral motor cortex fields, inadvertantly creating two hypothetical centers that simply may not exist.
Byrne & Russon have argued that imitation is not an all-or-none phenomenon but may instead occur at different levels. Although I applaud their theoretical framework, their data provide little empirical support for the theory. Data from studies of human infants, however, are consistent with the view that imitation may occur at different levels. These data may provide better support for Byrne & Russon's hierarchical view of imitation than the nonhuman primate data that their theory was developed to explain.
Conditional mating strategies and within-sex variation in mating patterns occur across a wide range of primate taxa. Attempts to model the evolution of human mating strategies should incorporate current primatological data sets and phylogenetic perspectives. However, comparisons between interview and questionnaire-based human behavioral data and observationally and experimental generated nonhuman behavioral data should be conducted with prudence.
We suggest that anecdotes have evidentiary value in interpreting nonhuman primate behavior. We also believe that any outcome from the experiments proposed by Heyes can be interpreted as a product of previous experience with trainers or as associative learning using the experimental cues. No potential outcome is clearcut evidence for or against the theory of mind proposition.
Reconstructing the evolution of cognition requires maximal extraction of information from very sparse data. The role that archaeology plays in this process is important, but strong empirical tests of plausible hypotheses are absolutely critical. Quantitative measures of symmetry must be devised, a much deeper understanding of nonhuman primate spatial cognition is needed, and a better understanding of brain/behavior relationships across species is necessary to properly ground these hypotheses.