Josep Call

Understanding and sharing intentions: The origins of cultural cognition

We propose that the crucial difference between human cognition and that of other species is the ability to participate with others in collaborative activities with shared goals and intentions: shared intentionality. Participation in such activities requires not only especially powerful forms of intention reading and cultural learning, but also a unique motivation to share psychological states with others and unique forms of cognitive representation for doing so. The result of participating in these activities is species-unique forms of cultural cognition and evolution, enabling everything from the creation and use of linguistic symbols to the construction of social norms and individual beliefs to the establishment of social institutions. In support of this proposal we argue and present evidence that great apes (and some children with autism) understand the basics of intentional action, but they still do not participate in activities involving joint intentions and attention (shared intentionality). Human childrens skills of shared intentionality develop gradually during the first 14 months of life as two ontogenetic pathways intertwine: (1) the general ape line of understanding others as animate, goal-directed, and intentional agents; and (2) a species-unique motivation to share emotions, experience, and activities with other persons. The developmental outcome is childrens ability to construct dialogic cognitive representations, which enable them to participate in earnest in the collectivity that is human cognition.

Does the chimpanzee have a theory of mind? 30 years later

On the 30th anniversary of Premack and Woodruffs seminal paper asking whether chimpanzees have a theory of mind, we review recent evidence that suggests in many respects they do, whereas in other respects they might not. Specifically, there is solid evidence from several different experimental paradigms that chimpanzees understand the goals and intentions of others, as well as the perception and knowledge of others. Nevertheless, despite several seemingly valid attempts, there is currently no evidence that chimpanzees understand false beliefs. Our conclusion for the moment is, thus, that chimpanzees understand others in terms of a perception-goal psychology, as opposed to a full-fledged, human-like belief-desire psychology.

Fission-Fusion Dynamics: New Research Frameworks

Renewed interest in fission‐fusion dynamics is due to the recognition that such dynamics may create unique challenges for social interaction and distinctive selective pressures acting on underlying communicative and cognitive abilities. New frameworks for integrating current knowledge on fission‐fusion dynamics emerge from a fundamental rethinking of the term “fission‐fusion” away from its current general use as a label for a particular modal type of social system (i.e., “fission‐fusion societies”). Specifically, because the degree of spatial and temporal cohesion of group members varies both within and across taxa, any social system can be described in terms of the extent to which it expresses fission‐fusion dynamics. This perspective has implications for socioecology, communication, cognitive demands, and human social evolution.

Ratcheting up the ratchet: on the evolution of cumulative culture

Some researchers have claimed that chimpanzee and human culture rest on homologous cognitive and learning mechanisms. While clearly there are some homologous mechanisms, we argue here that there are some different mechanisms at work as well. Chimpanzee cultural traditions represent behavioural biases of different populations, all within the species’ existing cognitive repertoire (what we call the ‘zone of latent solutions’) that are generated by founder effects, individual learning and mostly product-oriented (rather than process-oriented) copying. Human culture, in contrast, has the distinctive characteristic that it accumulates modifications over time (what we call the ‘ratchet effect’). This difference results from the facts that (i) human social learning is more oriented towards process than product and (ii) unique forms of human cooperation lead to active teaching, social motivations for conformity and normative sanctions against non-conformity. Together, these unique processes of social learning and cooperation lead to humans’ unique form of cumulative cultural evolution.

Apes Save Tools for Future Use

Planning for future needs, not just current ones, is one of the most formidable human cognitive achievements. Whether this skill is a uniquely human adaptation is a controversial issue. In a study we conducted, bonobos and orangutans selected, transported, and saved appropriate tools above baseline levels to use them 1 hour later (experiment 1). Experiment 2 extended these results to a 14-hour delay between collecting and using the tools. Experiment 3 showed that seeing the apparatus during tool selection was not necessary to succeed. These findings suggest that the precursor skills for planning for the future evolved in great apes before 14 million years ago, when all extant great ape species shared a common ancestor.

A Nonverbal False Belief Task: The Performance of Children and Great Apes

A nonverbal task of false belief understanding was given to 4- and 5-year-old children (N = 28) and to two species of great ape: chimpanzees and orangutans (N = 7). The task was embedded in a series of finding games in which an adult (the hider) hid a reward in one of two identical containers, and another adult (the communicator) observed the hiding process and attempted to help the participant by placing a marker on the container that she believed to hold the reward. An initial series of control trials ensured that participants were able to use the marker to locate the reward, follow the reward in both visible and invisible displacements, and ignore the marker when they knew it to be incorrect. In the crucial false belief trials, the communicator watched the hiding process and then left the area, at which time the hider switched the locations of the containers. When the communicator returned, she marked the container at the location where she had seen the reward hidden, which was incorrect. The hider then gave the subject the opportunity to find the sticker. Successful performance required participants to reason as follows: the communicator placed the marker where she saw the reward hidden; the container that was at that location is now at the other location; so the reward is at the other location. Children were also given a verbal false belief task in the context of this same hiding game. The two main results of the study were: (1) childrens performance on the verbal and nonverbal false belief tasks were highly correlated (and both fit very closely with age norms from previous studies), and (2) no ape succeeded in the nonverbal false belief task even though they succeeded in all of the control trials indicating mastery of the general task demands.

What's in it for me? Self-regard precludes altruism and spite in chimpanzees

Sensitivity to fairness may influence whether individuals choose to engage in acts that are mutually beneficial, selfish, altruistic, or spiteful. In a series of three experiments, chimpanzees (Pan troglodytes) could pull a rope to access out-of-reach food while concomitantly pulling another piece of food further away. In the first study, they could make a choice that solely benefited themselves (selfishness), or both themselves and another chimpanzee (mutualism). In the next two experiments, they could choose between providing food solely for another chimpanzee (altruism), or for neither while preventing the other chimpanzee from receiving a benefit (spite). The main result across all studies was that chimpanzees made their choices based solely on personal gain, with no regard for the outcomes of a conspecific. These results raise questions about the origins of human cooperative behaviour.

The learning and use of gestural signals by young chimpanzees: A trans-generational study

Observations of chimpanzee gestural communication are reported. The observations represent the third longitudinal time point of an ongoing study of the Yerkes Primate Center Field Station chimpanzee group. In contrast to observations at the first two time points, the current observations are of a new generation of infants and juveniles. There were two questions. The first concerned how young chimpanzees used their gestures, with special focus on the flexibility or intentionality displayed. It was found that youngsters quite often used the same gesture in different contexts, and different gestures in the same context. In addition, they sometimes used gestures in combinations in a single social encounter, these combinations did not convey intentions that could not be conveyed by the component gestures, however. It was also found that individuals adjusted their choice of signals depending on the attentional state of the recipient. The second question was how chimpanzees acquired their gestural signals. In general, it was found that there was little consistency in the use of gestures among individuals, especially for non-play gestures, with much individual variability both within and across generations. There were also a number of idiosyncratic gestures used by single individuals at each time point. It was concluded from these results that youngsters were not imitatively learning their communicatory gestures from conspecifics, but rather that they were individually conventionalizing them with each other. Implications of these findings for the understanding of chimpanzee communication and social learning are discussed.

The Evolution of Self-Control

Significance Although scientists have identified surprising cognitive flexibility in animals and potentially unique features of human psychology, we know less about the selective forces that favor cognitive evolution, or the proximate biological mechanisms underlying this process. We tested 36 species in two problem-solving tasks measuring self-control and evaluated the leading hypotheses regarding how and why cognition evolves. Across species, differences in absolute (not relative) brain volume best predicted performance on these tasks. Within primates, dietary breadth also predicted cognitive performance, whereas social group size did not. These results suggest that increases in absolute brain size provided the biological foundation for evolutionary increases in self-control, and implicate species differences in feeding ecology as a potential selective pressure favoring these skills. Cognition presents evolutionary research with one of its greatest challenges. Cognitive evolution has been explained at the proximate level by shifts in absolute and relative brain volume and at the ultimate level by differences in social and dietary complexity. However, no study has integrated the experimental and phylogenetic approach at the scale required to rigorously test these explanations. Instead, previous research has largely relied on various measures of brain size as proxies for cognitive abilities. We experimentally evaluated these major evolutionary explanations by quantitatively comparing the cognitive performance of 567 individuals representing 36 species on two problem-solving tasks measuring self-control. Phylogenetic analysis revealed that absolute brain volume best predicted performance across species and accounted for considerably more variance than brain volume controlling for body mass. This result corroborates recent advances in evolutionary neurobiology and illustrates the cognitive consequences of cortical reorganization through increases in brain volume. Within primates, dietary breadth but not social group size was a strong predictor of species differences in self-control. Our results implicate robust evolutionary relationships between dietary breadth, absolute brain volume, and self-control. These findings provide a significant first step toward quantifying the primate cognitive phenome and explaining the process of cognitive evolution.

All great ape species follow gaze to distant locations and around barriers

Following the gaze direction of conspecifics is an adaptive skill that enables individuals to obtain useful information about the location of food, predators, and group mates. In the current study, the authors compared the gaze-following skills of all 4 great ape species. In the 1st experiment, a human either looked to the ceiling or looked straight ahead. Individuals from all species reliably followed the humans gaze direction and sometimes even checked back when they found no target. In a 2nd experiment, the human looked behind some kind of barrier. Results showed that individuals from all species reliably put themselves in places from which they could see what the experimenter was looking at behind the barrier. These results support the hypothesis that great apes do not just orient to a target that another is oriented to, but they actually attempt to take the visual perspective of the other.