[Show abstract][Hide abstract] ABSTRACT: Orang-utans played a communication game in two studies testing their ability to produce and comprehend requestive pointing. While the ‘communicator’ could see but not obtain hidden food, the ‘donor’ could release the food to the communicator, but could not see its location for herself. They could coordinate successfully if the communicator pointed to the food, and if the donor comprehended his communicative goal and responded pro-socially. In Study 1, one orang-utan pointed regularly and accurately for peers. However, they responded only rarely. In Study 2, a human experimenter played the communicator’s role in three conditions, testing the apes’ comprehension of points of different heights and different degrees of ostension. There was no effect of condition. However, across conditions one donor performed well individually, and as a group orang-utans’ comprehension performance tended towards significance. We explain this on the grounds that comprehension required inferences that they found difficult – but not impossible. The finding has valuable implications for our thinking about the development of pointing in phylogeny.
PLoS ONE 12/2015; 10(6). DOI:10.1371/journal.pone.0129726 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Animals react in many different ways to being watched by others. In the context of cooperation, many theories emphasize reputational effects: Individuals should cooperate more if other potential cooperators are watching. In the context of competition, individuals might want to show off their strength and prowess if other potential competitors are watching. In the current study, we observed chimpanzees and human children in three experimental conditions involving resource acquisition: Participants were either in the presence of a passive observer (observed condition), an active observer who engaged in the same task as the participant (competition condition), or in the presence of but not directly observed by a conspecific (mere presence condition). While both species worked to acquire more resources in the competition condition, children but not chimpanzees also worked to acquire more resources in the observer condition (compared to the mere presence condition). These results suggest evolutionary continuity with regard to competition-based observer effects, but an additional observer effect in young children, potentially arising from an evolutionary-based concern for cooperative reputation.
[Show abstract][Hide abstract] ABSTRACT: In two experiments, we investigated whether chimpanzees, Pan troglodytes, can use self-experience to infer what another sees. Subjects first gained self-experience with the visual properties of an object (either opaque or see-through). In a subsequent test phase, a human experimenter interacted with the object and we tested whether chimpanzees understood that the experimenter experienced the object as opaque or as see-through. Crucially, in the test phase, the object seemed opaque to the subject in all cases (while the experimenter could see through the one that they had experienced as see-through before), such that she had to use her previous self-experience with the object to correctly infer whether the experimenter could or could not see when looking at the object. Chimpanzees did not attribute their previous self-experience with the object to the experimenter in a gaze-following task (experiment 1); however, they did so successfully in a competitive context (experiment 2). We conclude that chimpanzees successfully used their self-experience to infer what the competitor sees. We discuss our results in relation to the well-known 'goggles experiment' and address alternative explanations.
[Show abstract][Hide abstract] ABSTRACT: Humans often must coordinate co-occurring activities, and their flexible skills for doing so would seem to be uniquely powerful. In 2 studies, we compared 4- and 5-year-old children and one of humans' nearest relatives, chimpanzees, in their ability to focus and shift their attention when necessary. The results of Study 1 showed that 4-year-old children and chimpanzees were very similar in their ability to monitor two identical devices and to sequentially switch between the two to collect a reward, and that they were less successful at doing so than 5-year-old children. In Study 2, which required subjects to alternate between two different tasks, one of which had rewards continuously available whereas the other one only occasionally released rewards, no species differences were found. These results suggest that chimpanzees and human children share some fundamental attentional control skills, but that such abilities continue to develop during human ontogeny, resulting in the uniquely human capacity to succeed at complex multitasking. (PsycINFO Database Record
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[Show abstract][Hide abstract] ABSTRACT: A central challenge of investigating the underlying mechanisms of and the individual differences in young children's behavior is the measurement of the internal physiological mechanism and the involved expressive emotions. Here, we illustrate two paradigms that assess concurrent indicators of both children's social perception as well as their emotional expression. In one set of studies, children view situations while their eye movements are mapped onto a live scene. In these studies, children's internal arousal is measured via changes in their pupil dilation by using eye tracking technology. In another set of studies, we measured children's emotional expression via changes in their upper-body posture by using depth sensor imaging technology. Together, these paradigms can provide new insights into the internal mechanism and outward emotional expression involved in young children's behavior.
Frontiers in Psychology 07/2015; 6:858. DOI:10.3389/fpsyg.2015.00858 · 2.80 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Humans often strategically manipulate the informational access of others to their own advantage. Although chimpanzees know what others can and cannot see, it is unclear whether they can strategically manipulate others' visual access. In this study, chimpanzees were given the opportunity to save food for themselves by concealing it from a human competitor and also to get more food for themselves by revealing it to a human cooperator. When knowing that a competitor was approaching, chimpanzees kept more food hidden (left it covered) than when expecting a cooperator to approach. When the experimenter was already at the location of the hidden food, they actively revealed less food to the competitor than to the cooperator. They did not actively hide food (cover up food in the open) from the competitor, however. Chimpanzees thus strategically manipulated what another could see in order to maximize their payoffs and showed their ability to plan for future situations.
[Show abstract][Hide abstract] ABSTRACT: We provide an analysis of holdout and giving (Ho&G) behaviours in prelinguistic infants and investigate their relationship with index finger pointing. The frequency of Ho&Gs at 10 and 11 months along with the length of the following social interaction correlated with index finger pointing at 12 months. We conclude that Ho&Gs are a precursor to index finger pointing and that this provides support for social-pragmatic approaches to communicative development.
[Show abstract][Hide abstract] ABSTRACT: In face-to-face bargaining tasks human adults almost always agree on an equal split of resources. This is due to mutually recognized fairness and equality norms. Early developmental studies on sharing and equality norms found that egalitarian allocations of resources are not common before children are 5 or 6 years old. However, recent studies have shown that in some face-to face collaborative situations, or when recipients express their desires, children at much younger ages choose equal allocations. We investigated the ability of 3.5 and 5-year-olds to negotiate face-to-face, whether to collaborate to obtain an equal or an unequal distribution of rewards. We hypothesized that the face-to-face interaction and interdependency between partners would facilitate egalitarian outcomes at both ages. In the first experiment we found that 5-year-olds were more egalitarian than 3.5-year-olds, but neither of the age classes shared equally. In the second experiment, in which we increased the magnitude of the inequality, we found that children at both ages mostly agreed on the unequal distribution. These results show that communication and face-to-face interactions are not sufficient to guarantee equal allocations at 3-5 years of age. These results add to previous findings suggesting that in the context of non-collaboratively produced resources it is only after 5 years of age that children use equality norms to allocate resources.
PLoS ONE 03/2015; 10(3):e0120494. DOI:10.1371/journal.pone.0120494 · 3.23 Impact Factor