Domestic dogs (Canis familiaris) perform above chance on invisible displacement tasks despite showing few other signs of possessing the necessary representational abilities. Four experiments investigated how dogs find an object that has been hidden in 1 of 3 opaque boxes. Dogs passed the task under a variety of control conditions, but only if the device used to displace the object ended up adjacent to the target box after the displacement. These results suggest that the search behavior of dogs was guided by simple associative rules rather than mental representation of the object's past trajectory. In contrast, Experiment 5 found that on the same task, 18-and 24-month-old children showed no disparity between trials in which the displacement device was adjacent or nonadjacent to the target box.The invisible displacement task was originally conceived by Piaget (1937Piaget ( /1954) as a measure of toddlers' transition to Stage 6 in his theory of object permanence. In the classic task, the subject sees the experimenter hide a desired object under a displacement device, typically a small opaque container. The experimenter slides the displacement device under one of several hiding boxes, surreptitiously deposits the object beneath this box, and shows the subject that the displacement device is now empty. To find the object, the subject cannot rely on perceptual information alone but rather must infer the object's location by mentally representing its past trajectory (e.g., Call, 2001). The task is thus thought to provide evidence of representational thought: the ability to entertain representations of objects or events that cannot be directly perceived.As such, Piaget's invisible displacement task continues to feature strongly in both developmental and comparative research and theory. In Perner's (1991) theory of representational development, for example, passing the invisible displacement task is one of several markers of the emergence of a capacity for secondary representation. Perner suggests that prior to the middle of their 2nd year, infants have access only to primary representations; that is, they maintain a direct model of reality that is continually updated with incoming perceptual information. Passing the invisible displacement task indicates that the child can go beyond a single updating model to entertain multiple models of the world. That is, the child is able to hold in mind a model of the current world (primary representation: displacement device empty) as well as a model of the past world (secondary representation: displacement device with object under large box). By collating these two models the child can infer the likely location of the surreptitiously displaced object. Children typically begin passing the invisible displacement task at approximately 18 -24 months of age (e.g., Kramer, Hill, & Cohen, 1975;Piaget, 1937Piaget, /1954. Perner (1991) argues that several other abilities emerging in the 2nd year, such as mirror self-recognition and pretend play, also involve secondary representations. At le...

Using the cups task, in which subjects are presented with limited visual or auditory information that can be used to deduce the location of a hidden reward, Call (2004) found prima facie evidence of inferential reasoning by exclusion in several great ape species. One bonobo (Pan paniscus) and two gorillas (Gorilla gorilla) appeared to make such inferences in both the visual and auditory domains. However, common chimpanzees (Pan troglodytes) were successful only in the visual domain, and Bornean orangutans (Pongo pygmaeus) in neither. The present research built on this paradigm, and Experiment 1 yielded prima facie evidence of inference by exclusion in both domains for two common chimpanzees, and in the visual domain for two Sumatran orangutans (Pongo abelii). Experiments 2 and 3 demonstrated that two specific associative learning explanations could not readily account for these results. Because an important focus of the program of research was to assess the cognitive capacities of lesser apes (family Hylobatidae), we modified Call's original procedures to better suit their attentional and dispositional characteristics. In Experiment 1, testing was also attempted with three gibbon genera (Symphalangus, Nomascus, Hylobates), but none of the subjects completed the standard task. Further testing of three siamangs (Symphalangus syndactylus) and a spider monkey (Ateles geoffroyi) using a faster method yielded prima facie evidence of inferential reasoning by exclusion in the visual domain among the siamangs (Experiment 4).

Social information use is a pivotal characteristic of the human species. Avoiding the cost of individual exploration, social learning confers substantial fitness benefits under a wide variety of environmental conditions, especially when the process is governed by biases toward relative superiority (e.g., experts, the majority). Here, we examine the development of social information use in children aged 4–14 years (n = 605) across seven societies in a standardised social learning task. We measured two key aspects of social information use: general reliance on social information and majority preference. We show that the extent to which children rely on social information depends on children’s cultural background. The extent of children’s majority preference also varies cross-culturally, but in contrast to social information use, the ontogeny of majority preference follows a U-shaped trajectory across all societies. Our results demonstrate both cultural continuity and diversity in the realm of human social learning.

Osvath and Osvath (Anim Cogn 11: 661-674, 2008) report innovative studies with two chimpanzees and one orangutan that suggest some capacity to select and keep a tool for use about an hour later. This is a welcome contribution to a small, but rapidly growing, field. Here we point out some of the weaknesses in the current data and caution the interpretation the authors advance. It is not clear to what extent the apes really engaged in any foresight in these studies.

The human aptitude for imitation and social learning underpins our advanced cultural practices. While social learning is a valuable evolutionary survival strategy, blind copying does not necessarily facilitate survival. Copying from the majority allows individuals to make rapid judgments on the value of a trait, based on its frequency. This is known as the majority bias: an individual's tendency to copy the behavior elicited by the largest number of individuals in a population. An alternative approach is to follow those who are the most proficient. While there is evidence that children do show both processes, no study has directly pitted them against each other. To do this, in the current experiment 36 children aged between 4 and 5 years watched live actors demonstrate, as a group or individually, how to open novel puzzle boxes. Children exhibited a bias to the majority when group and individual methods were successful, but favored the individual if the group method was unsuccessful. Affiliating children with the unsuccessful majority group did not impact on this pattern.

Previous research suggests that chimpanzees understand single invisible displacement. However, this Piagetian task may be solvable through the use of simple search strategies rather than through mentally representing the past trajectory of an object. Four control conditions were thus administered to two chimpanzees in order to separate associative search strategies from performance based on mental representation. Strategies involving experimenter cue-use, search at the last or first box visited by the displacement device, and search at boxes adjacent to the displacement device were systematically controlled for. Chimpanzees showed no indications of utilizing these simple strategies, suggesting that their capacity to mentally represent single invisible displacements is comparable to that of 18-24-month-old children.

Mirror self-recognition typically emerges in human children in the second year of life and has been documented in great apes. In contrast to monkeys, humans and great apes can use mirrors to inspect unusual marks on their body that cannot be seen directly. Here we show that lesser apes (family Hylobatidae) fail to use the mirror to find surreptitiously placed marks on their head, in spite of being strongly motivated to retrieve directly visible marks from the mirror surface itself and from their own limbs. These findings suggest that the capacity for visual self-recognition evolved in a common ancestor of all great apes after the split from the line that led to modern lesser apes approximately 18 Myr ago. They also highlight the potential of a comparative approach for identifying the neurological and genetic underpinnings of self-recognition and other higher cognitive faculties.

Chimpanzees (Pan troglodytes) and young children (Homo sapiens) have difficulty with double invisible displacements in which an object is hidden in two nonadjacent boxes in a linear array. Experiment 1 eliminated the possibility that chimpanzees' previous poor performance was due to the hiding direction of the displacement device. As in Call (2001), subjects failed double nonadjacent displacements, showing a tendency to select adjacent boxes. In Experiments 2 and 3, chimpanzees and 24-month-old children were tested on a new adaptation of the task in which four hiding boxes were presented in a diamond-shaped array on a vertical plane. Both species performed above chance on double invisible displacements using this format, suggesting that previous poor performance was due to a response bias or inhibition problem rather than a fundamental limitation in representational capacity.