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Living psychology: animal minds
Living psychology: animal minds

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6.3 Chimpanzees’ understanding of perception and knowledge

Understanding another’s perspective − appreciating that what someone else sees can be different from what we see ourselves, and that what they see will influence both their knowledge and behaviours − has been considered to be a basic element of Theory of Mind (ToM).

Stronger evidence that chimpanzees may understand seeing in a way that implies an understanding of mental states originates from what has come to be known as the food competition paradigm (Call and Tomasello, 2008; this procedure was first introduced by Hare et al., 2000).

In their natural social environments, chimpanzees are often in situations involving competition for food with other conspecifics in their group. It has been suggested that considering these more naturalistic types of behaviours, rather than those involving (for example) cooperative interactions with humans, might be a better and more sensible way to test for any understanding of other minds in chimpanzees, and other animals (Hare et al., 2000).

The food competition paradigm involves a procedure in which a dominant chimpanzee and a subordinate chimpanzee are competing for food. Box 3 describes the basic procedure used in this type of study.

Box 3 The food competition paradigm procedure

Figure 11 displays the basic procedure used in the food competition paradigm. A subordinate chimpanzee and a dominant chimpanzee are each placed in a room, located on opposite sides of a middle room. Each of the side rooms has a door that leads into the middle room. As depicted in Figure 11, these doors can be partly raised, which allows each individual to see into the middle room, and to see the other chimpanzee looking under their own door. The experimental procedure involves a human placing pieces of food at various locations within the room, in view of one or both of the chimpanzees (where the food is placed, and which of the chimpanzees is able to watch it being placed, varies according to the experimental condition). Once the food has been placed, the doors for both individuals are opened wide so they can enter the middle room.

The basic problem for the subordinate chimpanzee is that the dominant chimpanzee will take all of the food it can see (or has seen being placed, and so knows where it is). The small barriers (labelled ‘occluders’ in Figure 11), allow the food to be placed so that only one or other chimpanzee can see it.

Described image
Figure 11 The food competition paradigm (Source: based on Hare et al., 2000)

Hare et al. (2000) used variations on the food competition procedure in order to create two main conditions. In one condition, food was placed so that both animals could see it; and in the other condition (Figure 12), the food was placed behind a small barrier (occluder) so the subordinate chimpanzee could see it, but the dominant chimpanzee could not . The question of interest was whether the subordinate chimpanzee would take into account whether the dominant competitor was able to see the food or not, and act accordingly.

Described image
Figure 12 The food competition paradigm − variation

It was found that the subordinate chimpanzee did seem to detect whether the dominant chimpanzee could or could not see the food, as they approached the food more frequently when it could not be seen by the dominant chimpanzee. This finding does suggest that the subordinate chimpanzee had the ability to understand perception, at least to the extent of being able to track what others see.

A number of variations on this study design, based on the same food competition paradigm, have been implemented, which have generally led to further evidence of an understanding of perception in chimpanzees. Hare and colleagues (2001) adapted this procedure in order to test whether chimpanzees seem to understand what another has seen, as well as what they can currently see, and thus in a sense what the other ‘knows’ (Apperly, 2011). In their study, they manipulated the procedure described in Box 3, so that the dominant chimpanzee could not see the food that was hidden behind the barrier in any of the conditions, but either had or had not seen it being placed behind the barrier. The question then becomes: is the subordinate chimpanzee less likely to approach the food that the dominant chimpanzee has seen placed, and thus knows is there? Indeed, this is the result that was found, suggesting that chimpanzees may also understand that seeing something leads to possessing knowledge in the future.

While behavioural rules might explain the chimpanzees’ behaviours in any one of these various food competition studies, Call and Tomasello (2008) have argued that, taking all these studies together, they present strong evidence for an understanding that others have perceptions that lead them to see and know things. Thus, chimpanzees arguably do behave − even in controlled laboratory studies − in ways that can reasonably be interpreted as indicating that they do have an understanding of the mental states of perception and knowledge.

In the next section of this course you will consider the evidence regarding chimpanzees’ understanding of false belief, that is beliefs that are not consistent with reality.