Chimps, like humans, focus on faces

July 23, 2009

A chimp's attention is captured by faces more effectively than by bananas. A series of experiments described in BioMed Central's open access journal Frontiers in Zoology suggests that the apes are wired to respond to faces in a similar manner to humans.

Masaki Tomonaga and Tomoko Imura from the Primate Research Institute at Kyoto University, Japan, tested the effects of a series of different images on chimps' reaction times. Tomonaga said, "It is well known that faces are processed in a different manner from other types of complex visual stimuli. Recent studies of face perception in humans clarified that faces represent special stimuli with regard to visuospatial attention as well. That is, they are able to capture our attention. We've shown that chimps share this tendency to notice and pay attention to faces in preference to other objects."

The researchers gave chimps the option of playing a game for food. If the chimps chose to, they could approach a computer screen where an image would be displayed, followed by a target. If the chimps pressed the target, they would receive a reward. In one set of experiments, the image was displayed on one side of the screen followed by the target either on the same side or the previously blank side. Reaction times were shown to improve when the target appeared behind the image. The chimps were then presented with two images side by side, one of which was a chimpanzee face. When the target appeared behind the face, reaction times were better than when it appeared behind the other object - showing that attention had indeed been drawn to the face-side of the screen.

Chimpanzee faces were shown to attract attention more effectively than bananas and other objects such as flowers, houses or trains. This effect was reduced when the faces were inverted, suggesting that it is the specific configuration of an upright face that catches the eye. According to Tomonaga, "This attentional capture was also observed when upright human faces were presented, indicating that this effect is not limited to their own species".

More information: Faces capture the visuospatial attention of chimpanzees (Pan troglodytes): evidence from a cueing experiment, Masaki Tomonaga and Tomoko Imura, Frontiers in Zoology (in press), http://www.frontiersinzoology.com/

Source: BioMed Central (news : web)