original text: http://www.nature.com/nsu/010419/010419-2.html

Wednesday 18 April 2001

lifelines: Chimps touched by television

If you reach for your hanky as Leonardo DiCaprio slips beneath the freezing Altlantic waves in Titanic, or dive behind the sofa during Alien, you may not be alone. A new study suggests that humans are not the only animals to feel sad or scared when watching television — chimpanzees are also moved by video clips of fearful or appealing scenes.

What's more, Lisa Parr of Yerkes Regional Primate Research Center in Atlanta, Georgia has found that chimps (Pan troglodytes) respond physically to events portrayed in videos just as they would to the events themselves¹.

The ability to respond appropriately to the emotions of others is widely recognized as a human trait. Other animals — particularly primates — express emotional information by screaming, for example, or by making a scared face so that other members of their species can make use of the information.

Whether these expressions are simply for communication purposes, or whether primates are aware of the emotional importance of the faces they make is the subject of much debate.

Parr worked with three lab-reared chimps, trained to move a cursor on a computer monitor with a joystick to select and match different images on the screen. She presented the chimps with short video clips of situations resembling those they experience during a medical check-up, such as scenes in which a veterinarian gives another chimp an injection, or a chimp expresses fear at being approached by a veterinarian holding a dart gun.

Given pictures of chimps' faces — a 'play' face featuring a relaxed, open-mouthed expression, a fear grimace (bared teeth) or an alarm face (screaming) — the chimps consistently matched negative faces with videos of unpleasant scenes. Conversely, after watching videos showing 'positive scenes' that did not involve other chimps, such as clips of favourite foods, the chimps regularly chose the play face.

The animals had previously used the apparatus to match images that belong in the same category — such as pictures of different food items — but had never before matched incongruous images that could only be connected according to their emotional content.

Parr believes these new results show that the chimps were making their decisions solely on the basis of the emotional implications of the images, rather than the images themselves. "Outside the context of the social environment we were able to show that [emotional scenes] have meaning in a representative way," she said.

Parr also recorded the skin temperature of the chimpanzees while they watched the video clips, and found that it fell in response to scary scenes. A drop in skin temperature is typically representative of fear or sadness, which hints that the chimps were empathizing with their on-screen fellows.

"It tells us a lot about the amount of information they share in their social group," says Parr. "It's clear that they get a lot of information from each other and can use that information in complex ways."

1. Parr, L. Cognitive and physiological markers of emotional awareness in Chimpanzees (Pan troglodytes). Animal Cognition (2001) (In the press).

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