Yawning is so contagious¹ that chimpanzees can "catch" it from cartoons, according to research.

研究显示，打呵欠也会传染，黑猩猩能从卡通片里“学会”打呵欠。

Chimps³ are social animals and respond to facial expressions" width="226" border="0" src="/upimg/090909/4_032923_1.jpg" />
Chimps are social animals and respond to facial expressions

Scientists from Emory University in Atlanta, US, have discovered that an animation⁴ of a yawning chimp² will stimulate⁵ real chimps to yawn.

They describe in the Royal Society journal, Proceedings⁶ B, how this could assist in the future study of empathy（移情作用，神入）.

The work could also help unravel⁷（阐明，解释） if and how computer games might cause children to imitate what they see on screen.

Previous studies have already shown contagious（传染性的） yawning in chimpanzees - stimulated⁸ by video-recorded footage of yawns.

"We wanted to expand on that," explained Matthew Campbell, a researcher from Emory University's Yerkes National Primate⁹ Research Center and lead author of the study.

"We're interested in using animation for presenting stimuli¹⁰ to animals, because we can control all the features of what we show them," he continued.

Although Dr Campbell doesn't think the chimps were "fooled" by the animations¹¹ into thinking they were looking at real chimps, he explained that there was evidence that chimpanzees "process animated¹² faces the same way they process photographs of faces".

He said: "It's not a real chimpanzee, but it kind of looks like a chimpanzee, and they're responding to that."

He and his team, including Devyn Carter who designed the animations, showed the animals the yawning sequences.

"We also had the animations doing other movements with their mouths that the chimps often do," he said.

"The chimps showed a lot more yawning during the yawn video than when the control videos were playing.

He told BBC News that the only way he and his colleagues could explain the "very strong difference" they saw was that seeing the yawns was making the animals yawn.

On screen

This is an introductory experiment that the researchers say has demonstrated the utility of animations in behavioural experiments.

In his future work, Dr Campbell would like to pin down exactly how these measurable behaviours are related to the more difficult to measure phenomenon of empathy.

"We'd like to know more about behaviours related to empathy, like consolation¹³ - when an individual does something nice to the victim of aggression," he told BBC News.

"So we want to see if our good contagious yawners are also good consolers."

As well as tracing the development of empathy in our primate relatives, the research could have a more direct human perspective.

"There's a lot of concern about children and what they see on TV and the video games they play, so one possibility is to look at what factors in animations promote more or less imitation in non-humans," said Dr Campbell.

"So if we make the animations more realistic, are we going to get more contagious yawning out of the chimpanzees?

"And does that imply that realism promotes mimicry（模仿，拟态伪装）? If so, that could be really useful for work with humans as well."