By Victoria Gill
Science reporter, BBC News
The animations were designed by copying the pattern of real chimps' yawns
Yawning is so contagious that chimpanzees can "catch" it from cartoons, according to research.
Scientists from Emory University in Atlanta, US, have discovered that an animation of a yawning chimp will stimulate real chimps to yawn.
They describe in the Royal Society journal, Proceedings B, how this could assist in the future study of empathy.
The work could also help unravel if and how computer games might cause children to imitate what they see on screen.
Previous studies have already shown contagious yawning in chimpanzees - stimulated by video-recorded footage of yawns.
"We wanted to expand on that," explained Matthew Campbell, a researcher from Emory University's Yerkes National Primate Research Center and lead author of the study.
"We're interested in using animation for presenting stimuli 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 animations into thinking they were looking at real chimps, he explained that there was evidence that chimpanzees "process animated 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.
Chimps are social animals and respond to facial expressions
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 consolation - 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? If so, that could be really useful for work with humans as well."