"When you watch a shocking, emotional event in a movie, you remember the event well, and later on, when you watch the same movie, you anticipate the event," co-author Fumihiro Kano of Kyoto University said in a press release.
"Thanks to a recent advance of state-of-the-art eye-tracking technologies," he added, "we could examine event anticipation by great apes while watching a movie by means of ‘anticipatory looks' to the impending events."
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To do this, Kano and his team created two short films starring themselves. In the first flick, an aggressive person in an ape suit comes out from one of two identical doors. In the second film, a human actor grabs one of two objects and attacks the ape-like character with it.
Both films were shown to six chimps and six bonobos, who were riveted to the screen, so much so that they did not want any distractions, however tasty.
"We were giving juice while showing the videos to them," Kano explained, "but some of them even forgot to drink juice and stared at the movies!"
An eye tracker, which monitored all of the eye movements of the chimps and bonobos as they watched the films, showed that the primates anticipated what they were about to see after a single viewing of the movie.
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On a second viewing of the first movie, the primates directed their attention to the door where they knew the person dressed as an ape would appear. While watching the second film again, the animals looked in anticipation at the object they knew would soon be used as a kind of weapon, even when that object was placed in a different location than they had seen earlier.
All of this means that the chimps and bonobos stored information from the first film into their long-term memories, just as humans do. They were then able to use that info later to anticipate events that were about to happen.
Aside from the novelty of the findings, the research is enabling the scientists to determine what high-level cognitive functions non-human primates are capable of performing. Kano and his team next hope to test whether or not the animals understand that others have beliefs, desires, intentions, and perspectives that differ from their own.