Orangutans favoured food linked to laughter in a six-ape study
In a five-day experiment with six orangutans, researchers found the apes generally preferred food hidden under material they had searched while hearing recordings of other orangutans laughing. Four of the six showed a clear preference; the Indiana University team said positive mood may have made the associated reward more valuable.
Bottom line — Four of six orangutans favoured the laughter-linked food, though the experiment did not directly measure a change in mood.
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The study appeared in Biology Letters and involved orangutans at zoos in Belgium and the United States, according to the research coverage.
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Researchers paired laughter with one bowl-covering material and environmental sounds, such as wind, with another.
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On the fifth day, both materials concealed food, allowing researchers to test which association the orangutans preferred.
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The study involved only six animals; DongA Science noted that it did not directly establish that laughter caused a positive emotional change.
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Senior author Erica Cartmill said the findings suggest an animal’s emotional state while learning may influence how it values what it later remembers.