Orangutans chose bowls with material associated with laughter — The Guardian

Orangutans that heard recordings of other individuals playing and laughing were more likely to choose bowls containing material that had previously been associated with those sounds. In a study involving six animals, four orangutans showed a clear preference for this choice, The Guardian reports.

How the experiment was conducted

Scientists worked with six orangutans from two zoological institutions. First, the animals were taught to look for treats in bowls. In one bowl, food was hidden under safe material, including moss or sawdust, while the other contained different material without treats.

Before showing the bowls, researchers played recordings of orangutans playing and laughing, or environmental sounds such as wind. The type of audio recording depended on which of the two materials covered the food that day.

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What the results showed

On the fifth day of the experiment, both bowls contained treats hidden beneath different materials. The orangutans were offered a choice of one bowl. Across several trials, the animals generally chose the bowl with material associated with laughter sounds more often.

The work was published in the journal Biology Letters. The study’s senior author, Erika Cartmill, a professor of anthropology and cognitive sciences at Indiana University, suggested that laughter may have created a more positive emotional state in the animals while they formed an association between the material and food. In her view, learning such associations may be influenced not only by the amount or frequency of reward, but also by the animal’s emotional state.