Effectively, hearing others clearly having a good time, orangutans placed their food order: ‘I will have what they are having, please!’
That is how Dr. Adriano Lameira, a primatologist and evolutionary psychologist at the University of Warwick, described the results of a new study suggesting that orangutans base their food choices on whether their peers appear to be enjoying themselves. According to research published in the journal Biology Letters, captive orangutans valued food rewards more highly when they heard the sounds of other apes laughing before searching for the treats.
The study was led by Dan Lameris, a postdoctoral researcher at Indiana University, and senior author Erica Cartmill, a professor of anthropology and cognitive science at the same institution. The team worked with six orangutans—four males and two females ranging in age from 8 to 51 years, with an average age of 31.7—located at the Oregon Zoo and the Indianapolis Zoo. The animals were trained to find treats, such as cashew nuts and almonds, buried under materials like sawdust, wooden pieces, or moss.
Researchers Test Orangutan Reactions to Specific Sounds
Researchers presented the orangutans with two bowls. One bowl contained a treat hidden under a specific material, while the other contained a different material but no food. Before the bowls were presented, the team played a five-minute recording: either environmental sounds, such as wind or rustling leaves, or the sounds of orangutans playing and laughing. The specific soundtrack played depended on which material was covering the food that day.
On the fifth day of the experiment, the researchers altered the parameters so that both bowls contained treats hidden under the two different materials. Over 30 observations, the researchers tracked which bowl each animal chose. The results showed that the apes generally preferred the bowl containing the material associated with the sounds of laughter. Specifically, four of the six orangutans displayed a clear preference pattern.
The research team suggests that the laughter of other individuals may have shifted the orangutans into a more positive emotional state during the learning process. This indicates that associations with rewards are not solely based on the frequency or quantity of the food, but are influenced by the animal’s internal emotional state at the time of learning.
Implications for Human Learning
Cartmill noted that these findings could have direct applications for human educational environments. She suggested that while students might learn at the same rate regardless of their mood, they may value the information more if they are in a positive emotional state during the process.
Cartmill explained that this could help clarify why certain information is more trusted or why students choose specific paths of study. For instance, she said that if a student is anxious while learning mathematics, that feeling could impact whether they prefer the subject in the future.
While the results suggest that the influence of emotion on memory may be an evolutionarily ancient trait, the researchers acknowledged certain limitations. Because the study involved only six animals and did not directly measure whether the laughter recordings caused a positive emotional change, the team stated that further research is required to rigorously establish the causal link between emotion and learning.
Who you are in that moment – the context, the emotional states, what you’re feeling, what you’re thinking about – can also influence and can carry over in how you remember these things that you’ve learned, Cartmill said