Laughter Sounds Boost Orangutans’ Appetite for Rewards

WHO:

The Guardian - The study involved six captive orangutans at two zoological institutions.

The Guardian - Erica Cartmill, professor of anthropology and cognitive science at Indiana University, was a senior author of the study.

The Guardian - Dr Adriano Lameira, a primatologist and evolutionary psychologist at the University of Warwick, was not involved in the study.

Phys.org - The study came from the lab of Erica Cartmill, professor of animal behavior, anthropology and cognitive science in the College of Arts and Sciences at Indiana University Bloomington.

Phys.org - Daan Laméris, a postdoctoral researcher at Indiana University, led the study.

WHAT:

The Guardian - Researchers reported in the journal *Biology Letters* that orangutans generally preferred a bowl containing the material previously associated with recordings of orangutans playing and laughing; four of the six showed a clear preference.

The Guardian - The researchers said the results suggest an animal’s emotional state while learning an association can influence how it remembers and values what it learned.

The Guardian - Cartmill said the findings might apply to education: students may value information more if they learn it in a good mood, even if their learning rate is similar.

The Guardian - Cartmill said mood while learning mathematics could affect whether a student later prefers mathematics over other subjects.

The Guardian - Lameira called the findings “fascinating” and described the orangutans’ response as, “I will have what they are having, please!”

Phys.org - The study found that hearing laughter may lead orangutans to value learned rewards more strongly.

WHY:

The Guardian - Cartmill said the research is part of a larger project investigating whether animals feel joy and how emotions affect cognition and learning.

The Guardian - Cartmill said the researchers aimed to extend human research on how emotion affects rational thought to animals, in this study orangutans.

HOW:

The Guardian - Researchers trained the orangutans to search bowls for food treats, then offered a bowl with a treat under moss or sawdust and another bowl containing a different material without a treat.

The Guardian - Before presenting the bowls, researchers played either recordings of orangutans playing and laughing or environmental sounds such as wind; the soundtrack depended on which covering substance was used that day.

The Guardian - On the fifth day, both bowls contained treats beneath one of the two covering substances, and the orangutans chose a bowl.

The Guardian - The researchers ran multiple trials and found that the orangutans generally chose the covering material associated with laughter.

Phys.org - The study examined whether hearing laughter affected how strongly orangutans valued what they had learned.

(UPDATED October 22, 2026 11:12 UTC)

Six captive orangutans took part in a study suggesting that hearing laughter can make them value a learned reward more strongly. Researchers trained the animals to find treats hidden under moss or sawdust, pairing each covering material with either recordings of orangutans playing and laughing or environmental sounds. On the fifth day, both bowls held treats, and the orangutans chose between them. Four showed a clear preference for the material previously paired with laughter. The study, published in *Biology Letters*, was led by Indiana University postdoctoral researcher Daan Laméris, with professor Erica Cartmill as a senior author. Cartmill said the findings suggest emotions during learning can shape how information is remembered and valued. She said the idea may also apply to education: a positive mood could affect whether students later favor a subject, even if it does not change how quickly they learn.