How do babies laugh? Like a chimpanzee!

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November 7, 2018

November 7, 2018, Acoustical Society of America

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Some things can please adults more easily than children's unavoidable laughter. But baby laughter, a new study shows, different from adult laughter in a key way: Babies laugh when they exhale and breathe in a way that is very similar to non-human primates.

This research will be explained by Disa Sauter, a psychologist and professor at the University of Amsterdam in the Netherlands, while speaking at the 176th Meeting of the Acoustical Society of America, held in conjunction with the Canadian Acoustics 2018 Acoustics Association in Canada, Nov 5-9 at the Victoria Conference Center in Victoria, Canada.
Together with his colleagues – psychologist Mariska Kret and graduate student Dianne Venneker from Leiden University in the Netherlands, and Bronwen Evans, a phonetic at University College London – Sauter studied laughter clips taken from 44 babies and children between the ages of 3 and 18 months . Records are taken from online videos where babies engage in pleasant interactions. The recording was then analyzed by 102 listeners, who were recruited from the psychology student population, who evaluated the extent of laughter in each clip produced on breath versus inhaling.
Sauter and his colleagues found that the youngest babies generally laugh when inhaling and exhaling, as do non-human primates such as chimpanzees. However, in the older infants studied, laughter is mainly produced only when exhaling, as in older children and adults.
Credit: Acoustical Society of America
"Adult humans sometimes laugh when they breathe, but the proportions are very different from the laughter of babies and chimpanzees. Our results so far show that this is a gradual shift, not sudden, "said Sauter, who pointed out that the transition does not seem to be related to certain milestones. He noted, however, that these results were based on the listener's absence. "We are currently examining these results against judgments by phonetics, which make detailed annotations about laughter."
Credit: Acoustical Society of America Sauter said that there is no acceptable reason why humans, alone among primates, only laugh when exhaled. One possibility, he said, is that it is a result of human vocal control developing when they learn to speak.
Credit: Acoustical Society of America Researchers are currently examining whether there is a relationship between the amount of laughter produced during inhalation and breathing and the reason why individuals laugh, which also changes with age. In infants and younger babies, as in nonhuman primates, laughter occurs as a result of physical play such as tickling. In older individuals, laughter can arise from physical play but also from social interaction.
"Beyond that, I would be interested to see if our findings apply to other vocalizations other than laughter," Sauter said. In the end, research can offer insight into the vocal production of children with developmental disorders. "If we know what a baby's voice usually develops, it can be interesting to study babies at risk to see if there are early signs of atypical development in their emotional nonverbal vocalizations."

Explore more:
The ability to identify genuine laughter goes beyond culture, studies found

Further information:
Presentation # 3aSC5, "How do babies laugh?" By Disa Sauter, Bronwen Evans, Dianne Venneker and Mariska Kret will be Wednesday, November 7, 9:25 at SALON A from the Victoria Conference Center in Victoria, British Columbia, Canada. acousticalsociety.org/asa-meetings/