Detecting affiliation in colaughter across 24 societies
- aDepartment of Communication Studies, University of California, Los Angeles, CA 90095;
- bUCLA Center for Behavior, Evolution, and Culture, University of California, Los Angeles, CA 90095;
- cDepartment of Anthropology, University of California, Los Angeles, CA 90095;
- dInteracting Minds Center, Aarhus University, 8000 Aarhus C, Denmark;
- eCenter for Semiotics, Aarhus University, 8000 Aarhus C, Denmark;
- fDepartment of Political Science and Government, Aarhus University, 8000 Aarhus C, Denmark;
- gDepartment of Psychology, University of Pennsylvania, Philadelphia, PA 19104;
- hDepartment of Political Science and Government, Aarhus University, 8000 Aarhus C, Denmark;
- iIndependent Scholar;
- jDepartment of Anthropology, College of DuPage, Glen Ellyn, IL 60137;
- kDepartment of Psychology, Pontificia Universidad Catolica del Peru, San Miguel Lima, Lima 32, Peru;
- lDepartment of Interdisciplinary Study of Law, Private Law and Business Law, Ghent University, 9000 Ghent, Belgium;
- mDepartment of Biology, University of Trnava, 918 43 Trnava, Slovakia;
- nDepartment of Biblical and Ancient Studies, University of South Africa, Pretoria 0002, South Africa;
- oDepartment of Biology, University of Auckland, Aukland 1142, New Zealand;
- pDepartment of Sociology, Fudan University, Shanghai 200433, China;
- qDepartment of Psychology, Karnatak University Dharwad, Karnataka 580003, India;
- rDepartment of Social Psychology, University of Tokyo, 7 Chome-3-1 Hongo, Tokyo, Japan;
- sDepartment of Psychology, Singapore Management University, 188065 Singapore;
- tInstitute of Zoology, Slovak Academy of Sciences, 845 06 Bratislava, Slovakia;
- uInternational Strategy & Marketing Section, University of Amsterdam, 1012 Amsterdam, The Netherlands;
- vDepartment of Psychology, Pusan National University, Pusan 609-735, Korea;
- wDepartment of Anthropology, Montclair State University, Montclair, NJ 07043;
- xDepartment of Psychology, University of Konstanz, 78464 Konstanz, Germany;
- yDepartment of Psychology, University of Vienna, 1010 Vienna, Austria;
- zDepartment of Behavioral Science, Hokkaido University, Sapporo, Hokkaido Prefecture, 5 Chome-8 Kita Jonshi, Japan;
- aaDepartment of Product Innovation and Management, Delft University of Technology, 2628 Delft, The Netherlands;
- bbDepartment of Philosophy, Université Paris 1 Panthéon-Sorbonne, 75005 Paris, France;
- ccDepartment of Molecular Biology and Genetics, Uludag University, Bursa 16059, Turkey;
- ddJakarta Field Station, Max Planck Institute for Evolutionary Anthropology, Jakarta 12930, Indonesia
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Edited by Susan T. Fiske, Princeton University, Princeton, NJ, and approved March 9, 2016 (received for review December 18, 2015)

Significance
Human cooperation requires reliable communication about social intentions and alliances. Although laughter is a phylogenetically conserved vocalization linked to affiliative behavior in nonhuman primates, its functions in modern humans are not well understood. We show that judges all around the world, hearing only brief instances of colaughter produced by pairs of American English speakers in real conversations, are able to reliably identify friends and strangers. Participants’ judgments of friendship status were linked to acoustic features of laughs known to be associated with spontaneous production and high arousal. These findings strongly suggest that colaughter is universally perceivable as a reliable indicator of relationship quality, and contribute to our understanding of how nonverbal communicative behavior might have facilitated the evolution of cooperation.
Abstract
Laughter is a nonverbal vocal expression that often communicates positive affect and cooperative intent in humans. Temporally coincident laughter occurring within groups is a potentially rich cue of affiliation to overhearers. We examined listeners’ judgments of affiliation based on brief, decontextualized instances of colaughter between either established friends or recently acquainted strangers. In a sample of 966 participants from 24 societies, people reliably distinguished friends from strangers with an accuracy of 53–67%. Acoustic analyses of the individual laughter segments revealed that, across cultures, listeners’ judgments were consistently predicted by voicing dynamics, suggesting perceptual sensitivity to emotionally triggered spontaneous production. Colaughter affords rapid and accurate appraisals of affiliation that transcend cultural and linguistic boundaries, and may constitute a universal means of signaling cooperative relationships.
Footnotes
- ↵1To whom correspondence should be addressed. Email: gabryant{at}ucla.edu.
Author contributions: G.A.B. designed research; G.A.B., R.F., E.C., L.A., C.L.A., M.B.P., S.T.B., A.B., B.C., D.D.S., C.D., J.F., M.F., P.G.-P., A.H., S.V.K., T.K., N.P.L., F.R.L., P.P., K.Q., B.A.S., H.J.S., M.S., S.S., W.T., E.A.v.d.H., H.V.-A., S.E.Y., J.C.Y., T.Y., and Y.Z. performed research; G.A.B. and R.F. analyzed data; G.A.B., D.M.T.F., and R.F. wrote the paper; D.M.T.F. conceived and organized the cross-cultural component; and E.C. coordinated cross-cultural researchers.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
Data deposition: Experimental response data from all study sites and acoustic data from all laugh stimuli are available at https://escholarship.org/uc/item/99j8r0gx.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1524993113/-/DCSupplemental.
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