Cohesion and Joint Speech: Right Hemisphere Contributions to Synchronized Vocal Production.
Synchronized behavior (chanting, singing, praying, dancing) is found in all human cultures and is central to religious, military, and political activities, which require people to act collaboratively and cohesively; however, we know little about the neural underpinnings of many kinds of synchronous behavior (e.g., vocal behavior) or its role in establishing and maintaining group cohesion. In the present study, we measured neural activity using fMRI while participants spoke simultaneously with another person. We manipulated whether the couple spoke the same sentence (allowing synchrony) or different sentences (preventing synchrony), and also whether the voice the participant heard was "live" (allowing rich reciprocal interaction) or prerecorded (with no such mutual influence). Synchronous speech was associated with increased activity in posterior and anterior auditory fields. When, and only when, participants spoke with a partner who was both synchronous and "live," we observed a lack of the suppression of auditory cortex, which is commonly seen as a neural correlate of speech production. Instead, auditory cortex responded as though it were processing another talker's speech. Our results suggest that detecting synchrony leads to a change in the perceptual consequences of one's own actions: they are processed as though they were other-, rather than self-produced. This may contribute to our understanding of synchronized behavior as a group-bonding tool.



Synchronized human behavior, such as chanting, dancing, and singing, are cultural universals with functional significance: these activities increase group cohesion and cause participants to like each other and behave more prosocially toward each other. Here we use fMRI brain imaging to investigate the neural basis of one common form of cohesive synchronized behavior: joint speaking (e.g., the synchronous speech seen in chants, prayers, pledges). Results showed that joint speech recruits additional right hemisphere regions outside the classic speech production network. Additionally, we found that a neural marker of self-produced speech, suppression of sensory cortices, did not occur during joint synchronized speech, suggesting that joint synchronized behavior may alter self-other distinctions in sensory processing.
Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom, Laboratory of Brain and Cognition, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20492.
Kyle M
KM
Jasmin
Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom, Department of Psychology, Royal Holloway, University of London, London TW20 0EX, United Kingdom.
Carolyn
C
McGettigan
Department of Otolaryngology, University of California-San Francisco, San Francisco, California 94143.
Zarinah K
ZK
Agnew
Department of Psychology, Royal Holloway, University of London, London TW20 0EX, United Kingdom.
Nadine
N
Lavan
Institute of Neurology, University College London, London WC1N 3BG, United Kingdom, and.
Oliver
O
Josephs
School of Computer Science, University College Dublin, Dublin 4, Ireland.
Fred
0000-0003-4722-723X
F
Cummins
Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom, sophie.scott@ucl.ac.uk.
Sophie K
0000-0001-7510-6297
SK
Scott
D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D001303:Auditory Cortex / Q000502:physiology; D001307:Auditory Perception / Q000502:physiology; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D012938:Social Perception; D013060:Speech / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology*
coordinated action; fMRI; joint speech; right hemisphere; social cohesion; speech control