Evolutionary Psychology
www.epjournal.net – 2007. 5(1): 92-101
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Original Article
Yawning as a Brain Cooling Mechanism: Nasal Breathing and Forehead
Cooling Diminish the Incidence of Contagious Yawning
Andrew C. Gallup, Department of Psychology, State University of New York at Albany, Albany, NY
12222, USA.
Gordon G. Gallup Jr., Department of Psychology, State University of New York at Albany. Email:
gallup@albany.edu (Corresponding author)
Abstract: We conducted two experiments that implicate yawning as a thermoregulatory
mechanism. The first experiment demonstrates that different patterns of breathing
influence susceptibility to contagious yawning. When participants were not directed how
to breathe or were instructed to breathe orally (inhaling and exhaling through their
mouth), the incidence of contagious yawning in response to seeing videotapes of people
yawning was about 48%. When instructed to breathe nasally (inhaling and exhaling
through their nose), no participants exhibited contagious yawning. In a second
experiment, applying temperature packs to the forehead also influenced the incidence of
contagious yawning. When participants held a warm pack (460C) or a pack at room
temperature to their forehead while watching people yawn, contagious yawning occurred
41% of the time. When participants held a cold pack (40C) to their forehead, contagious
yawning dropped to 9%. These findings suggest that yawning has an adaptive/functional
component that it is not merely the derivative of selection for other forms of behavior.
Keywords: yawning, contagious yawning, nasal breathing, forehead cooling, brain
temperature, thermoregulation, information processing, group vigilance.
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Introduction
Yawning is characterized by gaping of the mouth accompanied by a long
inspiration followed by a shorter expiration. In humans, yawning begins in utero by 20
weeks gestation