mise à jour du
13 mars 2002
 Psychonomic Bulletin & Review
 cas cliniques
On yawning and its functions
Ronald Baenninger
Department of psychology and biology, Temple University
Philadelphia Pennsylvania
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The forms and behavioral correlates of yawning are described, and the phylogenetic and ontogenetic aspects of the act are examined with particular attention to its possible functions. Much evidence supports the view that yawning is an important mediator of behavioral arousal levels, a view that is further strengthened by a review of endocrine, neurotransmitter, and pharmacological mechanisms of yawning: A major function of yawning appears to involve maintenance or increase of arousal when environments provide relatively little stimulation.

Why do humans and many other species of mammals, birds, fish, amphibians, and reptiles perform the elaborate behavioral display that we call a yawn? In this review I examine research on yawning by psychologists, pharmacologists, ethologists, and neuroscientists during the past century, paying particular attention to the possible role of yawning in regulating arousal.

Respiration or Arousal ?

Yawning may have different functions in different species, but on the basis of evidence reviewed in this paper, I suggest that yawning is one important way of regulating arousal in a remarkable variety of species, including humans. In particular, according to this hypothesis, yawning is likely in situations where wakefulness and the maintenance of arousal level are important, but where the environment is relatively unstimulating. Arousal permits vigilance, attentiveness, and wakefulness, and is typically measured in terms of motor activity and physiological variables such as heart rate, galvanic skin response, electroencephalogram (EEG), or muscle tension.

The Oxford English Dictionary describes yawning in the context of boredom, whereas Gray's Anatomy (Clemente, 1985) and the Encyclopedia of Human Biology (Dulbecco, 199 ) do not even show yawning in their indexes. To the extent that they consider it at all, most lay people and physicians appear to believe that yawning is a respiratory phenomenon, a way to get oxygen to the brain (Greco, Baenninger, & Govern, 1993). In fact, there is meager evidence for this respiratory hypothesis and, on the basis of this review, it appears to be an incomplete explanation at best.

Ordinary behavioral acts such as yawning, laughing, crying, scratching, belching, sneezing, or sighing are rarely studied per se in any detail by psychologies, except insofar as they communicate or express something to others about an individual's state. Niko Tinbergen, the Nobel Prize winning ethologist, suggested in 1963 that the analysis of any behavioral act should include four basic aspects: (1) the way in which the act develops normally in individuals and the extent to which it becomes modified during ontogeny; (2) its evolution and phylogenetic history; (3) mechanisms underlying the behavior, including its physiology and the stimuli that elicit it; (4) its functions or adaptive value for individuals and species. In this review, a thorough description of yawning and its behavioral correlates in several species is followed by an examination of its ontogeny, phylogeny, and underlying mechanisms. The thread used to tie all the diverse data and observations together is the basic hypothesis that a major function of yawning is to regulate levels of arousal..............

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voir aussi
Baenninger R, Binkley S, Baenninger M Field observations of yawning and activity in humans.
Baenninger R On yawning and its functions
Baenninger R, Greco M Some antecedents and consequences of yawning
Greco M, Baenninger R On the context of yawning: when, where, and why ?
Baenninger R Some comparative aspects of yawning in Betta sleepnes, Homo Sapiens, Pantera leo and Papio sphinx
Greco M , Baenninger R Effects of yawning and related actvities on skin conductance and heart rate
Is yawning an arousal defense reflex ? Askenasy JJ
Yawning in old world monkey, Macaca nigra, Hadidian J Behaviour 1980