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
