Department of psychology and
biology, Temple University
Philadelphia
Pennsylvania
The validity of selfreport of Sef-reportfor
studuying yawning in the laboratory was
examined. Thirty undergraduate students were
assigned to one of two groups. Both groups
recorded their own yawns using an Esterline
Angus Chart Recorder. One group was given
complete privacy, and the other group was
videotaped through a two-way mirror. The
observed group accurately recorded yawn
frequency, yawn duration, and interyawn
interval. The unobserved group did not differ
from the observed group in recorded yawn
frequency. Yawn duration and frequency were
uncorrelated, and there was no correlation
between duration and interyawn interval.
Self-report is a valid measure of yawning and
may be one of the only ways to study yawns in
the laboratory, because it removes any
inhibition against yawning in public.
Yawning may be ubiquitous in several
vertebrate classes (Dumpert, 1921), but until
recently it has not been the subject of much
rigorous study. In humans, yawns have been
observed as early as 5 min after birth (Blanton,
1917) and occur throughout the life span
(Gesell, 1928; TaylorJones, 1927). Charles
Darwin (1873-1965) described yawning as an act
of deep inspiration with the mouth opened wide,
followed by a forceful expiration simultaneously
accompanied by the rapid closing of the mouth
and a strong contraction of skeletal muscle
groups. The stereotyped and repetitive nature of
yawning has led to the suggestion that it is a
fixed action pattern released by the sight of a
yawning person or the mere thought of a yawn
(Provine, 1986).
One aspect of yawning that has interested
psychologists is its "infectious" nature. Moore
(1942) reported that trained yawners could
stimulate others to yawn and that motion
pictures of a yawn initiated yawns in
experimental subjects. Provine's (1986) subjects
reported that their yawning frequency increased
while observing others yawn, and also while
reading or thinking about yawning. In contrast,
Baenninger (1987) found that college students
did not yawn while being observed in the
laboratory whether they were observing another
student live or on a TV monitor. Also, students
who read a passage concerning yawning did not
yawn more than those who read about scratching
or daydreaming (Baenninger & Greco, 1988).
This absence of infectious yawning can be
explained by hypothesizing that subjects
actively inhibit yawns while being observed
alone in a laboratory. Subjects are likely to
experience anxiety about being observed by
people who may be evaluating them.
Alternatively, they may consider overt yawning
in the presence of others to be rude. Yawning in
the presence of others certainly occurs
(Baenninger, 1987), but may require some social
support from peers (e.g., yawning during
lectures).
In any event, a method of recording
naturally occurring yawns must be devised before
antecedents and consequences of yawning can be
studied in the laboratory. Provine (1986)
reported that when subjects were placed in a
room by themselves and told to record their own
yawns, yawning did take place, making possible
the determination of the frequency and the
duration of yawns, as well as the interval
between yawns. This technique is not objective,
by definition, since the subjects may not report
their yawns accurately. The present study was an
attempt to detèrmine the validity of such
self-reports.
METHOD
Subjects : Thirty undergraduate students
from introductory psychology were assigned to
one of two groups. Subjects in one group
reported their own yawns, replicating the
procedure described by Provine (1986); subjects
in the other group reported their yawns, but
were also monitored by a hidden video
camera.
Design and Procedure : Each subject in the
unobserved group was seated in a comfortable
armchair and read the following
instructions:
You are a participant in a study of the
naturally occurring frequency and duration of
yawns. In this experiment you will be recording
your own yawning behavior. Yawning is easy. It
is important that you relax and do not force
yawns. It will be unnecessary; most people can
yawn by just thinking about it. When you start
to yawn, push down the button on the box in
front of you. Consider the yawn to start when
you begin to inhale. Consider the yawn to end
when you finish exhaling. Keep the button
depressed for the duration of the yawn. You will
record the duration of each yawn for 15 min. It
is important to record your yawns as accurately
as possible because, other than the responses
you record, you will not be observed in any
other way. You will have complete privacy. I
will now demonstrate how to respond to a yawn.
(The experimenter yawns and depresses the button
as instructed above.) Think about yawning and
you can produce a real yawn. Do you have any
questions? After I leave the room, relax and
think about yawning throughout the session and
record your yawns as they occur. You will be
notified when time is up.
When the subject depressed the button in
response to a yawn, his/her responses were
recorded by an Esterline Angus Chart Recorder
driven at 2.5 mm/sec. After the subject produced
his/her third yawn, the chart recorder was
turned on and yawns were recorded for 15 min. If
a subject did not yawn within the first 5 mm,
the recorder was turned on and 15 min of
activity was recorded. Yawn duration was the
time the subject kept the button depressed. The
time from the onset of one yawn to the onset of
the next was the interyawn interval.
The subjects in the observed group received
the same treatment except that the assurance of
complete privacy was deleted from their
instructions, and they were videotaped through a
small opening in a curtain covering a two-way
mirror.
RESULTS
In the group that was not observed by the
video camera, 12 of the 15 subjects yawned at
least once, and 1 yawned 22 times. The overall
rate of yawning was 0.49 yawns per person per
minute. In the videotaped group, 11 of the 15
subjects yawned at least once, and 1 yawned 13
times (a rate of 0.34 yawns per person per
minute). The major results are shown in Table 1.
There was no significant difference between the
number of yawns reported and the number of yawns
observed in the videotaped group[t(14) =
1.0, p> .301. Subjects in the videotaped
group were accurate, with the exception of 1 who
reported 6 yawns, whereas the video record
showed only 4. There was no significant
difference between the duration of yawns
recorded by the subjects in the videotaped group
and the duration recorded on the videotape
[t(14) = .01, p > .901. The videotaped
group did not differ from the unobserved group
in the number of yawns reported [t(28) =
1.00, p > .20]. Frequency of yawns and
their duration were uncorrelated in both groups,
and there was no correlation between duration
and interyawn interval.
A contrast analysis of the distribution of
yawns over the 15-min recording session revealed
a linear trend in the frequency of yawns. The
greatest number of yawns occurred in the first 5
min. Yawn frequency decreased during minutes 6
to 10. The last 5 min of the session yielded the
lowest frequency of yawns [F(1,58) = 12.747,
p < .001].
Since the videotaped group and the
unobserved group did not differ in the number of
yawns they reported, the results of these two
groups were combined and compared with the
results Provine (1986) reported. The mean yawn
duration Provine reported is significantly
higher than the duration we found [t(55) =
2.49, p < .01], and the mean yawn
frequency reported by Provine is significantly
greater than the frequency we observed
[t(55) = 2.512, p < .011. However, there
was no significant difference between the
interyawn intervals in the two studies.
DISCUSSION
Self-report appears to be a valid measure of
yawning frequency, duration, and timing in that
self-reports did not differ significantly from
videotaped records. No relationships were found
between the frequency, duration, and timing of
yawns. Subjects who yawned infrequently did not
appear to compensate by yawning for longer
durations, and a high frequency of yawning was
not associated with shorter intervals between.
yawns. The relative independence of these
measures suggests that our subjects did not have
any kind of "yawning time" distributed according
to some lawful temporal pattern.
The downward trend of yawn frequency
suggests that subjects may have been yawning in
response to instruction rather than boredom.
Since the subjects had been instructed to think
about yawning, the waning that we found may have
resulted because they stopped thinking about
yawning as time passed. If their yawning had
been a response to boredom, we would have found
an increase in yawning frequency over time. In
any event, our results confirm the contention
that thinking about yawning is sufficient to
produce yawning in a laboratory situation. It
can also be concluded that self-report is a
valid measure of yawning, despite the fact that
it violates the basic maxim of objective
science, namely that data must be public. In
fact, self-report may be one of the only ways to
observe yawns in the laboratory because it
removes any inhibition against yawning in
public.
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R (1987). Some comparative aspects of
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Baenninger
R, Greco M. (1988). Yawning and arousal.
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