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Experimental evidence of contagious yawning in budgerigars (Melopsittacus undulatus)

  • SUNY Polytechnic Institute


Experimental evidence of contagious yawning has only been documented in four mammalian species. Here, we report the results from two separate experimental studies designed to investigate the presence of contagious yawning in a social parrot, the budgerigar (Melopsittacus undulatus). In Study 1, birds were paired in adjacent cages with and without visual barriers, and the temporal association of yawning was assessed between visual conditions. In Study 2, the same birds were exposed to video stimuli of both conspecific yawns and control behavior, and yawning frequency was compared between conditions. Results from both studies demonstrate that yawning is contagious. To date, this is the first experimental evidence of contagious yawning in a non-mammalian species. We propose that future research could use budgerigars to explore questions related to basic forms of empathic processing.
Experimental evidence of contagious yawning in budgerigars
(Melopsittacus undulatus)
Andrew C. Gallup
Lexington Swartwood
Janine Militello
Serena Sackett
Received: 1 January 2015 / Revised: 15 April 2015 / Accepted: 23 April 2015 / Published online: 27 May 2015
ÓSpringer-Verlag Berlin Heidelberg 2015
Abstract Experimental evidence of contagious yawning
has only been documented in four mammalian species.
Here, we report the results from two separate experimental
studies designed to investigate the presence of contagious
yawning in a social parrot, the budgerigar (Melopsittacus
undulatus). In Study 1, birds were paired in adjacent cages
with and without visual barriers, and the temporal asso-
ciation of yawning was assessed between visual conditions.
In Study 2, the same birds were exposed to video stimuli of
both conspecific yawns and control behavior, and yawning
frequency was compared between conditions. Results from
both studies demonstrate that yawning is contagious. To
date, this is the first experimental evidence of contagious
yawning in a non-mammalian species. We propose that
future research could use budgerigars to explore questions
related to basic forms of empathic processing.
Keywords Yawning Contagious yawning Empathy
Avian cognition
Yawning is characterized by a powerful gaping of the jaw
with inspiration, a brief period of peak muscle contraction,
and a passive closure of the jaw with shorter expiration
(Barbizet 1958). Nonsocial yawning, also known as spon-
taneous yawning, is believed to be relatively widespread
among vertebrates (Baenninger 1987) and may function in
promoting cortical arousal (Baenninger 1997) and/or state
change (Provine 1986,1996,2005) by decreasing brain
temperature (Eldakar et al. in press; Gallup and Gallup
2007,2008; Gallup and Eldakar 2012; Massen et al. 2014;
Shoup-Knox et al. 2010). Contagious yawning, which can
be elicited by sensing or thinking about the action in others
(Provine 2005), appears to be a more recently derived
behavior that may function in group coordination and
vigilance in social species (Gallup and Gallup 2007; Gallup
2011; Miller et al. 2012a).
To date, experimental evidence of contagious yawning
is restricted to humans (Homo sapiens; e.g., Provine 1986;
Platek et al. 2003), chimpanzees (Pan troglodytes) in re-
sponse to conspecifics (Amici et al. 2014; Anderson et al.
2004; Campbell et al. 2009; Campbell and de Waal 2011;
Massen et al. 2012) and human yawns (Campbell and de
Waal 2014; Madsen et al. 2013; but see Amici et al. 2014),
domesticated dogs (Canis familiaris) in response to human
yawns (Joly-Mascheroni et al. 2008; Madsen and Persson
2013; Romero et al. 2013; Silva et al. 2012; but see Harr
et al. 2009; O’Hara and Reeve 2011; Buttner and Strasser
2014), and, most recently, a subline of high-frequency
yawning Sprague–Dawley rats (Rattus norvegicus;
Moyaho et al. 2014). Video-induced yawning has also been
reported in stumptail macaques (Macaca arctoides;
Paukner and Anderson 2006), but this response also co-
occurred with heightened self-directed behaviors and thus
appears to be due to social tension or stress rather than
contagion. Species that have thus far failed to show con-
tagious yawning in an experimental design include bono-
bos (Pan paniscus), orangutans (Pongo abelii), and gorillas
(Gorilla gorilla) in response to both conspecific and human
yawns (Amici et al. 2014), and domesticated dogs and red-
footed tortoises (Geochelone carbonaria) in response to
conspecifics (Harr et al. 2009; Wilkinson et al. 2011).
&Andrew C. Gallup
Psychology Department, State University of New York
at Oneonta, Oneonta, NY 13820, USA
Anim Cogn (2015) 18:1051–1058
DOI 10.1007/s10071-015-0873-1
Observational evidence for contagious yawning to con-
specifics has been reported in bonobos (Demuru and Palagi
2012; Palagi et al. 2014), gelada baboons (Theropithecus
gelada; Palagi et al. 2009), budgerigars (Melopsittacus
undulatus; Miller et al. 2012b), and wolves (Canis lupus
lupus; Romero et al. 2014).
Research suggests that contagious yawning is triggered
by mechanisms that differ from those involved in other in-
voluntary actions (Amici et al. 2014). In particular, conta-
gious yawning is thought to represent a basic form of
empathy rooted in a perception–action mechanism known as
state matching or emotional contagion (Preston and de Waal
2002). Consistent with this view, previous research has
documented a strong association between contagious
yawning and empathy (for a discussion, see Campbell and de
Waal 2014). For example, in humans, contagious yawning is
more common among participants who score high on em-
pathy measures (Platek et al. 2003; but see Bartholomew and
Cirulli 2014), and thinking about yawning has been shown to
activate brain areas implicated in empathic processing (e.g.,
Platek et al. 2005; Nahab et al. 2009). Comparative studies
investigating the developmental onset and decline of con-
tagious yawning also generally support this view (Anderson
and Meno 2003; Bartholomew and Cirulli 2014; Giganti
et al. 2012; Madsen et al. 2013; Madsen and Persson 2013;
Massen et al. 2014), since empathy-related capacities in
humans emerge in early childhood and decline in old age
(Bailey and Henry 2008; Perner and Lang 1999). Growing
comparative research also demonstrates a positive rela-
tionship between contagious yawning and group affiliation
or social closeness/bonding (Campbell and de Waal 2011;
Demuru and Palagi 2012; Norscia and Palagi 2011; Palagi
et al. 2009; Romero et al. 2013,2014; Silva et al. 2012),
which supports a connection with empathic processing. For
example, an initial study on chimpanzees provided evidence
for an ingroup bias for contagious yawning (Campbell and
de Waal 2011). In particular, captive chimpanzees shown
video stimuli of other chimpanzees yawning demonstrate
contagion to ingroup members but not to unfamiliar con-
specifics. Subsequent studies, however, have failed to
demonstrate a familiarity bias for chimpanzees viewing
human yawns (Campbell and de Waal 2014; Madsen et al.
2013), and at least one study provided evidence that rela-
tionship quality among chimpanzees did not predict yawn
contagion (Massen et al. 2012). There has also been mixed
support for domesticated dogs to yawn more in response to
yawns from familiar humans (Madsen and Persson 2013;
O’Hara and Reeve 2011).
Since contagious yawning may represent a primitive
form of empathy, unequivocally demonstrating the pres-
ence of this behavior in a laboratory animal, with the
ability to manipulate it experimentally, could be important
for exploring basic questions related to this cognitive
capacity. For example, budgerigars (M. undulatus), a spe-
cies of social parrot indigenous to Australia, represent a
good candidate species because these birds form lasting
bonds with breeding pairs and interact within coordinated
flocks throughout the year (Wyndham 1980). Furthermore,
previous research has demonstrated that these birds show
automatic imitation to video stimuli (Mui et al. 2008),
whereby the sight of another’s action tends to elicit the
same action in the observer (Sturmer et al. 2000). Using a
naturalistic approach, Miller et al. (2012b) initially exam-
ined this species and revealed that yawns were temporally
clustered in an undisturbed, established flock of captive
budgerigars. These findings suggest yawning is contagious,
similar to the other aforementioned observational studies;
however, such methods cannot completely account for
circadian physiological synchrony and/or collectively
sensed environmental stimuli (both of which influence the
expression of yawning, see Baenninger 1997).
Here, we describe two separate experimental studies
designed to investigate the presence of contagious yawning
in budgerigars in a controlled laboratory setting. Study 1
paired birds in adjacent cages with and without visual
barriers, and the frequency of potentially contagious yawns
(i.e., those occurring within a restricted temporal prox-
imity) was compared based on the opportunity for visual
information transfer. Given that in the wild, the group size
and composition of budgerigars can fluctuate depending
upon the season (Wyndham 1983) and that both sexes
within this species show vocal call convergence to ingroup
members when housed in captivity (Farabaugh et al. 1994;
Hile et al. 2000), pairs of familiar and unfamiliar birds
were tested together in this experiment to assess the po-
tential for a familiarity bias in this response. Unlike
chimpanzees or wolves, however, in which observing un-
familiar conspecifics may elicit hostility and familiarity
biases for contagious yawning have been reported
(Campbell and de Waal 2011; Romero et al. 2014),
budgerigars show more fluid flocking and thus we did not
expect a strong bias for contagious yawning. Since previ-
ous research has demonstrated that budgerigars respond to
video displays of real and virtual conspecifics (Mui et al.
2008; Moravec et al. 2010; Mottley and Heyes 2003),
Study 2 compared the yawn frequency of the same birds
from Study 1 during exposure to video presentations of
yawns versus control behaviors.
Methods and results
The budgerigars in these studies were from a population
maintained within the vivarium at the State University of
1052 Anim Cogn (2015) 18:1051–1058
New York at Oneonta, Oneonta, NY, USA. The tem-
perature of this indoor facility is maintained at 21 °C, the
light/dark cycle is set to 12:12 hours (0700; 1900 hours),
and food, water, and supplements are provided ad libitum.
With the intention of testing for ingroup/outgroup effects,
two isolated populations of budgerigars (11-bird group,
13-bird group) were purchased as juveniles from com-
mercial vendors in March 2014. From the onset, these
groups have been kept in the same room, but within
separate aviaries (1.626 m 90.533 m 91.575 m) with a
visual barrier between them to prevent the birds from
seeing one another. To enhance potential ingroup/outgroup
effects, the birds in each group were initially selected for
different coloration. One group is comprised of all dark and
light green birds, whereas the other group consists of a
combination of varied colored birds (e.g., Greywing blue,
Skyblue Cinnamon, Albino, Lutino). The two experiments
reported below tested the same 16 birds (15 males, three
females), which included eight from each aviary (seven
males, one female; six males, two females). Both ex-
periments were approved by the local Institutional Animal
Care and Use Committee (# 2014–02; 2014–05).
Procedure and analysis: Study 1
The first experiment was conducted across a period of
3 weeks during July 2014. Each testing day, two birds were
caught from their main aviaries at 1115 hours, taken to a
separate testing room within the vivarium, and placed in
individual housed cages (0.305 m 90.254 m 90.279 m)
connected to one another (see Fig. 1). The cage was de-
signed to accommodate a plastic opaque barrier that could
be positioned between the two individual cages, which
allowed for conditions with and without visual contact/
information transfer. The cage was positioned toward a
tripod with a digital camcorder, and to ensure the birds
faced in this direction, all other external surfaces of the
cage were covered with cardboard. The perches in each
individual cage were positioned at an angle to promote
visual contact between the pair while still providing a view
of yawning behavior (Fig. 1). No food or water was pro-
vided during testing in order to maximize visual attention
between the birds and the rate of behavioral responses.
After the birds were caught and transferred to the testing
room, an experimenter started a digital camcorder and then
exited the facility. The birds were given an acclimation
period of 1 h and 45 min, and during this time, the opaque
barrier was positioned between the cages to keep the birds
visually occluded from one another. A researcher would
then reenter the room at designated times to remove the
barrier while remaining occluded from the birds. Depending
upon the condition sequence for the given pair (see below),
the visual barrier could be removed at 1300 hours after the
acclimation. Another 15-min acclimation period was pro-
vided before the first behavioral recording session began
from 1315 to 1415 hours. At the end of this session, the
visual barrier was then either replaced or removed (given
the sequence), and another 15-min acclimation period was
provided. The second and final recording session then began
at 1430 hours and concluded at 1530 hours. Therefore, a
total of 2 h of behavioral recordings were taken each day.
Each bird was tested twice in this fashion, once paired
with a bird from the same main aviary (ingroup member)
and once paired with an unfamiliar bird from the visually
occluded aviary (outgroup member). The unfamiliar/out-
group pairings represented the first visual contact between
these birds. The sequence and order of conditions were
counterbalanced to account for documented circadian ef-
fects of yawning in this species (Miller et al. 2012b). The
trial orders of testing were as follows: (1) an ingroup
pairing starting with the visible condition and followed by
the occluded condition, then an outgroup pairing starting
with the occluded condition followed by the visible con-
dition, (2) an ingroup pairing starting with the occluded
condition and followed by the visible condition, then an
outgroup pairing starting with the visible condition and
followed by the occluded condition, (3) an outgroup pair-
ing starting with the visible condition and followed by the
Fig. 1 Experimental setup. In Study 1, two birds were placed in
individually housed cages connected to one another. A slight
separation between the adjacent cages allowed for an opaque barrier
to be positioned within, providing conditions with and without visual
contact to the neighboring bird. The perches were positioned at an
angle to promote visual contact between the pair while still providing
a view of yawning behavior from the camcorder. This cage was also
used in Study 2, but a total of four birds (two in each side) were tested
at a time. The opaque barrier was removed to allow visual contact
between the group, and a laptop computer display was positioned just
in front of the camcorder
Anim Cogn (2015) 18:1051–1058 1053
occluded condition, then an ingroup pairing starting with
the occluded condition followed by the visible condition,
and (4) an outgroup pairing starting with the occluded
condition followed by the visible condition, then an in-
group pairing starting with the visible condition and fol-
lowed by the occluded condition. Four birds were tested in
each trial order.
Trained researchers scored the 32 h of recordings for
time spent with visual access toward the matched pair
during the visible condition and all yawns across condi-
tions. Visual attention toward the matched pair was con-
sidered present except in cases when the bird was directly
facing in the opposite direction. Yawning is characterized
as a wide opening of the beak with stretching of the neck,
followed by a brief pause and then a passive closure (see
Fig. 2). There was moderate agreement between the three
raters for both attention and yawning behavior (12.5 %
overlap: attention, k =0.530; yawns, k =0.584). Fol-
lowing the same criteria of a previous study on gelada
baboons (Palagi et al. 2009), yawns that occurred within
5 min of a previous yawn from the adjacent bird were
considered contagious. Those that occurred outside of this
window were classified as spontaneous. Statistical analyses
consisted of a Mann–Whitney test to assess potential dif-
ferences in yawning rate between the two groups, and
Wilcoxon signed-rank tests to assess differences in total
attention, and contagious and spontaneous yawns between
conditions. Since previous research has already shown
significant observational support for contagious yawning in
this species (Miller et al. 2012b), a one-tailed test was
applied when comparing contagious yawns between the
visual and occluded conditions. All means and SEM re-
ported are per bird. Analyses were performed with IBM
SPSS Statistics version 21 for Mac OS, with aset to 0.05.
Results: Study 1
A total of 131 yawns were recorded (M=8.188,
SEM =1.137) during the 32 h of behavioral observation.
There was no difference in the total yawn frequency be-
tween the green and multicolored birds (M±SEM
8.000 ±2.087 vs. 8.375 ±1.085; Z=-0.427, p=
0.669), and visual attention (s) toward the adjacent bird did
not vary as a function of ingroup and outgroup parings
(M±SEM 3382.87 ±95.372 vs. 2851.81 ±295.209;
Z=-0.785, p=0.433).
A total of 37 yawns occurred within 5 min of a previous
yawn from the adjacent bird (M=2.31, SEM =0.590).
As predicted, these temporally clustered yawns were more
frequent when the birds could see one another (i.e., cued
visually) compared to when visual access was occluded
(M±SEM 1.750 ±0.544 vs. 0.561 ±0.241; Z=
-1.740, p=0.041; see Fig. 3). These findings provide
further evidence that this behavior is socially contagious in
this species. There was, however, no difference in the
number of contagious yawns between ingroup and out-
group pairings (M±SEM 0.690 ±0.218 vs. 1.060 ±
0.243; Z=-0.849, p=0.396).
There was no difference between visible and occluded
conditions for yawns occurring outside a 5-min window
(i.e., spontaneous yawns) of a previous yawn from the
matched pair (M±SEM 3.250 ±0.536 vs. 2.625 ±
0.591; Z=-0.885, p=0.376). That is, in general,
yawning was not more frequent when the birds could see
one another. Similar to the results pertaining to contagious
yawning, there was no difference in the number of spon-
taneous yawns between ingroup and outgroup pairings
(M±SEM 2.938 ±0.661 vs. 2.938 ±0.544; Z=
-0.396, p=0.692).
Fig. 2 Images of a budgerigar yawning (beginning to peak)
1054 Anim Cogn (2015) 18:1051–1058
Procedure and analysis: Study 2
Having confirmed the existence of contagious yawning
using an ecologically valid approach in Study 1, the second
experiment was designed to test whether video stimuli
could be used to induce this response. This experiment was
conducted across two successive days in December 2014.
Each testing day, two independent trials were performed
consecutively, in which four birds were caught from a
single aviary, moved to a testing room within the vivarium,
and placed as pairs in two individually housed cages con-
nected to one another (same testing cage as Study 1;
Fig. 1). A laptop computer (0.376 90.259 m) used to
present the video stimuli was placed 0.230 m from the
testing cage, and a tripod with a digital camcorder was
positioned just above the display screen. As in Study 1, all
other external surfaces of the cage were covered with
cardboard to ensure the birds faced toward the laptop and
camera. No food or water was provided during testing in
order to maximize the rate of behavioral responses.
The video stimuli were created from an HD video
recording of a single budgerigar perched in an isolated cage
in which we identified a total of seven yawns. Because
Study 1 showed no ingroup bias for contagious yawning,
we did not take recordings of birds from both aviaries.
Using iMovie, all yawns were extracted as individual clips
ranging from 2.5 to 4.5 s. These clips were then multiplied,
randomized, and coupled together to form a contagious
yawning stimulus (4 min, 26 s). Using the same HD video,
seven matched non-yawning clips were extracted, multi-
plied, and coupled together to form a comparison control
stimulus (4 min, 32 s). During the experiment, each
stimulus was set to repeat using Microsoft Windows Media
Player during the respective conditions. Testing within
groups was not a methodological concern given that even if
the birds responded contagiously to the yawns from cage
mates, it would be expected that the frequency of these
behaviors would be lower in the control condition.
After being caught and transferred to the testing room,
the birds were provided a 45-min acclimation period. The
first 15 min of this period included a muted display of a
national geographic video of penguins accessed from This video was presented to habituate
the birds to a video presentation. Following this, the birds
were presented with consecutive 15-min displays of the
experimental and control stimuli (order counterbalanced).
The first 5 min of each stimulus was treated as an addi-
tional acclimation period, since this represented the first
video footage of a conspecific presented to these birds. This
also allowed us to account for a brief interruption with the
manual transition from the first to the second stimulus
display on the laptop. Unlike Study 1, a trained researcher
remained in the testing room to coordinate the display of
video stimuli. In total, this provided 10 min of behavioral
recording for each condition.
Each day, the first group of birds was caught at 1345 hours
(Time 1) and released at 1500 hours. Immediately following
this, the second group was caught and positioned in the
testing cage at 1515 hours (Time 2). The second group fol-
lowed the same procedures as the first before being released
at 1630 hours. On the first testing day, two groups of four
green birds were tested, and the next day, the eight remaining
multicolored birds were tested in two additional independent
trials. The trial and condition order were counterbalanced to
control for documented circadian effects of yawning in this
species (Miller et al. 2012b). The order of testing was as
follows: (1) Time 1, control–experimental, (2) Time 2, ex-
perimental–control, (3) Time 1, experimental–control, and
(4) Time 2, control–experimental. Four birds were tested in
each trial order.
A trained researcher, blind to the condition, scored the
subsequent recordings for time spent attending toward the
video display (s) and all yawns. Self-directed behaviors
(scratching and preening) were also recorded as a measure
of anxiety or stress between conditions, yet these were very
infrequent (see below). A second independent rater showed
moderate to perfect agreement when scoring these videos
(25 % overlap: attention, k =0.583; yawning, k =0.882
and self-directed behaviors, k =1.000). Statistical ana-
lyses consisted of a Mann–Whitney test to compare the
yawning frequency between the two groups of birds and
Wilcoxon signed-rank tests to assess differences in total
attention and yawns between conditions. Similar to Study
1, a one-tailed test was applied when comparing yawns
between experimental and control conditions. All means
Fig. 3 Study 1. The frequency of yawning within 5 min of a previous
yawn from the adjacent bird was significantly higher in the visible
condition, suggesting that this behavior is contagious (M ±SEM;
Anim Cogn (2015) 18:1051–1058 1055
and SEM reported are per bird. Analyses were performed
with IBM SPSS Statistics version 21 for Mac OS, with a
set to 0.05.
Results: Study 2
A total of 26 yawns were recorded across the 80 min of
behavioral observation (M=1.625, SEM =0.531). There
was no difference in yawn frequency between the green and
multicolored groups (M±SEM 1.000 ±0.732 vs.
2.250 ±0.750; Z=-1.494, p=0.135), and the time spent
attending to the video stimulus (s) did not vary between the
control and experimental conditions (M±SEM
536.25 ±32.926 vs. 567.25 ±13.203; Z=-0.628,
p=0.530). As predicted, yawning frequency was sig-
nificantly higher during the presentation of the experimental
(yawning) stimulus (M±SEM 1.188 ±0.430 vs.
0.438 ±0.157; Z=-1.897, p=0.029; see Fig. 4). Only
five self-directed behaviors were recorded across the entire
observation period (three occurring in the control condition
and two in the experimental), suggesting that stress/anxiety
was not contributing to this effect. Thus, these findings
demonstrate that contagious yawning can be manipulated
experimentally in this species through the use of visual
Yawning in response to sensing or thinking about the ac-
tion in others may represent a primitive form of empathy.
Despite the potential importance of identifying various
non-human species showing this capacity, comparative
investigations of contagious yawning have been limited.
These two experimental studies reveal the presence of
contagious yawning in budgerigars in a controlled labora-
tory setting, corroborating a previous observational report
assessing the temporal distribution of yawns in an undis-
turbed flock (Miller et al. 2012b). The experiment in Study
1 provides an ecologically valid measure of social conta-
gion utilizing the signaling of a live demonstrator pro-
ducing real yawns (improving upon Wilkinson et al. 2011).
Temporally classified contagious yawns during these trials
(i.e., those occurring within 5 min of a yawn from the
matched pair) occurred more than three times as often
when the birds could see one another, whereas there was no
difference in the frequency of spontaneous yawning across
visibility conditions. The experiment in Study 2 used a
more traditional laboratory-based methodology for testing
contagious yawning (e.g., Anderson et al. 2004), by pre-
senting small groups of birds with repeated video clips of
conspecific yawns and control behavior. In comparison
with matched control stimuli, budgerigars in this ex-
perimental condition yawned more than twice as often and
this response was not linked with indicators of stress or
anxiety (i.e., self-directed behaviors). It is important to
note, however, that this represents a modest effect given
the magnitude of the video stimulus (over 150 yawns were
displayed during the 10-min experimental session).
We found no evidence of an ingroup bias for contagious
yawning in budgerigars. That is, yawns appeared similarly
contagious between birds housed within the same aviary
and across outgroup pairs. Previous experiments on chim-
panzees and domesticated dogs have demonstrated mixed
support for a familiarity bias in contagious yawning
(Campbell and de Waal 2011; Romero et al. 2013; Silva
et al. 2012; but see Madsen et al. 2013; Madsen and
Persson 2013), while observational studies on primates
(human and non-human) and wolves have shown a positive
association with social closeness and affiliation (Demuru
and Palagi 2012; Norscia and Palagi 2011; Palagi et al.
2009,2014; Romero et al. 2014). There may be reasons to
suspect that budgerigars would be less sensitive to famil-
iarity or social closeness for various forms of state
matching since they naturally live in much larger, more
fluid groups of unrelated individuals than the abovemen-
tioned species and can form flocks of over 1000 coordi-
nated members in the wild (Wyndham 1980). Conversely,
we have recently discovered evidence of an ingroup bias
for stretching in this species (unpublished data), a more
overt behavior directly relevant to flocking. It remains
possible that limitations in the current study do not permit a
true comparison to the documented ingroup/outgroup ef-
fects of contagious yawning in other species. For example,
since all of the budgerigars were housed in the same room,
this permitted vocal communication between the two
Fig. 4 Study 2. The frequency of yawning was significantly higher
during the presentation of the experimental (yawn) stimulus, demon-
strating that contagious yawning can be experimentally manipulated
(M ±SEM; *p\0.05)
1056 Anim Cogn (2015) 18:1051–1058
groups and perhaps created some degree of familiarity or
social affiliation prior to testing. Previous research has
demonstrated that vocal call convergence occurs among
budgerigars housed in captivity (Farabaugh et al. 1994;
Hile et al. 2000), though in our study, vocalizations be-
tween the pairs were uncommon to nonexistent. Another
limitation to the current study was that the degree of social
closeness between cage mates was not recorded prior to the
experiment, so this effect could not be assessed along a
In summary, budgerigars represent the first non-mam-
malian species, and only the fifth species to date (including
humans, chimpanzees, domesticated dogs, and a subline of
high-yawning Sprague–Dawley rats), to show contagious
yawning in an experimentally controlled setting. These
findings provide an example of convergent evolution.
Given the association between contagious yawning and
empathy, we suggest additional comparative research be
conducted to assess the prevalence of contagious yawning
in other social vertebrates. Furthermore, since empathic
responses have already been demonstrated in avian species
(e.g., Edgar et al. 2011; Wascher et al. 2008), and the
current findings show that contagious yawns can be ex-
perimentally manipulated, we propose that budgerigars
represent a good model for exploring primitive forms of
empathic processing.
Acknowledgments We would like to specifically acknowledge
Anne B. Clark, Michael L. Miller, and Andrea Vogel for contributing
to the experimental design of Study 1. ACG is also grateful for all the
fruitful discussions on contagious behavior in budgerigars that took
place in the Bird Yawning Lab at Binghamton University.
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... affiliation and kinship increase the susceptibility to respond to others' yawns in several species [10][11][12]14,16,18,27 . Concurrently, the available data do not always go in the same direction, with different examples of social closeness not influencing YC [28][29][30][31] , thus challenging the view about the positive effect of familiarity on the phenomenon. Species scoring low affiliation and/or high degrees of ingroup competition do not seem to show YC 32,33 and, moreover, while xenophilic species show similar levels of YC towards known and unknown individuals 34 , species classified as xenophobic show contagion strictly towards ingroup subjects 18 . ...
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Yawn contagion (YC) is, compared to spontaneous yawning, an evolutionary recent phenomenon probably linked to behavioral synchronization in highly social species that is more likely when it involves familiar subjects. Here, we investigate for the first time in monkeys which factors modulate intra- and interspecific YC. Through an experimental approach, we exposed 17 red-capped mangabeys to video stimuli (Yawn vs Control) depicting familiar/unfamiliar red-capped mangabeys and humans, and unfamiliar hamadryas. We found that mangabeys yawned more often in response to Yawn than Control videos independently from the species depicted, demonstrating both intra- and interspecific YC in the tested species. Moreover, both mangabey and human familiar yawning stimuli evoked a stronger yawning response in the subjects compared to the unfamiliar counterparts. Neither the amount of time spent looking frontally at the screen (probability of stimulus perception) nor the levels of self-directed behaviors (a proxy of anxiety) accounted for the results. In conclusion, we provide the first evidence that in non-human primate familiarity modulates both intra- and inter-specific YC. Stimuli emitted by familiar faces somehow ease the mechanisms underlying YC, and this modulation can also apply to heterospecific subjects when previous shared experiences provide the prerequisites for the development of social bonds.
... In human, those with the highest facial temperature were found to have yawned faster and more frequently (117). A recent study reported that the change in facial temperature in highyawning rats is closely similar to the pattern of decreased facial temperature in avian species with more yawns (118). Newborns experience an average temperature decrease of −0.36 • C in the cerebral and eye region 10-20 s after yawning, which is consistent with the results of a decrease in facial temperatures in the high-yawning rats (115,119). ...
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Therapeutic hypothermia (TH), which prevents irreversible neuronal necrosis and ischemic brain damage, has been proven effective for preventing ischemia-reperfusion injury in post-cardiac arrest syndrome and neonatal encephalopathy in both animal studies and clinical trials. However, lowering the whole-body temperature below 34°C can lead to severe systemic complications such as cardiac, hematologic, immunologic, and metabolic side effects. Although the brain accounts for only 2% of the total body weight, it consumes 20% of the body's total energy at rest and requires a continuous supply of glucose and oxygen to maintain function and structural integrity. As such, theoretically, temperature-controlled selective brain cooling (SBC) may be more beneficial for brain ischemia than systemic pan-ischemia. Various SBC methods have been introduced to selectively cool the brain while minimizing systemic TH-related complications. However, technical setbacks of conventional SBCs, such as insufficient cooling power and relatively expensive coolant and/or irritating effects on skin or mucosal interfaces, limit its application to various clinical settings. This review aimed to integrate current literature on SBC modalities with promising therapeutic potential. Further, future directions were discussed by exploring studies on interesting coping skills in response to environmental or stress-induced hyperthermia among wild animals, including mammals and birds.
... The absence of yawn and stretch contagion in ravens is also in contrast to observational and experimental studies in budgerigars [36,37]. However, potential comparative differences in these responses are to be expected, based on ecological factors and evolutionary history [5]. ...
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The overt and reflexive matching of behaviors among conspecifics has been observed in a growing number of social vertebrates, including avian species. In general, behavioral contagion—such as the spread of yawning—may serve important functions in group synchronization and vigilance behavior. Here, we performed an exploratory study to investigate yawn contagion among 10 captive juvenile ravens (Corvus corax), across two groups. Using observational methods, we also examined the contagiousness of three other distinct behaviors: stretching, scratching, and shaking. A total of 44 20 min observations were made across both groups, including 28 in the morning and 16 in the afternoon. The time and occurrence of all the behaviors from each bird were coded, and the temporal pattern of each behavior across both groups was then analyzed to assess the degree of social contagion. Overall, we found no evidence for contagious yawning, stretching, scratching, or shaking. However, yawns were relatively infrequent per observation (0.052 ± 0.076 yawns/bird) and thus experimental methods should be used to support this finding.
... Empathy is an ability to experience and share the mental state of others de Waal and Preston, 2017;Meyza et al., 2017;Preston and de Waal, 2002). The existence of empathy has been suggested in a variety of species, including non-human primates (Campbell and de Waal, 2011;Koski and Sterck, 2010;Pruetz, 2011), dogs (Palagi et al., 2015), birds (Gallup et al., 2015), and rodents (Bartal et al., 2011Sato et al., 2015). In mammals, prosocial behaviors such as helping and consolation are essential for the development of society and are thought to be elicited by empathy (de Waal and Preston, 2017). ...
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Several studies suggest that rodents show empathic responses and helping behavior toward others. We examined whether prairie voles would help conspecifics who were soaked in water by opening a door to a safe area. Door-opening latency decreased as task sessions progressed. Female and male voles stayed close to the soaked voles' side at equal rates and opened the door with similar latencies. When the conspecific was not soaked in water, the door-opening latency did not decrease. This suggests that the distress of the conspecific is necessary for learning to open the door and that the door-opening performed by prairie voles corresponds to helping behavior. Additionally, we examined the helping behavior in prairie voles in which oxytocin receptors were genetically knocked out. Oxytocin receptor knockout voles demonstrated less learning of the door-opening behavior and less interest in soaked conspecifics. This suggests that oxytocin is important for the emergence of helping behavior.
... geladas, Theropithecus gelada, Gallo et al., 2021;Palagi et al., 2009; Tonkean macaque, Macaca tonkeana, ; but see: stump-tailed macaques, Macaca arctoides: Paukner & Anderson, 2006; Japanese macaque, Macaca fuscata, . Finally, no evidence of yawn contagion was found in strepsirrhines (Lemur catta and Varecia variegata, Reddy et al., 2016) even though contagious yawning is present in non primates (Gallup et al., 2015;for review: Palagi et al., 2020). Hence, yawning might have been co-opted as a communicative signal multiple times over the course of the evolution, in relation to the type of sociality. ...
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In primates, yawn contagion (the yawning response elicited by others' yawn) is variably influenced by individual (e.g., sex, age) and social factors (e.g., familiarity) and possibly linked to interindividual synchronization, coordination, and emotional contagion. Two out of three studies on yawn contagion in bonobos (Pan paniscus), found the presence of the phenomenon with mixed results concerning the effect of familiarity and no replication on its modulating factors. To address this puzzling issue, we recorded all occurrences data on yawn contagion in a captive bonobo group (March-June 2021; 18 individuals; La Vallée des Singes, France). Contrary to chimpanzees and humans, the number of triggering yawns increased contagion, possibly owing to a higher stimulus threshold. This aspect may explain the interindividual variability observed in yawn contagion rates. In subjects under weaning, we did not detect yawn contagion and, as it occurs in certain human cohorts, yawn contagion declined with age, possibly due to reduced sensitivity to others. Females responded more than males and elicited more responses from females when showing sexual swelling. As reproductive females are central in bonobo society, our results support the hypothesis that-as in other Hominini-the most influential sex can influence yawn contagion. The relationship quality (measured via grooming/play) did not affect yawn contagion, possibly due to bonobos' xenophilic nature. Overall, this study confirms the presence of yawn contagion in bonobos and introduces new elements on its modulating factors, pointing toward the necessity of cross-group studies.
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Despite presenting several physiological and social benefits, yawning remains a highly stigmatized behavior across various cultures. Given evidence for an association between illness and the proclivity to yawn, it could be possible that yawning provides a heuristic cue to disease transmission between conspecifics. This aversion to yawning could thus serve as a disease avoidance strategy. The current study identified how individual differences in disease avoidance motivations could foster stigmatization of yawning. Participants completed personality inventories, including those related to disease avoidance and disgust, while indicating their attitudes toward various bodily functions. Individual differences in germ aversion and pathogen disgust were particularly associated with stigmatization of yawning, such that higher levels of these traits fostered greater aversion toward yawning. These data provide initial evidence for how fundamental social motives can facilitate reactions to involuntary behaviors.
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Yawning is a stereotyped action pattern that is prevalent across vertebrates. While there is growing consensus on the physiological functions of spontaneous yawning in neurovascular circulation and brain cooling, far less is known about how the act of yawning alters the cognition and behaviour of observers. By bridging and synthesizing a wide range of literature, this review attempts to provide a unifying framework for understanding the evolution and elaboration of derived features of yawning in social vertebrates. Recent studies in animal behaviour, psychology and neuroscience now provide evidence that yawns serve as a cue that improves the vigilance of observers, and that contagious yawning functions to synchronize and/or coordinate group activity patterns. These social responses to yawning align with research on the physiological significance of this behaviour, as well as the ubiquitous temporal and contextual variation in yawn frequency across mammals and birds. In addition, these changes in mental processing and behaviour resulting from the detection of yawning in others are consistent with variability in the expression of yawn contagion based on affinity and social status in primates. Topics for further research in these areas are discussed.
Turn-taking is universally seen in humans during the completion of various tasks. Turn-taking is also reported in non-human animals in the wild; however, in these cases turn taking is displayed during innate and stereotypic behaviors, so it may differ from turn-taking seen in humans. In the present study, budgerigars were trained to take turns between two individuals under operant control. Two cages were placed adjacent to one another and each cage contained one bird of a pair. Each bird pecked a response key in turn to produce a peck sequence for a reward. All pairs learned this task and one bird of the pairs often pecked the LED slightly before the signal onset, indicating that the peck was not a mere reaction to the LED signal. Furthermore, the preference examination suggested that a male bird pecked more rapidly while paired with a bird he preferred. Thus, they created a “pseudo” turn-taking sequence similar to humans. In addition, results from the male bird suggests a possibility that peck timing may be influenced by their preference. This study did not show whether birds collectively worked for a goal; however, the partner dependent behavior may be elements to form “true” turn-taking behavior.
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Considerable variation exists in the contagiousness of yawning, and numerous studies have been conducted to investigate the proximate mechanisms involved in this response. Yet, findings within the psychological literature are mixed, with many studies conducted on relatively small and homogeneous samples. Here, we aimed to replicate and extend upon research suggesting a negative relationship between psychopathic traits and yawn contagion in community samples. In the largest study of contagious yawning to date (N = 458), which included both university students and community members from across 50 nationalities, participants completed an online study in which they self-reported on their yawn contagion to a video stimulus and completed four measures of psychopathy: the primary and secondary psychopathy scales from the Levenson Self-Report Psychopathy Scale (LSRPS), the psychopathy construct from the Dirty Dozen, and the Psychopathic Personality Traits Scale (PPTS). Results support previous findings in that participants that yawned contagiously tended to score lower on the combined and primary measures of psychopathy. That said, tiredness was the strongest predictor across all models. These findings align with functional accounts of spontaneous and contagious yawning and a generalized impairment in overall patterns of behavioral contagion and biobehavioral synchrony among people high in psychopathic traits.
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Yawn contagion occurs when individuals yawn in response to the yawn of others (triggers). This is the first account of yawn contagion in wild geladas ( Theropithecus gelada ), a monkey species that shows yawn contagion in captivity and is organized in core units (one-male/bachelor groups) forming multilevel associations. In a population of geladas from the Kundi plateau (Ethiopia) we found that the yawning response was highest when geladas could perceive a triggering yawn, which confirms that yawn contagion is present in the wild. Yawn duration, mouth-opening degree and presence/absence of vocalisation (possibly modulating yawn detectability) did not affect the likelihood of contagion. Males and females, known to be both implicated in movement initiation within groups, were similarly powerful as yawn triggers. Instead, group membership and responder sex had a significant role in shaping the phenomenon. Yawn contagion was highest between individuals belonging to different core units and males were most likely to respond to others’ yawns. Because males have a non-negligible role in inter-group coordination, our results suggest that yawn contagion may have a communicative function that goes beyond the basic unit level.
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On the basis of observational and experimental evidence, several authors have proposed that contagious yawn is linked to our capacity for empathy, thus presenting a powerful tool to explore the root of empathy in animal evolution. The evidence for the occurrence of contagious yawning and its link to empathy, however, is meagre outside primates and only recently domestic dogs have demonstrated this ability when exposed to human yawns. Since dogs are unusually skilful at reading human communicative behaviors, it is unclear whether this phenomenon is deeply rooted in the evolutionary history of mammals or evolved de novo in dogs as a result of domestication. Here we show that wolves are capable of yawn contagion, suggesting that such ability is a common ancestral trait shared by other mammalian taxa. Furthermore, the strength of the social bond between the model and the subject positively affected the frequency of contagious yawning, suggesting that in wolves the susceptibility of yawn contagion correlates with the level of emotional proximity. Moreover, female wolves showed a shorter reaction time than males when observing yawns of close associates, suggesting that females are more responsive to their social stimuli. These results are consistent with the claim that the mechanism underlying contagious yawning relates to the capacity for empathy and suggests that basic building blocks of empathy might be present in a wide range of species.
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Most vertebrates yawn in situations ranging from relaxation to tension, but only humans and other primate species that show mental state attribution skills have been convincingly shown to display yawn contagion. Whether complex forms of empathy are necessary for yawn contagion to occur is still unclear. As empathy is a phylogenetically continuous trait, simple forms of empathy, such as emotional contagion, might be sufficient for non-primate species to show contagious yawning. In this study, we exposed pairs of male rats, which were selected for high yawning, with each other through a perforated wall and found that olfactory cues stimulated yawning, whereas visual cues inhibited it. Unexpectedly, cage-mate rats failed to show yawn contagion, although they did show correlated emotional reactivity. In contrast, stranger rats showed auditory contagious yawning and greater rates of smell-facilitated auditory contagious yawning, although they did not show correlated emotional reactivity. Strikingly, they did not show contagious yawning to rats from a low-yawning strain. These findings indicate that contagious yawning may be a widespread trait amongst vertebrates and that mechanisms other than empathy may be involved. We suggest that a communicatory function of yawning may be the mechanism responsible for yawn contagion in rats, as contagiousness was strain-specific and increased with olfactory cues, which are involved in mutual recognition.
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In humans and apes, yawn contagion echoes emotional contagion, the basal layer of empathy. Hence, yawn contagion is a unique tool to compare empathy across species. If humans are the most empathic animal species, they should show the highest empathic response also at the level of emotional contagion. We gathered data on yawn contagion in humans (Homo sapiens) and bonobos (Pan paniscus) by applying the same observational paradigm and identical operational definitions. We selected a naturalistic approach because experimental management practices can produce different psychological and behavioural biases in the two species, and differential attention to artificial stimuli. Within species, yawn contagion was highest between strongly bonded subjects. Between species, sensitivity to others' yawns was higher in humans than in bonobos when involving kin and friends but was similar when considering weakly-bonded subjects. Thus, emotional contagion is not always high-est in humans. The cognitive components concur in empowering emotional affinity between individuals. Yet, when they are not in play, humans climb down from the empathic podium to return to the "understory", which our species shares with apes.
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The thermoregulatory theory of yawning posits that yawns function to cool the brain in part due to counter-current heat exchange with the deep inhalation of ambient air. Consequently, yawning should be constrained to an optimal thermal zone or range of temperature, i.e., a thermal window, in which we should expect a lower frequency at extreme temperatures. Previous research shows that yawn frequency diminishes as ambient temperatures rise and approach body temperature, but a lower bound to the thermal window has not been demonstrated. To test this, a total of 120 pedestrians were sampled for susceptibly to self-reported yawn contagion during distinct temperature ranges and seasons (winter: 1.4 °C, n = 60; summer: 19.4 °C, n = 60). As predicted, the proportion of pedestrians reporting yawning was significantly lower during winter than in summer (18.3% vs. 41.7%), with temperature being the only significant predictor of these differences across seasons. The underlying mechanism for yawning in humans, both spontaneous and contagious, appears to be involved in brain thermoregulation.
(from the introduction) describes a [neuroethological] research program concerned with ldots involuntary copying / in this case, the S of study is the species one might imagine to be least likely to exhibit mindless imitation ldots human beings / in a series of ingenious studies involving everything from yawning through one's nose to listening to laughter played backwards, Provine seeks to describe the critical features that release such contagious behaviors, to define the conditions under which they occur, and to cast light on their potential functions (from the chapter) begins with the description of the motor acts of yawning & laughter because ldots the motor act is both the stimulus and the response, and defines the nature of the stimulus feature detector supporting contagion
The Budgerigar Melopsittacus undulatus was studied in the field in eastern Australia. Flocks occurred throughout the year, during most diurnal activities and at most stages of the life cycle. Daily activity began about sunrise and ceased during dusk. It consisted of feeding in the morning and afternoon and resting and preening in the foliage of trees during the middle of the day. Birds drank intermittently and at no specific time of the day. Different ages and sexes mixed in flocks and there was no obvious hierarchical construction nor high- and low-status groups within flocks or popula- tions. At times, flocks occurred that were composed predominantly of young birds. Eight discrete calls were identified. Slight differences between juveniles and adults, little sexual dimorphism and few discrete calls suggests that the social organization of the Budgerigar is simple compared to that of the Eastern Rosella Platycercus eximius. Behaviour of birds in the field is compared to that described from studies of domestic birds in cages.
Budgerigars Melopsittacus undulatus range and breed throughout inland Australia. In the far south, where there is a well defined cold wet winter and hot dry summer, Budgerigars arrive in spring, breed and depart in summer. In mid-latitudes Budgerigars normally are present and breed during the hot months; from the mid-south to mid-north there is a shift from a predominance of winter rainfall to that of summer rainfall and from a predominance of Budgerigars abundant and breeding in spring and summer to abundant and breeding in summer and autumn. In years of high rain-fall, in mid-latitudes reduced numbers may remain resident during the winter, but they do not breed. In the north, where there is a well defined summer wet season and the rest of the year is dry, Budgerigars often are scarce at the end of the dry season and during the wet season. Breeding in the north occurs predominantly in the earlier part of the dry season, in autumn and winter.