ArticlePDF Available

Human attention affects facial expressions in domestic dogs


Abstract and Figures

Most mammalian species produce facial expressions. Historically, animal facial expressions have been considered inflexible and involuntary displays of emotional states rather than active attempts to communicate with others. In the current study, we aimed to test whether domestic dog facial expressions are subject to audience effects and/ or changes in response to an arousing stimulus (e.g. food) alone. We presented dogs with an experimental situation in which a human demonstrator was either attending to them or turned away, and varied whether she presented food or not. Dogs produced significantly more facial movements when the human was attentive than when she was not. The food, however, as a non-social but arousing stimulus, did not affect the dogs’ behaviour. The current study is therefore evidence that dogs are sensitive to the human’s attentional state when producing facial expressions, suggesting that facial expressions are not just inflexible and involuntary displays of emotional states, but rather potentially active attempts to communicate with others.
This content is subject to copyright. Terms and conditions apply.
Scientific RepoRts | 7: 12914 | DOI:10.1038/s41598-017-12781-x
Human attention aects facial
expressions in domestic dogs
Juliane Kaminski , Jennifer Hynds, Paul Morris & Bridget M. Waller
Most mammalian species produce facial expressions. Historically, animal facial expressions have
been considered inexible and involuntary displays of emotional states rather than active attempts
to communicate with others. In the current study, we aimed to test whether domestic dog facial
expressions are subject to audience eects and/ or changes in response to an arousing stimulus (e.g.
food) alone. We presented dogs with an experimental situation in which a human demonstrator was
either attending to them or turned away, and varied whether she presented food or not. Dogs produced
signicantly more facial movements when the human was attentive than when she was not. The
food, however, as a non-social but arousing stimulus, did not aect the dogs’ behaviour. The current
study is therefore evidence that dogs are sensitive to the human’s attentional state when producing
facial expressions, suggesting that facial expressions are not just inexible and involuntary displays of
emotional states, but rather potentially active attempts to communicate with others.
Most mammalian species produce facial expressions, which form meaningful and adaptive components of the
animal’s behavioural repertoire. e facial architecture underlying such facial expressions is highly conserved
among mammals1, suggesting that human facial expression is based on evolutionarily ancient systems. erefore,
it would seem reasonable to debate the extent to which such facial expressions are underpinned by sophisticated
cognitive processes. Historically, animal facial expressions (including human, to an extent) have been considered
inexible and involuntary displays e.g.2,3, reecting an individual’s emotional state rather than active attempts to
communicate with others. ere is some evidence that non-human primate facial expressions can be mediated by
the presence of an audience, suggesting that the sender has some understanding of whether the expressions can
be seen by others48. Waller et al. (2015) showed that the production of facial expressions in orangutans is more
intense and more complex during play when a recipient is directed towards them suggesting that the production
of these expressions is not necessarily an automated response and subject to audience eects6. Similarly, Scheider
et al. (2016) showed that Gibbons presented their facial expressions more oen and over a longer duration when
facing other individuals compared to non-facing situation7.
To date there is no systematic experimental evidence, however, that facial expressions in species other than
primates, are produced with similar sensitivity to the attention of the audience.
With the current study, we aimed to test whether domestic dog facial expressions change in response to an
highly arousing but non-social stimulus (food) and/or the changing attentional state of their human audience.
Domestic dogs are a potentially interesting model for this kind of research as they have a unique history. Dogs
have been living with humans for about 30,000 years9, during which time selection pressures seem to have acted
on dogs’ ability to communicate with humans. [see for a review10 and11,12 for a recent discussion].
ere is broad evidence that domestic dogs attend to a human’s attentional state1315, which is one indicator
of intentionality16. Aer being told not to take a piece of food, dogs steal the food more oen when the human’s
eyes are closed compared to situations during which the human’s eyes are open, the human has her back turned
to the dog or she is distracted13,15. Dogs are also sensitive to the human’s attentional state during communicative
interactions with humans. Dogs follow communicative gestures more once the humans eyes are visible and the
gesture is clearly directed at them16. Dogs also follow the gaze of a human to a target only if eye contact had been
established prior to the gaze shi17.
Waller et al. (2013) analysed the facial expressions of dogs waiting to be rehomed in shelters, and found
a negative correlation between the frequency of facial movements the dogs produced when interacting with a
stranger, and the rate at which they were re-homed. e more oen dogs produced a specic facial movement,
Action Unit 101 (which raises the inner eyebrow) the quicker they were re-homed18. Raising the inner eyebrow
changes the visual appearance of the eyes and makes them look bigger, a key feature of paedomorphism (juvenile
University of Portsmouth King Henry 1st Street, Portsmouth, PO12DY, UK. Correspondence and requests for
materials should be addressed to J.K. (email:
Received: 18 May 2017
Accepted: 18 September 2017
Published: xx xx xxxx
Content courtesy of Springer Nature, terms of use apply. Rights reserved
Scientific RepoRts | 7: 12914 | DOI:10.1038/s41598-017-12781-x
features present in the adult). One hypothesis is therefore that by picking dogs that raise their inner eye brow
more, humans simply follow their preference for paedomorphic facial characteristics, a preference which might
have acted as a selection pressure during dog domestication18,19.
It is possible, therefore, that dogs have also evolved the ability to use these facial expressions dierentially
depending on their audience. In which case, during domestication dogs may have gained additional cognitive
control of their facial expressions.
e current study investigated whether dog facial expressions can be subject to so called audience eects, and
can therefore be tailored to the human’s attentional state, which might suggest some social communicative func-
tion and possible voluntary control. e alternative is that dog facial expressions are a simple emotional display
based on the dog’s state of arousal. In order to try and discriminate between these two possible explanations, the
human, depending on the condition, presented a piece of food, as a non-social and arousing stimulus (a recent
study, using thermal imaging, shows that food seems to be more arousing for dogs than social contact with a
human as long as the human remains silent20).
erefore, if dogs produce facial expressions merely as an emotional display, we would expect them to not
necessarily dierentiate between the social (human attention) and the non social (food) conditions. However, if
the dogs behave in dierent ways in responds to the social and the non-social stimuli, this would provide some
evidence that dogs discriminate between the conditions based on social context and one possible explanation for
such discrimination that dogs exercise some voluntary control.
Analysis of FACS Coding. A 2 × 2 × 2 multivariate MANOVA was conducted as the design used repeated
measures and multiple dependent variables. ere were three repeated measures: attention (attentive vs. not
attentive), food (food present vs. food absent) and trial (trial 1 vs. trial 2). e multiple dependent variables were
the nine AUs (see Table1 for a list of AUs used in the analysis). To reduce the data and focus on the most com-
monly occurring movements, Action Units that one third of the dogs or more never produced in any of the four
conditions were excluded from the analysis. e analysis showed no 3 - way interaction of attention, food and trial
(Wilks’ λ = 0.058, F(8,16), p = 0.24, ηp2 = 0.43) and so we excluded the factor trial from further analysis.
A 2 × 2 doubly multivariate MANOVA showed that there was no main effect of food, Wilksλ = 0.072,
F(9,15) = 0.65, p = 0.74, ηp2 = 0.28 and no attention x food interaction, Wilks’ λ = 0.63, F(9,15) = 95, p = 0.51,
ηp2 = 0.36. ere was a signicant main eect of attention with a large eect size, Wilks’ λ = 0.071, F(9,15) = 21.78,
p < 0.0001, ηp2 = 0.93. e origin of the signicant main eect of attention was that for all except one of the
AUs (AU 145: blink), there was more activity in the attention condition than in the no attention condition (see
Two of the AUs, AU 101 (“eye brow raiser”, see Fig.1) and AD 19 (“tongue show”) reached signicance indi-
vidually with the main factor attention having an eect on the amount of AU101 and AD19 movements produced
(see Table1, Fig.1).
Analysis of Behavioural Coding. We also examined the other behavioural measures to see if condition
had an eect. We compared the frequency of vocalizing bouts across the four conditions using a Friedman test
(data were non normally distributed). Condition had an eect on the frequency of vocalizations produced with a
medium eect size, χ2(3, N = 23) = 17.69, p = 0.001, W = 0.26. e pattern of medians revealed that the human’s
attention increased the frequency of the vocalizations produced by the dogs (attention/food Mdn = 2.76; atten-
tion/no food Mdn = 2.65; no attention/food Mdn = 2.37; no attention/no food Mdn = 2.11). Wilcoxon pair-
wise comparisons revealed signicant dierences between attention/food vs. no attention/food, Z(23) = 2.31,
p = 0.021; attention/no food vs. no attention/food, Z(23) = 2.65p = 0.008; and attention/no food vs. no attention/
no food, Z(23) = 2.49, p = 0.013. No other combinations revealed signicant eects.
We also compared the frequency of tail wagging across the four conditions. ere was no eect of condi-
tion, χ2(3, N = 23) = 6.49, p = 0.09, although the pattern of medians was similar to that found for vocalizing
(attention/food Mdn = 2.76; attention/ no food Mdn = 2.65; no attention/food Mdn = 2.37; no attention/no food
Mdn = 2.2) with attention and food increasing the frequency of the behaviour. None of the pairwise comparisons
was signicant.
AU/AD F(df) p d ηp2M(SD) Attention M(SD) No Attention
101 102.58 (1,23) <0.0001 1.62 0.82 0.121 (0.04) 0.056 (0.04)
145 0.04 (1,23) =0.84 0.02 0.002 0.197 (0.06) 0.199 (0.09)
12 0.89 (1,23) =0.35 0.09 0.04 0.044 (0.05) 0.039 (0.06)
25 1.33 (1,23) =0.26 0.17 0.06 0.128 (0.12) 0.108 (0.11)
26 1.98 (1,23) =0.17 0.21 0.08 0.139 (0.13) 0.113 (0.12)
118 0.88 (1,23) =036 0.18 0.04 0.049 (0.07) 0.037 (0.05)
19 5.87 (1,23) =0.024 0.19 0.20 0.071 (0.07) 0.057 (0.07)
102 2.21 (1,23) =0.15 0.19 0.09 0.014 (0.02) 0.011 (0.01)
105 2.76 (1,23) =0.11 0.26 0.11 0.047 (0.05) 0.036 (0.03)
Table 1. AU unit activity as a function of attention or not for individual univariate ANOVAs Signicant results
in bold.
Content courtesy of Springer Nature, terms of use apply. Rights reserved
Scientific RepoRts | 7: 12914 | DOI:10.1038/s41598-017-12781-x
We conducted similar analyses on the other behaviours (laying, sitting, standing and moving, see Table1) but
no signicant eects were revealed.
e study has two main ndings. First, human attentional state aected the production of dogs’ facial expressions.
Dogs produced signicantly more facial expressions when the human was oriented towards them, than when the
human had her back turned to the dog. is eect was strongest for AUs, AU101 (“inner brow raiser”) and AD19
(“tongue show”). Human attentional state also aected one of the dogs other behaviours, the frequency of vocal-
izations produced. e visibility of the food, however, did not aect dogs’ facial movements and there is also no
conclusive evidence that it aected any of the dogs other behaviours. So, while dogs produce more facial expres-
sions when the human is oriented towards them and in a position to communicate, the visibility of non-social but
arousing stimulus (the food) did not alter their facial movements in the same way.
One interpretation of the dogs’ behaviour could be that dogs produce their facial expressions communica-
tively and that the dogs’ facial expressions are not just mediated by the individual’s emotional state. erefore,
dogs increase the frequency of their production dependent on the other individual’s attentional state but not
in response to being presented with a non social but arousing stimulus (the food). However, our data show an
increase of all facial movements when the human is attentive, but no evidence that dogs specically modulate
their facial movements depending on the attentional state of the human. Human attention had an eect on one
of the dogs other behaviours, the frequency of the vocalizations produced, but not their non-communicative
behaviours, such as sitting and standing. erefore, it seems that there might be a specic communicative func-
tion of this sensitivity to human attention. ere is substantial evidence supporting the importance of visibility
of the humans eyes for dogs during communicative interactions with humans. Teglas et al. (2012) showed that
dogs do not follow the gaze of a human to a certain location unless eye contact had been established beforehand17.
Kaminski et al. (2012) showed that dogs follow a human’s communicative gestures (e.g. pointing or gazing) but
ignore a human’s actions which resembled the communicative gestures but are not intended to be communicative
and during which the humans eyes were not directed at the dog16. Here we now add to this evidence by showing
that the visibility of the human’s eyes might be important for dogs for the production of facial expressions. is
might be evidence that dogs produce facial expressions as a exible signal and that its production depends on the
attentional state of the receiver of the signal. Without taking any physiological measures it is obviously impossible
to say to what extent seeing the human’s and the human’s eyes is also arousing for the dog. But our study high-
lights that a non-social stimulus which has been proven to be arousing for dogs, does not have any eect on the
production of their facial expressions. It is however possible impossible to say whether dogs behaviour in this and
other studies is evidence for a exible understanding of another individuals perspective, hence constituting a true
understanding of another individual’s mental state, or is a rather hardwired or learnt response to seeing the face
or the eyes of another individual (see for a discussion21,22).
Interestingly there are two Action Units that stand out from the overall analysis, the AD 19 (tongue show) and
the AU101 (inner brow raiser). e tongue shows movement can potentially be associated with stress (e.g. nose
lick behavior) but could also indicate panting behavior, which dogs use for heat regulation23. However, a facial
expression ethogram based on systematic analysis using tools like DogFACS does not exists, which is why we can
only speculate. Interestingly in the general dog literature a relaxed open mouth with tongue show is sometimes
described as generally attentive, which would be an interpretation in line with the results we see here.
However, AU101 may be of greatest signicance as the response of humans to this unit may have had the
greatest inuence on selection. Waller et al. (2013) showed that dogs from a shelter that produced the AU101
more frequently were rehomed quicker18. is could be for two possible reasons. Firstly, AU101 resembles a facial
movement which in humans indicates sadness, hence potentially making humans feels more empathic towards
dogs that produce this movement more. Another possibility is that the AU101 lets the eyes of the dogs appear
Figure 1. Mean rate (±1 SD) of facial movement AU101 (Inner eye brow raise) as a function of condition.
Content courtesy of Springer Nature, terms of use apply. Rights reserved
Scientific RepoRts | 7: 12914 | DOI:10.1038/s41598-017-12781-x
bigger and more infant like potentially tapping into the preference of humans for paedomorphic characteristics
and/ or humans innate tendency to respond to ostensive cues, one of which is ‘eyebrow raising’24,25. Regardless of
the exact mechanism, it seems that humans are particularly responsive to this facial movement in dogs. Increased
production of this movement in response to human attention could benet dogs in their interaction with humans,
In conclusion, we have demonstrated that dogs’ production of facial expressions is subject to audience eects,
and can be tailored to the human attentional state suggesting some communicative function and are not simple
emotional displays based on the dogs arousal state. Facial expressions are oen considered to be an automatic,
reexive and emotionally based system3, but these data point to a more exible system (at least in domestic dogs)
combining both emotional and potentially cognitive processes.
Subjects. 24 family dogs (13 male and 11 female) of various breeds and ages (age range = 1–12 years,
Mage = 4.75, SD = 3.33) participated in the study (see Table2). e dogs were normal family dogs with a train-
ing background typical for a pet dog. Dogs were randomly selected from a database of dogs at the Max Planck
Institute for Evolutionary Anthropology in Leipzig/ Germany. e only criterion for selection was that dogs had
to be comfortable to be without their owner and comfortable with a stranger in a strange environment. Research
was non-invasive and strictly adhered to the legal requirements of Germany. e study was ethically approved by
an internal committee at the Max Planck Institute for Evolutionary Anthropology (members of the committee are
Prof. M. Tomasello, Dr. J. Call and Susanne Mauritz). e animal research complies with the “Guidelines for the
Treatment of Animals in Behavioral Research and Teaching” of the Association for the Study of Animal Behavior
(ASAB). IRB approval was not necessary because no special permission for the use of animals in purely behav-
ioural or observational studies is required in Germany (TierSchGes §7 and §8). Dogs were fed by their owners
according to their normal daily routine and not food deprived in any way. Water was available to the dogs ad
libitum. In the conditions during which food was presented to the dogs, ©Frolic was used, which is a food mainly
used by owners as a treat in between meals. Dogs received regular breaks and observations were stopped in case
the dogs showed any sign of severe stress.
Materials. Dogs were observed in a quiet room (2.85 m × 3.60 m) and to ensure that dogs did not move
around extensively so their facial expressions could be observed easily, dogs were tied with a lead (1 m) to a prede-
termined spot in the room. Dogs were situated 1 m away from the human who was standing on a predetermined
and marked spot. A video camera was placed on a stationary tripod such that the dogs’ faces were visible (see
Name Breed Gender Age (Years)
Anouk Eurasier Male 1
Arik Hovawart Male 4
Bacardi Mongrel (German Shepherd mix) Female 11
Balou Schapendoes Male 11
Basma Basenji Female 2
Caja Mongrel (Doberman Mix) Female 8
Cody Mongrel Male 4
Dusky Basenji Male 2
Fefo Parson Jack Russell Male 3
Gerda Mongrel (Poodle & Labrador Mix) Female 3
Gordo Mongrel (Canario & Doberman Mix) Male 4
Guenni Whippet Male 2
Guiness Dalmation Male 5
Kendra Border Collie Female 2
Kenny Labrador Male 3
Lea Mongrel (Leonberger & German Shepherd Mix) Female 11
Luna German Shepherd Female 4
Mira Mongrel (Podenco & Magyar Vizsla Mix) Female 5
Paul Golden Retriever Male 3
Romy Mongrel (Rottweiler Mix) Male 2
Scully Border Collie Female 5
Sparky Boxer Male 2
Tina Mongrel Female 12
Wilma Mongrel (Rottweiler and Rhodesian Ridgeback Mix) Female 5
Table 2. List of the dogs included in the study with information about breed, gender and age (years).
Content courtesy of Springer Nature, terms of use apply. Rights reserved
Scientific RepoRts | 7: 12914 | DOI:10.1038/s41598-017-12781-x
Procedure. Before testing started, each dog was allowed to familiarise itself with the experimenter and the
room in which testing was conducted, and was allowed to move around freely for several minutes. Aer that the
dog was attached to a lead and the experimenter positioned herself in front of the dog and behaved according to
the following four conditions:
Attentive Food. e experimenter stood facing the dog with arms pointing towards the dog and palms placed
together displaying the food (see Fig.2A).
Attentive No Food. e experimenter stood facing the dog with palms in the same position but not displaying
food (see Fig.2B).
Not Attentive Food. e experimenter had her back turned towards the dog but had her arms behind her back,
palms placed together displaying the food (see Fig.2C).
Not Attentive No Food. e experimenter had her back turned towards the dog and her arms behind her back,
palms placed together but not displaying food (see Fig.2D).
e design was a within subjects design in which each dog received all four conditions. e order of condi-
tions was counterbalanced across dogs.
During each trial the experimenter stood still and did not respond to any of the dog’s behaviours. e exper-
imenter looked at a predetermined spot at the opposite wall and did not actively seek eye contact with the dog
when she was oriented towards the dog. Aer 2 minutes the trial ended and the human briey interacted with the
dog before she then changed her position according to the condition presented in the next trial.
Each dog received two trials per condition, summing up to 8 trials altogether. Trials were split in two sessions
to prevent fatigue and sessions were presented on two dierent days, with a break of up to four days between
sessions. e order of condition was counterbalanced across dogs.
FACS Coding. Coding of the facial movements was based on the DogFACS manual (Waller et al. 2013: www. DogFACS (Waller et al., 2013) is based on e Facial Action Coding System (FACS), an anatom-
ically based facial expression coding system rst developed for humans (Ekman & Friesen, 1978). It identies
observable facial changes associated with underlying muscle movement (Action units, AUs) allowing an objec-
tive, reliable and standardized measurement of facial movements. DogFACS was used to identify the facial move-
ments produced during each condition. A certied DogFACS coder (JH) coded the frequency and duration of
Figure 2. Experimenter’s position in the (A) Attentive Food (B) Attentive No food (C) Not attentive Food (D)
Not attentive no Food condition.
Content courtesy of Springer Nature, terms of use apply. Rights reserved
Scientific RepoRts | 7: 12914 | DOI:10.1038/s41598-017-12781-x
the dierent action units. Action Units that one third of the dogs or more never produced in any of the four con-
ditions were excluded from the analysis (for a list of all possible AUs, see Waller et al. 2013 or
is le 9 AUs (Action Units), ADs (Action Descriptors) and EADs (Ear Action Descriptors) that were included
in the analysis (see Table3 for a description).
Behavioural Coding. In addition to the FACS coding we also coded the general behaviour of the dogs to
see if we could identify any changes across conditions. We coded lying, sitting, standing, moving, tail-wagging,
yawning, nose licking and vocalizing (see Table3 for a list of the coded behaviours and their denitions).
Reliability coding. For the FACS coding JH (a trained FACS coder) did intra-rater reliability coding of 20%
of the original material (frequency of AUs produced) 1 year aer her original coding. Reliability was excellent
with all ric > 0.88, N = 40, p < 0.001. For the behavioural data (frequency of behaviours), a second coder unaware
of the research question coded 20% of the original material for the dierent behaviours. Reliability was excellent
for each of the behaviours (Stand: ric = 0.099, N = 40, p < 0.0001, Sit: ric = 0.99, N = 40, p < 0.0001 Move: r = 0.98,
N = 40, p < 0.0001, Lying: ric = 1, N = 40, p < 0.0001, Tail wagging: ric = 0.99, N = 40, p < 0.0001Vocalize: r = 0.99,
N = 40, p < 0.0001).
Data Availability Statement. All data will be made available.
1. Diogo, ., Wood, B. A., Aziz, M. A. & Burrows, A. On the origin, homologies and evolution of primate facial muscles, with a
particular focus on hominoids and a suggested unifying nomenclature for the facial muscles of the Mammalia. J. Anat. 215, 300–319
2. Darwin, C. e expression of emotion in animals and man. Lond. Methuen1877 Biogr. Sketch Infant. Mind 2, 285–294 (1872).
3. Tomasello, M. Origins of Human Communication (MIT Press, 2010).
4. Poss, S. ., uhar, C., Stoinsi, T. S. & Hopins, W. D. Differential use of attentional and visual communicative signaling by
orangutans (Pongo pygmaeus) and gorillas (Gorilla gorilla) in response to the attentional status of a human. Am. J. Primatol. 68,
978–992 (2006).
5. Leavens, D. A., ussell, J. L. & Hopins, W. D. Multimodal communication by captive chimpanzees (Pan troglodytes). Anim. Cogn.
13, 33–40 (2010).
6. Waller, B. M., Caeiro, C. C. & Davila-oss, M. Orangutans modify facial displays depending on recipient attention. PeerJ 3, e827
7. Scheider, L., Waller, B. M., Oña, L., Burrows, A. M. & Liebal, . Social use of facial expressions in hylobatids. PloS One 11, e0151733
8. Demuru, E., Ferrari, P. F. & Palagi, E. Emotionality and intentionality in bonobo playful communication. Anim. Cogn. 18, 333–344
9. almann, O. et al. Complete mitochondrial genomes of ancient canids suggest a European origin of domestic dogs. Science 342,
871–874 (2013).
10. Marshall-Pescini, S., aminsi, J., aminsi, J. & Marshall-Pescini, S. e social dog: History and evolution. Soc. Dog Behav. Cogn.
3–33 (2014).
11. Hare, B. et al. e domestication hypothesis for dogs’ sills with human communication: a response to and. Anim. Behav. 79, e1–e6
12. Udell, M. A., Dorey, N. . & Wynne, C. D. Wolves outperform dogs in following human social cues. Anim. Behav. 76, 1767–1773
13. Xitco Jr, M. J., Gory, J. D. & uczaj II, S. A. Dolphin pointing is lined to the attentional behavior of a receiver. Anim. Cogn. 7,
231–238 (2004).
Behaviour Denition
AU 101(1) Inner brow raiser. Liing of the inner brow region performed by the frontalis muscle.
AU 145(1) Blink: the relaxation of the levator palpebrae muscle and contraction of the orbicularis occuli circular muscle act to move the upper and lower
eyelid, closing the eye. e retractor anguli occuli lateralis pulls the outer corner of the eye caudally, aiding in closing the eye.
AU 12(1) Lip corner puller. e zygomaticus pulling the lip corners towards the ears.
AU 25(1) Lips part.
AU 26(1) Jaw drop.
AU 118(1) Lip pucker. e buccinators and orbicularis oris muscles act to push the lip corners rostrally, towards a medial point.
AD 19(1) Tongue show. e tongue is shown and it reaches at least the inner lower lip.
EAD 102(1) Ears adductor. e ears are adducted and the base of both pinnas becomes closer together by being pulled towards the head midline.
EAD 105(1) Ears downward. e ears are pulled ventrally, laterally.
Laying(2) e dog’s legs laid at on the ground while the head could rest on the ground, legs, or remain o the ground.
Sitting(2) e dog’s forelegs were extended and perpendicular to the ground while the hind legs were exed with the tarsus resting at on the ground.
Standing(2) All legs were extended and perpendicular to the ground.
Moving(2) e dog displaced its body from one location to another by alternately moving its legs more than two steps.
Tail-wagging e dog’s tail is extended and moves side to side in quick motion.
Vocalising Any sound emitted from the dog.
Table 3. Facial movements (DogFACS: Action Units, AUs, Action Descriptors, ADs and Ear Action Descriptors,
EADs) and general behaviours coded. Listed denitions were partly obtained from (1)Waller et al. 2013 and (2)Call
et al. (2003).
Content courtesy of Springer Nature, terms of use apply. Rights reserved
Scientific RepoRts | 7: 12914 | DOI:10.1038/s41598-017-12781-x
14. D’Entremont, B., Hains, S. & Muir, D. A demonstration of gaze following in 3-to 6-month-olds. Infant Behav. Dev. 20, 569–572
15. S chwab, C. & Huber, L. Obey or not obey? Dogs (Canis familiaris) behave dierently in response to attentional states of their owners.
J. Comp. Psychol. 120, 169 (2006).
16. Moll, H., Carpenter, M. & Tomasello, M. Fourteen-month-olds now what others experience only in joint engagement. Dev. Sci. 10,
826–835 (2007).
17. Téglás, E., Gergely, A., upán, ., Milósi, Á. & Topál, J. Dogs’ gaze following is tuned to human communicative signals. Curr. Biol.
22, 209–212 (2012).
18. Waller, B. M. et al. Paedomorphic facial expressions give dogs a selective advantage. PLoS One 8, e82686 (2013).
19. Archer, J. & Monton, S. Preferences for infant facial features in pet dogs and cats. Ethology 117, 217–226 (2011).
20. Travain, T. et al. How good is this food? A study on dogs’ emotional responses to a potentially pleasant event using infrared
thermography. Physiol. Behav. 159, 80–87 (2016).
21. Premac, D. & Woodru, G. Does the chimpanzee have a theory of mind? Behav. Brain Sci. 1, 515–526 (1978).
22. Penn, D. C. & Povinelli, D. J. On the lac of evidence that non-human animals possess anything remotely resembling a ‘theory of
mind’. Philos. Trans. R. Soc. Lond. B Biol. Sci. 362, 731–744 (2007).
23. Goldberg, M. B., Langman, V. A. & Taylor, C. . Panting in dogs: paths of air ow in response to heat and exercise. Respir. Physiol.
43, 327–338 (1981).
24. Csibra, G. & Gergely, G. Natural pedagogy. Trends Cogn. Sci. 13, 148–153 (2009).
25. Gergely, G. & Csibra, G. Teleological reasoning in infancy: e naıve theory of rational action. Trends Cogn. Sci. 7, 287–292 (2003).
We thank the owners for volunteering their dogs for our research. We also thank Katrin Schumann from the
Max Planck Institute for Evolutionary Anthropology in Leipzig for their help with data collection. We thank
Becky Spooner and Hoi-Lam Jim for help with coding some of the behavioural data of the dogs and for reliability
coding. We thank Jerome Micheletta for help with Figure 2.
Author Contributions
J.K., P.M. and B.W. wrote the main manuscript text and J.H. coded the video materials and wrote parts of the
method section. All authors reviewed the manuscript.
Additional Information
Competing Interests: e authors declare that they have no competing interests.
Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and
institutional aliations.
Open Access This article is licensed under a Creative Commons Attribution 4.0 International
License, which permits use, sharing, adaptation, distribution and reproduction in any medium or
format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Cre-
ative Commons license, and indicate if changes were made. e images or other third party material in this
article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the
material. If material is not included in the article’s Creative Commons license and your intended use is not per-
mitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the
copyright holder. To view a copy of this license, visit
© e Author(s) 2017
Content courtesy of Springer Nature, terms of use apply. Rights reserved
Terms and Conditions
Springer Nature journal content, brought to you courtesy of Springer Nature Customer Service Center GmbH (“Springer Nature”).
Springer Nature supports a reasonable amount of sharing of research papers by authors, subscribers and authorised users (“Users”), for small-
scale personal, non-commercial use provided that all copyright, trade and service marks and other proprietary notices are maintained. By
accessing, sharing, receiving or otherwise using the Springer Nature journal content you agree to these terms of use (“Terms”). For these
purposes, Springer Nature considers academic use (by researchers and students) to be non-commercial.
These Terms are supplementary and will apply in addition to any applicable website terms and conditions, a relevant site licence or a personal
subscription. These Terms will prevail over any conflict or ambiguity with regards to the relevant terms, a site licence or a personal subscription
(to the extent of the conflict or ambiguity only). For Creative Commons-licensed articles, the terms of the Creative Commons license used will
We collect and use personal data to provide access to the Springer Nature journal content. We may also use these personal data internally within
ResearchGate and Springer Nature and as agreed share it, in an anonymised way, for purposes of tracking, analysis and reporting. We will not
otherwise disclose your personal data outside the ResearchGate or the Springer Nature group of companies unless we have your permission as
detailed in the Privacy Policy.
While Users may use the Springer Nature journal content for small scale, personal non-commercial use, it is important to note that Users may
use such content for the purpose of providing other users with access on a regular or large scale basis or as a means to circumvent access
use such content where to do so would be considered a criminal or statutory offence in any jurisdiction, or gives rise to civil liability, or is
otherwise unlawful;
falsely or misleadingly imply or suggest endorsement, approval , sponsorship, or association unless explicitly agreed to by Springer Nature in
use bots or other automated methods to access the content or redirect messages
override any security feature or exclusionary protocol; or
share the content in order to create substitute for Springer Nature products or services or a systematic database of Springer Nature journal
In line with the restriction against commercial use, Springer Nature does not permit the creation of a product or service that creates revenue,
royalties, rent or income from our content or its inclusion as part of a paid for service or for other commercial gain. Springer Nature journal
content cannot be used for inter-library loans and librarians may not upload Springer Nature journal content on a large scale into their, or any
other, institutional repository.
These terms of use are reviewed regularly and may be amended at any time. Springer Nature is not obligated to publish any information or
content on this website and may remove it or features or functionality at our sole discretion, at any time with or without notice. Springer Nature
may revoke this licence to you at any time and remove access to any copies of the Springer Nature journal content which have been saved.
To the fullest extent permitted by law, Springer Nature makes no warranties, representations or guarantees to Users, either express or implied
with respect to the Springer nature journal content and all parties disclaim and waive any implied warranties or warranties imposed by law,
including merchantability or fitness for any particular purpose.
Please note that these rights do not automatically extend to content, data or other material published by Springer Nature that may be licensed
from third parties.
If you would like to use or distribute our Springer Nature journal content to a wider audience or on a regular basis or in any other manner not
expressly permitted by these Terms, please contact Springer Nature at
... Des Weiteren sind Hunde dem Menschen gegenüber sehr aufmerksam. Sie können zwischen Situationen unterscheiden, in denen ein Mensch sie beachtet oder abgelenkt ist (Call, Bräuer, Kaminski & Tomasello, 2003;Kaminski, Hynds, Morris & Waller, 2017;Viranyi, Topal, Gacsi, Miklosi & Csanyi, 2004). Sie sind sensibel für die menschliche Perspektive Kaminski, Bräuer, Call & Tomasello, 2009) und können beurteilen, was Menschen hören und was nicht (Bräuer, Keckeisen, et al., 2013;Kundey et al., 2010). ...
Full-text available
Zusammenfassung: Die Entwicklungspsychologie beschreibt ontogenetische Prozesse, bei denen es um zeitlich überdauernde, aufeinander aufbauende Veränderungen menschlichen Erlebens und Verhaltens über die gesamte Lebensspanne geht. In diesem Artikel erläutern wir den Zusammenhang zwischen ontogenetischen und phylogenetischen Prozessen, die das zentrale Forschungsinteresse der Vergleichenden Psychologie darstellen. Untersuchungsgegenstand sind hierbei Gemeinsamkeiten und Unterschiede zwischen Menschen und verschiedenen Tierarten, die zum Beispiel Aufschluss über die Evolution von Kognition geben können. Hunde spielen dabei eine besondere Rolle: sie haben durch ihre lange Domestikationsgeschichte einzigartige Fähigkeiten in den Bereichen Kommunikation, Aufmerksamkeit und Kooperation erlangt. Durch die konvergente Entwicklung von Hund und Mensch durch den ähnlichen Selektionsdruck auf beide Spezies, kann man bei einigen dieser Eigenschaften sogar von menschenähnlichen Fähigkeiten sprechen.
... The recent wealth of studies on the dog (Fig. 1) reveal this species is highly sensitive to visual social cues, particularly when it comes to human-dog communication. For example, dogs can take into account what other individuals can see Savalli et al. 2013) or know (Catala et al. 2017;Maginnity and Grace 2014), follow human action to solve a task (Pongrácz et al. 2001), respond and adapt to human behaviour (Gácsi et al. 2013;Kaminski et al. 2017), understand human intentions and beliefs (Lonardo et al. 2021;Schünemann et al. 2021), and act to manipulate others' attention (Horowitz 2009). These abilities in perspective taking and attention sensitivity have been used to argue initially for a "rudimentary Theory of Mind" (ToM) in dogs (Horowitz 2011), and since then evidence on different aspects of ToM in dogs has been growing (Lea and Osthaus 2018; however, see (Wynne 2021) for an opposing view). ...
Full-text available
Comparative studies of human–dog cognition have grown exponentially since the 2000’s, but the focus on how dogs look at us (as well as other dogs) as social partners is a more recent phenomenon despite its importance to human–dog interactions. Here, we briefly summarise the current state of research in visual perception of emotion cues in dogs and why this area is important; we then critically review its most commonly used methods, by discussing conceptual and methodological challenges and associated limitations in depth; finally, we suggest some possible solutions and recommend best practice for future research. Typically, most studies in this field have concentrated on facial emotional cues, with full body information rarely considered. There are many challenges in the way studies are conceptually designed (e.g., use of non-naturalistic stimuli) and the way researchers incorporate biases (e.g., anthropomorphism) into experimental designs, which may lead to problematic conclusions. However, technological and scientific advances offer the opportunity to gather much more valid, objective, and systematic data in this rapidly expanding field of study. Solving conceptual and methodological challenges in the field of emotion perception research in dogs will not only be beneficial in improving research in dog–human interactions, but also within the comparative psychology area, in which dogs are an important model species to study evolutionary processes.
... At the same time, dogs play an active role in this interspecific non-verbal communication. For instance, getting human attention increases the number of facial movements and expressions by dogs, this being suggestive of some communicative intention (Kaminski et al., 2017). Facial movements addressed to humans differ from facial expressions directed to their conspecifics (Caeiro et al., 2017). ...
Full-text available
Different factors seemingly account for the emergence of present-day languages in our species. Human self-domestication has been recently invoked as one important force favouring language complexity mostly via a cultural mechanism. As a consequence, evolutionary changes impacting on aggression levels are expected to have fostered this process. Here we hypothesise about a positive effect of dog-human interactions on aggression management and more generally, on our self-domestication, ultimately, contributing to aspects of language evolution. We review evidence of diverse sort (ethological mostly, but also archaeological, genetic, and physiological) supporting a positive feedback loop between dog domestication and human-self domestication that might have favoured the mechanisms promoting structural complexity in human languages.
... Rights reserved. person who can see the dog or the reward being requested than someone who cannot (Cooper et al. 2003;Gácsi et al. 2004;); (vi) they take into account humans' field of view when communicating and interacting with us (Hare et al. 1998;Savalli et al. 2013); (vii) they take into account a human's visual attentional state when communicating, by increasing communicative behaviours once eye contact is established and when the human attends to them (Kaminski et al. 2017;Savalli et al. 2016); (viii) they show susceptibility to an audience effect across different tasks by modulating their communicative behaviour (gaze alternation) depending on a human recipient's attentional state (Kiss et al. 2020;Marshall-Pescini et al. 2013;Savalli et al. 2014); and (ix) they are sensitive to and can manipulate conspecifics' attentional state during play (Horowitz 2009). In sum, dogs recognise and react appropriately to many different cues of visual attention, have some understanding of humans' visual field, and can make use of this information in a functional way both in cooperative (e.g., begging, obeying a command) and competitive contexts (e.g., stealing). ...
Full-text available
An important question in the study of canine cognition is how dogs understand humans, given that they show impressive abilities for interacting and communicating with us. In this review, we describe and discuss studies that have investigated dogs’ perspective-taking abilities. There is solid evidence that dogs are not only sensitive to the gaze of others, but also their attention. We specifically address the question whether dogs have the ability to take the perspective of others and thus come to understand what others can or cannot perceive. From the latter, they may then infer what others know and use this representation to anticipate what others do next. Still, dogs might simply rely on directly observable cues and on what they themselves can perceive when they assess what others can perceive. And instead of making inferences from representations of others' mental states, they may have just learned that certain behaviours of ours lead to certain outcomes. However, recent research seems to challenge this low-level explanation. Dogs have solved several perspective-taking tasks instantly and reliably across a large number of variations, including geometrical gaze-following, stealing in the dark, concealing information from others, and Guesser/Knower differentiation. In the latter studies, dogs' choices between two human informants were strongly influenced by cues related to the humans’ visual access to the food, even when the two informants behaved identically. And finally, we review a recent study that found dogs reacting differently to misleading suggestions of human informants that have either a true or false belief about the location of food. We discuss this surprising result in terms of the comprehension of reality-incongruent mental states, which is considered as a hallmark of Theory of Mind acquisition in human development. Especially on the basis of the latter findings, we conclude that pet dogs might be sensitive to what others see, know, intend, and believe. Therefore, this ability seems to have evolved not just in the corvid and primate lineages, but also in dogs.
... This shows that DogFACS can also serve to investigate dog facial expressions not only as cues (i.e., producing behaviour changes that accompany emotional states) but also as signals (i.e, behaviours specifically produced for the purpose of communicating an emotion to a communication partner), see also 25 . The AnimalFACS systems hence provide an important means of promoting understanding of animal facial expressions. ...
Full-text available
In animal research, automation of affective states recognition has so far mainly addressed pain in a few species. Emotional states remain uncharted territories, especially in dogs, due to the complexity of their facial morphology and expressions. This study contributes to fill this gap in two aspects. First, it is the first to address dog emotional states using a dataset obtained in a controlled experimental setting, including videos from (n = 29) Labrador Retrievers assumed to be in two experimentally induced emotional states: negative (frustration) and positive (anticipation). The dogs’ facial expressions were measured using the Dogs Facial Action Coding System (DogFACS). Two different approaches are compared in relation to our aim: (1) a DogFACS-based approach with a two-step pipeline consisting of (i) a DogFACS variable detector and (ii) a positive/negative state Decision Tree classifier; (2) An approach using deep learning techniques with no intermediate representation. The approaches reach accuracy of above 71% and 89%, respectively, with the deep learning approach performing better. Secondly, this study is also the first to study explainability of AI models in the context of emotion in animals. The DogFACS-based approach provides decision trees, that is a mathematical representation which reflects previous findings by human experts in relation to certain facial expressions (DogFACS variables) being correlates of specific emotional states. The deep learning approach offers a different, visual form of explainability in the form of heatmaps reflecting regions of focus of the network’s attention, which in some cases show focus clearly related to the nature of particular DogFACS variables. These heatmaps may hold the key to novel insights on the sensitivity of the network to nuanced pixel patterns reflecting information invisible to the human eye.
... For example, grimace scales with facial expressions considered to be associated with pain have been developed for domesticated species [17][18][19][20] . Although audience and directed attention are shown to affect the production of facial expressions in non-human primates and dogs, facial cues may potentially indicate emotional experiences determining generalized patterns as well as accommodating individual variation [21][22][23][24] . ...
Full-text available
Changes in facial expression provide cues for assessing emotional states in mammals and may provide non-verbal signals of pain. This study uses geometric morphometrics (GMM) to explore the facial shape variation in female Japanese macaques who underwent experimental laparotomy. Face image samples were collected from video footage of fourteen macaques before surgery and 1, 3, and 7 days after the procedure. Image samples in the pre-surgical condition were considered pain-free, and facial expressions emerging after surgery were investigated as potential indicators of pain. Landmarks for shape analysis were selected based on the underlying facial musculature and their corresponding facial action units and then annotated in 324 pre-surgical and 750 post-surgical images. The expression of pain is likely to vary between individuals. Tightly closed eyelids or squeezed eyes and lip tension were the most commonly observed facial changes on day 1 after surgery (p < 0.01974). A good overall inter-rater reliability [ICC = 0.99 (95% CI 0.75–1.0)] was observed with the method. The study emphasizes the importance of individualized assessment and provides a better understanding of facial cues to pain for captive macaque care.
Full-text available
There is extensive literature on the human-dog bond, less however on the role of owner psychological characteristics within this bond, and less still on how these might mediate dog behaviour. Accordingly, the aim of this study was to explore the relationship between owner levels of depression, anxiety and self-esteem and dog behaviour. Multiple linear regression was conducted to determine the predictive power of the psychological variables on dog behaviour using self-report. Conceptual content analysis was performed on three open questions to assess owner beliefs regarding their psychological influence on their dogs’ behaviour. 497 responses were collected. Anxiety and depression positively predicted increased levels of dog attachment and attention-seeking (p = < 0.001; p = 0.006), separation-related behaviour (p = < 0.001; p = < 0.001), stranger-directed aggression (p = < 0.001; p = < 0.001), stranger-directed fear (p = < 0.001; p = < 0.001), non-social fear (p = < 0.001; p = 0.01), dog-directed fear (p = 0.01; p = 0.01), touch sensitivity (p = < 0.001; p = < 0.001) and excitability (p = 0.004; p = < 0.001). Decreased self-esteem predicted dog non-social fear (p = 0.01). Fourteen themes were identified, including strong perceived bond, emotional dependency and anthropomorphism. Whilst only minimal within the vast interplay of factors impacted in canine ethology, owner psychological functioning plays a significant role in dog behaviour via numerous routes including interaction, emotion contagion and attachment. Understanding owner influence on dog behaviour can improve behaviour modification programmes, success of rehoming schemes, and improve wellbeing for both members of the human-dog dyad.
Full-text available
Dogs are good models for studying behaviour and cognition as they have complex social capabilities. In the current study, we observed how human emotional valences (positive, neutral and negative) affected aspects of dogs’ behaviour. We expected that dogs would exhibit more approaching behaviours in the positive condition and more signs of avoidance in the negative one. We analysed videos of 70 adult pet dogs of various breeds taken from an experiment in which one of two actors expressed an emotion and dogs could freely explore the environment for 30 s. Our results show that dogs exhibit differential behaviour when presented with different emotional valences. Two behaviours arose that might be linked to a reciprocal positive emotional state in dogs: tail raised between 90° and 180° and physical contact during sniffing. These behaviours are associated with an active search for information. In the positive conditions, dogs were more willing to explore the social environment and gather information from the actors.
Full-text available
Personal wellbeing is greatly influenced by our childhood and adolescence, and the relationships formed during those phases of our development. The human-dog bond represents a significant relationship that started thousands of years ago. There is a higher prevalence of dog ownership around the world, especially in households including children. This has resulted in a growing number of researchers studying our interactions with dogs and an expanding evidence base from the exploration of child-dog interactions. We review the potential effects of child-dog interactions on the physical, mental, and social wellbeing of both species. A search of the SCOPUS database identified documents published between January 1980 and April 2022. Filtering for key inclusion criteria, duplicate removals, and inspecting the references of these documents for additional sources, we reviewed a total of 393 documents, 88% of which were scientific articles. We were able to define the numerous ways in which children and dogs interact, be it neutral ( e.g ., sharing a common area), positive ( e.g ., petting), or negative ( e.g ., biting). Then, we found evidence for an association between childhood interaction with dogs and an array of benefits such as increased physical activities, a reduction of stress, and the development of empathy. Nonetheless, several detrimental outcomes have also been identified for both humans and dogs. Children are the most at-risk population regarding dog bites and dog-borne zoonoses, which may lead to injuries/illness, a subsequent fear of dogs, or even death. Moreover, pet bereavement is generally inevitable when living with a canine companion and should not be trivialized. With a canine focus, children sometimes take part in caretaking behaviors toward them, such as feeding or going for walks. These represent opportunities for dogs to relieve themselves outside, but also to exercise and socialize. By contrast, a lack of physical activity can lead to the onset of obesity in both dogs and children. Dogs may present greater levels of stress when in the presence of children. Finally, the welfare of assistance, therapy, and free-roaming dogs who may interact with children remains underexplored. Overall, it appears that the benefits of child-dog interactions outweigh the risks for children but not for dogs; determination of the effects on both species, positive as well as negative, still requires further development. We call for longitudinal studies and cross-cultural research in the future to better understand the impact of child-dog interactions. Our review is important for people in and outside of the scientific community, to pediatricians, veterinarians, and current or future dog owners seeking to extend their knowledge, and to inform future research of scientists studying dogs and human-animal interactions.
The ability to engage in some form of communication is essential for any social species. Communication generally relies on species-specific adaptations that provide animals with a cognitive tool to pass on messages from one conspecific to the other. This means that communication between members of different species is relatively rare and potentially requires qualitatively different cognitive abilities. This form of communication is not only challenging due to the fact that different species may rely on distinct sets of codes to convey messages but also because the primary modality used for this purpose may be different. Dogs represent a special case in the animal kingdom as they have been uniquely adapted to be receptive to the communicative signals of a species relatively distant in terms of their genome: humans. In this chapter, we will first focus on those characteristics of canids’ intraspecific communication that are shared between the dog and their phylogenetically closest relative, the wolf. Similarities in these forms of communication are likely the result of the common ancestry of the two species. Next, we turn to describing those attributes of canine communication that selectively pertain to how dogs communicate with their conspecifics. Finally, we discuss the ubiquitous nature of heterospecific communication between dogs and humans.
Full-text available
Non-human primates use various communicative means in interactions with others. While primate gestures are commonly considered to be intentionally and flexibly used signals, facial expressions are often referred to as inflexible, automatic expressions of affective internal states. To explore whether and how non-human primates use facial expressions in specific communicative interactions, we studied five species of small apes (gibbons) by employing a newly established Facial Action Coding System for hylobatid species (GibbonFACS). We found that, despite individuals often being in close proximity to each other, in social (as opposed to non-social contexts) the duration of facial expressions was significantly longer when gibbons were facing another individual compared to non-facing situations. Social contexts included grooming, agonistic interactions and play, whereas non-social contexts included resting and self-grooming. Additionally, gibbons used facial expressions while facing another individual more often in social contexts than non-social contexts where facial expressions were produced regardless of the attentional state of the partner. Also, facial expressions were more likely 'responded to' by the partner's facial expressions when facing another individual than non-facing. Taken together, our results indicate that gibbons use their facial expressions differentially depending on the social context and are able to use them in a directed way in communicative interactions with other conspecifics.
Full-text available
The recent explosion of studies on dogs' social behaviour and cognitive abilities are impressive, opening a new field of studies on a species that has economic, social, and emotional significance to humans across the globe. The origin of domestic dogs has been firmly established to be from an ancestor common to wolves, but the 'where, when, and how' of domestication, as well as the effects of this event on the dogs' mind and behaviour have engendered lively debates in journals and at conferences. In this chapter, we aim to introduce the reader of this book to some of the more salient and some of the more neglected aspects in the field. Hence, in the first part of this chapter (Section 1.1), we set dogs within the framework of their canine family, presenting some of the intriguing features that appear to set canids apart from other mammal families and that may have set the ground on which the wolf-human encounter took place. We also highlight areas where more research is needed because so little has been carried out to compare different canid species from a behavioural and cognitive perspective. In the second part (Section 1.2), we focus more on the dog-human story, summarising the archaeological evidence and genetic data helping us to draw the picture of the early history of men and dogs and presenting a brief overview of the different hypotheses put forward as regards the effects of domestication on dogs' social behaviour and cognition. Finally, in this section, we also outline some of the key issues that need to be addressed to assess the competing hypotheses and move the field of canine cognition forward. We conclude (in Section 1.3) by suggesting that dogs' sociality and their potentially 'special' socio-cognitive skills likely emerge both from the specific characteristics of their canid ancestry and the unique event of having encountered and started living alongside humans. We further present an overview of the chapters in this book, highlighting how contributions cover studies looking at both dogs' social behaviour and cognitive skills directed at both conspecifics and humans, because both are equally necessary for a well-rounded understanding of our four-legged companion.
Full-text available
Primate facial expressions are widely accepted as underpinned by reflexive emotional processes and not under voluntary control. In contrast, other modes of primate communication, especially gestures, are widely accepted as underpinned by intentional, goal-driven cognitive processes. One reason for this distinction is that production of primate gestures is often sensitive to the attentional state of the recipient, a phenomenon used as one of the key behavioural criteria for identifying intentionality in signal production. The reasoning is that modifying/producing a signal when a potential recipient is looking could demonstrate that the sender intends to communicate with them. Here, we show that the production of a primate facial expression can also be sensitive to the attention of the play partner. Using the orangutan (Pongo pygmaeus) Facial Action Coding System (OrangFACS), we demonstrate that facial movements are more intense and more complex when recipient attention is directed towards the sender. Therefore, production of the playface is not an automated response to play (or simply a play behaviour itself) and is instead produced flexibly depending on the context. If sensitivity to attentional stance is a good indicator of intentionality, we must also conclude that the orangutan playface is intentionally produced. However, a number of alternative, lower level interpretations for flexible production of signals in response to the attention of another are discussed. As intentionality is a key feature of human language, claims of intentional communication in related primate species are powerful drivers in language evolution debates, and thus caution in identifying intentionality is important.
Full-text available
Great apes show very complex systems for communicating emotions and intentions. Whereas gestures are intentional signals, facial expressions can disclose both emotions and intentions. The playful context is a good field to explore the possible dichotomy between intentionally and emotionally driven signals as it has been suggested that one of its functions is to learn producing and decoding communicative patterns. To understand how signals are produced during play and how they are modified in the course of ontogeny, we investigated the use of playful facial expressions and gestures in bonobos (Pan paniscus), a tolerant species showing a high propensity to play even as adults. Our results showed that the use of play faces and gestures is strongly influenced by the characteristics of the play session. Both play faces and gestures were more often performed when social play involved physical contact and when the receiver was visually attending, thus suggesting that both signals can be strategically employed when communicating becomes more urgent. Compared to play faces, gestures were more frequent during dyadic than polyadic sessions, when a unique receiver was involved. Being gestures not context specific, they are probably used more selectively by the sender. On the contrary, play faces are context specific and transmit an unequivocal positive message that cannot be misconceived. These features legitimize a broad use of playful facial expressions, independently of the number of playmates. The similarities and differences in the production of these signals are probably linked to the different degree of emotionality and intentionality characterizing them.
Full-text available
How wolves were first domesticated is unknown. One hypothesis suggests that wolves underwent a process of self-domestication by tolerating human presence and taking advantage of scavenging possibilities. The puppy-like physical and behavioural traits seen in dogs are thought to have evolved later, as a byproduct of selection against aggression. Using speed of selection from rehoming shelters as a proxy for artificial selection, we tested whether paedomorphic features give dogs a selective advantage in their current environment. Dogs who exhibited facial expressions that enhance their neonatal appearance were preferentially selected by humans. Thus, early domestication of wolves may have occurred not only as wolf populations became tamer, but also as they exploited human preferences for paedomorphic characteristics. These findings, therefore, add to our understanding of early dog domestication as a complex co-evolutionary process.
Full-text available
Dog Domestication The precise details of the domestication and origins of domestic dogs are unclear. Thalmann et al. (p. 871 ; see the cover) analyzed complete mitochondrial genomes from present-day dogs and wolves, as well as 18 fossil canids dating from 1000 to 36,000 years ago from the Old and New Worlds. The data suggest that an ancient, now extinct, central European population of wolves was directly ancestral to domestic dogs. Furthermore, several ancient dogs may represent failed domestication events.
This second edition of The Expression of the Emotions in Man and Animals was edited by his son Francis Darwin and published in 1890. As Sir Francis notes in his brief preface, because the first edition did not sell out in Charles Darwin’s lifetime, ‘he had no opportunity of publishing the material collected with a view to a second edition.’ This material, in the form of ‘a mass of letters, extracts from and references to books’ was utilised in the second edition, as were Darwin’s pencilled corrections in his own volume of the first. The book is a study of the muscular movements of the face (both human and animal) triggered by the emotions being felt - a ‘physical’ response to a ‘mental’ sensation. Darwin’s detailed analysis of what actually happens to a body in a state of fear, or joy, or anger is illustrated by photographic images.