Interspecific behavioural synchronization: Dogs exhibit locomotor synchrony with humans

Abstract

Behavioural synchronization is widespread among living beings, including humans. Pairs of humans synchronize their behaviour in various situations, such as walking together. Affiliation between dyadic partners is known to promote behavioral synchronization. Surprisingly, however, interspecific synchronization has recived little scientific investigation. Dogs are sensitive to human cues, and share strong affiliative bonds with their owners. We thus investigated whether, when allowed to move freely in an enclosed unfamiliar space, dogs synchronize their behaviour with that of their owners'. We found that dogs visibly synchronized their location with their owner (staying in close proximity and moving to the same area), as well as their activity and temporal changes in activity (moving when their owner moved, standing still when their owner stood still, and gazing in the same direction as their owner). The present study demonstrates that owners act as attractors for their dogs in an indoor space, as mothers do for their children.

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Scientific RepoRts | 7: 12384 | DOI:10.1038/s41598-017-12577-z
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Interspecic behavioural
synchronization: dogs exhibit
locomotor synchrony with humans
Charlotte Duranton
1,2, Thierry Bedossa2,3 & Florence Gaunet1
Behavioural synchronization is widespread among living beings, including humans. Pairs of humans
synchronize their behaviour in various situations, such as walking together. Aliation between
dyadic partners is known to promote behavioral synchronization. Surprisingly, however, interspecic
synchronization has recived little scientic investigation. Dogs are sensitive to human cues, and share
strong aliative bonds with their owners. We thus investigated whether, when allowed to move freely
in an enclosed unfamiliar space, dogs synchronize their behaviour with that of their owners’. We found
that dogs visibly synchronized their location with their owner (staying in close proximity and moving
to the same area), as well as their activity and temporal changes in activity (moving when their owner
moved, standing still when their owner stood still, and gazing in the same direction as their owner). The
present study demonstrates that owners act as attractors for their dogs in an indoor space, as mothers
do for their children.
Behaving similarly to others is typical of many groups and dyads. Behavioural non-conscious synchronization is
a widespread phenomenon, found in various taxa, such as insects, birds, and mammals; it has various adaptive
values, such as increasing the eciency of anti-predator strategies and increasing social cohesion (see ref.1 for
a review). In non-human animals, synchronization is said to be non-conscious/implicit as there is no reliable
method to demonstrate consciousness2; further, we do not consider here non-conscious synchronisation as a
function of the optomotor reex system3, as it is a complex behaviour that can be modulated by life experiences,
such as attachement or learning - as described below.
Synchronization is indeed a broad term that encompasses dierent types of synchronies, such as temporal
synchrony (switching actions at the same time, the actions can be identical or dierent, the important feature is
the timing), location synchrony (being in the same place at the same time, the actions can be identical or dierent,
the important feature is the localisation), and activity synchrony (exhibiting the same behaviour at the same time;
for a review see refs4,5). All types of synchronies are present at the dyadic level, between two interacting indi-
viduals such as synchronization of swimming and breathing period in bottlenose dolphins (Tursiops aduncus)6,
of bouts of vigilance in red-necked pademelons (ylogale thetis)7, and of nest visiting in pairs of zebra nches
(Taeniopygia guttata)8.
In humans, interpersonal interaction oen results in the two partners coordinating/synchronizing their move-
ments9,10. Synchronization is linked to aliation between the partners: being synchronized strengthens social
bonds between individuals, and conversely, the more aliated two individuals are, the more they behave synchro-
nously11–13. Synchronization is present in various situations, from rocking in rocking chairs9 to walking side by
side14,15. e two latter studies investigated whether two people walking together would synchronize their behav-
iour even if they were not instructed to do so. e authors found that when walking together, the movements of
each partner in a pair were not independent, but synchronized15. Social interaction with visual contact between
the partners is thus sucient to elicit behavioural synchronization, even in common activities such as walking
together, and aliation increases the degree of synchrony9,16,17.
One common situation in which humans walk with another individual is owners walking their dog. It has been
suggested that synchronization of behaviour between humans and dogs can only emerge if there is attachment
1Laboratoire de Psychologie Cognitive, Aix-Marseille Université, CNRS, UMR7290, Fédération 3C, 3 Place Victor
Hugo, CS 80249, Bât. 9, Case D, 13331, Marseille, CEDEX 03, France. 2AVA Association, 40 Le Quesnoy, 76220, Cuy-
Saint-Fiacre, France. 3Ecole Nationale Vétérinaire d’Alfort, 7 Avenue du Général de Gaulle, 94704, Maisons-Alfort,
France. Correspondence and requests for materials should be addressed to C.D. (email: charlotte.duranton@
cegetel.net)
Received: 9 January 2017
Accepted: 6 September 2017
Published: xx xx xxxx
OPEN
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between the individuals, and that this synchrony relies on dogs ‘sensitivity to humans’ behavioural cues through
previous learning experiences18. Current research would suggest that all conditions for synchronization between
the two partners are present: dogs are well integrated into human societies, are highly sensitive to our behavioural
cues (such as e.g. direction of attention) thanks to learning during life experiences, have typically developed
strong aliative bonds with humans (see ref.4 for a review), and are even proposed to resemble to their owners
concerning stylistic attitudes/temperament19. However, the existence of temporal, location or activity synchrony
between these two dierent species is poorly documented. Two studies have investigated dog-human behavioural
synchronization while walking and yielded to the same conclusion. Guide dogs with their blind partner, as well as
pet dogs with their blind-folded owner, presented non-conscious behavioural synchronization when walking, for
instance in the start of movement or in the direction of walk18. During silent walks in the street, sighted owners
and their dogs also presented synchrony in their direction and speed20. However, in both studies the majority
of dogs were observed on leash (although in one study 6% were o-leash20). erefore, it might be thought that,
rather than non-conscious synchronization, most dogs observed had no choice but to synchronize their move-
ments with those of their owners.
We decided to investigate the existence of behavioural synchronization between dogs and their owners when
walking freely – i.e., without a leash. We tested dog-owner dyads moving in an enclosed unfamiliar room. We
hypothesized that during a walk where both partners are physically free to move independently, the dogs would
still synchronize their behaviour with that of their owners. More precisely, we hypothesized that the dogs would
synchronize their location with their owner (i.e., move to the same part of the room and stay into close proximity
with their owner). We also hypothesized that the dogs would synchronize their activity and switch of activity
with their owner (i.e. walk if their owner walks, stop walking when their owner does, switching activities at the
same time). Additionally, it has been found that when confronted with a stranger in an enclosed room, shepherd
dogs remained more focused on their owners than molossoid dogs when the owner stayed still, but the dierence
disappeared when the owner was moving21. We thus also investigated potential eects of these breeds, as well as
sex and age, on dogs’ behavioural synchronization.
Results
All means and standard errors are presented in TableS2 and non-significant results in TableS3, in the
Supplemental Material available.
Location synchrony. Proximity to owner. e main aim of this study was to assess whether dogs modify
their location in a room according to their owners’ location. e dogs spent an average of 23.84 ± 0.46 seconds
within close range of their owners, for an average of 79.47% of total testing time. ere was no eect of condition,
breed, sex, or age on the amount of time that the dogs spent close to their owners (LMERs, p > 0.05 for all, see
TableS3 in the Supplemental Material available).
Occupation of the room. ere was no signicant eect of breed, sex, or age on any of the following variables:
time spent by the dogs in the centre of the room, on the right side of the room, or on the le side of the room
(LMERs, p > 0.05 for all, see TableS3 in the Supplemental Material available).
Dogs spent signicantly more time in the centre of the room in the control and still-move conditions com-
pared to the other conditions (see Table1 and Fig.1)
In this line, we found that the time the dogs spent in the centre of the room was signicantly positively cor-
related with the time the owner spent in the centre of the room for all conditions pooled (Pearson’s correlation,
r = 0.51, p < 0.001, 95% CI = [0.41–0.60]).
As the time the dogs spent on the right side of the room and time spent on the le of the room did not signif-
icantly dier (t-test, p = 0.39), we pooled these two variables together (see TableS1 in the Supplemental Material
available). When dogs were not in the center of the room, they were on the sides; dogs’ time spent at the sides of
the room is the complement of the dogs’ time spent in the centre of the room; the corresponding statistical results
are provided in the TableS4 in the Supplemental Material available.
Activity synchrony. Another aim of this study was to assess whether dogs modulated their activity accord-
ing to that of their owners. Tests (LMERs) revealed no eect of breed, sex, or age on the dogs’ activity (time still,
time moving, gaze direction; p > 0.05 for all, see TableS3 in the Supplemental Material available).
Locomotor activity. Dogs spent more time stationary in the control and still conditions than in the still-move,
move-still, and move conditions (see Table1 and Fig.2). is is conrmed by a signicant positive correlation
between the time dogs spent stationary and the time the owners spent stationary (Pearson’s correlation for all
conditions pooled: r = 0.60, p < 0.001, 95% CI = [0.51–0.68]).
Obviously, when dogs were not still, they were moving. When considering the total time of activity, dogs’ time
spent moving is thus the complement of the dogs’ time staying still; the corresponding results are provided in the
TableS4 in the Supplemental Material available.
Gazing activity. We found a signicant eect of condition on the amount of time the dogs spent gazing toward
the front of the room, with longer times in the control and still conditions than in the still-move, move-still, and
move conditions (see Table1 and Fig.3).
e time the dogs spent gazing at the front of the room was signicantly positively correlated with the time the
owners spent gazing at the front of the room for all conditions pooled (Pearson’s correlation, r = 0.47, p < 0.001,
95% CI = [0.36–0.56]).
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Dependant
Variables Results Post-hoc
comparisons χ2Df PCohen’s
d95% CI
Time in the
centre
Overall eect — 111.93 4 <0.001 — —
Post-hoc Control/Still 58.20 1 <0.001 0.80 11.07–19.12
Control/Move 35.19 1 <0.001 0.64 8.04–17.10
Control/SM 1.41 1 0.23 0.14 −1.66–6.35
Control/MS 17.45 1 <0.001 0.40 4.53–13.36
Still/Move 3.71 1 0.054 0.12 −0.33–5.39
Still/SM 77.19 1 <0.001 0.73 9.80–15.71
Still/MS 23.52 1 <0.001 0.43 3.57–8.73
Move/SM 45.95 1 <0.001 0.99 −13.29–−7.16
Move/MS 6.17 1 0.01 0.30 0.64 – 6.60
SM/MS 18.19 1 < 0.001 0.46 −9.75–−3.45
Time stationary
Overall eect — 215.51 4 <0.001 — —
Post-hoc Control/Still 0.00 1 0.98 0.00 −2.01–1.97
Control/Move 111.80 1 <0.001 1.30 11.14–16.45
Control/SM 31.74 1 <0.001 0.84 3.94–8.40
Control/MS 51.13 1 <0.001 0.91 5.74–10.30
Still/Move 141.49 1 <0.001 1.49 −16.18–−11.45
Still/SM 26.70 1 <0.001 0.58 −8.63–−3.75
Still/MS 50.63 1 <0.001 0.85 −10.33–−5.74
Move/SM 54.40 1 <0.001 1.09 −9.72–−5.52
Move/MS 24.87 1 <0.001 0.66 3.42–8.13
SM/MS 3.23 1 0.07 0.22 3.93–0.24
Gaze to the
front
Overall eect — 76.22 4 <0.001 — —
Post-hoc Control/Still 0.24 1 0.62 0.05 −1.91–3.13
Control/Move 65.44 1 <0.001 0.90 5.61–9.38
Control/SM 17.14 1 <0.001 0.46 2.14–6.29
Control/MS 12.20 1 < 0.001 0.38 1.55–5.90
Still/Move 50.29 1 <0.001 0.71 8.89–−4.88
Still/SM 14.71 1 <0.001 0.47 −5.52–−1.69
Still/MS 6.97 1 <0.01 0.26 −5.55–−0.68
Move/SM 22.49 1 <0.001 0.53 −4.68–−1.87
Move/MS 27.82 1 <0.001 0.48 2.31–5.22
SM/MS 0.31 1 0.57 0.05 −1.30–2.28
Table 1. Signicant results for the eect of testing conditions on dependant variables. Results of the LMERs
are provided. All signicant post-hoc comparisons were still signicant aer correction for multiple tests.
Time in the centre = time spent by the dogs in the centre of the room. Time stationary = time spent by the
dogs stationary. Gaze to the front = time spent by the dogs gazing to the front of the room. MS = Move-Still
condition. SM = Still-Move condition. 95% CI and eect size, corresponding to Cohen’s d, are provided.
Figure 1. Time spent by the dogs in the centre of the testing room. Dogs (N = 48) spent signicantly more time
in the centre of the room in the control and still-move conditions compared to the other conditions. Dierent
letters represent statistical dierences. Data are presented as mean + SE.
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Time spent by the dogs gazing towards the sides of the room is presented in the TableS4 in the Supplemental
Material available.
Temporal synchrony. e nal aim of this study was to assess whether dogs changed their activity when
their owners’ changed theirs during the still-move and the move-still conditions. As the latency before dogs’
switched activity in both conditions did not signicantly dier (t-test, p = 0.25), we pooled these two variables
together (see the three denitions in TableS1 in the Supplemental Material available). In average, dogs switched
their activity 3.40 ± 0.52 seconds aer the owner switched their activity. Tests (LMs) revealed no eect of sex on
the dogs’ latency before switching activity (p > 0.05, see TableS3 in the supplemental material). We found a breed
eect, with shepherd dogs exhibiting a shorter latency (2.22 ± 0.44 seconds) before switching to the same activity
as the owner compared to molossoid dogs (4.73 ± 0.93 seconds; LM, χ2 = 70.95, Df = 1, p < 0.01, Cohen’s d = 0.76,
95% CI = [0.51–4.50]). Such a breed eect can easily be explained by physical issues: molossoids are generally
heavier than shepherds, and weight is known to be linked to dogs’ velocity22. is would explain why molossoids
needed more time to switch of activity. We will thus not further discuss this result.
We also found an eect of age, with older dogs having a shorther latency than younger dogs (Pearson’s corre-
lation, r = −0.35, p = 0.01, 95% CI = [−0.58–−0.06]).
Discussion
e present study is the rst to nd evidence of behavioural synchronization of a dog toward its owner when both
are moving freely in an enclosed room.
e rst key nding was a strong location synchrony between dogs and their owners. When the owners started
in the centre of the room and spent time there (i.e., in the control and still-move conditions), the dogs spent more
time in the centre of the room. is is conrmed by the positive correlation between the time that dogs and
owners spent in the centre of the room. Location synchrony was also evidenced by the fact that in the conditions
Figure 2. Dogs’ time spent stationary by experimental condition. Dogs (N = 48) spent signicantly more time
stationary in the control, still, and still-move conditions. Dierent letters represent statistical dierences. Data
are presented as mean + SE.
Figure 3. Dogs’ time spent gazing toward the front of the room, by experimental condition. Dogs (N = 48)
spent signicantly more time gazing toward the front of the room in the control and still conditions. Dierent
letters represent statistical dierences. Data are presented as mean + SE. G. = Gaze.
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where the owners spent most of their time on the sides of the room (i.e., in the still and move conditions), the
dogs also spent more time on the sides of the room. is relationship was conrmed by positive correlations
between the amounts of time that owners and dogs spent on each side of the room. Finally, the results showed
that the dogs spent almost 80% of the time in close proximity to their owners. ese eects did not depend on the
dogs’ breed, sex, or age.
Second, the present study evidenced strong temporal and activity synchronies between the dogs and owners.
Dogs switched to the same behaviour as their owners in 3.4 seconds on average. When their owner stayed still,
dogs also stayed still. is was conrmed by a positive correlation between owners’ and dogs’ stationary time,
as well as by the fact that the dogs’ stationary time in the control and still conditions was longer than in the
still-move and move-still conditions, which in turn were longer than their stationary time in the move condi-
tion. Conversely, when their owner was moving, the dogs were moving too. Even more subtly, synchrony in gaze
direction was also found. e more the owners looked toward the front of the room, the more the dogs did so as
well (i.e., in the control and still conditions compared to other conditions, and cf. the positive correlation between
gazing toward the front of room by the owners and the dogs).
e results thus conrmed all of our hypotheses. Like two people walking side by side14, when a person and a
dog walk indoors, their movements are not independent, but synchronized.
Our results are in line with intraspecic ndings. Dogs show behavioural synchronization with conspecif-
ics in many activities, such as howling, sleeping, and moving23. Two other studies have observed synchroni-
zation when two dogs were running together: they inuenced each other and the two synchronized their pace
of running24,25. It has also been recently shown that dogs follow their conspecics’ direction of walking during
group departures26. e dogs were more synchronized (both location and activity synchrony) with their favourite
social partners26. e authors proposed that it may reect rules evolved for adaptation to the environment before
domestication. As dogs evolved from wolves27, which usually follow their more experienced parents, dogs may be
predisposed to follow their favourite partners and/or the more experienced individuals in their group26.
How might such a phenomenon appear at the interspecic level? Various mechanisms could be at play that
would explain the non-conscious behavioural synchronization observed. One could argue that not talking to the
dogs would have put them in an unatural setting, making them more stressed. We reject this possibility because
dogs were behaving in a relaxed manner before we started the testing phases and throughout the experiment.
Additionnaly, it was only during the 30 seconds of each condition that the owners were instructed not to talk or
engage with their dogs, i.e. being ignored during only 30 seconds was not too stressful nor unusual for the dogs,
as for example when the owners are answering calls while walking or not their dogs, dogs are indeed ignored.
It is thus unlikely that dogs followed their owner because they were seeking proximity due to anxiety, as we
controlled for stress-associated behaviour, and as all dogs were evaluated by their owners as behaving normally.
Nevertheless, elevated physiological measures which could inuence their behavior could have been at play. Even
if not visibly stressed, dogs could have been more alert and could have been seeking proximity to owners as social
support. We thus encourage further study to control for physiological parameters, or to test dogs in more familiar
places, such as for example in their usual walking area.
However, another mechanism could explain the behavioural synchronization we found. It is known that dogs
develop strong aliative bonds with their owners28–30 and that oen owners are the favourite social partners for
their dogs28,29. Moreover, in daily life owners control access to the dogs’ food, leash, leisure time and various activ-
ities; the owners choose the timing, direction, and duration of walks, the place where the dog encounters other
dogs, etc. Interestingly, it is known that in dogs, aliation is of great inuence in leadership26. e fact that the
owner is mainly making decisions, such as initiating new directions of walks, may be considered as a type of lead-
ership31. Additionally, leaders are oen individuals possessing special skills about for instance the environment,
which can be applied to humans over dogs in our societies31. Nevertheless one could argue that our results did not
evidence an aer-eect of aliation, i.e. leadership, but instead local enhancement, a form of information transfer
that can be observed in mixed-species stable groups32,33. In the broad sense, local enhancement is observed when
the presence of a group mate at a specic location increases the probability that an observer goes to that location34.
But in the stricto sensu, the display of this processes is linked to foraging contexts: local enhancement is how the
presence of foragers at a location make it more obvious to others searchers32,35. In the present setting, we were very
careful for the dogs not to be in a foraging context: the owners were not allowed to have food with them nor to
provide food to the dog during the whole session (habitution, breaks, and testing conditions). In order to rule out
the possibility that only local enhancement in the broad sense was at play, future studies might measure duration
of ownership and owner’s attachment to their pet dogs to determine if dyads with stronger reported attachment
would also show stronger synchronization. Another, probably more likely, explanation for location and activity
synchrony between dogs and humans, is that dogs are reinforced for following their owners under many dierent
circumstances. When dogs are on-leash, many owners tug on the leash whenever the dog trys to pull away, creat-
ing painful sensations that stop when the dog follows them: this is negative reinforcement for synchronizing their
movements with those of their owners36. Whether dogs are on- or o-leash, many owners pet their dogs or give
them treats for following them, or for coming back when called: this is positive reinforcement for synchronizing
their movements with those of their owners. All of these phenomena may contribute to fostering the dog-human
relationship and to making it benecial for dogs to synchronize their movements (location, direction, walking
speed) with those of their owner. Eect of learning through life experiences is conrmed by our ndings that the
older the dogs, the greater temporal synchrony we observed when switching activites. is latter hypothesis is also
consistent with the gazing behaviour observed in the present study: dogs gazed where their owner gazed. is is
congruent with recent studies on gaze following into distant space that emphazises the eect of training as well as
daily experiences in gaze following behaviour37,38. is suggests that social cognition, learning and aliation are
involved in the synchronization of dogs’ behavior with that of the owner, conrming that the optomotor reex
hypothesis is less likely. Furthermore, as in humans, not moving in synchrony may be too costly for the dyad (e.g.
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decrease of cohesion and communication)16, or at least not being synchronized with their owners may be too
costly for the dogs. Finally, it is worth mentioning that all dog-owner dyads tested were recruited over voluntary
participation. It is thus possible that only owners with an interest in their dog’s behaviour, indicating a strong
relationship with their dogs, participated in the study, explaining the high level of synchronization observed. at
would be consistent with the nding that hormonal state synchronization has been found in dog-human dyads
with a strong relationship39.
A question that nally arises is whether behavioural synchronization between dogs and humans is an invar-
iant phenomenon across situations and dierent populations of owners and dogs. Given that in the present
study dog-human non-conscious synchronization was found, even though dogs were observed in an unfamiliar
enclosed room with a little time of familiarization with the environment, one could suggest that this phenomenon
is likely to be robust and should be present in other contexts. For instance, it has been shown that sheep are more
synchronized in larger spaces40. In open outside areas dogs spontaneously return towards their owners31 even if
they are not very attentive to their owners41. However behavioural synchronization between humans and dogs
was not the main focus of the two above-mentioned studies. It could thus be interesting to observe dogs in larger
outdoor areas to see whether dogs’ movements still follow those of their owners as found in the present study. e
results could possibly then be used in the development of strategies for managing dog behaviour. Additionnally,
it would have been interesting to test the eect of the human’s sex. Due to unbalanced sex ratios, the design of our
current study did not allowed us to properly test this parameter. However, since at least two studies have revealed
that male and female owners do not behave in the same way with their dogs42,43, the eect of owner sex on the
degree of behavioural synchronization would be justied to study. Furthermore, dierent populations of dogs
with dierent aliative bonds to humans, such as pet dogs and shelter dogs, are known to dier in their degree
of sensitivity to humans’ behavioural cues (see ref.44 for a review). In humans, it is known that crawling/walking
infants synchronize with their mothers, as proximity to the mother is critical for social development45,46. So, char-
acterizing the eect of the degree of aliation on dogs’ behavioural synchronization with humans is another issue
of both theoretical and societal relevance. Investigating the attractive eect of the caregiver on shelter dogs, or of
strangers on pet and/or shelter dogs, should shed light on the processes underlying behavioural synchronization.
e present study demonstrated for the rst time the existence of dog-human behavioural synchronization
when both partners move freely in an enclosed room. e phenomenon is so strong that it is visually observable
(see movieS1): aliated humans act as attractors for dogs. Pet dogs spontaneously synchronized their location
and activity with their owners. is paper extends our understanding of the interspecic relationship between
dogs and humans and adds data about the ability of dogs to read human communicative cues in general. We con-
clude that pet dogs act like their owners’ shadows.
Methods
Participants. Twenty-four molossoid and 24 shepherd pet dogs (12 males and 12 females in each group)
were tested. Sample size was dened a priori on the basis of previous research (see ref.47). e dogs were between
1 and 11 years old (mean ± SE = 4.5 ± 0.41 years) and did not show any signs of health problems related to ageing
(e.g., eye or joint problems) or behavioural problems (according to their owner’s reports). e testing room was
novel to all dogs.
Ethical note. e study was conducted in accordance to the legal requirements of France (where it was car-
ried out), and the institutional guidelines of the Aix-Marseille Université, France. e owners all signed a consent
form for study participation, and publication of identifying images. e dogs were not physically or psycholog-
ically harmed in the course of our study. All of the dogs were free to move in the room without physical con-
straints. e dogs did not undergo any physical intervention (such as blood or saliva sampling). Aer the test, all
dogs returned home with their owners.
Procedure. Dogs were tested in an unfamiliar empty quiet room (23 m2, Fig.4a) in the National Veterinary
School of Maisons-Alfort (France). At the beginning of the experiment, dogs were given 10 minutes to roam freely
in the room in the presence of their owner and the experimenter. is allowed the dogs to become familiar with
the space. Meanwhile, the experimenter explained the procedure of the test to the owners, with instructions on
how to behave in each testing condition. All dogs were tested in all conditions, and the order of conditions was
randomly assigned. e dog, its owner, and the experimenter then le the room. In all conditions, the owner then
entered the room with the dog o leash, and walked to a predened location. In the control condition, the owner
went to location C and stayed still there for 30 seconds (see Fig.4c). In the still condition, the owner went to loca-
tion L or R – the side was randomly assigned but counterbalanced across dogs – and stayed still for 30 seconds
(see Fig.4b le, 4c). In the move condition, the owner went to location L or R – the side was randomly assigned
but counterbalanced across dogs – and then started to walk along line W for 30 seconds; the back and forth
walk ended wherever the owner was at the end of the 30-second period (see Fig.4b right, 4c). In the still-move
condition, the owner went to location C and stayed still for 15 seconds, then walked back and forth along line W
for 15 seconds; the walk ended wherever the owner was at the end of the 15-second period (see Fig.4c). In the
move-still condition, the owner went to location C and walked back and forth along line W for 15 seconds, then
stopped at location C and stayed still for 15 seconds (see Fig.4c).
During the habituation phase, when the dogs were exploring the room, owners were authorized to speak to
their pet and oer social support to the dogs when they felt it was necessary. Additionnally, during each break
between the conditions, owners could talk and engage in any activity they wanted with their dogs to ensure that
the dogs were comfortable. Owners had to behave as usual with their dogs.
roughout the test, the dogs were o leash. When the owners were still, they were always looking towards
the front of the room (see Fig.4). During the testing conditions, owners were instructed not to show any
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Scientific RepoRts | 7: 12384 | DOI:10.1038/s41598-017-12577-z
emotional reaction, talk to their dogs, or look at them. Conditions were separated by a 10-minutes break. Owners
could interact normally with their dogs during the habituation phase as well as each break between the testing
conditions.
See MovieS1 to watch 10 seconds-long excerpts of each condition.
Behavioural analysis. Two cameras recorded the movements of both dogs and owners. Main studied var-
iables (6) were: time spent in close range (<1 m radius circle) with the owner, time spent stationary, time spent
in the centre of the room, time spent moving, time spent gazing toward the front of the room, and latency before
dogs’ switching to same activity as owners; cf. results below. Secondary variables, that were complement of the
main variables or additional variables were: time spent moving, time spent on the right side of the room, time
spent on the le side of the room, time spent on either side of the room, time spent gazing toward the le side of
the room, time spent gazing toward the right side of the room, time spent gazing toward the sides of the room,
time spent on line W, time spent gazing at the owner, latency before dogs’ switching to still in the move-still
condition, latency before dogs’ switching to move in the still-move condition. Results for secondary variables are
presented only in the Supplemental Material available. TableS1 in the Supplemental Material available presents a
denition of each variable and details of the behavioural analyses are also provided in the Supplemental Material
available.
Statistical analysis. To analyze the potential eects of experimental condition, sex, age, and breed and any
interactions between them on dogs’ behavioural responses, we used R (version 3.2.0). We used a linear mixed
model for dependent data (LMER; normal distribution of the residuals was graphically checked) to test the eects
of condition, breed, sex and age on all measures of dogs’ behaviour (details are provided in the Supplemental
Material available). Where needed, we carried out post hoc comparisons with Holm-Bonferroni corrections
for multiple tests. Where necessary, we used Pearson’s correlations to characterize the relationship between
Figure 4. Experimental setting. Photography Credits: Charlotte Duranton. Cam = camera.
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Scientific RepoRts | 7: 12384 | DOI:10.1038/s41598-017-12577-z
dog-related variables and owner-related variables. Eect size (Cohen’s d for LMER, and r coecient for Pearson’s
correlations) and 95% condence intervals (CI) are provided.
Data availability. e datasets generated during and/or analysed during the current study are available in
the Open Science Framework repository, https://osf.io/hux6w/?view_only=1843f609097f4b929efa694cabe96646.
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Acknowledgements
e authors are grateful to Ciska Girault and Marie Legain who helped during the study, and to Dr. Monique
Udell who reviewed our manuscript. We also thank the owners who volunteered for the study. is work was
funded by the Association Nationale de la Recherche et de la Technologie, the Association Aide aux Vieux
Animaux, the Centre National de la Recherche Scientique, Aix-Marseille Université, LABX-0036 (BLRI) and
Institut Convergences for Programme d’Investissements d’Avenir (ILCB).
Author Contributions
All authors designed the experiment. C.D. conducted the experiments and analyses. C.D. and F.G. wrote the main
manuscript text. All authors reviewed the manuscript.
Additional Information
Supplementary information accompanies this paper at https://doi.org/10.1038/s41598-017-12577-z.
Competing Interests: e authors declare that they have no competing interests.
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