Access to this full-text is provided by PLOS.
Content available from PLOS ONE
This content is subject to copyright.
RESEARCH ARTICLE
Turning preference in dogs: North attracts
while south repels
Jana Ada
´mkova
´ID
1
, Kateřina Benediktova
´
1
, Jan Svoboda
1
, Luděk Bartos
ˇ
2,3
,
Lucie Vynikalova
´
4
, Petra Nova
´kova
´
1
, Vlastimil Hart
1
, Michael S. Painter
1
, Hynek BurdaID
1
*
1Faculty of Forestry and Wood Sciences, Department of Game Management and Wildlife Biology, Czech
University of Life Sciences, Praha, Czech Republic, 2Department of Ethology, Institute of Animal Science,
Praha, Czech Republic, 3Faculty of Agrobiology, Food and Natural Resources, Department of Ethology and
Companion Animal Science, University of Life Sciences, Praha, Czech Republic, 4Faculty of Agrobiology,
Food and Natural Resources, Department of Zoology and Fisheries, Czech University of Life Sciences,
Praha, Czech Republic
*burda@fld.czu.cz
Abstract
It was shown earlier that dogs, when selecting between two dishes with snacks placed in
front of them, left and right, prefer to turn either clockwise or counterclockwise or randomly
in either direction. This preference (or non-preference) is individually consistent in all trials
but it is biased in favor of north if they choose between dishes positioned north and east or
north and west, a phenomenon denoted as “pull of the north”. Here, we replicated these
experiments indoors, in magnetic coils, under natural magnetic field and under magnetic
field shifted 90˚ clockwise. We demonstrate that "pull of the north" was present also in an
environment without any outdoor cues and that the magnetic (and not topographic) north
exerted the effect. The detailed analysis shows that the phenomenon involves also "repul-
sion of the south". The clockwise turning preference in the right-preferring dogs is more pro-
nounced in the S-W combination, while the counterclockwise turning preference in the left-
preferring dogs is pronounced in the S-E combination. In this way, south-placed dishes are
less frequently chosen than would be expected, while the north-placed dishes are appar-
ently more preferred. Turning preference did not correlate with the motoric paw laterality
(Kong test). Given that the choice of a dish is visually guided, we postulate that the turning
preference was determined by the dominant eye, so that a dominant right eye resulted in
clockwise, and a dominant left eye in counterclockwise turning. Assuming further that mag-
netoreception in canines is based on the radical-pair mechanism, a "conflict of interests"
may be expected, if the dominant eye guides turning away from north, yet the contralateral
eye "sees the north", which generally acts attractive, provoking body alignment along the
north-south axis.
Introduction
Dogs in two-choice experiments, when selecting between two dishes with snacks placed in
front of them, 90˚ apart, left and right, prefer to turn either clockwise (“right-preferring”) or
PLOS ONE
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 1 / 15
a1111111111
a1111111111
a1111111111
a1111111111
a1111111111
OPEN ACCESS
Citation: Ada
´mkova
´J, Benediktova
´K, Svoboda J,
Bartos
ˇL, Vynikalova
´L, Nova
´kova
´P, et al. (2021)
Turning preference in dogs: North attracts while
south repels. PLoS ONE 16(1): e0245940. https://
doi.org/10.1371/journal.pone.0245940
Editor: Gregg Roman, University of Mississippi,
UNITED STATES
Received: October 3, 2020
Accepted: January 8, 2021
Published: January 28, 2021
Peer Review History: PLOS recognizes the
benefits of transparency in the peer review
process; therefore, we enable the publication of
all of the content of peer review and author
responses alongside final, published articles. The
editorial history of this article is available here:
https://doi.org/10.1371/journal.pone.0245940
Copyright: ©2021 Ada
´mkova
´et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the original
author and source are credited.
Data Availability Statement: All relevant data are
within the paper and its Supporting Information
files.
Funding: The grant "EVA4.0", No. CZ.02.1.01/0.0/
0.0/16_019/0000803 financed by OP RDE to JA,
counterclockwise (“left-preferring”) or randomly in either direction (“irresolute”). This turn-
ing preference (or non-preference) is individually consistent in all trials but it is biased in favor
of north if they choose between dishes positioned north and east or north and west, a phenom-
enon we denoted as “pull of the north” [1]. This phenomenon was particularly pronounced in
older dogs, females, smaller and medium-sized breeds, dogs exhibiting a turning preference,
and especially in the north-east choice. We suggested that “pull of the north” represents a fur-
ther indication of magnetoreception in dogs, the other being non-random directional align-
ment during marking [2], which was, however, significantly changed when exposed to bar
magnets [3], the ability to find a bar magnet [4], or the existence of the so-called "compass run"
exhibited during homing [5].
We are, however, aware that for the ultimate evidence of magnetoreception, experiments in
defined manipulated magnetic field and/or under conditions of disturbed magnetoreception
are necessary. Moreover, the proximate reason for “pull of the north” remains unclear and
should be at least hypothesized.
Laterality, i.e. a predictable, non-random preference for using one side of the body (limbs,
brain hemisphere, sensory organs) spontaneously or if forced or restricted to choose between
two sides, is a known phenomenon in humans and animals. Laterality may be inborn,
imprinted, or entrained and has to be taken into account in maze and behavioral two-choice
animal experiments [6–10].
Laterality in dogs has been intensively studied with regard to the motoric (efferent) aspect
(paw laterality, Kong-test: [11–15]; sensory (afferent) aspect [16–18]; cognitive [19], and emo-
tional aspects [20–22]. Interestingly, and contrary to studies in humans, turning (directional,
rotational) preference has remained understudied.
Most people are right-handed, yet tend to instinctively veer to the left upon entering a new
space [23]. Interestingly, the counterclockwise action goes also for most athletic tracks, horse
and car races, and for baseball players running the bases [24]. There is even evidence that the
chariot races at ancient Rome’s Circus Maximus ran counterclockwise, too [25,26]. So, in
sports, where competitors enter the field of play from the outside of a traced circle, a right-
directional choice would lead to a counter-clockwise motion. But when entering the field of
action from within the circle—walking out of your apartment to take the dog for a walk, and
encountering intersections—right directional choices would tend towards tracing a clockwise
path [23]. Interestingly, in the countries, where people drive on the left side of the road, retail
shoppers tend to turn counterclockwise—when navigating store aisles, while in the countries,
where people drive and keep on sidewalks right, veer clockwise [23]. Tendencies of people to
turn either direction are known to architects who use them to design shopping galleries to fun-
nel shoppers in the wished direction [23].
While the preference to turn in a certain direction can be explained by individual inborn
laterality (handedness) and experience (facilitation), or–e.g. in the context of our experiment
of choice between two dishes, which is a visually guided task, through visual laterality—the
“pull of north” is expected to have a magnetoreceptive ground. Examination of this phenome-
non has a heuristic potential in getting insight into the very seat and mechanism of magnetore-
ception, which still remain enigmatic [27].
Sensory laterality (or asymmetry) has been described also in the context of spatial orienta-
tion in general and magnetoreception in particular. It has been found that homing pigeons
rely more on the right olfactory system in processing the olfactory information needed for the
operation of the navigational map [28]. An earlier study [29] has shown that the magnetic
compass of a migratory bird, the European robin (Erithacus rubecula), was lateralized in
favour of the right eye/left brain hemisphere. However, it has been later demonstrated [30]
that the described lateralization is not present from the beginning, but develops only as the
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 2 / 15
KB, HB, VH, MSP; the Grant Agency of the Czech
University of Life Sciences in Prague, CIGA (Project
No. 20174319) to JA, HB, KB, VH, PN, JS, LV; the
grant of the Ministry of Agriculture of the Czech
Republic MZE-RO0718 to LB.
Competing interests: No authors have competing
interests.
birds grow older. In another study [31], it was shown that pigeons can perceive and process
magnetic compass directions with the right eye and left brain hemisphere as well as the left eye
and right brain hemisphere. However, while the right brain hemisphere tended to confuse the
learned direction with its opposite (axial response), the left brain hemisphere specifically pre-
ferred the correct direction (angular response). The findings thus demonstrated bilateral pro-
cessing of magnetic information, but also suggested qualitative differences in how the left and
the right brain deal with magnetic cues.
Based on the hitherto knowledge and the above arguments,
1. We hypothesize that if “pull of the north” is due to magnetoreception (and indeed no other
explanation is apparent), it should be demonstrated also in an artificial magnetic field
shifted by magnetic coils, i.e. the artificially shifted magnetic North should exert the same
effect as the natural geomagnetic North.
2. We expect that, consistently with results of the previous study [1] “pull of the north” is
more pronounced in “lateralized” dogs and more in the North-East (N-E) combination
than in the North-West (N-W) choice.
Furthermore, following questions can be raised (and should be tested) to get insight into
the nature of the turning preference:
3. Does the directional preference for turning correlate with motoric laterality (such as paw-
laterality, i.e. “handedness”)?
4. Is pull of the north a) symmetrical (bilateral, i.e. of the same strength in the clockwise as
in counterclockwise direction), or b) asymmetrical (unilateral, i.e. stronger in one partic-
ular direction)?
Material and methods
Ethics statement
The study did not involve any disturbance or discomfort to the study subjects. The Profes-
sional Ethics Commission of the Czech University of Life Sciences in Prague has decided that
according to the law and national and international rules, this study has not a character of an
animal experiment and does not require a special permit.
Subjects
Altogether, 23 domestic dogs Canis familiaris (11 M, 12 F) from six breeds with pedigree and
an average age of 4.8 (±2.8) years (Table 1) were used in this study. The dogs were pets living
in households. All the dog owners were present with their dogs at trials.
Experimental equipment
The experiment took place in a magnetic coil at the field research station Truba, Kostelec nad
Černy
´mi lesy, (N 50˚0.40480’, E 14˚50.11145’), a detached workplace of the Faculty of Forestry
and Wood Sciences, Czech University of Life Sciences in Prague, Czech Republic. The mag-
netic coil (a Merritt coil, built according Kirschvink [32]) was 4 x 4 x 4 m and was located in a
separate special building. It was shielded from radiofrequency waves. It was controlled from a
separate building next to the coil building. The magnetic field in coils was manipulated by a
MagFieldG control software through a GMP4 RJ4.01 control unit and three current amplifiers,
each for the Bx axis, the By axis and the Bz axis. The generation system for GMP4 3D coil
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 3 / 15
system was used to create a defined direct and slowly changing magnetic field and it served to
drive the coil system to create a defined magnetic field.
Magnetic induction values in the Cartesian coordinate system (axis Bx = -3225 nT; axis
By = 17800 nT; axis Bz = 45448 nT) were set for the experiment, thereby rotating the magnetic
field by 90˚ magnetic North was shifted to the topographic (= geomagnetic) East. The mag-
netic field strength and inclination were maintained as for geomagnetic values for local geo-
graphic conditions. The magnetic coil space was used also for the control experiment to test
the dogs under local geomagnetic conditions, while other experimental conditions were pre-
served identic, i.e. shielding of radiofrequency waves, avoiding other influences (wind, sun,
outside sounds). The coil room was equipped with cameras (AXIS P5624-E 50HZ—PTZ IP
camera, TD / N, 18x zoom, HD 720p, IP66, PoE +) for video recording of the entire experi-
mental space, network speaker with SIP, PoE support (AXIS C3003-E NETWORK HORN
SPEAKER, Double—sided audio) and microphone (AXIS T8353A MICROPHONE 3.5MM)
at the control station to secure communication of the leading experimenter in the control
workplace with two experimenters in the coil.
Experimental procedure
Dogs were tested indoors, in a room housing the magnetic coils, and should make the choice
between two identical dishes. The dishes were placed at a distance of 2.9 m from the point of
Table 1. List of the tested dogs and resulting indices of directional preference.
Dog Owner Breed Sex Age Paw motorical laterality Initial turning preference Mean turning preference
Amalka KB Dachshund D F 5 51 17 46
Arthur ES Dachshund N M 2 n.m. -32 -45
Azizi JS Beagle M 6 6 -4 19
Barca LS Fox Terrier F 12 0 67 42
Bertik KB Dachshund D M 6 8 -29 -48
Bessy JA Fox Terrier F 8 26 22 42
Figy KB Dachshund D F 5 9 -4 8
Gofi JA Fox Terrier F 3 -70 -95 -96
Hard JA Fox Terrier M 2 -46 22 2
Hugo KB Dachshund D M 3 n.m. -25 -17
Hurvinek KB Dachshund D M 7 51 -46 -45
Jimmy ES Dachshund N M 2 n.m. 60 35
Kacka KB Dachshund D F 5 25 -17 -18
Kuky KB Dachshund D M 7 27 50 40
Naty ES Mu¨nsterla¨nder M 3 n.m. -45 -62
Offi JS Beagle F 9 -3 8 6
Pecka KB Dachshund D F 2 -44 17 29
Plysak KB Dachshund D F 2 10 -37 -60
Punta KB Dachshund D M 3 -1 -8 -34
Roxxy JS Beagle F 9 100 62 67
Shedy ES Weimaraner M 5 n.m. 27 40
Sisi KB Dachshund D F 3 n.m. 12 42
Zofka KB Dachshund D F 2 -20 54 46
Paw motoric laterality = laterality index based on the Kong test; Initial turning preference Turning preference index in the first trials of each dog. Mean turning
preference = = mean turning preference index over all trials of each dog. The value of the index can range from -100 to -25 (= left-turning dog) to 25–100 (= right-
turning dog). Sex: F = female, M = male. Age is given in years. Dachshund N = normal-sized dachshund, Dachshund D = dwarf-sized dachshund, n.m. = not measured.
https://doi.org/10.1371/journal.pone.0245940.t001
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 4 / 15
release of the dog, always a plus and minus 30˚ from the starting point. Both dishes contained
the same treats and dogs were always allowed to empty both. After placing the dishes, the dog
was ready for the starting point and waited to obtain a permit to go to a dish. The dogs could
not see the placement of the reward dishes. Three experimenters were involved in the experi-
ment; two were present in the magnetic coil (the owner was guarding the dog and prohibited
it from seeing the preparation procedure, and the other was preparing the placement of the
rewarded dishes), the third experimenter was in the control room using a microphone and
headsets to communicate with the two other colleagues, changed the experimental magnetic
conditions (switching between control and experimental conditions) according to a random-
ized schedule and recorded the results (direction of dog first choice) (Fig 1). Note that this per-
son was the only one who knew the actual position of the magnetic North inside the coil.
Each dog was tested in three to five test series under the control conditions with the mag-
netic North (mN) being 0˚, and in the same number of test series in an artificially shifted mag-
netic field with mN = 90˚ (where magnetic north was set on topographic east). The order of
the test series (control first, shifted field second or shifted field first, control second) was taken
into account. Tests series were performed at different days, at different daytimes, evenly dis-
tributed over the whole day.
Because a series included four trials in each dish combination alignment (i.e. N-E, E-S,
S-W, and W-N), individual dogs experienced either 48 or 80 trials (in 12 or 20 complete series)
in which their turning preference (first dish choice) was recorded under control conditions
and the same number of records was gathered for experiments in the shifted magnetic field.
The difference in the number of series and trials experienced by individual dogs was given by
their availability for our study.
In addition, the dog’s identity, date, time, sequence of trials combinations, and the order of
the trials in the respective series were recorded.
Paw preferences
To determine paw preference (motoric laterality of dogs), a modified Kong test [e.g. 12,16,33]
was used. In this test, it is recorded with which paw (left or right) the dog holds a Kong, a dog
toy (KONG Company) when trying to get the food stuffed inside. A plastic yoghurt cup was
used instead of Kong. The inner walls and bottom of the cup were covered with a dog’s deli-
cacy such as lard, cream cheese. Each dog was tested at home in an open area for 10 minutes
while the dog played with the cup and tried to lick it out and the number of touches with either
paw was recorded. Simultaneous touches with both paws were also recorded but were not
included in the calculation of the index of laterality. The dogs who did not touch the cup dur-
ing test of paw preference are excluded from the analysis of the Kong test.
Data analyses
From the recorded choices for each dog, in each trial, the left and right turning preferences
were summed, for all four combinations (W-N; N-E; E-S; S-W) separately. For data analysis,
the turning preference index was calculated in tests performed in the control and shifted mag-
netic field. The formula (R-L / R + L) x 100 was used, where the R = right and L = left sides are
the total numbers of the first choice of left or right dishes. The laterality index for the paw
preference (Kong test) was calculated using the same formula. The value of the index can
range from -100 to -25 (= left-pawed dog) to 25–100 (= right-pawed dog). Dogs with index val-
ues between -24 and 24 were considered ambilateral. For the turning preference, altogether
ten indices (LI) were calculated; one for each dish combination alignment (N-E, E-S, S-W, and
W-N), i.e. four altogether in the control conditions and four altogether in the shifted magnetic
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 5 / 15
field conditions. Furthermore, we calculated one mean index for control conditions and one
mean index for shifted magnetic field (S1 Table). The dogs were divided in turning preference
left-preferring, right-preferring or irresolute (ambilateral) preference according to [33] based
Fig 1. Experimental setup as monitored from above by a camera placed at the ceiling of the room, showing the sequence from release of the dog (A) to its choice of one of
two dishes (D).
https://doi.org/10.1371/journal.pone.0245940.g001
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 6 / 15
on results of the first trials (Initial turning preference in Table 1). Generalized Linear Model
(GLM) contained the interaction between Magnetic field and Turning preference classes.
From the recorded choices, preferences for either left or right turn were calculated for all
test combinations (N-E, E-S, S-W, W-N) within each trial, and the sum of all trials of each
dog. Index of directional preference was then calculated (according to the above formula) for
each dog.
All data were analyzed using the SAS System (SAS, version 9.4). For calculating Spearman
correlation coefficient we used PROC CORR. To analyze the factors affecting the directional
preference index (dependent variable) we used a multivariate Generalized Linear Mixed
Model (GLM, PROC MIXED). We constructed two GLMs. The models were applied as a
fixed-effect models designed for the repeated measures, i.e., in SAS, with REPEATED = order
of testing and the SUBJECT = Name of the dog with compound symmetric covariance struc-
tures for repeated measures (TYPE = cs). The first GLM was constructed with the predicted
fixed factors Magnetic coil in an interaction with the Turning preference classes, and then we
added other variables listed in S2 Table in case they could affect the directional preference
index. None of these variables appeared significant and therefore we will not mention them in
the text any more. Least squares means (LSMEANs) were calculated for the categorical fixed
effects by computing the mean of each treatment and averaging the treatment means. These
means of means were then used to compare the factors.
The second model was designed to estimate repeatability of the directional preference
across experimental conditions. The GLM contained the only fixed factor Magnetic coil. We
calculated repeatability as the intraclass correlation coefficient [34] by adding the RCORR
option to the REPEATED.
Independently, mean directional compass preference based on the frequency of first choices
in a given combination in all pooled trials was calculated for each dog using circular statistics
with Oriana 4.02 (Kovach Computing). Grand mean vectors were then calculated on the base
of those mean dog vectors for all the dogs, and subgroups with respect to turning preference,
experimental condition, sex, and age.
Results
Paw preference (motoric laterality, Kong test)
Following the a priori set criterion, out of altogether 17 dogs tested, 3 dogs were classified as
left-lateral, 6 as right-lateral, and 8 as irresolute (ambi-lateral) (Table 1). There was no apparent
effect of sex, age, breed or owner on this type of laterality. The correlation between the Kong
and overall turning preference tests was rather weak (r
s
= 0.317, P = 0.22).
Turning preference under the control (mN = 0˚) and experimental
(mN = 90˚) conditions
Following the a priori set criterion, out of altogether 23 dogs tested, 6 dogs were classified as
clockwise-preferring (right-lateral), 7 dogs as counterclockwise-preferring (left-lateral), and 10
as irresolute (ambi-lateral) (Table 1). There was no significant difference in turning prefer-
ences of individual dogs between control conditions (mN = 0˚) and the shifted magnetic field
conditions (mN = 90˚) (Fig 2). There was a variation in the turning preference index according
to the magnetic north direction and Turning preference classes (F
(23, 131)
= 4.59, P<0.0001,
Figs 2and 3). For the dogs with clockwise turning preference, there was a trend towards
increasing the turning preference index from NE, SE, SW and NW. In other words, the clock-
wise turning dogs exhibited the lowest turning preference index in the combination North-
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 7 / 15
East. However, only the difference between NE vs NW and between NE and SW, and only in
the shifted magnetic field, reached the level of significance (P = 0.05) (Fig 2 left). For the dogs
with counterclockwise turning preference, the most intensive counterclockwise preference
was shown in SE orientation in comparison with NW and partly NE, while the weakest prefer-
ence was in shown in the NW combination. Significant differences were achieved in the shifted
magnetic field in SE vs NW, and under control conditions in NE vs SE, SE vs NW, SW vs NW
(Fig 2, middle). No trend nor differences were detected for dogs showing irresolute turning
preference (Fig 2, right).
There was significant bias from the overall turning preferences in the eastern hemisphere,
expressed as the "pull of the north", in that a dish placed eastwards was more frequently chosen
than a dish placed southwards and a dish placed northwards more frequently chosen than a
dish placed eastwards, resulting in an average (theoretical) preference for NNE (Fig 4,
Table 2). In a more differentiated view, this result was due to a dominant preference of females
and/or clockwise preferring dogs for North (over East) and to an additional weaker pull of the
East over South in males and/or counterclockwise preferring dogs. "Pull of the north" in irreso-
lute dogs was indicated but not significant (Table 2, Figs 2and 3).
Repeatability of turning preference. A single factor of Magnetic coil was not significant
(F
1, 22
= 1.16, P = 0.86). On the other hand, Repeatability was high (r = 0.76).
Discussion
Turning preference did not correlate with the motoric paw laterality (Kong test). Apparently,
both types of preferences are controlled by different proximate mechanisms / pathways. This
conclusion is consistent with earlier findings [35] showing that visual (sensory) and paw
(motoric) laterality in dogs are independent of each other. None of the dogs had any previous
experience with emptying cups (i.e. Kong-type tests). None of the dogs used in this study had a
history of being trained "Heel" to come and follow the master at her/his left (or right) side.
Consequently, their turning preferences can be considered natural, spontaneous, inborne, and
Fig 2. Turning preference index. (Least Square Means ±SE) for clockwise-preferring (left), counterclockwise-preferring (middle), and irresolute (right) dogs under the
conditions of the magnetic North (mN) = 0˚ (control) and mN = 90˚ (shifted magnetic field) for the four particular combinations of the placement of dishes.
https://doi.org/10.1371/journal.pone.0245940.g002
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 8 / 15
not entrained. Accordingly, there was no significant difference in the turning preference in
particular dogs between the first and second experimental series and there was no effect of the
respective owner. Interestingly, among the dogs who turned clockwise there were more
females, while among the dogs turning counterclockwise there were more males. The sample
was, however, too small to allow any general conclusion with regard to the effect of sex on
turning preference. In fact, no clear effect of sex on turning preference was found in a previous
study (with a different composition of the study sample) [1].
Consistently with results, of the previous study in open field [1], the turning preference was
consistent for each particular dog for all combinations of placement of dishes also in an inte-
rior with uniform walls, no apparent landmarks, and no sun or wind cues. Concordantly with
the results of the previous study, this preference was slightly, yet significantly disturbed (or
pronounced) in that the north-placed dishes were more frequently chosen than would be
expected according to the average turning preference of each particular dog. Most important
in the context of the present study is the finding that, magnetic and not topographic, north
affected the mentioned bias.
The detailed analysis shows, however, that the "pull of the north" is a more complex phe-
nomenon, involving also "repulsion of the south". These effects are unilateral: the clockwise
turning preference in the right-preferring dogs is more pronounced ("accelerated") in the S-W
combination, while the counterclockwise turning preference in the left-preferring dogs is
Fig 3. Numbers in each quadrant (in the respective four compass combinations: N-E, E-S, S-W, W-N) show mean values of turning preference indices calculated
from individual dogs and pooled across all trials (both control and shifted magnetic field conditions). The value of the index can range from -100 to -25 (= left-
turning dog) to 25–100 (= right-turning dog). Data were partitioned by turning preference (left figure shows clockwise turning preference, right figure shows
counterclockwise turning preference; irresolute dogs were not calculated. The green arrow over the dog’s head in the centre of the circle indicates the direction of view of
the (supposedly) dominant eye which guides turning direction, while the red arrow shows the direction of view of the contralateral eye, supposed to exert "pull of the
north" if heading northwards. Green arrow outside the circle designates the preferred direction of turning, the shorter red arrow designates "pull of the north".
https://doi.org/10.1371/journal.pone.0245940.g003
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 9 / 15
"accelerated" in the S-E combination. On the other hand, N-E combination decreases ("decel-
erates") clockwise turning preference in the right-preferring dogs, while in the N-W combina-
tion, the counterclockwise turning preference in the left-preferring dogs will be reduced. In
Fig 4. Mean preference for compass direction of a dish with snacks of the first choice. Angular means over dogs preferring to turn clockwise, those preferring to turn
counterclockwise, dogs which were irresolute in their preference, and over all dogs. The arrow indicates the grand mean axial vector (μ) calculated over all angular means.
The length of the mean vector (r) provides a measure of the degree of clustering in the distribution of the mean vectors. The inner circle marks the 0.05 level of significance
border of the Rayleigh test. See Table 2 for statistics.
https://doi.org/10.1371/journal.pone.0245940.g004
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 10 / 15
this way, in the total, south-placed dishes are less frequently chosen than would be expected,
while the north-placed dishes are apparently more preferred. Since "rotational deceleration" is
stronger in N-E than the N-W combination, while the "acceleration" is stronger in the S-E
than in the S-W combination, the resulting theoretical mean preference is for Northeast.
It may be of relevance and significance in this context that the analysis of published results
on magnetic alignment behaviour in a variety of vertebrate species revealed that magnetic
alignment typically coincides with the north-south magnetic axis, however, the mean direc-
tional preferences of an individual or group of organisms is often rotated clockwise from the
north-south axis [36–38]. The deviation from the magnetic north-south axis could originate at
different levels in the sensory hierarchy: it could be related either to asymmetries at the sensor
level or to functional brain asymmetries, i.e. central processing.
Although the mode of the perception of the magnetic compass direction in animals remains
enigmatic [27], findings from behavioral, histological, neuroanatomical, and electrophysiolog-
ical studies have led to several physically viable theoretical models that might also apply to
dogs. Two mechanisms are most widely discussed in the literature: the magnetite-based mech-
anism and the radical-pair mechanism.
Perhaps the most intuitively appealing mechanism to explain magnetosensitivity in animals
is the idea of a small permanent magnet inside the animal that acts like a compass needle [39].
Magnetite-based sensors may be located anywhere in the body, they do not need to be concen-
trated in (paired) organs and they can be very tiny.
Another proposed mechanism for magnetoreception in animals is based on an effect of the
magnetic field on the quantum spin states of a photo-excited chemical reaction that forms
long-lived, spin correlated radical pair intermediates (radical pair mechanism; [40,41]. It is
believed to occur in the specialized retinal cells [42,43]. It is assumed that the magnetic field
may generate a “visual” pattern of varying light intensity, color, and/or contrast superimposed
on the normal visual scene [40,44,45]. The model suggests that north or south “patterns” are
Table 2. Circular statistics for frequencies of choices of a dish placed in different cardinal compass directions in front of a dog in dualchoice experiments, where
the dog chose between north or east, east or south, south or west, west or north.
Variable All trials mN = 0˚ mN = 90˚ 1st series 2nd series
Number of dogs tested 23 23 23 23 23
Mean vector (μ) 21˚ 43˚ 350˚ 22˚ 17˚
Length of mean vector (r) 0.485 0.557 0.464 0.347 0.566
Circular standard deviation 69˚ 622˚ 71˚ 83˚ 61˚
95% Confidence interval (-/+) for μ349˚-53˚ 16˚-70˚ 316˚-23˚ 335˚-68˚ 351˚-44˚
99% Confidence interval (-/+) for μ339˚-63˚ 7˚-78˚ 305˚-34˚ 321˚-82˚ 342˚-52˚
Rayleigh test (Z) 5.402 7.134 4.945 2.766 7.378
Rayleigh test (p) 0.004 4.92E-04 0.006 0.061 3.68E-04
Variable males females clockwise preferring counterclockwise preferring irresolute
Number of dogs tested 11 12 6 7 10
Mean vector (μ) 44˚ 0˚ 6˚ 48˚ 3˚
Length of mean vector (r) 0.517 0.529 0.637 0.655 0.356
Circular standard deviation 66˚ 65˚ 54˚ 53˚ 82˚
95% Confidence interval (-/+) for μ358˚-90˚ 318˚-42˚ 318˚-53˚ 9˚-90˚ 279˚-87˚
99% Confidence interval (-/+) for μ344˚-105˚ 304˚-56˚ 303˚-68˚ 354˚-103˚ 252˚-113˚
Rayleigh test (Z) 2.939 3.357 2.431 3.005 1.268
Rayleigh test (p) 0.049 0.031 0.084 0.043 0.288
Each compass direction was offered with the same frequency. Mean vectors in this table represent thus grand mean vectors. Cf. Fig 4.
https://doi.org/10.1371/journal.pone.0245940.t002
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 11 / 15
more clearly recognizable and easier to be followed than east or west “patterns”. Accordingly,
and alternatively, the “pull of the north” could be also interpreted as a “deflection / repellence
by the east or west”.
Given that the choice of a dish in our experiment was visually guided, we may postulate
that the turning preference was determined by the dominant eye, so that a dominant right eye
resulted in clockwise, and a dominant left eye in counterclockwise turning. Assuming further
that magnetoreception in canines is based on the radical-pair mechanism [46,47], a "conflict of
interests" may be expected, if the dominant eye guides turning away from north, yet the con-
tralateral eye "sees the north", which generally acts attractive, provoking body alignment along
the north-south axis. To test this hypothesis, visual dominance (eyedness) in particular dogs
should be studied in an independent test, e.g. sensory jump test [35].
Magnetic alignment might have an adaptive function in that it provides a global reference
frame that helps to structure and organize spatial behavior and perception over many different
spatial scales. For example, one possibility is that magnetic alignment helps to put the animal
into register with a known orientation of a mental (cognitive) map, reducing the complexity of
local and long-distance navigation, and reduces the demands on spatial memory [44]. This
would be analogous to strategies used in human orientation; it is much simpler and intuitive
to navigate when the navigators align themselves with a physical map (i.e. the users rotate their
body direction to coincide with the alignment of the physical map), rather than to navigate by
mentally rotating the physical map to align with the user’s orientation. Therefore, we suggested
that the mental map in animals is fixed in alignment with respect to the magnetic field [2,38].
Indeed, important component(s) of the cognitive map may be derived from the magnetic field
(see below) and spontaneous magnetic alignment behavior may help to place the animal into
register with this map. This relatively simple alignment strategy would help animals to reliably
and accurately ‘read’ their cognitive map and/or extend the range of their maps when explor-
ing unfamiliar environments. Accordingly, animals of different taxa were frequently reported
to prefer to head about northwards when feeding (reviewed in [36–38]).
We suggest that the described simple turning test has a high heuristic potential and should
be extended for tests of visual laterality and be performed under a wider array of experimental
conditions to get more insight into the very mechanism, seat and function of
magnetoreception.
Supporting information
S1 Table. Indices of laterality each tested dog. ITP = index of turning preference; W-N desig-
nates the combination in which the test dishes were placed west and north; N-E = designates
the combination in which the test dishes were placed north and east; E-S designates the combi-
nation in which the test dishes were placed east and south; S-W = designates the combination
in which the test dishes were placed south and west, mN = 0˚ designates a control experiment;
mN = 90˚ designates an experimental condition with a shifted magnet field.
(DOCX)
S2 Table. Variables available for statistical analysis.
(DOCX)
S3 Table. Source data.
(XLSX)
Author Contributions
Conceptualization: Jana Ada
´mkova
´, Kateřina Benediktova
´, Vlastimil Hart, Hynek Burda.
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 12 / 15
Data curation: Jana Ada
´mkova
´, Kateřina Benediktova
´.
Formal analysis: Jana Ada
´mkova
´, Kateřina Benediktova
´, Lude
ˇk Bartos
ˇ, Hynek Burda.
Funding acquisition: Jana Ada
´mkova
´, Kateřina Benediktova
´, Jan Svoboda, Lude
ˇk Bartos
ˇ,
Vlastimil Hart, Hynek Burda.
Investigation: Jana Ada
´mkova
´, Kateřina Benediktova
´, Jan Svoboda, Lucie Vynikalova
´, Petra
Nova
´kova
´, Michael S. Painter.
Methodology: Jana Ada
´mkova
´, Kateřina Benediktova
´, Vlastimil Hart, Michael S. Painter,
Hynek Burda.
Project administration: Jana Ada
´mkova
´, Kateřina Benediktova
´, Vlastimil Hart, Hynek Burda.
Resources: Vlastimil Hart, Hynek Burda.
Supervision: Jana Ada
´mkova
´, Kateřina Benediktova
´, Vlastimil Hart, Hynek Burda.
Validation: Jana Ada
´mkova
´, Kateřina Benediktova
´, Hynek Burda.
Visualization: Jana Ada
´mkova
´, Lude
ˇk Bartos
ˇ, Hynek Burda.
Writing – original draft: Jana Ada
´mkova
´, Kateřina Benediktova
´, Lude
ˇk Bartos
ˇ, Michael S.
Painter, Hynek Burda.
Writing – review & editing: Hynek Burda.
References
1. Ada
´mkova
´J, Svoboda J, Benediktova
´K, Martini S, Nova
´kova
´P, Tůma D, et al. Directional preference
in dogs: Laterality and "pull of the north". PLOS ONE. 2017; 12(9): e0185243. https://doi.org/10.1371/
journal.pone.0185243 PMID: 28945773
2. Hart V, Nova
´kova
´P, Begall S, Malkemper EP, Hanzal V, Jez
ˇek M, et al. Dogs are sensitive to small var-
iations of the Earth’s magnetic field. Front Zool. 2013; 10: 80. https://doi.org/10.1186/1742-9994-10-80
PMID: 24370002
3. Yosef R, Raz M, Ben-Baruch N, Shmueli L, Kosicki JZ, Fratczak M, et al, Directional preferences of
dogs’ changes in the presence of a bar magnet: Educational experiments in Israel. J Vet Behav. 2020;
35: 34e37. https://doi.org/10.1016/j.jveb.2019.10.003.
4. Martini S, Begall S, Findeklee T, Schmitt M, Malkemper EP, Burda H. Dogs can be trained to find a bar
magnet. PeerJ. 2018; 6: e6117. https://doi.org/10.7717/peerj.6117 PMID: 30588405
5. Benediktova
´K, Ada
´mkova
´J, Svoboda J, Painter MS, Bartos
ˇL, Nova
´kova
´P, et al. Magnetic alignment
enhances homing efficiency of hunting dogs. eLife. 2020 9: e55080. https://doi.org/10.7554/eLife.
55080 PMID: 32539933
6. Rogers LJ. Laterality in animals. Internat J Comp Psychol. 1989; 3: 5–25. https://escholarship.org/
content/qt9h15z1vr/qt9h15z1vr.pdf.
7. Rogers LJ. Lateralization in vertebrates: its early evolution, general pattern, and development. Adv
Study Behav. 2002; 31: 107–161. 10.1016/S0065-3454(02)80007-9
8. Rogers LJ, Vallortigara G, Andrew R.J. Divided brains. The biology and behaviour of brain asymme-
tries. 2013; Cambridge University Press, New York. ISBN: 9781107005358.
9. Schaafsma SM, Riedstra BJ, Pfannkuche KA, Bouma A, Groothuis TG. Epigenesis of behavioural later-
alization in humans and other animals. Phil Trans Roy Soc B. 2009; 364: 915–927. https://doi.org/10.
1098/rstb.2008.0244 PMID: 19064352
10. Warren JM. Handedness and laterality in humans and other animals. Physiol. 1980; 8:351–359. https://
doi.org/10.3758/BF03337470.
11. Batt L, Batt M, McGreevy P. Two tests for motor laterality in dogs. J Vet Behav. 2007; 2(2): 47–51.
https://doi.org/10.1016/j.jveb.2007.01.002.
12. McGreevy PD, Brueckner A, Thomson PC, Branson NJ. Motor laterality in 4 breeds of dog, J Vet
Behav. 2010; 5(6): 318323. https://doi.org/10.1016/j.jveb.2010.05.001.
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 13 / 15
13. Lee S, Konno A, Hasegawa T. Asymmetrical paw preference and personality. J Vet Behav. 2011; 6(1):
84–85. https://doi.org/10.1016/j.jveb.2010.09.002.
14. Plueckhahn TC, Schneider LA, Delfabbro PH. Assessing lateralization in domestic dogs: Performance
by Canis familiaris on the Kong test. J Vet Behav. 2016; 15: 25–30. https://doi.org/10.1016/j.jveb.2016.
08.004.
15. Ocklenburg S, Isparta S, Peterburs J, Papadatou-Pastou M. Paw preferences in cats and dogs: Meta-
analysis. Laterality. 2019; 24(6): 647–677. https://doi.org/10.1080/1357650X.2019.1578228.
16. Siniscalchi M, d’Ingeo S, Formelli S, Quaranta A. Relationship between visuospatial attention and paw
preference in dogs. Sci Reps. 2016; 6: 31682. https://doi.org/10.1038/srep31682 PMID: 27545695
17. Siniscalchi M, d’Ingeo S, Minunno M, Quaranta A. Communication in dogs. Animals. 2018; 8(8): 131.
https://doi.org/10.3390/ani8080131 PMID: 30065156
18. Tomkins LM, Thomson PC, McGreevy PD. Associations between motor, sensory and structural laterali-
sation and guide dog success, Vet J. 2012; 192(3): 359–367. https://doi.org/10.1016/j.tvjl.2011.09.010
PMID: 22023850
19. Pongra
´cz P., Ujva
´ri V, Farago
´T, Miklo
´si À, Pe
´ter A. Do you see what I see? The difference between
dog and human visual perception may affect the outcome of experiments, Behav Proc. 2017; 140: 53–
60. https://doi.org/10.1016/j.beproc.2017.04.002.
20. Batt LS, Batt MS, Baguley JA, McGreevy PD. The relationships between motor lateralization, salivary
cortisol concentrations and behavior in dogs. J Vet Behav. 2009; 4(6), 216–222. https://doi.org/10.
1016/j.jveb.2009.02.001.
21. Schneider LA, Delfabbro PH, Burns NR. Temperament and lateralization in the domestic dog (Canis
familiaris). J Vet Behav. 2013; 8(3): 124–134. https://doi.org/10.1016/j.jveb.2012.06.004.
22. Siniscalchi M, d’Ingeo S, Formelli S, Quaranta A. Lateralized behavior and cardiac activity of dogs in
response to human emotional vocalizations. Sci Reps, 2018; 8(1): 77. https://doi.org/10.1038/s41598-
017-18417-4 PMID: 29311574
23. Sorensen H. Inside the mind of the shopper. 2nd ed. 2017; Pearson Education, Old Tappan, New Jer-
sey. ISBN: 9780137013005.
24. Scharine AA, McBeath MK. Right-handers and Americans favor turning to the right. Human Factors.
2002; 44(2): 248–256. https://doi.org/10.1518/0018720024497916 PMID: 12452271
25. Eber A. Clandestine Curses: Hidden dangers to charioteers Roman spectacles and entertainment.
2010; Available at: https://www.brown.edu/academics/archaeology/sites/academics-archaeology/files/
publication/document/Eber2010.pdf.
26. Tavakkoli MH, Jose TP. The reason why do athletes run around the track counter- clockwise? 2013;
Internat Edu E-J. 2(4): 23–30. https://www.oiirj.org/ejournal/oct-nov-dec2013/phy-edu/04.pdf.
27. Nordmann GC, Hochstoeger T, Keays DA. Unsolved mysteries: Magnetoreception—A sense without a
receptor. PLoS Biol. 2017; 15(10): 1–10. https://doi.org/10.1371/journal.pbio.2003234.
28. Gagliardo A, Flannino C, IoalèP, Pecchia T, Wikleski M, Vallortigara G. Olfactory lateralization in hom-
ing pigeons: A GPS study on birds released with unilateral olfactory inputs’, J Exp Biol. 2011; 214(4),
593–598. https://doi.org/10.1242/jeb.049510.
29. Wiltschko W, Traudt J, Gu¨ntu¨rku¨n O, Prior H, Wiltschko R. Lateralization of magnetic compass orienta-
tion in a migratory bird. Nature. 2002; 419: 467–470. https://doi.org/10.1038/nature00958 PMID:
12368853
30. Gehring D, Wiltschko W, Gu¨ntu¨rku¨n O, Denzau S, Wiltschko R. Development of lateralization of the
magnetic compass in a migratory bird. Proc Roy Soc B. 2012; 279(1745), 4230–4235. https://doi.org/
10.1098/rspb.2012.1654.
31. Wilzeck C., Wiltschko W, Gu¨ntu¨rku¨n O, Buschmann J-U, Wiltschko R, Prior H. Learning of magnetic
compass directions in pigeons. Anim Cogn. 2010; 13(3): 443–451. https://doi.org/10.1007/s10071-
009-0294-0 PMID: 19937359
32. Kirschvink JK. Uniform Magnetic Fields and Double-Wrapped Coil Systems: Improved Techniques for
the Design of Bioelectromagnetic Experiments. Biectromagnetix. 1992; 13: 401–411. https://doi.org/
10.1002/bem.2250130507 PMID: 1445421
33. Tomkins LM, Thomson PC, McGreevy PD. First-stepping Test as a measure of motor laterality in dogs
(Canis familiaris). J Vet Behav. 2010; 5(5): 247–255. https://doi.org/10.1016/j.jveb.2010.03.001.
34. Sokal RR, Rohlf FJ. Biometry. 1981; W. H. Freeman, San Francisco.
35. Tomkins LM, Williams KA, Thomson PC, McGreevy PD. Sensory Jump Test as a measure of sensory
(visual) lateralization in dogs (Canis familiaris). J Vet Behav. 2010 5: 256–267.
36. Begall S, Malkemper EP, Červeny
´J, Němec P, Burda H. Magnetic alignment in mammals and other
animals. Mammal Biol. 2013; 78(1): 10–20. http://dx.doi.org/10.1016/j.mambio.2012.05.005.
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 14 / 15
37. Malkemper EP, Painter MS, Landler L. Shifted magnetic alignment in vertebrates: Evidence for neural
lateralization? J Theor Biol. 2016; 399:141–147. https://doi.org/10.1016/j.jtbi.2016.03.040 PMID:
27059891
38. Burda H, Begall S, Hart V, Malkemper EP, Painter MS, Phillips JB, 2020. Magnetoreception in Mam-
mals. In: Fritzsch B (ed.) and Bleckmann H (Volume ed.), The Senses: A Comprehensive Reference,
vol. 7. Elsevier, Academic Press, pp. 421–444.
39. Yorke ED. A possible magnetic transducer in birds. J Theor Biol. 1979; 77(1): 101–105. https://doi.org/
10.1016/0022-5193(79)90140-1 PMID: 449364
40. Ritz T, Adem S, Schulten K. A model for photoreceptor-based magnetoreception in birds. Biophys J.
2000; 78: 707–718. https://doi.org/10.1016/S0006-3495(00)76629-X PMID: 10653784
41. Hore PJ, Mouritsen H. The radical-pair mechanism of magnetoreception. Ann Rev Biophys. 2016; 45
(1): 299–344. https://doi.org/10.1146/annurev-biophys-032116-094545.
42. Liedvogel M, Mouritsen H. Cryptochromes—A potential magnetoreceptor: What do we know and what
do we want to know? J Roy Soc Interface. 2010; 7: S147–S162. https://doi.org/10.1098/rsif.2009.0411.
focus PMID: 19906675
43. Worster S, Kattnig DR, Hore PJ. Spin relaxation of radicals in cryptochrome and its role in avian magne-
toreception. J Chem Phys. 2016; 145(3): 1–13. https://doi.org/10.1063/1.4958624 PMID: 27448908
44. Phillips JB, Jorge PE, Muheim R. Light-dependent magnetic compass orientation in amphibians and
insects: Candidate receptors and candidate molecular mechanisms, J Roy Soc Interface. 2010; 7:
S241–S256. https://doi.org/10.1098/rsif.2009.0459.focus.
45. Solov’yov IA, Mouritsen H, Schulten K. Acuity of a cryptochrome and vision-based magnetoreception
system in birds, Biophys J. 2010; 99(1): 40–49. https://doi.org/10.1016/j.bpj.2010.03.053 PMID:
20655831
46. Červeny
´J, Begall S, Koubek P, Nova
´kova
´P, Burda H. Directional preference may enhance hunting
accuracy in foraging foxes. Biol Letters. 2011; 7:355–357. https://doi.org/10.1098/rsbl.2010.1145
PMID: 21227977
47. Niessner C, Denzau S, Malkemper EP, Gross JC, Burda H, Winklhofer M, et al. Cryptochrome 1 in reti-
nal cone photoreceptors suggests a novel functional role in mammals. Sci Reps. 2016; 6: 21848.
https://doi.org/10.1038/srep21848 PMID: 26898837
PLOS ONE
Turning preference in dogs
PLOS ONE | https://doi.org/10.1371/journal.pone.0245940 January 28, 2021 15 / 15
Content uploaded by Michael S Painter
Author content
All content in this area was uploaded by Michael S Painter on Feb 02, 2021
Content may be subject to copyright.
