Walking blindfolded unveils unique contributions of behavioural approach and inhibition to lateral spatial bias

Abstract

Healthy individuals display a tendency to allocate attention unequally across space, and this bias has implications for how individuals interact with their environments. However, the origins of this phenomenon remain relatively poorly understood. The present research examined the joint and independent contributions of two fundamental motivational systems – behavioural approach and inhibition systems (BAS and BIS) – to lateral spatial bias in a locomotion task. Participants completed self-report measures of trait BAS and BIS, then repeatedly traversed a room, blindfolded, aiming for a straight line. We obtained locomotion data from motion tracking to capture variations in the walking trajectories. Overall, walking trajectories deviated to the left, and this tendency was more pronounced with increasing BIS scores. Meanwhile, BAS was associated with relative rightward tendencies when BIS was low, but not when BIS was high. These results demonstrate for the first time an association between BIS and lateral spatial bias independently of variations in BAS. The findings also contribute to clarify the circumstances in which BAS is associated with a rightward bias. We discuss the implications of these findings for the neurobiological underpinnings of BIS and for the literature on spatial bias.

Full text

Walking blindfolded unveils unique contributions of behavioural
approach and inhibition to lateral spatial bias
Mario Weick
a,
⇑
, John A. Allen
a
, Milica Vasiljevic
b
, Bo Yao
c
a
School of Psychology, University of Kent, UK
b
Behaviour and Health Research Unit, University of Cambridge, UK
c
School of Psychological Sciences, University of Manchester, UK
article info
Article history:
Received 7 January 2015
Revised 2 November 2015
Accepted 11 November 2015
Keywords:
Approach (BAS)
Inhibition (BIS)
Spatial bias
Lateralization
Motion tracking
abstract
Healthy individuals display a tendency to allocate attention unequally across space, and this bias has
implications for how individuals interact with their environments. However, the origins of this phe-
nomenon remain relatively poorly understood. The present research examined the joint and independent
contributions of two fundamental motivational systems – behavioural approach and inhibition systems
(BAS and BIS) – to lateral spatial bias in a locomotion task. Participants completed self-report measures of
trait BAS and BIS, then repeatedly traversed a room, blindfolded, aiming for a straight line. We obtained
locomotion data from motion tracking to capture variations in the walking trajectories. Overall, walking
trajectories deviated to the left, and this tendency was more pronounced with increasing BIS scores.
Meanwhile, BAS was associated with relative rightward tendencies when BIS was low, but not when
BIS was high. These results demonstrate for the first time an association between BIS and lateral spatial
bias independently of variations in BAS. The findings also contribute to clarify the circumstances in which
BAS is associated with a rightward bias. We discuss the implications of these findings for the neurobio-
logical underpinnings of BIS and for the literature on spatial bias.
Ó2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license(http://
creativecommons.org/licenses/by/4.0/).
1. Introduction
Striving for outcomes that benefit the organism, and being
vigilant for threats, are two fundamental survival strategies in
many species (Wilson, Coleman, Clark, & Biederman, 1993). The
behavioural approach system (BAS; Gray, 1972)andthe
behavioural inhibition system (BIS; Gray, 1975, 1990) are two
analogous regulatory mechanisms that are manifested in affec-
tive, cognitive, and behavioural traits (Carver & White, 1994;
Fowles, 1980). Activation of BAS is linked to the experience of
positive affect and goal-directed behaviour. In contrast, activation
of BIS is linked to the experience of anxiety, increased sensitivity
to threatening cues, and disruption of ongoing processes. The aim
of the present research is to probe the independent and joint
associations of these motivational orientations with spatial
attention.
1.1. Lateral bias and BAS
Activation in the contralateral cerebral hemisphere modulates
the orientation of attention (e.g., Kinsbourne, 1970; Milner,
Brechmann, & Pagliarini, 1992). Accordingly, temporal or enduring
shifts in the balance of activation in the two hemispheres are asso-
ciated with a bias in attention to the left or to the right side of
space. Researchers often employ the line-bisection task to examine
such shifts in hemispatial attention (for review see Jewell &
McCourt, 2000). The task requires individuals to segment lines into
two equidistant elements. The magnitude and the extent of
bisection errors correlate with lateralised neural activity (Nash,
McGregor, & Inzlicht, 2010).
Approach motivation is associated with greater relative left (vs.
right) prefrontal brain activation (see Coan & Allen, 2003a;
Harmon-Jones & Allen, 1997), reflecting asymmetries in dopamin-
ergic signalling (Berridge, España, & Stalnaker, 2003). Several stud-
ies have linked approach motivation to right-oriented lateral bias.
For example, Tomer (2008) observed a strong association between
lateral bias assessed using a greyscale task (Nicholls, Bradshaw, &
Mattingley, 1999) and self-reported novelty seeking – a construct
that correlates with self-reported approach motivation (Carver &
White, 1994; Mardaga & Hansenne, 2007). Employing an
http://dx.doi.org/10.1016/j.cognition.2015.11.006
0010-0277/Ó2015 The Authors. Published by Elsevier B.V.
This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
⇑
Corresponding author at: School of Psychology, University of Kent, Keynes
College, Canterbury, Kent CT2 7NP, UK.
E-mail address: m.weick@kent.ac.uk (M. Weick).
Cognition 147 (2016) 106–112
Contents lists available at ScienceDirect
Cognition
journal homepage: www.elsevier.com/locate/COGNIT

experimental manipulation of approach motivation, Friedman and
Förster (2005, Study 3) found a greater right-oriented bias relative
to participants in a neutral state of mind.
The circumstances in which approach motivation induces a
shift in attention have come under scrutiny. Roskes, Sligte, Shalvi,
and De Dreu (2011) argued that the right-oriented bias observed in
approach-motivated individuals only arises under high time pres-
sure. In their analysis of Fédération Internationale de Football
Association (FIFA) World Cup penalty shootouts, Roskes and col-
leagues found that goalkeepers were more likely to dive to the
right than to the left in penalty shootouts, but only when their
team was behind. Following a failed attempt to replicate these
results in other major football tournaments (Price & Wolfers,
2014), Roskes, Sligte, Shalvi, and De Dreu (2014) conceded that it
remains unclear under which circumstances approach-motivation
is linked with a right-oriented bias. Their remark dovetails the
findings of Nash et al. (2010, Study 2), who found that people with
high self-esteem are more oriented to the right than people with
low self-esteem, but this discrepancy only emerged after people
re-lived a personal dilemma.
In sum, converging evidence suggests that approach-motivation
is associated with a right-oriented bias, but little is known about
the circumstances that engender the bias. In the present research
we sought to address this, separating the contributions of BAS
and BIS to lateral bias.
1.2. Lateral bias and BIS
Compared to BAS, the neurological underpinnings of BIS have
been elusive and subject to conceptual disagreements (see
Amodio, Master, Yee, & Taylor, 2008, for a review). Some research-
ers conceptualised BIS as behavioural avoidance, anatomically
linked to right-sided activity in the prefrontal cortex. However, this
conceptualisation ignores the fact that the motivation to escape
harm (withdrawal) is not mediated by BIS in Gray’s framework
(Gray & McNaughton, 2003). Furthermore, a number of studies
failed to establish a link between BIS and frontal asymmetry,
casting further doubt on the lateralisation of BIS (e.g., Coan &
Allen, 2003b; De Pascalis, Cozzuto, Caprara, & Alessandri, 2013;
Harmon-Jones & Allen, 1997; Wacker, Heldmann, & Stemmler,
2003; but see Peterson, Gable, & Harmon-Jones, 2008).
According to Heller (1993), threatening conditions prime the
right hemisphere and trigger higher activity in right posterior
areas. This anxiety/arousal function is consistent with a right-
sided orienting network for attention, which responds to novel
and unexpected events and acts as a ‘‘circuit breaker” for focal pro-
cessing (Corbetta & Shulman, 2002, p. 212). Increased activation in
BIS mediates the experience of anxiety and facilitates the disrup-
tion of ongoing behaviour (Carver & White, 1994; Fowles, 1980,
1988; Gray, 1982). Thus, there are strong grounds to assume an
association between BIS and posterior hemisphericity. This
assumption has received preliminary support in EEG studies
(Balconi, Brambilla, & Falbo, 2009; Hewig, Hagemann, Seifert,
Naumann, & Bartussek, 2006).
To date, little is known about the independent association
between BIS and orientating bias. Some studies examined the con-
sequences of behavioural avoidance for performance on the line
bisection task (Friedman & Förster, 2005; Roskes et al., 2011).
However, since avoidance was conceptualised as withdrawal in
these studies, which as discussed above is not mediated by BIS,
the findings have limited relevance. In another line of work,
Wilkinson, Guinote, Weick, Molinari, and Graham (2010), found
that inducing a sense of powerlessness experimentally fostered a
left-oriented bias in two motor tasks. Whilst consistent with the
framework discussed here, one can only speculate about the
involvement of BIS in the effects of powerlessness. It is important
to note that experimental manipulations aimed at increasing acti-
vation in BIS may also inadvertently reduce activation in BAS, thus
confounding the individual contributions of the two motivational
systems to lateral bias.
Garner et al. (2012) found that individuals scoring simultane-
ously high on BIS and low on BAS exhibited a stronger leftward bias
in visual orienting than individuals scoring simultaneously high on
BAS and low on BIS. These results are consistent with a right-sided
specialisation for BIS (inducing a leftward attentional bias). How-
ever, grouping participants into two quadrants – high BIS/low
BAS and low BIS/high BAS – creates a perfect correlation between
BIS and BAS. Consequently it remains unknown whether Garner
and colleagues’ findings speak to an effect of BIS that occurs
independently of variation of BAS, an effect of BAS that occurs
independently of variation in BIS, or an effect that derives from
an interaction of the two motivational systems.
To summarise, the cognitive neuroscience literature points to a
right hemisphere specialisation for BIS. However, compared to BAS,
the hemisphericity of BIS is less well understood. Importantly, at
present there is no conclusive evidence that activation in BIS
fosters a left-oriented bias in attention independently of variation
in BAS.
1.3. The present research
In the present research, we sought to probe the individual and
joint contributions of BAS and BIS to lateral spatial bias. Doing so
provides the first empirical test of an independent association
between BIS and lateral spatial bias, and furthers our understand-
ing of how individual differences are manifested in neurobiological
processes. It also sheds light on the circumstances in which activa-
tion in BAS is associated with a right-oriented bias (cf. Price &
Wolfers, 2014; Roskes et al., 2014).
In order to probe spatial bias in a task that is sufficiently
demanding for self-regulatory dispositions to manifest (see Coan,
Allen, & McKnight, 2006), we asked participants to walk across a
room in a straight line, blindfolded, aiming for a target on the other
side. This task capitalises on the fact that the orientation bias
manifests itself in mental representations of space (see Brooks,
Della Sala, & Darling, 2014, for a review). In absence of visual feed-
back, people often depart from a straight trajectory and deviate to
either side (e.g., Boyadjian, Marin, & Danion, 1999; Vuillerme,
Nougier, & Camicioli, 2002). We expected individual differences
in self-reported BIS and BAS to uniquely account for variations in
participants’ walking trajectories. We used motion tracking to
capture participants’ locomotion during task performance.
2. Method
2.1. Participants
Eighty right-handed students at a British University partici-
pated for course credits. Locomotion data from two participants
were lost due to a technical error, thus leaving a final sample of
78 participants (60 females, 17 males, 1 other gender; M
Age
= 20.15,
SD
Age
= 4.15). All participants had normal or corrected-to-normal
vision, and none reported any history of motor problems or neuro-
logical disease.
2.2. Materials
2.2.1. Individual difference measures
Participants completed the trait BAS/BIS inventory (Carver &
White, 1994), embedded in a battery of unrelated questionnaires.
M. Weick et al. / Cognition 147 (2016) 106–112 107

They also provided information on demographic background and
handedness.
2.2.2. Locomotion task
Participants were asked to walk up to a target (an ‘X’ marked on
the floor), 6 metres away from the starting position, along an imag-
inary straight line perpendicular to the boundaries of a rectangular
room (8.25 m (L)4.2 m (W)2.37 m (H)). They did this wearing
dedicated blindfold goggles, and with an optical marker affixed
midline at the top of the head. Walking trajectories were digitised
with a WorldViz PPT-H camera system using three degrees of
freedom position tracking.
2.3. Procedure
Participants volunteered consent and then completed individ-
ual difference measures on a PC. The subsequent walking task pro-
ceeded as follows: After viewing the target, participants covered
their eyes with the goggles. They then walked up to the target until
they were stopped by the experimenter and led back to the start
position. At this point, participants were allowed to lift the goggles,
adjusted their position in preparation for the next trial, took new
aim, covered their eyes with the goggles, and then set off. Alto-
gether, participants traversed the room 20 times. At the end, par-
ticipants were thanked and debriefed.
3. Results
For four participants, the experimenter concluded the walking
task prematurely, resulting in the omission of five walking
attempts (0.32% of all trials). Altogether, participants made 1555
walking attempts with a combined distance of 8.38 km (see Fig. 1).
We aggregated the items measuring individual differences in
behavioural approach (BAS:
a
= .85, M
Sum
= 40.81, SD
Sum
= 5.43)
and behavioural inhibition (BIS,
a
= .78, M
Sum
= 22.13,
SD
Sum
= 3.58). The correlation between the two items was unreli-
able, r(76) = .19, p= .10, 95% CI [.18, .48]. All analyses reported
below were carried using z-standardised BIS and BAS scores.
3.1. Variations in lateral bias
At first, we examined final deviations from the sagittal plane (in
cm) captured at the end of each walking attempt before partici-
pants were stopped and led back to the starting position. Thus,
each data point marks the end-point of a single walking attempt
at an average walking distance of 5.39 m (SD = .40). Negative val-
ues indicate deviations to the left, and positive values indicate
deviations to the right. The data revealed a small but robust bias
to the left (M=8.42, SD = 40.69), t(1554) = 8.16, p< .001, 95%
CI [10.44, 6.39]. The magnitude of lateral drifts to the left was
similar to the magnitude of lateral drifts to the right, although
the former was slightly more pronounced (left: |M| = 34.25,
SD = 26.41, |95% CI| [32.53, 35.94], right: |M| = 29.54, SD = 26.17,
|95% CI| [27.54, 31.53], t
diff
(1537) = 3.44, p= .001, 95% CI
diff
[2.02,
7.38]. Overall, 16 trials ended on target, 918 walks concluded with
a drift to the left, and 621 walks concluded with a drift to the right
(
v
2
(1, N= 1539) = 57.32, p< .001, for the comparison between
left- and right-sided drifts).
For each participant, we also calculated the proportion of trials
(out of 20)
1
ending to either side (or on target). Participants exhib-
ited a leftward bias on 60% of trials on average (12 out of 20 trials;
SD = 29%). This figure differs significantly from 50% and thus points
to the presence of a systematic bias, t(77) = 3.05, p= .003, 95%
CI
diff
[67%, 53%]. Forty-eight participants (61.5%) concluded their
walks more frequently to the left (>10 out of 20 trials), and
twenty-three participants (29.5%) more frequently to the right
(>10 out of 20 trials). One participant (1.2%) was always biased to
the right (20 out of 20 trials), and seven participants (8.9%) always
erred to the left (20 out of 20 trials).
3.2. Contributions of BAS/BIS
Finally, we turned our attention to the individual walking tra-
jectories depicted in Fig. 1. Our aim was to see if differences in
BIS and BAS relate to differences in the shape, or more precisely
the slope of the trajectories (k= 1555). In a growth regression,
trial-by-trial deviations from the sagittal plane (in cm) at 0, 1, 2,
3, 4, and 5 m displacement (Y) can be described with the equation
2
:
Y
t
¼b
0
þb
1
P
t
þe
t
Whereby tdenotes the measurement occasion (i.e., displace-
ments) and Pis a polynomial that depicts a linear trend (P=0,1,
2, 3, 4, 5). The constant b
0
indicates the lateral deviation for P=0
(i.e., the start of a trial). Running this initial model confirmed that,
overall, the walking trajectories were biased to the left, B
1
=1.51,
SE = .14, p< .001, 95% CI [1.78, 1.23]. This becomes especially
clear when looking at the predictions for Y: after a distance of
1 m walking, the model predicts an average lateral deviation of
0.67 cm (0.48 + (1 ⁄(1.15)), 1.82 cm after 2 m ((0.48 + (2 ⁄
(1.15)), 2.97 cm after 3 m (0.48 + (3 ⁄(1.15)), 4.12 cm after
4 m (0.48 + (4 ⁄(1.15)), and 5.27 after 5 m (0.48 + (5 ⁄(1.15)).
Next, we added the effects of BIS and BAS to the model:
Y
t
¼b
0
þb
1
P
t
þb
2
BIS þb
3
BAS þb
4
P
t
BIS þb
5
P
t
BAS
þe
t
The intercept and the unconditional effects of BIS (b
2
) and BAS
(b
3
) were not significant. More importantly, the results showed
that both BIS and BAS moderated the linear trend (P). The direction
of the effects indicates that walking trajectories were more
strongly biased to the left with increasing BIS scores, B
4
=.40,
SE = .14, p= .004, 95% CI [.68, .13], and more strongly biased
to the right with increasing BAS scores, B
5
= .30, SE = .14, p= .032,
95% CI [.03, .58].
In a final step, we also added the interaction between BIS and
BAS:
Y
t
¼b
0
þb
1
P
t
þb
2
BIS þb
3
BAS þb
4
P
t
BIS þb
5
P
t
BAS
þb
6
BIS BAS þb
7
P
t
BIS BAS þe
t
As can be seen in Table 1, the three-way interaction between P,
BIS and BAS was significant, B
7
=.24, SE = .08, p= .006, 95% CI
[.40, .07]. Importantly, controlling for the interaction with
BAS, the effects of BIS remained significant, B
4
=.51, SE = .45,
p< .001, 95% CI [.80, .23]. Thus, variations in BAS did not qualify
the effects of BIS. However, variations in BIS did qualify the effects
of BAS (b
5
), which were no longer significant when the three-way
interaction (b
7
) was added to the model.
1
As indicated earlier, data were unavailable for five trials in all. Thus, for one
participant we calculated the proportion on the basis of 17 available trials, and for
two participants on the basis of 19 available trials.
2
Readers familiar with multi-level modelling will note that measurement occa-
sions are nested within trials (k), which in turn are nested within individuals (i). We
also used multi-level growth models to explore the contributions of BIS and BAS to
the walking trajectories. The random intercepts for level 2 and 3 were significant, but
the models did not converge when adding random slopes. The conclusions derived
from the multi-level model with random intercepts were the same as the conclusions
derived from a regression model with no random effects. In light of this, we chose to
report the results of the latter statistical technique.
108 M. Weick et al. / Cognition 147 (2016) 106–112

To illuminate the interaction, we carried out further analyses
probing the simple effects of BAS at high (+1SD) and low (1SD)
levels of BIS. These analyses showed that BAS was only associated
with rightward tendencies when combined with low levels of BIS,
B
5
= .38, SE = .14, p= .008, 95% CI [.10, .66], but not when
combined with high levels of BIS, B
5
=.09, SE = .20, p= .650, 95%
CI [.48, .30].
To gain a better understanding of these results, we examined
participants’ predicted walking trajectories at different levels of
BAS and BIS. As can be seen in Fig. 2, all combinations of BIS
and BAS yield a bias to the left, with the strongest bias
predicted for individuals high on BIS irrespective of the levels
of BAS. Meanwhile, higher levels of BAS are associated with an
increased (relative) rightward bias at low and medium levels
of BIS. As expected, the weakest (absolute) bias to the left is
evident for the combination of low levels of BIS and high levels
of BAS.
Finally, we were curious to see what combinations of BIS and
BAS would trigger an absolute bias to the right. To this end, we
examined the combination of extremely high levels of BAS
(
x+ 2.5SD) and low levels of BIS (
x1SD), which yields a straight
trajectory, B
1
=.00, p= .997, 95% CI [.87, .87]. The combination
of extremely high levels of BAS (
x+ 2.5SD) and extremely low
levels BIS (
x2.5SD) does translate into a rightward bias,
B
1
= 1.65, p= .028, 95% CI [.18, 3.12].
Taken together, these results lend support to the conclusion
that BIS is associated with a leftward bias independently of
variation in BAS, and further suggest that (relative) rightward
tendencies associated with BAS only emerge when BIS is low.
4. Discussion
Behavioural approach and inhibition are two fundamental
motivational systems manifested in affective, cognitive, and beha-
vioural traits. The aim of the present research was to examine the
individual and joint associations of these systems with lateral spa-
tial bias. Blindfolded participants traversed a room aiming for a
straight line. Locomotion data obtained from motion tracking
revealed systematic lateral biases in participants’ walking trajecto-
ries. Overall, participants exhibited a reliable leftward bias, consis-
tent with past research on spatial attention (for reviews see Brooks
et al., 2014; Jewell & McCourt, 2000). Importantly, this bias was
moderated by motivational dispositions, such that walking
trajectories deviated more to the left with increasing BIS scores,
and (relatively) more to the right with increasing BAS scores.
The present data demonstrate for the first time an association
between BIS and lateral bias independently of variations in BAS.
Whilst several attempts have been made to demonstrate the
association between BAS and spatial bias, the evidence for lateral
asymmetries in BIS is limited. Previous experimental studies
manipulated avoidance (Friedman & Förster, 2005; Roskes et al.,
2011)orpowerlessness (Wilkinson et al., 2010), raising questions
about the conceptual overlap between these constructs and BIS.
Measuring individual differences in BIS and BAS, Garner et al.
(2012) observed a leftward bias in people scoring simultaneously
high on BIS and low on BAS. The present findings echo Garner
and colleagues’ results but also demonstrate that the association
between BIS and lateral bias does not depend on, and cannot be
explained by, variations in BAS.
Fig. 1. Spaghetti plot of walking trajectories observed in the locomotion task. Negative values on the y-axis indicate a bias to the left, and positive deviations indicate a bias to
the right.
Table 1
Parameter estimates of growth regressions predicting lateral deviations (in cm) in the walking task.
Effect Model 1 Model 2 Model 3
BSE p95% CI BSE p95% CI BSE p95% CI
Intercept 0.49 0.42 .244 0.33 1.30 0.49 0.42 .239 0.33 1.30 0.47 0.42 .266 0.35 1.28
P(linear slope) 1.51 0.14 <.001 1.78 1.23 1.51 0.14 <.001 1.78 1.24 1.46 0.14 <.001 1.74 1.19
BIS 0.33 0.42 .429 0.49 1.15 0.39 0.43 .372 0.46 1.24
BAS 0.22 0.42 .605 1.04 0.61 0.13 0.45 .767 1.02 0.75
P⁄BIS 0.40 0.14 .004 0.68 0.13 0.51 0.15 <.001 0.80 0.23
P⁄BAS 0.30 0.14 .032 0.03 0.58 0.15 0.15 .338 0.15 0.44
BIS ⁄BAS 0.12 0.25 .625 0.37 0.62
P⁄BIS ⁄BAS 0.24 0.08 .006 0.40 0.07
M. Weick et al. / Cognition 147 (2016) 106–112 109

The present data corroborate previous studies showing an asso-
ciation between approach motivation and rightward attentional
bias. This is in line with evidence derived from EEG studies (e.g.,
Coan & Allen, 2003a; Harmon-Jones & Allen, 1997). However, to
the best of our knowledge, the present data present the first
attempt to ‘partial out’ the effects of inhibition in the relationship
between approach and lateral bias. Tomer (2008) reported an
association between individual differences in novelty seeking and
lateral bias, whilst Nash et al. (2010) found that in some
circumstances individuals with high self-esteem exhibit a stronger
rightward bias than individuals with low self-esteem. Neither of
these studies controlled for variations in behavioural inhibition.
This is important because higher levels of novelty seeking and
self-esteem are not only associated with increased approach moti-
vation, but also with reduced inhibition (e.g., Caseras, Avila, &
Torrubia, 2003; Erdle & Rushton, 2010). Thus, variations in BIS
may have contributed to effects observed in Tomer’s (2008) and
Nash et al. (2010) studies. Similarly, it cannot be ruled out that
by manipulating approach motivation previous experiments did
not also decrease inhibition tendencies (e.g., Friedman & Förster,
2005).
Whilst BIS was associated with a leftward bias in walking
trajectories irrespective of variations in BAS, we observed that
BAS was only associated with a relative rightward bias when
BIS was low, but not when BIS was high. In other words, BIS
moderated the link between BAS and the orienting bias. This
pattern of results could be explained by asymmetries in antago-
nistic links between the two motivational systems, in line with
the notion of BIS acting as a ‘circuit breaker’ (cf. Corbetta &
Shulman, 2002). This interpretation is tentative and further
research is needed to explore the interplay between BIS and
BAS (see also Corr, 2002). It stands to reason that behavioural
inhibition has a more central role in the orienting bias than
previously assumed.
The present findings advance our understanding of circum-
stances in which approach motivation biases attention and ensuing
behaviour to the right (Price & Wolfers, 2014; Roskes et al., 2011).
In our study, (relative) rightward tendencies associated with
approach-motivation were countered by leftward tendencies asso-
ciated with behavioural inhibition. All combinations of BIS and BAS
within a ‘normal’ range (
x1SD to 
x+ 1SD) yielded a bias to the
left. In order to elicit an absolute bias to the right, it would appear
that very high levels of approach-motivation have to be accompa-
nied by very low levels of inhibition. This suggests that a rightward
bias may only occur when individuals are not apprehensive about
the prospect of negative outcomes. Future studies may benefit
from examining spatial bias in situations that vary the salience of
appetitive and aversive stimuli, or probe hemispatial bias in
relevant clinical populations (see Waldie & Hausmann, 2010, for
an example).
The present research sheds some light on the hemisphericity of
BIS, which is poorly understood, perhaps in part due to conceptual
disagreements (see Amodio et al., 2008). Hemispatial bias provides
an indication of cortical activation. Thus, the present results point
to a right hemisphere specialisation for BIS, consistent with the
framework proposed by Heller (1993). This finding holds relevance
for our understanding of how individual differences are manifested
in neurobiological processes. Gaining an understanding of the neu-
rological underpinnings of motivational processes is important and
can have implications for the treatment of unilateral neglect. For
example, individuals suffering from right-sided neglect may bene-
fit from interventions to reduce anxiety (the affective component
of BIS). Conversely, elevated anxiety may ameliorate spatial bias
in individuals suffering from left-sided neglect – a common debil-
itating condition following right-sided brain damage. This is in line
with the findings of Robertson, Mattingley, Rorden, and Driver
(1998), who observed that administering a sudden sound burst
improved spatial awareness in left-neglect patients.
Recent studies have shown that a heightened state of alertness
biases attention to the left, whereas a reduced state of alertness
biases attention to the right (e.g., Manly, Dobler, Dodds, &
George, 2005; Newman, O’Connell, & Bellgrove, 2013). For exam-
ple, Linnell, Caparos, and Davidoff (2014) reported that urbanised
people have a left spatial bias whereas people living in remote
areas have no significant bias. The authors attributed this effect
to differences in alertness. The present findings complement these
streams of inquiry and further suggest a critical role of negative or
anxious arousal, as opposed to positive arousal triggered by excite-
ment or elation, in the alertness/spatial attention relationship.
Future research should examine in more detail how different types
of arousal (i.e., positive vs. negative) modulate spatial bias.
Previous studies examined walking trajectories in neglect
patients (Huitema et al., 2006), and lateral collisions in healthy
individuals performing a locomotion task (e.g., Nicholls, Loftus,
Mayer, & Mattingley, 2007). However, very few studies examined
spatial bias in blind-folded walking tasks. Paquet and colleagues
did not find any evidence for a systematic leftward bias in forward
locomotion (Paquet, Lajoie, Rainville, & Sabagh-Yazdi, 2008;
Paquet, Rainville, Lajoie, & Tremblay, 2007). In contrast, Mohr
and colleagues observed more frequent left-sided drifts (Mohr,
Brugger, Bracha, Landis, & Viaud-Delmon, 2004), while Kennedy
and colleagues reported a small left-sided bias using motion track-
ing (Kennedy et al., 2003). Neither of these effects was significant,
however, perhaps due to a relatively small number of observations.
Using a larger sample of participants, data derived from a much
larger number of trials, and motion tracking to minimise measure-
ment error, we found evidence for a small but reliable leftward bias
in individuals’ walking trajectories. This is noteworthy as the
consensus in the literature has been that individuals do not show
a systematic lateral bias when advancing blindfolded towards a
Fig. 2. Predicted walking trajectories at different levels of BIS and BAS. The simple effect of P(linear slope) indicates the extent to which trajectories are biased; a significant
negative weight (b
1
< 0) implies a bias to the left, a significant positive weight (b
1
> 0) a bias to the right, and a non-significant weight (b
1
= 0) implies no lateral deviation. The
results are as follows: BIS low (
x1SD) and BAS high (
x+ 1SD): B
1
=.57, p= .034, 95% CI [1.10, .04]; BIS medium (
x) and BAS high (
x+ 1SD): B
1
=1.32, p< .001, 95% CI
[1.71, .92]; BIS high (
x+ 1SD) and BAS high(
x+1SD):B
1
=2.07, p< .001, 95% CI [2.62, 1.52]; BIS low (
x1SD) and BAS medium (
x): B
1
=.95, p< .001, 95% CI [1.35, .55];
BIS medium (
xand BAS medium (
x:B
1
=1.46, p< .001, 95% CI [1.74, 1.19]; BIS high (
x+ 1SD) and BAS medium (
x:B
1
=1.98, p< .001, 95% CI [2.37, 1.59];
BIS low (
x1SD) and BAS low (
x1SD): B
1
=1.33, p< .001, 95% CI [1.78, .88]; BIS medium (
xand BAS low (
x1SD): B
1
=.1.61, p< .001, 95% CI [2.02, 1.20]; BIS high
(
x+ 1SD) and BAS low (
x1SD): B
1
=1.89, p< .001, 95% CI [2.44, 1.33].
110 M. Weick et al. / Cognition 147 (2016) 106–112

previously seen target.
3
Thus, the present research contributes to
reconcile the literature on walking trajectories and the literature
on spatial representations (see Brooks et al., 2014, for a review).
It is also interesting to ask why previous studies often failed to
observe evidence for the lateralisation of BIS. Studies examining
the neurological underpinnings of motivational dispositions often
measure cortical activity at rest (e.g., Coan & Allen, 2003b;
Harmon-Jones & Allen, 1997; Hewig et al., 2006; Sutton &
Davidson, 1997; but see Amodio et al., 2008; De Pascalis,
Varriale, & D’Antuono, 2010). This is problematic because individ-
ual differences in cortical activity are more likely to emerge in
situations where underlying dispositions are relevant for the
demands of the situation (see Coan et al., 2006). Participants in
the present walking task experienced a motivated performance
situation (Blascovich & Tomaka, 1996), and this enabled us to elicit
evidence for the lateralisation of BIS. The present findings demon-
strate that novel insights can be gained from methods that enable
individuals to actively engage with their environments. Virtual
Reality (VR) applications afford such a high degree of involvement,
and we anticipate that this technology will soon provide novel
insights into the neurobiological correlates of human motivation.
To conclude, using a blindfolded walking task we found
evidence that behavioural inhibition is associated with a leftward
spatial bias independently of variations in BAS. This finding points
to a right hemisphere specialisation for BIS. As expected, BAS was
associated with (relative) rightward tendencies, but this effect only
emerged when combined with low levels of BIS. This finding adds
to the literature on spatial bias suggesting that overt shifts to the
right (i.e., absolute rightward tendencies) may only be observed
in certain circumstances when levels of inhibition are very low.
Acknowledgements
The present research was supported by the Economic and Social
Research Council (ESRC) grant PTA-026-27-1908 to the first author.
We would like to thank Nicole van der Veen for assistance with
data collection.
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