Social power and approach-related neural activity

Abstract

It has been argued that power activates a general tendency to approach whereas powerlessness activates a tendency to inhibit.
The assumption is that elevated power involves reward-rich environments, freedom and, as a consequence, triggers an approach-related
motivational orientation and attention to rewards. In contrast, reduced power is associated with increased threat, punishment
and social constraint and thereby activates inhibition-related motivation. Moreover, approach motivation has been found to
be associated with increased relative left-sided frontal brain activity, while withdrawal motivation has been associated with
increased right sided activations. We measured EEG activity while subjects engaged in a task priming either high or low social
power. Results show that high social power is indeed associated with greater left-frontal brain activity compared to low social
power, providing the first neural evidence for the theory that high power is associated with approach-related motivation.
We propose a framework accounting for differences in both approach motivation and goal-directed behaviour associated with
different levels of power.

Full text

Social power and approach-related neural activity
Maarten A. S. Boksem, Ruud Smolders, and David De Cremer
Department of Social Psychology, Tilburg University, P.O. Box 90153, 5000 LE, Tilburg, The Netherlands
It has been argued that power activates a general tendency to approach whereas powerlessness activates a tendency to inhibit.
The assumption is that elevated power involves reward-rich environments, freedom and, as a consequence, triggers an approach-
related motivational orientation and attention to rewards. In contrast, reduced power is associated with increased threat,
punishment and social constraint and thereby activates inhibition-related motivation. Moreover, approach motivation has been
found to be associated with increased relative left-sided frontal brain activity, while withdrawal motivation has been associated
with increased right sided activations. We measured EEG activity while subjects engaged in a task priming either high or low
social power. Results show that high social power is indeed associated with greater left-frontal brain activity compared to low
social power, providing the first neural evidence for the theory that high power is associated with approach-related motivation. We
propose a framework accounting for differences in both approach motivation and goal-directed behaviour associated with
different levels of power.
Keywords: power; EEG; asymmetry; approach; inhibition
INTRODUCTION
Having and being able to exercise power is of prominent
importance to our status and our social position compared
to that of others (Flynn et al., 2006). On the one hand, high
status guarantees power; on the other hand, power can be a
means to achieve a higher status in our social environment.
This status with its associated power has a profound impact
on virtually every aspect of our lives. Being high or low in
power determines whether we have easy access to important
resources and whether we can achieve our goals without
interference from others (who may have their own goals
that differ from ours).
Power has been defined as an individual’s relative
capacity to modify others’ states by providing or withholding
resources or administering punishments (Keltner et al.,
2003). While these resources can be both material and
social, in many conceptualizations of power the capacity to
influence others is of primary importance. This type of power
has been called social power because it is derived from ones
relationship to others (Fiske, 1993). Therefore, Galinsky and
colleagues defined power as the ability to control resources,
own and others’, without social interference (Galinsky et al.,
2003). Having access to many resources without interference
from others suggest that people with power can behave in a
much more unconstrained manner compared to people lack-
ing power. Indeed, in their integrative review of the effects of
social power, Keltner and colleagues (2003) propose that
high power is associated with approach behaviour, while
low power is related to inhibitory behaviour.
Perspectives on approach and inhibition behaviour have
been shaped to a large extent by the theory postulated
by Gray (1987) that proposes two interacting motivational
systems: the behavioural approach system (BAS) and the
behavioural inhibition system (BIS). According to Gray,
the BIS is sensitive to signals of punishment and inhibits
behaviour that may lead to aversive or harmful outcomes.
In contrast, the BAS is proposed to be sensitive to positive
signals of reward. Although research has largely focussed
on individual (trait) differences in approach and inhibition
(e.g. Carver and White, 1994; Boksem et al., 2006), Keltner
and colleagues (2003) proposed that power influences the
relative balance between approach and inhibition. Their
theory holds that high power activates approach-related
processes, while low power activates inhibitory processes.
This, they propose, has two major reasons.
First, power is by definition related to controlling impor-
tant resources. Therefore, powerful people more often than
not find themselves in environments offering many potential
rewards, both of a material and a social nature, making
it easier for powerful people to approach these rewards.
Second, powerful people are less dependent on others to
acquire these resources compared to less powerful people,
which is why powerful people experience less constraints and
interference from others, making it easier for them to act in
ways that enable them to reach their goals.
For complementary reasons, less powerful people are
more inclined to inhibit approach behaviour. These people
lack access to material and social resources and experience
more social threat and punishments. They are more sensitive
to the limitations imposed upon them by people higher in
power and are therefore less able to attain their goals. The
environment of people lacking power is characterized by
a high degree of threat and potential punishment, limited
access to resources, and social constraints. Therefore, these
people are more inclined to inhibit approach behaviour.
Received 23 September 2008; Accepted 31 December 2008
Correspondence should be addressed to Maarten A. S. Boksem, P.O. Box 90153, 5000 LE Tilburg,
The Netherlands. Email: maarten@boksem.nl.
doi:10.1093/scan/nsp006 SCAN (2009) 1 of 5
ßThe Aut hor (2009). Published by Oxford University Press. For Permissions, please email: journals.permission s@ox fordjournals. org
Social Cognitive and Affective Neuroscience Advance Access published March 20, 2009

In the psychophysiological literature, approach and
inhibition have been related to different neural systems
that are associated with asymmetries in frontal cortical
activity as measured using electroencephalography (EEG;
Sutton and Davidson, 1997). Approach, a promotion
focus, and approach-related positive affect have been related
to greater left-sided frontal cortical activation (Tomarken
et al., 1992; Sutton and Davidson, 1997; Amodio et al.,
2004), while avoidance-related negative affect and a preven-
tion focus have been associated with greater right-sided, or
possibly reduced left-sided, frontal activation (Henriques
and Davidson, 1990; Amodio et al., 2004).
So far, the literature linking social power to approach
behaviour and the literature linking approach behaviour
to its neural correlates have not been integrated. This is
unfortunate, not only because finding the suggested relation-
ship between power and frontal asymmetry would support
the power-approach theory proposed by Keltner and collea-
gues (2003), but also because the neural correlates of power
may provide new insights in the origins and functionality of
power differences between individuals. The present research
aims to rectify this omission in the literature.
Here, we operationalized power by using a widely used
power prime (Galinsky et al., 2003, 2006), in which power is
made accessible by asking subjects to either write about an
experience in their lives in which they had power over others
(high power prime), or to write about an experience in
which others had power over them (low power prime).
While subjects were engaged in this priming task, we
recorded their EEG. If high power is indeed related to
approach, increased left frontal activity should be observed
in comparison to situations characterized by low power.
METHODS
Participants and task
Thirty-six right-handed undergraduate students from
Tilburg University [average age ¼20 years (s.d. ¼1.5); 15
males] participated for extra course credit. Subjects com-
pleted a writing task, adapted from Galinsky and colleagues
(2003) that served to prime high or low power. Participants
primed with high power (n¼18) wrote about ‘a particular
situation in which you had power over another individual or
individuals’. Participants primed with low power (n¼18)
wrote about ‘a particular situation in which someone else
had power over you’. Subjects were instructed to think of as
many details about this situation such as what exactly
happened, how they felt at that moment, and write them
down on the sheet of paper with 17 blank lines provided.
While participants were working on this task, their EEG
was recorded.
EEG acquisition and analysis
EEG was recorded from 43 sites using active Ag–AgCl
electrodes (Biosemi ActiveTwo, Amsterdam, Netherlands)
mounted in an elastic cap. Horizontal EOGs were recorded
from two electrodes placed at the outer canthi of both eyes.
Vertical EOGs were recorded from electrodes on the infra-
orbital and supraorbital regions of the right eye placed in line
with the pupil. The EEG and EOG signals were sampled at
a rate of 256 Hz, and offline rereferenced to an averaged
mastoid reference.
All EEG analyses were performed using the Brain Vision
Analyser software (Brain Products). The data was resampled
at 100 Hz and further filtered with a 0.53 Hz high-pass filter
and a 40 Hz low-pass filter both with a slope of 48 dB/oct.
Artefacts were rejected and eye movement artefacts were
corrected, using the Gratton et al. (1983) method. The
time period in which subjects were working on the writing
task was segmented into 50% overlapping, 5.12 s segments.
After artefact detection and ocular correction as described
above, the data was submitted to a fast Fourier transform
(FFT), using a 100% Hanning window. Using this window
results in complete attenuation of the jump discontinuity
effect caused by performing FFT on segmented EEG data,
while using a 50% overlap ensures that data at the edge of
one segment (where it is dampened the full 100%) is not
attenuated at all in the next segment, thus minimizing
data loss due to this attenuation of data near the edges of
the segments. To remove segment to segment differences in
total EEG power, FFT data was normalized in the 0.5–20 Hz
range for every channel. Following this, segments were
averaged using only the first 50 segments recorded. This
was done to arrive at an equal number of segments in the
average for all subjects and to make certain that subjects were
engaged in the writing task at every time segment analysed.
Averaged segments were then log-transformed to normalize
the distributions.
Because alpha power (activity in the 8–12 Hz frequency
range) is inversely related to cortical activity (Laufs et al.,
2003), averaged spectral power within the alpha frequency
range was calculated for every electrode, and used for statis-
tical analyses. To obtain a measure of left–right asymmetry
in frontal brain activation, asymmetry scores were calculated
for an array of three homologous frontal electrode pairs
(AF3, AF4, F3, F4, F5, F6) by subtracting the spectral
power value for the left side from the right side (e.g. F4 –
F3). This was also done to control for individual differences
from non-neural sources such as skull thickness (Tomarken
et al., 1992; Pivik et al., 1993). For alpha power, positive
asymmetry scores reflect greater left-sided neural activity.
To be able to show that effects are specific for frontal sites,
we also analysed asymmetry data from three homologous
posterior electrode pairs (C5, C6, CP5, CP6, P3, P4).
RESULTS
Differences in frontal left–right asymmetry of cortical
activation were examined for subjects primed with high or
low power. We predicted that priming high power would
result in greater left-sided frontal brain activation, consistent
with the theory by Keltner and colleagues (2003) that power
2of5 SCAN(2009) M. A. S. Boksem et al.

activates approach-related tendencies, which in turn have
been related to greater left-frontal cortical activation
(Sutton and Davidson, 1997).Our prediction was confirmed
by the pattern of activation from the homologous frontal
electrode pairs under consideration. Figure 1 presents the
difference in average alpha power between right and left
electrodes, recorded when subjects worked on the high or
low power prime. Greater left-sided (compared to right-
sided) neural activity was observed for all frontal electrode
pairs (2.13 < t(34) < 3.06, P< 0.05; Table 1). Combining
the separate electrodes into arrays over the left- and the
right-frontal hemisphere, respectively, clearly shows a greater
left-frontal activation for the high power condition com-
pared to the low power condition, t(34)¼3.30, P< 0.001.
As can be observed in Figure 2, this lateralization is not
perfectly symmetrical, stressing the importance of using an
aggregate measure of left–right differences by pooling
electrode pairs like we did. Moreover, this effect was specific
for frontal electrode pairs: no differences in alpha power
were observed between left and right posterior electrode
sites, t(34) < 1.36, n.s.
DISCUSSION
In their review of the literature, Keltner and colleagues
(2003) proposed that elevated power, involving reward-
rich environments, would trigger approach-related behav-
iour. Reduced power, in contrast, would be associated with
inhibition-related and constrained behaviour. Subsequently,
it was shown by Galinsky and colleagues (2003) that priming
subjects with high power indeed lead these subjects to take
more direct action.
The study presented here provides the first evidence that
the experience of power directly activates the motivational
systems in the brain that regulate approach behaviour.
Compared to subjects primed with low power, subjects
primed with high power showed a greater suppression of
alpha activity over left-frontal cortical areas, compared to
right frontal areas, indicating that high power is associated
with increased left-frontal brain activity (power in the
EEG alpha band is inversely related to brain activity).
Because enhanced left-frontal activity has been associated
with approach behaviour (e.g. Sutton and Davidson,
1997), these findings provide direct support for the premise
that high power is associated with approach motivation.
Importantly, left-frontal brain activity has been related
specifically to approach motivation and not to positive
affect, which may also be associated with high power
(Keltner et al., 2003). Although past research does seem to
indicate that positive emotions are related to left-frontal
−0,075
−0,025
Difference in LN a power (m\V2)
0,025
0,075
0,125
AF4-AF3 F4-F3 F6-F5 Frontal R-L
Low Power
High Power
Fig. 1 Difference in average alpha power (in V
2
) between right and left electrodes,
recorded when subjects worked on the high or low power prime. Greater left-sided
(compared to right-sided) neural activity was observed for all the frontal electrode
pairs. Combining the separate frontal electrodes into arrays over the left and the right
hemisphere, respectively, clearly shows a greater left frontal activation for the high
power condition compared to the low power condition.
Table 1 T-statistics for cortical asymmetries
Electrode pair t-value
AF4-AF3 2.48
a
F4-F3 2.13
a
F6-F5 3.06
b
C6-C5 1.36
CP6-CP5 1.07
P4-P3 0.98
Frontal right vs Left 3.30
b
Note:N¼36.
a
P< 0.05;
b
p< 0.005.
Fig. 2 Topographical map of cortical activation (in V
2
) on frontal electrode
positions in high vs low power conditions. Positive values indicate relative activation
in the high power condition, while negative values indicate relative deactivations.
Power, approach andlateralized brain activity SCAN (2009) 3 of 5

activity (e.g. Davidson et al., 1990; Tomarken et al., 1992),
more recent work by Harmon-Jones and co-workers suggests
that these findings resulted from confounds between
approach motivation and positive emotional valence
(Harmon-Jones, 2003; see also Harmon-Jones and Allen,
1998). This research shows that anger, a state involving
negative feelings and outcomes (e.g. Lazarus, 1991), but
also approach motivation (e.g. Berkowitz, 1999), is asso-
ciated with left-frontal brain activity (e.g. Harmon-Jones
and Allen, 1998), indicating that motivational direction
and not emotional valence is related to frontal asymmetry
(Harmon-Jones, 2003). In addition, Harmon-Jones and
co-workers (2008) recently showed that positive affect does
not increase relative left-frontal activation, while approach
motivation does. These findings are in clear support of our
interpretation that increased left-frontal brain activation is
associated with approach motivation. This is not to say that
high power is not associated with positive affect, but that
our findings specifically reflect that power is associated with
approach motivation.
In addition to facilitating approach, high power has also
been suggested to specifically facilitate behaviour that is
directed at achieving personal goals. High power individuals
have been shown to have a greater capacity for maintenance
of self-set goals and are better able to keep these goals at the
focus of their attention, while low power individuals are
more guided by situational constraints and have difficulties
inhibiting goal-irrelevant information (Overbeck and Park,
2006; Guinote, 2007). A key brain area in goal-directed
behaviour is the dorsolateral prefrontal cortex (dlPFC).
This area of the brain is thought to maintain the representa-
tion of goals, as well as the means to achieve them (Miller,
2000). Davidson and colleagues (Davidson and Irwin, 1999)
suggest that the left dlPFC (and other prefrontal areas) are
involved in Gray’s BAS and are specifically implicated in
approach behaviour, while the right dlPFC is proposed to
be an important component of the BIS and is related to
withdrawal behaviour. In turn, this differential activation
of left and right PFC is thought to underlie findings of
frontal EEG asymmetry. Supporting this interpretation, a
meta-analysis of PET and fMRI studies of human emotion
indicated that greater left-sided frontal activity was observed
for approach emotions (i.e. happiness and anger; Murphy
et al., 2003), while an EEG source localization study
confirmed that activity in left dlPFC was associated with a
stronger bias to response to reward-related cues (Pizzagalli
et al., 2005).
However, our findings appear to contradict earlier studies
reporting that powerful people tend to have a more global
attentional focus, which has been proposed to make them
more inclined to use heuristics in decision-making and to
stereotype those below them (Fiske, 1993; Smith and Trope,
2006). Because a global attentional focus has been associated
with increased right hemisphere activity (Fink et al., 1996;
Derryberry and Reed, 1998), this seems to be at odds with
the present findings of enhanced left-frontal activity in
powerful subjects. Indeed, Smith and Trope (2006) have
argued that high power may be related to enhanced right
hemisphere activation. This paradox may be resolved by
observing that approach motivation has been related to
left-frontal activity specifically, while a global attentional
focus has been related to more right posterior activation.
Indeed, an affective state characterized by both arousal and
positive valence (such as high power), has been proposed to
be associated with greater left- than right-frontal activity,
but also with enhanced right posterior (parietotemporal)
activity (Heller, 1993).
Thusfar, findings on the behavioural correlates of high
power, such as enhanced approach motivation (Keltner
et al., 2003) and more efficient goal-directed behaviour
(Smith et al., 2008), have been difficult to capture in a
single (neural) model. We propose that differences in
power may be related to differential activation of two
separate neural control (or attention) pathways that project
from limbic areas in the brain to the PFC (Tucker and
Williamson, 1984; Corbetta and Shulman, 2002). A medio-
dorsal pathway projects bilaterally to the dlPFC and is
involved in planning, goal-directed behaviour and applying
top-down control over selection of stimuli from the envir-
onment. A right lateralized ventrolateral pathway projects to
the orbitofrontal cortex and ventral PFC and is more sensi-
tive to external cues and is specialized in detecting salient
unexpected events in the environment. Importantly, the
‘dorsal’ control system is considered to be proactive in that
it is engaged when behaviour follows a predetermined action
plan, while the ‘ventral’ system is considered to be reactive,
interrupting dorsal goal-directed behaviour when events in
the environment call for a change of plans.
We suggest that powerful people may rely more on the
proactive dorsal control system, stimulating approach and
goal-directed behaviour, while the behaviour of powerless
people depends more on the right-lateralized, reactive
ventral system, which down-regulates approach and is sen-
sitive to salient external events, leaving powerless people less
able to inhibit distracting information from the environ-
ment. This would make adaptive sense: being relatively
unconstrained, powerful people are in a position to act in
accordance with predetermined plans, while powerless
people continuously have to monitor their unpredictable
environment for unexpected changes, perhaps caused by
more powerful people. Therefore, low power most likely
does not impair executive control, but rather activates a
more reactive mode of behavioural control that is actually
more adaptive for those low in power. Applying this proac-
tive/reactive model of behavioural control to the concept of
social power would integrate several separate lines of
research on the motivational, behavioural and neural
determinants of social power. In addition, it provides a
framework for guiding future research on the neural and
behavioural correlates of power.
4of5 SCAN(2009) M. A. S. Boksem et al.

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