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Do extraverts process social stimuli differently from introverts?

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The personality trait of extraversion has been linked to the network of brain systems controlling sensitivity to cues of reward and generating approach behavior in response, but little is known about whether extraverts' neural circuits are especially sensitive to social stimuli, given their preference for social engagement. Utilizing event-related potential (ERP) methodology, this study demonstrates that variation on the extraversion dimension is associated with the extent to which social stimuli evoke enhanced allocation of attention. Specifically, higher scores on extraversion were found to be associated with higher amplitudes of the P300 component of the ERPs elicited by human faces. This finding suggests that social stimuli carry enhanced motivational significance for individuals characterized by high extraversion, and that individual differences in personality are related to meaningful individual differences in neural responses to social stimuli.
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Do extraverts process social stimuli differently from introverts?
Inna Fishmana; Rowena Nga; Ursula Bellugia
a Salk Institute - Laboratory for Cognitive Neuroscience, La Jolla, CA, USA
Accepted uncorrected manuscript posted online: 30 September 2010
First published on: 05 November 2010
To cite this Article Fishman, Inna , Ng, Rowena and Bellugi, Ursula(2011) 'Do extraverts process social stimuli differently
from introverts?', Cognitive Neuroscience, 2: 2, 67 — 73, First published on: 05 November 2010 (iFirst)
To link to this Article: DOI: 10.1080/17588928.2010.527434
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COGNITIVE NEUROSCIENCE, 2011, 2 (2), 67–73
© 2010 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business
www.psypress.com/cognitiveneuroscience DOI: 10.1080/17588928.2010.527434
PCNS Do extraverts process social stimuli differently
from introverts?
Extraverts And Social StimuliInna Fishman, Rowena Ng, and Ursula Bellugi
Salk Institute – Laboratory for Cognitive Neuroscience, La Jolla, CA, USA
The personality trait of extraversion has been linked to the network of brain systems controlling sensitivity to cues
of reward and generating approach behavior in response, but little is known about whether extraverts’ neural
circuits are especially sensitive to social stimuli, given their preference for social engagement. Utilizing event-
related potential (ERP) methodology, this study demonstrates that variation on the extraversion dimension is
associated with the extent to which social stimuli evoke enhanced allocation of attention. Specifically, higher
scores on extraversion were found to be associated with higher amplitudes of the P300 component of the ERPs
elicited by human faces. This finding suggests that social stimuli carry enhanced motivational significance for
individuals characterized by high extraversion, and that individual differences in personality are related to
meaningful individual differences in neural responses to social stimuli.
Keywords: Extraversion; Event-related potentials; P300.
INTRODUCTION
Extraversion, a fundamental personality dimension,
captures the social aspect of personality. Extraverts
have a preference for seeking, engaging in, and enjoying
social interactions, whereas introverts prefer to avoid
social situations and tend to be reserved, withdrawn,
or shy in social settings (Costa & McCrae, 1980; John,
1990). From the early personality and trait theorists
(Allport, 1937; Eysenck, 1967) through contemporary
social neuroscience (e.g., Canli, 2004; Depue, 2007;
Wright et al., 2006), there continues to be a quest for
physiological and neural substrates of personality
traits, and extraversion in particular. Among the findings
pertaining to the neurobiological correlates of extra-
version (a comprehensive review of which is outside
this paper’s scope) are positive correlations with
neural activity in dopaminergically innervated,
reward-sensitive regions, including the ventral striatum,
amygdale, and medial prefrontal cortices (Cohen,
Young, Baek, Kessler, & Ranganath, 2005; Depue &
Collins, 1999; Johnson et al., 1999), although, as
noted by Canli (2004), it is clear that personality
factors such as extraversion are most likely widely
distributed in the brain. Yet, notwithstanding the
multitude of studies, the core question of whether
extraverts’ neural circuits are more sensitive to social
stimuli per se, befitting the very definition of extra-
version, has yet to be addressed. Given that social
engagement and preference for other people’s company
is one of the fundamental features of extraversion (cf.
Ashton, Lee, & Paunonen, 2002), it is essential to
establish whether social stimuli, such as images of
humans, are indeed assigned differential weights in
the brains of extraverts relative to introverts.
Electrophysiological indices of brain activity, such
as event-related potentials (ERPs), are well suited to
address this question as they directly measure brain
responses to discrete stimuli. Briefly, ERPs are
derived from an electroencephalogram (EEG) by
Correspondence should be addressed to: Inna Fishman, Salk Institute – Laboratory for Cognitive Neuroscience, 10010 N. Torrey Pines
Road, CA 92037, USA. E-mail: ifishman@mail.usf.edu
This report is based on work supported by the National Institute of Child Health and Human Development (NICHD) grant P01 HD 33113
awarded to UB and the National Institute of Mental Health (NIMH) fellowship 5 T32 MH20002 awarded to IF.
Downloaded By: [Fishman, Inna] At: 15:04 17 June 2011
68 FISHMAN, NG, BELLUGI
means of signal averaging, and are thought to arise
from the synchronous activities of neuronal populations
engaged in processing of information at hand. Among
many identified ERP components, the P300 component
is known as a marker of expectancy-related cognitive
operations and as such might prove useful in investi-
gating whether extraverts’ neural circuits are
activated by social stimuli to a higher degree than
those of introverts.
It has been well established that the amplitude of
the P3001—a positive-going ERP component with a
peak latency of approximately 300 to 500 ms (contin-
gent on stimulus modality and task difficulty) following
the onset of the eliciting event and maximum ampli-
tudes measured at centro-parietal scalp sites—is
proportional to the amount of attentional resources
engaged in processing a given stimulus (Donchin &
Coles, 1988; Johnson, 1988). The P300 is traditionally
assessed using an “oddball” paradigm, in which one is
presented with a sequence of events representing two
distinct categories that vary along a given dimension,
with one category occurring less frequently. A larger
P300 is elicited by the events representing the low-
probability (oddball) category (Donchin, 1981), even
in the absence of instructions to categorize along a
relevant dimension (Farwell & Donchin, 1991; Ito &
Cacioppo, 2000).
Importantly, in addition to the objective frequency
of the stimuli that the subject is facing, the P300
amplitude is further affected by the extent to which
these stimuli have an intrinsic psychological rele-
vance for the subject. For instance, Johnston and
Wang (1991) showed that identical pictures elicited
different P300 amplitudes in women at different
phases of the menstrual cycle, such that pictures of
babies and male models evoked larger P300s in
women in the high-progesterone phase as compared
to women in the low-progesterone phase. Recently,
Fishman, Goldman, and Donchin (2008) have demon-
strated P300 sensitivity to individual-specific experi-
ences with (and beliefs about the outcomes of) alcohol
use by employing experimental stimuli evoking a wide
range of consequences of alcohol ingestion. Only
those participants who reported frequent consumption
of alcohol in large amounts and believed in “positive”
effects of alcohol exhibited large P300 when presented
with stimuli suggesting opposite (i.e., negative) effects
of drinking. Further, Gray, Ambady, Lowenthal, &
Deldin (2004) have shown that autobiographical, self-
relevant information, such as one’s hometown or pet’s
name, elicited increased P300 amplitudes, which were
not significantly smaller than the P300 in response to
the neutral/objective oddballs to which the subjects
were explicitly instructed to direct their attention.
Taken together, these findings (along with those by
others; cf. Rosenfeld, Biroschak, & Furedy, 2005 on
autobiographical items and P300) suggest that otherwise
neutral or “objectively” chosen stimuli have a potential
to become subjectively relevant—due to prior exposure,
subjective preferences, or other individual history—
and, as a result, take on additional psychological
significance, which adds another source of variability
to the P300 amplitude. This notion is encapsulated by
a recent theory positing that P300 amplitude might
reflect the extent to which processed information is
motivationally significant or subjectively salient,
through the activity of the locus coeruleus–norepine-
phrine (LC-NE) system, which may be measurable at
the scalp as the P300 (Nieuwenhuis, Aston-Jones, &
Cohen, 2005).
Within this framework, the present study utilized
the P300 component of the ERPs to test the hypothesis
that extraverts, who by definition enjoy and seek the
company of others, would show increased P300
amplitudes when human faces serve as experimental
stimuli, as compared to other, nonsocial stimuli. The
key factor on which this prediction is based is the
assumption that extraverts and introverts have differ-
ential motivational values that they assign to social
stimuli, which, at the level of ERPs, should elicit dif-
ferential P300 effects. The main question addressed
by this study is whether the neural circuitry in individuals
characterized by high sociability (i.e., extraverts) is
more sensitive to processing information with social
content, in comparison to introverts.
METHOD
Twenty-eight healthy young adults (15 females)
between the ages of 18 and 40 (mean age = 21.5,
SD = 4.58) participated in the study. Participants
were recruited as part of an ongoing multicenter
research program and screened to rule out history of
central nervous system (CNS) disorder or injury, current
or past psychiatric conditions, and current use of
medications affecting CNS. The average number of
years of formal education was 13.5 years (SD = 1.4);
the sample’s ethnic composition was quite diverse,
with 43% reporting their ethnicity as Caucasian, 35%
as Asian-American, 11% as Hispanic, 7% as African-
American, and 4% as Native American. Individual
differences in extraversion were assessed using the
48-item Extraversion scale of the NEO Personality
1Also sometimes referred to as the P3b component (cf. Polich,
2003, 2004).
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EXTRAVERTS AND SOCIAL STIMULI 69
Inventory Revised (NEO PI-R; Costa & McCrae,
1992), from which Extraversion T-scores were calculated
based on gender-specific normative data. The Extra-
version scale was administered following the ERP task,
to avoid any unintended priming that might occur with
use of introspective questions about one’s personality.
A P300-eliciting “oddball” task was designed to
assess whether, in individuals with high Extraversion
scores, human faces evoke more attention allocation
(i.e., elicit larger P300 in response to oddball targets)
than nonsocial, but otherwise comparable, visual
stimuli. As reviewed above, a standard oddball task
requires that stimuli be clearly classifiable into two
distinct categories (e.g., high- vs. low-tone pitches, or
X vs. O letters), while one category is presented much
more frequently (e.g., on 80% of the trials) than the
other. Such an uneven probability setup robustly elicits
large P300 amplitudes in response to the infrequent—
oddball—stimuli, signifying enhanced resource
allocation to an out-of-ordinary event. Utilizing this
reliable experimental design, pictures of faces (males
vs. females), as a social condition, and flowers (purple
vs. yellow), as a nonsocial but equally complex visual
control condition, were used as follows. Thirty color
headshots of faces with neutral facial expression
(NimStim Face Stimulus Set; Tottenham et al., 2009;
15 of each gender, matched for ethnicity) were used in
Blocks 1 and 3, while 30 images of either purple or
yellow flowers (15 of each) were used in Blocks 2 and
4. In each block, stimuli from two distinct categories
(males and females in Blocks 1 and 3; purple and
yellow flowers in Blocks 2 and 4) were presented
semirandomly, with one of the categories appearing
on 80% of the trials (e.g., male; purple flower) and the
other, “target” event (e.g., female; yellow flower)
appearing on 20% of the trials (targets were counter-
balanced between the blocks). A semirandom presen-
tation, with the same stimulus prevented from being
presented on two consecutive trials, was chosen to
avoid potential sequential effects (i.e., reduced P300
amplitude in response to targets appearing on successive
trials; cf. Duncan-Johnson & Donchin, 1977; Johnson
& Donchin, 1980) that might obscure differences
between target and nontarget trials. Participants were
instructed to respond (by a key press) each time they
saw a specified target (i.e., oddball event). It was
predicted that individuals with high Extraversion
scores would exhibit larger P300 amplitudes in
response to oddball events in the Face (social) in
comparison to the Flower (non-social) blocks, despite
equivalent probability (.20) of the oddball targets in
the two conditions.
Overall, the task consisted of four blocks of 60 trials
each (semirandomly drawn from the 30 available
images), which, given a target probability of .20,
yielded 24 oddball trials for each Faces and Flowers
condition. Each trial consisted of a 500 ms presentation
of a fixation cross, followed by an 800 ms stimulus
presentation, to which ERPs were time-locked, with
an interstimulus interval (ISI) of 1000 ms. EEG data
were recorded using NetStation 4.0, an EEG recording
system (Electrical Geodesics; EGI, Eugene, OR), with
a 64-channel Geodesic Sensor Net with Ag/AgCl
electrodes. Data were sampled at a rate of 250/s and
filtered offline with a 0.1 to 40 Hz bandpass filter.
The filtered data were segmented into epochs starting
100 ms before stimulus onset to 900 ms after stimulus
onset, subjected to automated artifact detection (>70
μV in any one of the channels), corrected for vertical
and horizontal eye movements (Gratton, Coles, &
Donchin, 1983), re-referenced to a linked-mastoid
reference, and baseline-corrected using the average of
the 100 ms prestimulus epoch. Artifact-free trials
were then averaged by experimental condition gener-
ating four separate average waveforms: oddball
(target) vs. frequent stimuli, separately for Faces and
Flowers conditions. The average number of artifact-free
trials was 21.15 (SD = 3.07) for the Face targets and
20.07 (SD = 3.30) for the Flower targets.
For objective, data-driven, measurement of the
P300 amplitude, its magnitude was determined by
principal components analysis (PCA), a formal multi-
variate procedure which has a number of advantages
over traditional peak measures (see Donchin & Heffley,
1978; Spencer, Dien, & Donchin, 2001). PCA decom-
positions were based on covariance association matrices
and solutions were rotated using the Varimax proce-
dure to maximize the amount of variance associated
with the smallest number of variables; the number of
components to be rotated was determined by the
Scree test (Cattell, 1966). Correlational analysis with
PCA-derived P300 amplitude as primary outcome
variable was employed as the main inferential analytic
method. Correlational analysis, rather than group
variance analysis, was chosen given the continuous
nature of the Extraversion construct.
RESULTS
The participants’ Total Extraversion T-scores ranged
from 35 to 73, representing a wide spectrum of Extra-
version: The NEO-PI-R manual interprets T scores of
56 to 65 as high and scores of 35 to 44 as low; while
T> 65 and T < 35 are interpreted as very high and
very low, respectively. The mean T-score for the sample
was 56.2 (SD = 10.9). Extraversion scores were not
significantly correlated with either age or years of
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70 FISHMAN, NG, BELLUGI
formal education (both r values < .08, p values > .67).
There was no significant correlation between Extra-
version and accuracy as measured by error rates
(r= –.08, p = .66), most likely due to the overall
high accuracy of performance on this task (mean
accuracy = .98, SD = .03).
Figure 1 represents the ERP waveforms at the pari-
etal Pz electrode (where P300 is typically at its max-
imum) for the Faces and Flowers conditions, averaged
across individuals with low, mid-range and high
Extraversion scores, based on the tertiary split of the
sample (with cutoff points of 33% and 66% of the
sample Total Extraversion T-scores distribution,
resulting in semi-equal groups of n = 9, 10, and 9,
respectively.2) The P300, a characteristic large posit-
ive deflection with a peak latency of about 500 ms
following the stimulus onset, appears to vary system-
atically across these groups: While the P300 elicited
by Flower oddballs appears to be unchanged between
the groups, as was expected (since the intrinsic signif-
icance of flowers was not hypothesized to vary
according to one’s extraversion level), the amplitude
of the P300 elicited by Face oddballs appears to vary
as a function of participant’s extraversion, such that
the smallest positivity is observed in those with low
Extraversion scores (i.e., introverts) and the largest
positivity is seen in those with high Extraversion
scores (i.e., extraverts). To quantify these observable
differences, the P300 amplitude values were first
derived by applying the spatio-temporal principal
component analysis (PCA) to the data,3 as described
in Methods. Based on the scalp distribution (i.e., highest
loadings in the parietal electrodes) and the temporal
variance accounted for (i.e., highest loadings in the
500 ms range, the time window corresponding to the
peak positivity emerged in the averaged data; see
Figure 1), a P300-like component was identified. Its
PCA-derived factor scores for each experimental
condition were used as primary dependent variables
in all analyses.
Using the PCA-derived magnitude of the P300
amplitude, a correlation analysis revealed that, as
predicted, the P300 amplitude elicited by oddball
Face stimuli correlated significantly with Extraversion
scores (r = .54, p = .006), such that the higher an
individual’s Extraversion score, the larger the P300 in
response to Face oddballs (Figure 2). A bootstrapped
correlation analysis using 10,000 samples computed a
95% confidence interval ranging from .27 to .75
(SE = 0.12), indicating that this effect was not driven
by outlying values. Similar results were obtained
when analyzing the so-called P300 effect determined
as a difference wave between frequent and oddball
Face trials (r = .50, p = .005), suggesting that the asso-
ciation between Face-elicited P300 and Extraversion
is stable across different methods of calculating the
2The three groups did not differ on age, F (2, 27) = 1.02, p = .38;
however, as expected based on the NEO-PI manual and norms, the
Low Extraversion group included significantly more females than
the Mid- and High Extraversion groups, F(2, 27) = 5.22, p = .01;
pairwise comparison p values = .01. Both Mid- and High Extraversion
groups were characterized by equal number of males and females
(pairwise comparison p = .46). There was no difference between
the groups with respect to the reaction time (RT) to either faces,
F(2, 27) = 1.54, p = .23, or flowers, F(2, 27) = 2.01, p = .15.
3To capture variance across electrode sites, a spatial PCA was
conducted on a covariance matrix with the voltage readings at each
of the 65 electrodes (64 plus reference) as variables, and time points
across conditions and subjects as cases: 250 time points (1000 ms
epochs, sampled every 4 ms) × 4 conditions × 28 participants.
Using the Scree test, 8 spatial factors, accounting for 88.6% of the
total variance, were extracted for Varimax rotation. Next, to
achieve the analogous reduction in dimensionality in the temporal
domain, a temporal PCA was conducted, with the data matrix
consisting of spatial factor scores associated with the time points
(250) as variables, and 8 spatial factors × 4 conditions × 28 partici-
pants as cases. The Scree test suggested retention of 8 temporal
factors accounting for 93.1% of the variance, which were then
rotated to simple structure using Varimax.
Figure 1. Event-related potentials at Pz (midline parietal electrode, where P300 is at its maximum) averaged for individuals with low,
mid-range and high extraversion scores, based on the tertiary split of the sample. Black vertical arrows (corresponding to zero time) mark
stimulus onset. Positive voltages are plotted as downward deflections.
–2 LOW
–1
0
1
2
3
amplitude, µV
4
5
6
7
–100 0 100
Face, Frequent
Face, Oddball
Flower, Frequent
Flower, Oddball
300
time, ms
500 700 900
MID
time, ms
0 100 300 500 700 900
HIGH
time, ms
0 100 300 500 700 900
Downloaded By: [Fishman, Inna] At: 15:04 17 June 2011
EXTRAVERTS AND SOCIAL STIMULI 71
P300. On the other hand, there was no significant (or
sizeable) correlation between individuals’ Extraversion
scores and P300 amplitude in response to non-social
(i.e., flower) oddballs (r = .09, p = .32), indicating that
the association between Extraversion and P300 was
specific to social stimuli / faces. Finally, partial corre-
lation analysis was used to rule out any potential
confound of age on the Extraversion/Faces P300
effect. The magnitude of the partial correlation
between Extraversion scores and Face-oddball P300
remained very similar to the zero-order correlation
(r= .53, p = .009), indicating that controlling for age
had little effect on the strength of the relationship
between P300 amplitude and one’s Extraversion.
DISCUSSION
The study’s main finding is that variation on the
Extraversion dimension is strongly associated with
the extent to which social stimuli evoke enhanced
allocation of attention. The higher one’s score on
Extraversion, the larger the index of attention allocation
(P300 to oddball targets) to human faces. This finding
suggests that faces have increased motivational
significance for individuals characterized by high
extraversion. Importantly, face (social) and flower
(nonsocial) stimuli appeared with the same frequency
in different blocks. The central difference between
these two types of stimuli was the assumed absence of
personal relevance of flowers – in contrast to faces –
to participants across different levels of extraversion.
In other words, these two stimulus categories were
conceived to have differential motivational or
rewarding value for those high on extraversion, and
thereby were expected to elicit differential P300
amplitude in those individuals. This hypothesis was
supported by the present data.
The finding that extraverts showed larger P300
amplitudes in response to oddball social stimuli (but
not to oddball nonsocial stimuli) supports the idea that
human faces are especially noteworthy for these indi-
viduals, in comparison to other visual stimuli with
equivalent stimulus properties and frequency of
occurrence. In contrast, smaller P300 amplitudes
found in introverts in responses to faces suggest that
human faces are not a particularly attention-grabbing
category of visual information for these individuals.
Overall, these results suggest that the sociability char-
acterizing extraverts, including enjoyment of social
activities and preference for social interactions over
being alone, might be associated with enhanced
processing of social stimuli, likely due to a heightened
intrinsic psychological significance that such stimuli
carry for extraverts. Importantly, this effect does not
generalize to all categories of visual stimuli, as
demonstrated by lack of such association between
extraversion and P300 elicited by nonsocial visual
stimuli (in this study, images of flowers).
In sum, the results support the notion of differential
neurobiological processes associated with two distinct
personality profiles characterized by social approach
and social withdrawal. Although a causal relationship
cannot be inferred from these results (i.e., it is unclear
whether one’s extraversion/introversion might lead to
specific alterations in neural circuitry via different
lifetime experiences, including more or less social
contact, or whether differential brain circuitry deter-
mines one’s extraversion), these findings suggest that
individual differences in personality are related to
meaningful individual differences in neural responses
to social stimuli. Future research may utilize this
methodology to further explore the impact of intrinsic
biology vs. the cumulative effect of experience on
personality development during earlier life stages.
Finally, given the recent evidence of the LC-NE
system involvement in generation of the P300
(Nieuwenhuis et al., 2005; see also Polich, 2007), it is
conceivable that this system might be implicated in
the expression of the personality dimension descrip-
tively captured as extraversion (and its main facet of
social engagement).4 Although highly speculative, it
may be worth considering the possibility that the
Figure 2. Scatter plot of Extraversion scores and PCA-derived
P300 amplitude (P300 factor scores). The value of the factor scores
(Y-axis) is a unitless dimension.
4While we are aware of the dopaminergic hypothesis of extra-
version first put forward by Depue (1995), evidence for this model
has been inconsistent (cf. Wilt & Revelle, 2009).
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72 FISHMAN, NG, BELLUGI
P300 may serve as a probe of the processing pathways
sustaining the extraverts’ bias toward seeking and
enjoying social interactions. That is, within a few
hundred milliseconds of being exposed to a social
stimulus, the nervous system is already passing along
a signal that is consistent with differential behavioral
patterns encapsulated by the personality trait of extra-
version: In extraverts this signal is biased towards
allowing preferential access to the limited pool of
attentional resources, while in introverts social stimuli
are not granted such preferential status. Thus, given
the currently discussed LC-NE hypothesis of the P300
etiology and the variability of the P300 elicited by
social stimuli observed along the extraversion contin-
uum in the present study, the LC-NE system might be
another fundamental explanation for the difference in
nervous system function between extraverts and intro-
verts, perhaps originating with overall arousal, as has
been suggested by early personality theorists
(Eysenck, 1967; Eysenck & Eysenck, 1985).
Manuscript received 1 July 2010
Manuscript accepted 20 September 2010
First published online day month year
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Ett av de mest robusta fynden inom personlighets- och välbefinnandeforskning är det starka sambandet mellan personlighetsdraget extraversion och positiva emotioner, lycka samt subjektivt och psykologiskt välbefinnande. Vad som kunde förklara varför extraverta är lyckligare har i årtionden ingående undersökts, om än osystematiskt och från skilda utgångspunkter. Detta har även noterats på fältet, och för att underlätta fortsatt forskning belyser denna litteraturöversikt hur frågeställningen undersökts till dags dato. Utifrån McCraes och Costas (1991) ursprungliga uppdelning i instrumentella och temperamentella modeller samt Hampsons (2012) indelning av medierande och modererande personlighetsprocesser identifieras, systematiseras och presenteras de huvudsakliga förklaringarna som förekommer i litteraturen för sambandet mellan extraversion och lycka. Resultatet består av ett konceptuellt diagram (se Figur 1 s. 20–21) med två övergripande förklaringsmodeller, sex distinkta mekanismer, tio personlighetsprocesser och tretton hypoteser som redovisas med tillhörande forskningslitteratur. Förutom en historisk överblick över tillvägagångssätt i forskningen presenteras även aktuell metodik för personlighetsprocesser. Vidare behandlas även hur resultaten är symptomatiska för den rådande problematiken kring konceptualisering, operationalisering samt metodologi inom personlighets- och lyckoforskning, samt resultatens och socialpsykologins relevans för fortsatt forskning och befrämjande av lycka och välbefinnande. [One of the most robust findings in personality and well-being research is the strong relationship between the personality trait extraversion and positive emotions, happiness, and subjective and psychological well-being. The factors explaining why extraverts are happier has been investigated in depth for decades, albeit unsystematically and from different points of view. This has also been noted in the field, and to facilitate further research, this literature review highlights how the issue has been investigated to date. Based on the original division into instrumental and temperamental models by McCrae and Costa (1991), and the division of mediating and moderating personality processes by Hampson (2012), the main explanations that appear in the literature for the relationship between extraversion and happiness are identified, systematized, and presented. The result consists of a conceptual diagram (see Figure 1, pp. 20–21) with two overall explanatory models, six distinct mechanisms, ten personality processes, and thirteen hypotheses, which are reported with associated research literature. In addition to a historical overview of research approaches, current methodology for personality processes is also presented. Furthermore, the issue of how the results are symptomatic of the prevailing problems around conceptualization, operationalization, and methodology in personality and happiness research is also discussed, as well as the relevance of the results and social psychology for continued research and the promotion of happiness and well-being.]
... That is, trait activation theory favors situational specificity, in that a trait becomes active depending on the specific situation and situational cues an individual observes. For example, highly socialized situations, such as the annual stakeholder luncheon, activate a person's extroversion level, while in low socialized situations, such as reviewing expense reports, an individual's introversion level would become salient (Fishman et al., 2011;Grant, 2013). ...
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The purpose of this paper is to review literature about pertaining to best practices for virtual onboarding and to encourage discourse about employees with introverted tendencies who must onboard remotely. Accounting for these domains is relevant considering the increase in remote work and, subsequently, the increase in virtual onboarding. Of additional relevance is the importance for organizational leaders in position to influence culture and common practices to employ inclusive practices that consider new employees with introverted tendencies. Encouragement for further study of intersectional aspects, such as various dimensions of diversity, are also included within.
Chapter
Recent empirical advances on the relationship between the P3a and P3b event-related brain potentials (ERPs) have suggested a plausible approach to how these potentials may interact. The purpose of this chapter is to review the issues surrounding these developments. The chapter is organized into several sections: First, the empirical background of the P3a and P3b subcomponent distinction is limned. Second, a theoretical perspective of P300 is presented. Third, the neuropsychological basis for the P300 component is outlined in terms of how these subcomponents may be related. The goal is to provide a theoretical overview of the topic areas by integrating prior findings with current perspectives.
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Extraversion has two central characteristics: (1) interpersonal engagement, which consists of affiliation (enjoying and valuing close interpersonal bonds, being warm and affectionate) and agency (being socially dominant, enjoying leadership roles, being assertive, being exhibitionistic, and having a sense of potency in accomplishing goals) and (2) impulsivity, which emerges from the interaction of extraversion and a second, independent trait (constraint). Agency is a more general motivational disposition that includes dominance, ambition, mastery, efficacy, and achievement. Positive affect (a combination of positive feelings and motivation) is closely associated with extraversion. Extraversion is accordingly based on positive incentive motivation. Parallels between extraversion (particularly its agency component) and a mammalian behavioral approach system based on positive incentive motivation implicate a neuroanatomical network and modulatory neurotransmitters in the processing of incentive motivation. A corticolimbic-striatal-thalamic network (1) integrates the salient incentive context in the medial orbital cortex, amygdala, and hippocampus; (2) encodes the intensity of incentive stimuli in a motive circuit composed of the nucleus accumbens, ventral pallidum, and ventral tegmental area dopamine projection system; and (3) creates an incentive motivational state that can be transmitted to the motor system. Individual differences in the functioning of this network arise from functional variation in the Ventral tegmental area dopamine projections, which are directly involved in coding the intensity of incentive motivation. The animal evidence suggests that there are three neurodevelopmental sources of individual differences in dopamine: genetic, "experience-expectant," and "experience-dependent." Individual differences in dopamine promote variation in the heterosynaptic plasticity that enhances the connection between incentive con text and incentive motivation and behavior. Our psychobiological threshold model explains the effects of individual differences in dopamine transmission on behavior, and their relation to personality traits is discussed.
Book
Detection of Change: Event-Related Potential and fMRI Findings presents the first systematic overview of how event-related brain potential (ERP), cognitive electroencephalography (EEG), and functional magnetic imaging (fMRI) measures reflect the mental events arising from changes in sensory stimulation. Reviews by leading experts provide clarifying introductory background material that is well integrated with the cogently collated findings. Topics include the empirical and theoretical analysis of mismatch negativity, P300, human lesion studies, and stimulus binding. These areas provide the backdrop for summaries of auditory/visual ERP interactions, the conjoint use of fMRI methods, and neuroelectric processing models of attention and memory. The contents are fresh, the literature distillations highly informative, and the range of topics extremely useful. This book fills a major need by making contemporary results highly assessable to cognitive neuroscientists, psychologists, and researchers interested in the neural underpinnings of how the brain responds to stimulus change.