Extraversion, attention, and habituation of the auditory evoked response

Extraversion and behavioural approach system in stimulus analysis and motor response initiation

In this study, we attempt to validate previous findings on extraversion-related differences in speed of sensorimotor processing and to extend them into Behavioural Approach System (BAS) subtraits within the framework of the revised Reinforcement Sensitivity Theory (rRST) of personality. Here, we assessed psychological traits of extraversion (E), four BAS facets (Goal-Drive Persistence, BAS-GDP; Reward Interest, BAS-RI; Reward Reactivity, BAS-RR; Impulsivity, BAS-I), Behavioural Inhibition System (BIS), and Fight-Flight-Freeze System (FFFS) in 51 volunteers (28 women). Stimulus-locked lateralized readiness potential (S-LRP), response-locked LRP (R-LRP), stimulus-locked and response-locked forearm electromyogram (S-EMG and R-EMG), and P3 components of the event-related potentials (ERPs), were recorded during the performance of a two-choice Go/NoGo visual letter-digit discrimination task varying in task difficulty. High extraverts, relative to introverts and individuals high relative to low on BAS-RI, were more likely to exhibit shorter S-LRP latencies and stimulus- and response-locked EMG latencies. Additionally, high BAS-I had a shorter R-RLP latency than low BAS-I participants for the difficult task. High FFFS levels were associated with longer S-LRP and S-EMG latencies, while high BIS levels had larger response accuracy. Extraverts, relative to introverts, along with those high relative to low on BAS-RR and BAS-I, exhibited smaller P3 amplitudes. The faster cortical premotor initiation, found in individuals high on extraversion, BAS-RI and low on FFFS, may account for their faster peripheral motor response initiation and execution. Smaller P3 amplitudes in extraverts and individuals high on BAS-RR and BAS-I may indicate reduced perceptual processing capacity in these individuals.

Temperament and arousal systems: A new synthesis of differential psychology and functional neurochemistry

This paper critically reviews the unidimensional construct of General Arousal as utilised by models of temperament in differential psychology for example, to underlie 'Extraversion'. Evidence suggests that specialization within monoamine neurotransmitter systems contrasts with the attribution of a "general arousal" of the Ascending Reticular Activating System. Experimental findings show specialized roles of noradrenaline, dopamine, and serotonin systems in hypothetically mediating three complementary forms of arousal that are similar to three functional blocks described in classical models of behaviour within kinesiology, clinical neuropsychology, psychophysiology and temperament research. In spite of functional diversity of monoamine receptors, we suggest that their functionality can be classified using three universal aspects of actions related to expansion, to selection-integration and to maintenance of chosen behavioural alternatives. Monoamine systems also differentially regulate analytic vs. routine aspects of activities at cortical and striatal neural levels. A convergence between main temperament models in terms of traits related to described functional aspects of behavioural arousal also supports the idea of differentiation between these aspects analysed here in a functional perspective.

Sensory processing sensitivity: a review in the light of the evolution of biological responsivity

This article reviews the literature on sensory processing sensitivity (SPS) in light of growing evidence from evolutionary biology that many personality differences in nonhuman species involve being more or less responsive, reactive, flexible, or sensitive to the environment. After briefly defining SPS, it first discusses how biologists studying animal personality have conceptualized this general environmental sensitivity. Second, it reviews relevant previous human personality/temperament work, focusing on crossover interactions (where a trait generates positive or negative outcomes depending on the environment), and traits relevant to specific hypothesized aspects of SPS: inhibition of behavior, sensitivity to stimuli, depth of processing, and emotional/physiological reactivity. Third, it reviews support for the overall SPS model, focusing on development of the Highly Sensitive Person (HSP) Scale as a measure of SPS then on neuroimaging and genetic studies using the scale, all of which bears on the extent to which SPS in humans corresponds to biological responsivity.

Differences in the transmission of sensory input into motor output between introverts and extraverts: Behavioral and psychophysiological analyses

The present study was designed to investigate extraversion-related individual differences in the speed of transmission of sensory input into motor output. In a sample of 16 introverted and 16 extraverted female volunteers, event-related potentials, lateralized readiness potentials (LRPs), and electromyogram (EMG) were recorded as participants performed a visual choice reaction time task. As additional behavioral indicators of performance, measures of reaction time (RT) and response dynamics were obtained. Although extraversion-related differences were found neither for behavioral measures nor for the N1 and P3 components of the evoked potential, introverts showed a reliably shorter latency in stimulus-locked LRP than extraverts. This latter finding supports the notion of faster stimulus analysis in introverts compared to extraverts. Furthermore, there was no indication of extraversion-related individual differences in speed of response organization and response execution as indicated by response-locked LRP and EMG latencies, respectively. However, a significantly higher EMG amplitude observed with introverts pointed to a less accurately adjusted motor output system of introverts compared to extraverts.

Mismatch negativity in socially withdrawn children

BACKGROUND

Individual differences in auditory processing have been associated with social withdrawal, introversion, and other forms of dysfunction in social engagement. The goal of this study was to investigate the characteristics of an electrophysiologic response that is seen to index early cortical auditory processing (mismatch negativity, MMN) among socially withdrawn and more sociable control children.

METHODS

Auditory event-related potentials to standard and deviant tone stimuli were computed for 23 socially withdrawn children and 22 control subjects. We calculated MMN difference waveforms for frontal, central, and parietal electrode sites.

RESULTS

Socially withdrawn children had smaller MMN amplitude and longer MMN latencies compared with more sociable control children.

CONCLUSION

The findings point to the involvement of individual differences in early cortical auditory processing in childhood social withdrawal. Reduced MMN amplitude and delayed latency may index a component of social withdrawal seen in socially withdrawn children and in depressed and schizophrenic patients. The existence of a secondary MMN generator in the frontal cortex may provide a link between the hypothesized frontal lobe involvement in childhood social withdrawal, schizophrenia, and depression and the MMN reductions seen in these conditions.

Individual differences in mismatch negativity measures of involuntary attention shift

OBJECTIVE

The purpose of this study was to compare the automatic detection of deviance in introverts and extraverts. Event-related potentials were recorded to standard and deviant stimuli. These were presented either rapidly or slowly. Stimuli that are presented slowly may intrude into consciousness.

METHODS

Twenty subjects were tested and divided into introverted and extraverted groups. A 500 Hz standard stimulus was presented on 85% of trials. On the remaining 15% of trials, a 750 Hz deviant was presented. In separate conditions, stimuli were presented rapidly (every 500 ms) or slowly (every 1500 ms). Subjects ignored the stimuli while reading.

RESULTS

The deviant stimulus elicited a mismatch negativity (MMN) in both conditions. No inter-group differences in the MMN emerged when a rapid rate of presentation was employed. When a slower rate was employed, a late negativity was significantly larger for the extraverted than the introverted group. This was followed by a late positive wave.

CONCLUSION

The late negative-positive complex is thought to reflect intrusiveness. It would therefore appear that extraverts are more distractible than introverts when stimuli are presented slowly.

Odor identification: influences of age, gender, cognition, and personality

The aim of this study was to examine the influences of age, gender, cognitive abilities, and personality styles on odor identification. Participants (N = 532) aged 45-87 years from the Swedish Adoption/Twin Study of Aging were assessed with a Swedish version of the National Geographic Smell Survey. Both detection and identification of olfactory information were impaired with age. Gender had no effect on detection or identification. Hierarchical regressions revealed that proficiency in semantic memory, intensity perception, and personality style (i.e., neuroticism, impulsivity, and lack of assertiveness) were potent predictors for successful odor identification, even when individual variations in chronological age, sex, education, and global cognitive functioning were taken into account.

Augmenter vs. Reducer: Kortikale und autonome Reaktivität auf Reize unterschiedlicher Intensität

Zusammenfassung: Ziel dieser Studie war es, Unterschiede zwischen anhand der Reducer-Augmenter Skala als extrem eingestuften Augmentern (N = 19, Petrie Reducer) und Reducern in elektrokortikalen (EEG), peripher-physiologischen (EDA, EKG) und subjektiven Reaktionen (EMI) auf weißes Rauschen (65 bis 105 dB; ISI 15-25s) sowie in einer Reaktionszeitaufgabe zu prüfen. In der P1-N1-Amplitude unterschieden sich die Gruppen nicht. Entgegen der Erwartung reagierten die Reducer (Petrie Augmenter) in den N1-P2-Amplituden, der Hautleitfähigkeit und tendenziell auch der Herzrate stärker als die Augmenter. Reducer gaben an, nervöser und weniger optimistisch zu sein als die Augmenter. Die Geräusche beurteilten sie als lauter. In der Reaktionszeitaufgabe wiesen sie längere Reaktionszeiten auf als die Augmenter. Die Ergebnisse sprechen für eine generell erhöhte Reaktivität der Reducer (Petrie-Augmenter) und stehen damit in Übereinstimmung mit der ursprünglichen Konzeption von Augmenting-Reducing nach Petrie .

Event-related brain potentials and the processing of cardiac activity

The cortical processing of cardiac afferent input can be studied by means of event-related potentials (ERP), in which characteristic brain waves are seen to accompany rhythmic activity of the heart. In the present paper, results from three studies, investigating the heartbeat-evoked potential are summarized. These studies demonstrated that (a) cardio-afferent input is projected primarily to fronto-cortical areas; (b) typically, this activity is reflected as a broad positive wave form in a range of 300-600 ms after the EKG R-wave; (c) psychological factors such as level of attention and motivation exert influences on the heartbeat-evoked potential which are comparable to effects known from exteroceptive evoked potentials. On the basis of these data we infer that cardio-afferent input is for the most part transmitted along visceral fibers and that the cortical processing of cardiac activity is similar to the processing of external stimuli.

Heartbeat evoked potentials (HEP): topography and influence of cardiac awareness and focus of attention

Heartbeat evoked potentials (HEP) were recorded from good and poor heartbeat perceivers under two conditions differing in focus of attention. Under the first condition (ATT), subjects were instructed to count their heartbeats. Under the second condition (DIS), subjects were distracted from their heartbeats by having them count external tones. Electrical brain activity was recorded from 19 electrodes. EEG epochs were triggered by the R wave of the EKG. Analyses of variance yielded a significant difference for focus of attention in HEP amplitudes at central electrodes (Cz, C3, and C4) in the latency range 350-550 msec post R wave. No significant differences occurred between good and poor perceivers. The interaction between the Group and Condition factors was significant at F4, C4 and T6. The potential map of good perceivers showed a fronto-temporal positivity, which was reduced in poor perceivers. Our data suggest that paying attention to an internal event such as the heartbeat can modify the cortical evoked response associated with that event.

P300, probability, and introverted/extroverted personality types

Extreme introverted and extroverted subject groups (n = 24 each) containing equal numbers of male and females were assessed with the P300 (P3) component of the event-related potential (ERP). A two-tone auditory discrimination task in which the probability of the target stimulus varied systematically in different conditions (.20, .40, .60, .80) was used to elicit the ERPs. The P3 amplitude demonstrated a significant interaction between personality type, probability, and subject gender and was generally smaller for introverts than for extroverts. Female subjects tended to have larger overall P3 components than male subjects. P3 latency was not affected by the personality variable. The results support previous findings for ERP differences between introverts and extroverts and suggest that personality type differentially influences target stimulus probability effects. The findings are discussed in terms of individual differences in cortical activity on P3 amplitude and personality measures.

P300 and introverted/extraverted personality types

The P300 component of the event-related potential elicited with a two-tone auditory discrimination task and two-trial block replication procedure was obtained from 16 introverted and 16 extraverted undergraduate students. P300 demonstrated no overall significant effects for either the personality variable or the block variable. However, P300 amplitude to the target stimuli declined significantly between Block 1 and Block 2 for the extraverted subjects, but did not change across trial blocks for the introverted group. Female subjects tended to have larger P3 amplitudes than male subjects, but this factor did not interact with either the personality variable or the trial block variable. The results suggest that P3 amplitude habituates more rapidly for extraverts than for introverts.

Biological bases of extraversion: psychophysiological evidence

There is a good deal of evidence, particularly from electrodermal and electrocortical recording procedures, that introverts exhibit greater reactivity to sensory stimulation than extraverts. There is little evidence that introverts and extraverts differ in base level of arousal in neutral conditions, and there is no clear evidence that their differences in sensitivity to stimulation are determined by differences in attentional state. Faster auditory brainstem evoked response latencies observed for introverts implicate differences in peripheral sensory processes that are not determined by mechanisms in the reticular system as proposed in the arousal hypothesis. There is also evidence that individual differences in the expression of motor activity between introverts and extraverts involve differences in motoneuronal excitability.