Dieter Bartussek

Does resting electroencephalograph asymmetry reflect a trait? an application of latent state-trait theory.

Recent research on brain asymmetry and emotion treated measures of resting electroencephalograph (EEG) asymmetry as genuine trait variables, but inconsistency in reported findings and modest retest correlations of baseline asymmetry are not consistent with this practice. The present study examined the alternative hypothesis that resting EEG asymmetry represents a superimposition of a traitlike activation asymmetry with substantial state-dependent fluctuations. Resting EEG was collected from 59 participants on 4 occasions of measurement, and data were analyzed in terms of latent state-trait theory. For most scalp regions, about 60% of the variance of the asymmetry measure was due to individual differences on a temporally stable latent trait, and 40% of the variance was due to occasion-specific fluctuations, but measurement errors were negligible. Further analyses indicated that these fluctuations might be efficiently reduced by aggregation across several occasions.

On the selective relation of frontal cortical asymmetry and anger-out versus anger-control.

The model of anterior asymmetry and emotion proposes an asymmetric representation of approach and withdrawal systems in the left and right anterior brain regions. Within this framework, 3 different concepts have been related to anterior asymmetry: affective valence, motivational direction, and behavioral activation. The aim of the present study was an empirical investigation into the relation between anterior cortical activity and questionnaire measures related to the 3 dimensions positive versus negative affect, approach versus withdrawal motivation, and behavioral activation versus inhibition. Subjects with relative greater left than right frontal cortical activity showed higher anger-out scores and lower anger-control scores. These results support the hypothesis that motivational direction is related to frontal asymmetry (approach-left and withdrawal-right). Furthermore, subjects with greater bilateral (left and right) frontal cortical activity showed higher behavioral activation scores. This finding might suggest that behavioral activation is related to approach and withdrawal motivation.

Cortisol responses to psychological stress and correlations with personality traits

Abstract In two studies cortisol responses to psychological stress was monitored by saliva cortisol measurement at 10 min intervals and correlated with personality measures in a total of 87 healthy subjects. Personality traits were investigated with German version of the Eysenck Personality Questionnaire (EPQ-R), the Zuckerman Sensation Seeking Scale (SSS-R), and the Strelau Temperament Inventory (STI-RS). The stress of public speaking and mental arithmetic in front of an audience reliably induced 2- to 3-fold elevation of cortisol levels in both studies. However, no significant correlation was observed between hormone values and any of the personality measures studied.

The assessment of affective reactivity using films : Validity, reliability and sex differences

Abstract Researchers interested in individual differences of brain asymmetry and affective reactivity have recently used film clips to elicit emotions and provided some standardisation data of emotion ratings for English-speaking samples. The aim of the present study was to examine whether (1) a set of films which already proved to elicit different emotions in English-speaking samples would demonstrate a similar capacity to induce emotions in a German sample and (2) to explore the validity, reliability and sex differences of aggregated indices of affective reactivity. Based on two film sets which have been examined by other investigators in the field, we formed a set of 13 emotion-eliciting films and presented the films along with emotion rating scales to university students. Our findings indicate that most films had the capacity to elicit specific discrete target emotions and the emotions elicited by the negative clips were more distinct than the emotions due to the positive clips. The factor structure of the emotion rating scales indicated that a distinct positive and negative dimension was extracted. The indices of positive and negative affective reactivity demonstrated good reliability and internal consistency. Women reported on greater levels of affective reactivity than men, both for positive and negative affective reactivity.

The relation of cortical activity and BIS/BAS on the trait level.

The behavioral activation system (BAS) and the behavioral inhibition system (BIS) have been proposed to be related to anterior asymmetry in the BIS/BAS model of anterior asymmetry. As an alternative, it may be suggested that behavioral activation comprises approach and withdrawal motivation and that the BAS is related to bilateral frontal trait activity. The aim of the present study was an empirical investigation on the relation between cortical trait activity, BIS and BAS. Data of 59 subjects on four occasions were analyzed. On each occasion, cortical activity was evaluated with resting EEG, and the BIS and BAS strength was assessed with questionnaires. Subjects with greater bilateral frontal cortical activity showed higher BAS scores. The latter result may suggest that behavioral activation comprises approach and withdrawal motivation.

EEG asymmetry, dispositional mood and personality

Abstract Recent studies have demonstrated that dispositional positive affect (PA) and negative affect (NA) can be predicted by resting electroencephalographic (EEG) asymmetry in anterior brain regions. The aim of the present study was a conceptual replication of these results. An extensive literature review suggested that asymmetry might also be related to personality and we investigated the possibility to extend the association between asymmetry and dispositional mood to personality traits. Resting EEG of 36 subjects was recorded and questionnaires were administered to assess PA, NA, extraversion (E) and neuroticism (N). Subjects who scored high on NA had greater relative left-sided cortical activation than subjects scoring low on NA, which was due to greater absolute activation of the left anterior temporal site in high NA scorers. There were no associations between asymmetry and PA. A functional neuroanatomical model is presented which suggests that greater tonical activation of the left temporal cortex increases the susceptibility to experience negative emotions.

The scalp topography of P300 in the visual and auditory modalities: a comparison of three normalization methods and the control of statistical type II error

This study was designed to replicate recent findings suggesting that the P3 component of the event-related potential is dependent on the modality of the eliciting stimulus. When assessing this research hypothesis two methodological problems are of special interest: first, the amplitudes have to be normalized, due to problems with the model of the analysis of variance; second, special care has to be taken regarding the beta error, which is the probability of falsely accepting the null hypothesis of a statistical test. A possible modality independence is associated with the acceptance of a null hypothesis. The first problem was assessed by using different normalization procedures and comparing their results. The second was solved by controlling the beta error. Results for P3 amplitudes from two sessions in which 61 subjects performed in each session an auditory and a visual oddball task (EEG measured at 11 locations) showed no influence of modality on the P3 elicited by the rare, task relevant, stimulus. Influences of modality were observed for the P3 elicited by the frequent stimulus. As it is quite unlikely that P3 generating sources are strongly active during the processing of the frequent stimulus, this effect is possibly due to a component overlap from the vertex potential.

EXTRAVERSION, NEUROTICISM, AND EVENT-RELATED BRAIN POTENTIALS IN RESPONSE TO EMOTIONAL STIMULI

Abstract Following Grays theory of extraversion-introversion, extraverts should react more strongly to stimuli of reward than to stimuli of punishment, while introverts should be more susceptible to stimuli of punishment than to stimuli of reward. These predictions were tested in two experiments using measures of Event-Related Potentials (ERP) as cortical indicators of differential responses to stimuli of varied emotional valence. In Experiment 1, positive, neutral and negative adjectives were used as conditioned stimuli of reward and punishment. Subjects were involved in a processing task in which attention was either attracted to or drawn away from the emotionality of the stimulus material. An interaction of extraversion, emotional valence of stimuli and processing task was found, but did not meet the predictions. In Experiment 2, a startle probe paradigm was used. Foreground stimulation consisted of emotionally positive, neutral and negative slides. Again, extraverts exhibited higher ERP amplitudes to emotionally positive and negative stimuli compared to neutral ones, whereas introverts did not show a differential effect to the emotional content of the stimuli. Thus, Grays theory could not be confirmed in either one of the experiments. The results suggest that introverts and extraverts respond to emotional stimuli with different processes of compensatory disfacilitation. This interpretation is closer to the presumptions of Eysencks theory of extraversion.

Resting Brain Asymmetry and Affective Reactivity

Abstract. Neuropsychological evidence has given rise to alternative models on brain asymmetry in emotion, each with different implications concerning the biological basis of individual differences in affective responses. The present study tested these implications. Resting EEG and self-reported emotions after the presentation of film clips were collected on four occasions of measurement. Subjects with greater right-sided and smaller left-sided cortical activity reported greater intensities of felt emotions after the presentation of films irrespective of valence. This finding is in line with a recent formulation of the right-hemisphere hypothesis, which proposes that the right hemisphere may play an important role in the automatic generation of emotional responses, whereas the left hemisphere may be involved in the control and modulation of emotional reactions.

Introversion-extraversion and Event-Related Potential (ERP): A test of J.A. Gray's theory

Abstract Following Grays theory of introversion-extroversion, extraverts should demonstrate stronger reactions to stimuli of reward than to stimuli of punishment, while introverts should be more susceptible to stimuli of punishment than to stimuli of reward. In the present study reward and punishment were operationalized by winning and losing different amounts of money in a gambling situation while measuring Event-Related Potentials (ERPs) to the stimuli signalling winnings and losses and to the presentation of the amount to win or lose. The components P2, N2, and P3e of the ERPs to the feedback of winning and losing which are known to be influenced by stimulus meaning demonstrated the predicted interaction between extraversion and winning/losing. This interaction was found also for the late time region of the ERPs to the display of the amounts, according to winning or losing in the preceding trial. The results suggest that—on the background of an explicit theory—the ERP is a sensitive index for interindividual differences.