EEG correlates of cognitive time scales in the Necker-Zeno model for bistable perception

The Necker-Zeno model of bistable perception provides a formal relation between the average duration of meta-stable percepts (dwell times T) of ambiguous figures and two other basic time scales (t₀, ΔT) underlying cognitive processing. The model predicts that dwell times T covary with t₀, ΔT or both. We tested this prediction by exploiting that observers, in particular experienced meditators, can volitionally control dwell times T.Meditators and non-meditators observed bistable Necker cubes either passively or tried to hold their current percept. The latencies of a centro-parietal event-related potential (CPP) were recorded as a physiological correlate of t₀.Dwell times T and the CPP latencies, correlated with t₀, differed between conditions and observer groups, while ΔT remained constant in the range predicted by the model. The covariation of CPP latencies and dwell times, as well as their quadratic functional dependence extends previous psychophysical confirmation of the Necker-Zeno model to psychophysiological measures.     

EEG correlates of postural audio-biofeedback

The control of postural sway depends on the dynamic integration of multi-sensory information in the central nervous system. Augmentation of sensory information, such as during auditory biofeedback (ABF) of the trunk acceleration, has been shown to improve postural control. By means of quantitative electroencephalography (EEG), we examined the basic processes in the brain that are involved in the perception and cognition of auditory signals used for ABF. ABF and Fake ABF (FAKE) auditory stimulations were delivered to 10 healthy naive participants during quiet standing postural tasks, with eyes-open and closed. Trunk acceleration and 19-channels EEG were recorded at the same time. Advanced, state-of-the-art EEG analysis and modeling methods were employed to assess the possibly differential, functional activation, and localization of EEG spectral features (power in α, β, and γ bands) between the FAKE and the ABF conditions, for both the eyes-open and the eyes-closed tasks. Participants gained advantage by ABF in reducing their postural sway, as measured by a reduction of the root mean square of trunk acceleration during the ABF compared to the FAKE condition. Population-wise localization analysis performed on the comparison FAKE - ABF revealed: (i) a significant decrease of α power in the right inferior parietal cortex for the eyes-open task; (ii) a significant increase of γ power in left temporo-parietal areas for the eyes-closed task; (iii) a significant increase of γ power in the left temporo-occipital areas in the eyes-open task. EEG outcomes supported the idea that ABF for postural control heavily modulates (increases) the cortical activation in healthy participants. The sites showing the higher ABF-related modulation are among the known cortical areas associated with multi-sensory, perceptual integration, and sensorimotor integration, showing a differential activation between the eyes-open and eyes-closed conditions.     

EEG slow frequency and WISC-R correlates

On the basis of slow frequency indices obtained from computerized EEG assessments, 36 children were ranked the highest and 23 the lowest in a heterogeneous population of children involved in a brain-behavior assessment program. WISC-R results show the high or excess slow frequency group to have low verbal and normal performance subtest scores, while those with the least slow frequency activity were above normal on verbal and performance scores. Discriminant function analyses of the WISC-R profiles significantly separated the two EEG groupings, with the Information Subtest and Verbal IQ the best discriminating measures. The results suggested that diffuse EEG slow frequency reflected a maturational lag. Cluster analyses showed that the subtest profile was constant independently of IQ. Other findings indicated that the presence of excessive slow frequency activity was associated with less electrophysiological and psychometric differentiation.This work was supported by a contract awarded by The Ontario Ministry of Community and Social Services, a contract awarded by The Ontario Ministry of Education, a grant awarded to W. Corning by The National Science and Engineering Research Council, and by a University of Waterloo Faculty Research grant and a SSHRC leave fellowship to R. A. Steffy. The authors wish to acknowledge the assistence of K. Blom, B. Jones, J. Free, J. Washburn, L. MacDonald, G. Verspagen, the secretarial department, and the shop staff of the University of Waterloo, Psychology Department.     

EEG correlates of behavioural laterality: right-handedness

Among right-handers, the magnitude of differences in proficiency between the left and right hands varies considerably. Yet significance of the extent of right-handedness is still a controversial issue. To examine whether individual differences in asymmetry of hand skill can partly be attributed to individual differences in asymmetrical hemispheric activation, handedness and electroencephalographic (EEG) laterality were correlated in two large samples (ns = 60 and 128). Analysis indicated that part of the variability in right-handedness may arise from activation asymmetries in the cortex, but whether this relation becomes apparent depends on the cortical area examined and on the experimental condition under which the EEG measures are taken.     

Habituation of cognitive and physiological arousal and social anxiety

This study examined differences in habituation between high and low socially anxious Ss. Participants gave three impromptu speeches, each separated by a brief rest interval. Skin conductance and heart rate were monitored during the speeches. Following each speech participants completed self-ratings of nervousness, heart rate, and palmar sweat activity as well as a modified Social Interaction Self Statement Test. Low anxious controls showed significant reduction of negative expectations and self-reported nervousness, heart rate, and sweat activity across the three trials. Actual heart rate of low-anxious subjects also decreased significantly across trials. In contrast, high anxious subjects did not evidence significant decreases in any of the above measures of anxiety and stress across the three trials. Skin conductance measures increased across trials for both groups, but increased more for the high anxious group than low-anxious controls. Results indicate that high anxiety participants are slow to decrease cognitive and autonomic responsiveness to stressful social situations.     

EEG correlates of behavioural laterality: ear dominance

To examine whether ear dominance in a dichotic pitch-discrimination task is associated with asymmetrical activation of the two cortical hemispheres, ear dominance scores and electroencephalographic (EEG) laterality were correlated in two independent samples (ns=46 and 128). The results indicate that ear dominance can partly be attributed to a relatively stronger activation of the contralateral prefrontal cortex. The observed association may reflect the tendency to direct attention preferably to one ear.     

Mesomorphy correlates with experiential cognitive style

The purpose of this study was to test for a relationship between mesomorphy and experiential cognitive style (S. Epstein, 1994) in a sample of university students (30 women and 24 men). Anthropometric somatotypes were obtained using the Heath-Carter procedure (J. E. L. Carter, 2002). Experiential cognitive style was operationalized as scores on the experiential scale of the Rational Experiential Inventory for Adolescents (A. D. Marks, D. W. Hine, R. L. Blore, & W. J. Phillips, 2008). Nonparametric bootstrap correlations were calculated using 80% confidence intervals. There were significant correlations between mesomorphy and experiential cognitive style for men (r(s) = .33) and women (r(s) = .25). For men, experiential cognitive style was also correlated with endomorphy (r(s) = .39) and ectomorphy (rs = -.48).     

Behavioral and cognitive correlates of exercise self-schemata

The purpose of this study was to examine the relationship of exercise self-schemata to both cognitive and behavioral concomitants including exercise self-efficacy, attitudes toward fitness, self-perceptions of fitness, and self-report of exercise behavior. Participants were 161 undergraduate students who subsequently were categorized into groups defined by the authors as "exercise schematics," "nonexercise schematics," "aschematics," and unclassified. Results indicated that exercise schematics reported greater total caloric expenditure, higher frequency of exercise behavior in the past as well as future expectations to exercise, greater self-perceptions of physical fitness, and more favorable attitudes toward fitness than either nonexercise schematics or aschematics. Furthermore, exercise schematics expressed higher levels of exercise self-efficacy than did nonexercise schematics. The results clearly support earlier findings concerning exercise self-schemata and exercise behavior and further indicate that schematics also differ from others in important cognitive-motivational determinants of exercise such as self-efficacy and perceptions of physical fitness. Future research should define the role of exercise self-schemata both theoretically and practically in order to enrich our understanding of and facilitate the enhancement of exercise adherence.     

Autonomic arousal as a cognitive cue in stressful situations1

The need for further investigation and integration in a real world situation is demonstrated in a critical review of the literature on autonomic feedback and attribution of arousal in stressful situations. In the present study, actual autonomic arousal, arbitrary feedback of arousal, and attributions for arousal were manipulated in a dental clinic where the subjects were awaiting oral surgery. The main prediction was that cognized arousal (due either to perception of actual arousal or to arbitrary feedback about arousal level) in the absence of a nonemotional attribution for that cognized arousal would lead to higher subjective report of anxiety and to greater avoidance than would be found with either of these conditions unmet. The results on the subjective report measure generally supported this hypothesis. In addition, arbitrary feedback about arousal level did not interact with the actual arousal manipulation; nor did it produce changes in pulse rate or blood pressure, further supporting a cognitive interpretation of the effects of autonomic arousal on subjective report. However, the study illustrates difficulties in inducing beneficial beliefs in the real world. And the manipulations generally did not affect the behavioral measure, probably due to the expected consequences of that behavior.     

EEG correlates of Fitts's law during preparation for action

Humans' inability to move fast and accurately at the same time is expressed in Fitts's law. It states that the movement time between targets depends on the index of difficulty, which is a function of the target width and the inter-target distance. The present study investigated the electrophysiological correlates of Fitts's law during action planning using high-density electroencephalography. Movement times were scaled according to Fitts's law, indicating that participants could not overcome the speed-accuracy trade-off during a 1-s preparation period. Importantly, the index of difficulty of the planned movement correlated linearly with the amplitudes of the cognitive N2 and P3b components, which developed during the planning period over parieto-occipital areas. These results suggest that the difficulty of a movement during action planning is represented at a level where perceptual information about the difficulty of the ensuing action is linked to motor programming of the required movement.     

PTSD arousal and depression symptoms associated with increased right-sided parietal EEG asymmetry

Researchers have proposed that depression and particular types of anxiety are associated with unique patterns of regional brain activation. The authors examined the relationship among posttraumatic stress disorder (PTSD), anxiety, and depressive symptoms and frontal, temporal, and parietal EEG alpha asymmetry in female Vietnam War nurse veterans. The results indicate that PTSD arousal symptoms are associated with increased right-sided parietal activation. However, the combination of arousal, depression, and their interaction explain more than twice the variance in parietal asymmetry compared with arousal alone. The results support the contention that the association between anxiety and right-sided posterior activation is specific to the anxious arousal subtype. These findings underscore the importance of isolating, both theoretically and statistically, emotional subcomponents in studies of regional brain activation.     

Trait congruence in the study of the cognitive consequences of emotional arousal

This study investigated the possible influence of mood and emotional vulnerability on recall. Mood was induced by projecting highly emotionally laden slides. In the first experiment, 64 female subjects, rated low or high on emotional vulnerability, were tested on recall of mood-congruent, mood-incongruent and neutral words, under mood induction and non-mood induction conditions. Emotionally low-vulnerable subjects recalled more mood-congruent than mood-incongruent words in the mood induction condition, whereas the opposite was the case in the non-mood induction condition. Highly vulnerable subjects recalled more mood-congruent than mood-incongruent words in the non-mood induction condition and fewer mood-congruent words in the mood induction compared with non-mood induction condition. The results are discussed in terms of ‘mood congruence’ (to explain low-vulnerable (LV) subjects' performance) and in terms of ‘trait congruence’ (to explain highly-vulnerable (HV) subjects' performance). In a second experiment, which investigated LV and HV subjects' galvanic skin responses to highly- and low-emotionally laden slides, the highest values were those for HV subjects when exposed to emotional slides. The different activation of LV and HV subjects led us to reconsider previous reasoning regarding mood congruence and trait congruence in the light of the inverted U theory.