Lateral asymmetries in attentional priming during a semantic and a visuospatial task.

This study tests the hypothesis that lateral cueing of attention activates the contralateral hemisphere and also that performance on a semantic and a visuospatial task will differentially be affected depending on the visual field (right or left) to which attention was drawn. In an experimental setting, 68 subjects performed both a semantic and a visuospatial discriminating task, whereby visual priming signals unbeknownst were presented to either the left or the right visual field. For the semantic task (which is believed to engage primarily the left hemisphere) priming signals enhanced performance more when they were presented to the right visual field. For the visuospatial task, no difference was found between priming signals presented in either visual field. While there may be several alternative explanations for the observed difference in the effects of the priming signals presented to different visual fields, the importance of separating the components inherent in the tasks is stressed. While the process of decision-making may involve different relative activation of the two hemispheres, depending on whether the stimuli are semantic or visuospatial in nature, performance on the task also involves manual coordination which will depend especially on motor activation in the left hemisphere.

Relationship between attentional orientation and associative learning.

This study presents experimental evidence for a relationship between attentional orientation and associative learning. Learning to establish contingencies between warning signals and subsequent task stimuli is a phenomenon which we know from previous studies to be more associated with the left hemisphere. We investigated how hemispheric priming, i.e., activating one hemisphere by directing attention towards the contralateral hemispace, affected both the rate and the extent of associative and nonassociative learning. When attention was directed towards the right while perceiving a discrimination task stimulus, the rate of learning through contingency formation was increased since the relative activation of the left hemisphere was increased. Such a relationship was not found for relative activation of the right hemisphere following leftward orientation of attention.

Psychosocial predictors of psychological, neurochemical and immunological symptoms of acute stress among breast cancer patients.

The purpose of this study was to determine the impact of locus of control, social support and their interaction on acute stress indicators as a consequence of the communication of the results of a breast biopsy. Immunological and psychological indicators were evaluated in 50 patients with breast tenderness. We found little evidence for the existence of a relationship between psychosocial variables considered to be stress indicators and acute stress symptoms. Concerning the results of the first assessment, only the relation between locus of control and psychological distress was meaningful. With regard to the existence of a relationship between psychosocial variables and natural killer cell system indicators, only the number of natural killer cells (NKC) could be explained by the psychosocial model including locus of control, perceived social support from relatives and the interaction between locus of control and perceived social support from relatives.

Chronic and acute stress as predictors of relapse in primary breast cancer patients.

In this paper we present data on predictors of early relapse (at three and a half years post-surgery) in 44 patients with primary breast carcinoma. We expected that the degree to which receiving the diagnosis of malignancy would act as an acute stressor would allow a prediction of early relapse. Acute stress is measured by means of changes in psychological, neurochemical and immunological indicators of stress before and after the communication of the diagnosis. The results indicate that the assumption does not hold. Chronic stress, however, appears to be a strong predictor of early relapse. The measure of chronic stress is based on a self-report questionnaire of health complaints in the year before the diagnosis of breast cancer.

What determines primary breast cancer patients' hope to recover.

The main purpose was to offer evidence for the hypothesis that the stronger an acute real life stressor, namely, hearing from the physician that one has breast cancer and that one has to undergo mastectomy, the greater the induced noradrenaline (NA) depletion in the central nervous system (CNS) and the more the patient loses hope to recover. The data were derived from answers to interviews, questionnaires, and analyses of blood samples obtained from the patients on the day of admission to the hospital for a biopsy and 24 hours after the surgeon communicated the results of the biopsy to the patients. Analysis showed that a decline in 3-Methoxy 4-Hydroxy Methoxy 4-Hydroxy Phenylethylene Glycol (MHPG) concentration in blood plasma samples after being informed of the diagnosis is associated with less hope of recovery. MHPG is the main metabolite of CNS noradrenaline.

Can primary breast cancer patients sense the presence of lymph node metastasis? An unexpected research finding.

We found that primary breast cancer patients with lymph node metastasis, compared to patients without apparent metastasis, had a greater expectation that their breast lump biopsy would be malignant. This difference in expectation between the two groups remained after controlling for a range of possible confounding variables.

Self-reported locus of control is based on feelings of depression as well as on asymmetry in activation of cerebral hemispheres.

In a sample of 50 patients with primary breast cancer we obtained interviews, answers to questionnaires, blood samples, and reaction times on two stimulus discrimination tests on the day of admission to the hospital for a biopsy. Locus of control scores on Rotter's I-E Locus of Control Scale seemed to be directly associated with an indicator of depressed mood and one of relative activation of the right cerebral hemisphere. Other variables of which one might have expected a mediating role did not show significant partial relationships with the dependent variable.

Locus of control, latent inhibition and reaction times in a semantic (left-hemisphere) and visuospatial (right-hemisphere) stimulus discrimination task.

Rank correlations on latent inhibition learning among internal scorers versus external scorers on Rotter's I-E locus of control scale were compared between trial numbers and speed of correct reactions in a left- and in a right-hemispheric discrimination task. On the basis of previous research and theorizing reviewed by De Brabander, Boone, and Gerits (1992) we expected latent inhibition effects to show mainly on the left-hemisphere task and more clearly among internal scorers on Rotter's I-E locus of control scale. The findings seem to confirm our expectations.

Corroborative evidence for difference in arousability between internal and external scorers on Rotter's I-E Locus of Control Scale.

Here we report data about the answers on the Hopkins Symptom Check List for 68 students who participated in an experiment. About random half of the subjects were submitted to sham physiological measurements, the others not. Scores on Rotter's I-E Locus of Control Scale were also available. Analysis indicated that sham physiological measurement treatment is associated with more health complaints and more among external scorers on the Locus of Control Scale. These findings are interpreted as the result of increased arousal by the treatment and higher arousability among external scorers.

Locus of control, sensation seeking, and stress.

We explored the relations among locus of control, sensation seeking, and stress (N = 68 students). Corroborating evidence was found that subjects with an external locus of control are more vulnerable to stress. Subjects scoring higher on the thrill and adventure seeking-dimension of sensation seeking reported less severe physical and psychological complaints thought to be associated with stress. These results suggest that high sensation seeking is associated with protective mechanisms against life-stress. Some possible intervening mechanisms are further discussed.

Locus of control and cerebral asymmetry.

Data about the lack of synchronism of flexor carpi ulnaris peak EMG values of bimanual reactions during a semantic and during a visuospatial discrimination reaction time task are reported. The effects of type of task as well as the presence or absence of an unexpected stimulus preceding the reaction stimulus on lack of synchronism clearly depend upon the locus of control of the subjects, as measured on Rotter's I-E scale. On the basis of several arguments it is proposed that the measure of lack of synchronism reflects in an opposite sense the amount of dopaminergic activation or motor readiness in the sense in which Pribram and McGuinness in 1975 and Tucker and Williamson in 1984 have defined these concepts. The results for 15 women and 18 men show that more internally oriented subjects are more activated by a semantic task and by an unexpected preparatory stimulus in this type of task than more externally oriented subjects. The opposite appears to hold on the visuospatial task and unexpected preparatory stimuli therein. Together with earlier findings about reaction times and a number of relevant findings in the literature, the results are interpreted as indicative of basic differences in asymmetric tonic activation of the cerebral hemispheres between more internally and more externally oriented subjects. A model is proposed to explain phasic activating effects which ensue when tonically more left- or right-activated subjects perform left- or right-hemisphere tasks and when supplementary irrelevant stimuli are received.

Stability of choice reaction time and synchronicity of peak EMG values during bimanual reactions.

18 volunteers of our Faculty participated in two quasi-identical experiments six months apart. Repeated measurements of reaction time and synchronicity of peak forearm EMG values during bimanual reactions are analyzed by means of analysis of variance with subjects and measurement period as factors. Using Ebel's formula, test-retest reliabilities derived from the analysis vary between .82 and .94 for reaction times on different tasks and conditions and between .75 and .92 for synchronicity of peak EMG values.

The effect of stress and psychosocial variables on natural killer cells: a review.

In this review we discuss the results of studies about the effect of stress, depression, anxiety, social support and various psychosocial treatments on numbers and activity of Natural Killer (NK) cells. In general a suppressive effect is observed among depressive persons and persons who react to stressfull events with feelings of helplessness and anxiety. Lack of social support also seems to engender immunosuppression including NK suppression. Various forms of psychosocial care seem to be able to undo these negative consequences. However, the real clinical relevance of these findings is still a matter of dispute.

Relationships among locus of control, type of task (visuospatial versus semantic), and arousal or activation by an unexpected preparatory signal.

In this experiment, which is partly a replication of two earlier ones, we tested the hypothesis that the brain self-regulates its own arousal and activation. According to the underlying paradigm, arousal effectuates slower reaction times and depressed EMG activity after an unexpected preparatory signal on a visuospatial choice-reaction task, whereas activation effectuates faster reaction times and elevated EMG activity after an unexpected preparatory signal on a semantic choice-reaction task. The results basically confirm the predictions. The relationship of locus of control scores of the subjects with tonic and phasic EMG activity was also explored. The results clearly and consistently show elevated tonic EMG activity in the left forearm for subjects with an external locus of control. Together the results suggest that the mechanisms involved are partly preconscious and probably related to central catecholaminergic activation systems.

Relation of scores on Rotter's I-E scale to short-term and long-term control expectancies and fatalism.

The purpose of the present research was twofold. First, we analysed whether expectancies of personal control versus nonpersonal control could reliably be assessed by structured interviews recorded on videotape. Second, by means of factor analysis, we analysed the relation between the interview locus-of-control scores and the scores obtained by Rotter's I-E. scale. Analysis showed that the scores on Rotter's I-E scale are correlated with short-term expectancies but not with long-term expectancies or fatalism. Possible explanations for these findings are suggested.

Effect of short lateralized signals on arousal versus activation on tasks requiring visuospatial or elementary semantic stimulus processing, a replication with a modified experimental design.

In this experiment, which is basically a replication of an earlier experiment done in 1988, we tested the hypothesis that the brain self-regulates its own arousal and activation. When subjects perform a putative right-hemisphere task (visuospatial), the effect of a supplementary information-processing load is supposed to lead to a delayed reaction. The opposite is supposed to be true in a putative left-hemisphere task (semantic). The former effect is supposed to be the result of increased arousal, the latter is that of increased activation. In the present experiment the reactions subject to experimental treatment are compared with control reactions of the same subject. This was not the case in the earlier experiment. Still other improvements of the experimental design were made. The results clearly confirm the earlier findings. Additional evidence is offered to strengthen the plausibility of the basic hypothesis.

Effect of short lateralized signals on arousal versus activation on tasks requiring visuospatial or elementary semantic stimulus processing.

The results of the experiment offer indirect evidence for the basic hypothesis that the brain self-regulates its own arousal and activation as a function of the intensity and type of ongoing cortical activity. When subjects perform a task which can be assumed to be primarily attended to by the right hemisphere, the result of a supplementary information-processing load seems to be increased arousal. On a task primarily attended to by the left hemisphere, the consequence is increased activation. The evidence is indirect because no measurements have been made of the neurological events and processes which are assumed to intervene in this self-regulation process. Although indirect, the evidence may help to formulate more precise psychological hypotheses about the factors controlling the putative effort system which, according to Pribram and McGuinness in 1975, coordinates the arousal and activation of cerebral processes.