Sex differences in EEG correlates of a self-reported measure of hemisphere preference

Brain hemisphericity and developmental dyslexia

The present study examined the link between brain hemisphericity and dyslexia in secondary school students, using the Preference Test (PT), a widely used self-report index of preferred hemisphere thinking styles. The hypothesis was that differences would be revealed between the dyslexic group and their peers in hemispheric preference. A total of 45 secondary school students who were diagnosed with dyslexia and attended regular public schools formed the learning disabled group. A comparison group was formed of pupils who attended the same classes (N=90), and these were matched for age and sex with dyslexics (1 dyslexic: 2 control). The results revealed that significantly more dyslexic pupils displayed a preference for a right hemisphere thinking style compared to their peers who adopted a left hemisphere thinking style. This finding is in line with the suggestion of the greater right hemisphere involvement in the expression of developmental dyslexia.

An investigation of measurement validity for a hemispheric activation scale

In this paper we report the outcomes of two attempts to correlate the Zenhausern Preference Questionnaire (PT) with the Polarity Questionnaire (PQ). Across two laboratories we consistently found no correlation between these two scales. Our findings are consistent with a previous attempt to validate the PQ (Genovese, 2005). We conclude that researchers attempting to use the PQ should take note of this validity question.

Schizotypy and hemisphericity

There is considerable evidence that schizophrenia spectrum disorders are associated with a variety of abnormal asymmetries of brain structure, function, and behavior. Schizotypy is a personality trait dimension extending into the normal range, which at its extreme, is associated with a vulnerability to schizophrenia spectrum disorders. Schizotypy in the normal range is also associated with a variety of neurobiological characteristics associated with schizophrenia spectrum disorders, including abnormal brain and behavioral asymmetries. Previous studies have suggested that normal schizotypy (as well as belief in the paranormal) is associated with an increased reliance on the right hemisphere in a variety of tasks. Hemisphericity is a trait-related characteristic preference for the cognitive mode of one or the other cerebral hemispheres, putatively related to hemispheric activation asymmetry. A sample of 256 undergraduates was administered five schizotypy scales, as well as three hemisphericity measures. Higher schizotypy scores were associated with an increase in right hemisphericity and a decrease in integrated hemisphericity. Although the construct of hemisphericity has been criticized, there is evidence to suggest that questionnaire and eye movement measures of hemisphericity may yet have construct validity, and further research on hemisphericity may be warranted.

Cerebral signs of altered adaptability in females with acute psychosis

In psychosis, behavior is not guided by sensory cues from surroundings. Novel, meaningful behaviors require intact integrative functions such as short-term memory and motor planning, as well as an optimized level of arousal. In this study, we monitored markers of automatic auditory processing in 15 female never-medicated psychotic patients. Fifty-eight channels of EEG were recorded simultaneously with sympathetic skin responses while arousing auditory stimuli were delivered. Neuropsychological tests concentrating on frontal lobe functions were also performed. Prominent neurophysiological and behavioral signs of increased cortical activation were observed in psychotic patients. This widespread disinhibition may attempt to compensate for the impairment of neuronal processing of sensory input from surroundings in the earliest stages of a psychotic illness.

Interaction between cognitive style and school environment: consequences on self-evaluated anxiety and depression

This study investigated the effect of the interaction between cognitive style (CS) and school environment on self-perceived anxiety and depression. Two groups of 280 students each--one attending Fine Arts school and the other one Humanities school--were evaluated. CS was assessed by Preference Test, a paper-and-pencil test providing a measure of the extent to which individuals rely on the cognitive processes of each hemisphere. Anxiety and depression were assessed by a visual-analogue scale. Right-CS was associated to higher depressive tendencies than left-CS, and a similar but not significant pattern was observed for anxiety. A significant interaction between CS and school environment was found, i.e., the more the CS was in consonance with the environment cognitive demands, the less depressive tendencies were present, and vice versa.