Bulgarian Journal of Psychiatry, 2024; 8(4):33-41

New direction for laterality assessment in schizophrenia

Katerina Akabalieva
Department of Psychiatry and Medical Psychology, Medical University – Sofia

Abstract. Background: The investigation of reliability of a Combined Foot and Eye Dominance Scale in patients with schizophrenia to provide useful tool for assessing laterality. Subjects and methods: 98 schizophrenic patients were assessed with a Combined Foot and Eye Dominance Scale, consisting of two subscales: The Foot Dominance Subscale included a modified Chapman & Chapman Foot Dominance Scale and a new Complex Tasks Scale with four foot tests reflecting more complex tasks; the Eye Dominance Scale included three eye tests. Scale reliability statistics, non-parametric Mann-Whitney test and Spearman’s rank correlation coefficient were used. Results: Considerable differences were found in the contribution of the single items to the Combined Scale. The means of some items were 4,44 times greater than those of other items, suggesting a greater phenogenetic component and consequently greater contribution of these items to the total scale mean. The mean correlation between the items of the scale was positive, indicating good internal consistency of the scale. Conclusions: As hand dominance is confounded by culture, the Combined Scale provides an adequate tool for an objective assessment of leftedness, to a great degree unaffected by cultural impact. It would provide comparability of leftedness as an indirect clue of abnormal lateralization in studies of neurodevelopmental disorders with presumed abnormal cerebral asymmetry across cultures.

Key words: schizophrenia, dysmorphogenesis, laterality assessment, Combined Foot and Eye Dominance Scale

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