A Better Approach of Assessing Lalerality by Using Combined Foot and Eye Dominance Scale in Mentally Healthy Subjects

Abstract

Abstract Objective To investigate the reliability (internal consistency) of a Combined Foot and Eye Dominance Scale in healthy subjects. Materials and methods A total of 82 mentally healthy subjects were assessed with a Combined Foot and Eye Dominance Scale. 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 Subscale included three eye tests. Scale reliability statistics (item-scale statistics, summary statistics for the items, Cronbach’s alpha), nonparametric 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 37.83 times greater than those of other items (from 0.15 to 5.61), which suggested greater phenogenetic component and consequently greater contribution of these items to the total scale mean. The mean correlation between the items of the Combined Foot and Eye Dominance Scale was strongly positive (0.39), indicating good internal consistency of the scale. Conclusions Eye and foot dominance appear to be a much subtler indicator of altered hemispheric lateralization than hand dominance. The Combined Dominance Scale provides a more adequate tool for objective measuring of leftedness, as a way to assess laterality, since this scale is to a great degree unaffected by socio-cultural impact. The scale would provide comparability of leftedness as an indirect clue of abnormal lateralization in studies of mentally healthy subjects and subjects with neurodevelopmental disorders with presumed abnormal cerebral asymmetry across cultures.