A Comparison of Left-Handed and Right-Handed Subjects on Verbal and Non-Verbal Dichotic Listening Tasks

Abstract

Twenty-five left-handed and 25 right-handed subjects performed three dichotic listening tasks, two verbal and one non-verbal. Comparisons were made between mean scores obtained at the right and left ears, as well as between the handedness groups. The following results were obtained: The mean right ear score was higher than the mean left ear score for both handedness groups on both of the verbal dichotic tasks. This was significant for the right-handed group on both verbal tasks, but for the left-handed group it was significant on only one verbal task. The mean left ear score was higher than the mean right ear score for both handedness groups on the non-verbal dichotic task. This betweenears difference was statistically significant for the right-handed group only. Comparison of the two handedness groups on each of the three dichotic tests revealed that more left-handed subjects had ear leads which were the reverse of that found for the groups as a whole. This difference between the handedness groups, however, was statistically significant on only one of the dichotic tests. The mean left ear score was higher than the mean right ear score for both handedness groups on the non-verbal dichotic task. This betweenears difference was statistically significant for the right-handed group only. These data were re-analyzed comparing the size of the absolute between-ears difference scores of those individuals whose ear leads consistently were the reverse of the group as a whole, with subjects who showed no reversals. It was found that the reversal group had smaller mean scores on all three tests, and that this was significant on the two verbal tests. Although more left-handed subjects were found among the reversal group, the data tentatively indicate that the above finding holds true regardless of the handedness of the subjects in the reversal group. The above findings were interpreted as reflecting the different roles of the two cerebral hemispheres, as well as the degree of hemispheric equipotentiality.