Handedness effects in the detection of dichotically-presented words and emotions

Left-handed and right-handed subjects were given two dichotic listening tasks using identical material. In one task, they were asked to determine whether or not a specific target word was present (verbal task). In the other task, subjects were asked to indicate whether or not one of the dichotically-competing words was spoken in a particular affective tone (emotion task). Overall, a right-ear advantage (REA) was found with the verbal task and a left-ear advantage (LEA) with the emotion task. Left-handers showed a slightly smaller REA than right-handers on the verbal task, but a slightly larger LEA on the emotion task. This finding suggests that left- and right-hemispheric functions are not related in a complementary fashion and that handedness effects for nonverbal tasks are different from those seen with verbal tasks. The emotional LEA was much larger for angry stimuli than for happy, sad, or neutral stimuli. Rather than providing evidence for a hemisphere by affective valence interaction, such results suggest a stimulus-specific effect.