Dual-task performance in right- and left-handed adults: a finger-tapping and foot-tapping study

The dual-task paradigm has been used extensively to study laterality, with concurrent verbalization interfering with right finger-tapping in right handers. Only a few studies have used this paradigm to study interference patterns in left handers and have found inconsistent results. The dual-task paradigm has not been used to study interference effects with concurrent verbalization and foot-tapping. The objective of this study was to use this paradigm to assess whether verbal interference produces different effects on finger- and foot-tapping rate for right handers as compared to left handers. 12 right-handed and 12 left-handed men were studied, each with uncrossed hand and foot dominance, i.e., all individuals were either right handed and right footed or left handed and left footed. Subjects performed finger- and foot-tapping tasks with and without verbal interference. A significant relationship was found between handedness and finger- and foot-tapping rate; individuals with a stronger right-hand preference tended to tap at a higher rate on the right side and vice-versa. Analogous relationships were not found when participants were tapping and speaking concurrently. With verbal interference, both right and left handers had a significant asymmetric effect with a decremental response in right finger-tapping rate and a facilitative effect on left finger-tapping rate. In contrast, there was a bilateral decremental response in foot-tapping with verbal interference in both right and left handers. The implications of these findings are discussed with reference to cerebral laterality of language systems and to the differential organization and integration of the motor representations of the hand and the foot.