THE RELATIONSHIP BETWEEN HANDEDNESS AND FINE MOTOR PERFORMANCE E. Nalçacı 1 , C. Kalaycıo˘ glu 1 , M. Çiçek 1 and Y. Genç 2 ( 1 Cognitive Neurophysiology Unit, Department of Physiology, and 2 Department of Biostatistics, Faculty of Medicine, Ankara University, Ankara, Turkey) ABSTRACT The aim of this study was to re-investigate the relationship between handedness and asymmetry in hand performance, and the sex difference in motor asymmetry. Three-hundred and ten medical students volunteered as subjects. Handedness was assessed by a 13-item questionnaire adapted from Chapman and Chapman. Fine motor performance was measured using a finger tapping task. In this task, subjects were required to tap as rapidly as possible with their index finger on a mouse button for a period of 10 s. There was a significant correlation between handedness scores and the scores of the finger tapping task. In the total sample, the correlation between hand speed and the handedness score indicated that the distribution of hand preference is associated with left hand speed, but not right hand speed. Results confirmed that right-handed females tend to have more asymmetric motor function than right-handed males. Key words: handedness, finger tapping, cerebral asymmetry, fine motor performance, sex differences INTRODUCTION In human and most other species, the brain has the characteristic that its two hemispheres are functionally asymmetric. One of the most striking reflections of this functional asymmetry is motor asymmetry, as in preference of a hand or a foot. Hand preference is usually defined as the tendency to perform several tasks with one hand rather than the other, and handedness shows substantial individual variability. Hand preference has been measured by questionnaires developed by several authors (Annett, 1970; Oldfield, 1971; Raczkowski et al., 1974; Bryden, 1977; Chapman and Chapman, 1987). The other approach to measuring motor asymmetry is to monitor the skills of both hands as in finger-tapping and peg- moving tasks, which evaluate the difference between hand speeds (McKeever and VanDeventer, 1977; Peters and During, 1978; Gabbard et al., 1993). Annett (1970, 1976) defined handedness of subjects by using a questionnaire, and measured the movement time of each hand on a peg-moving task. Her results suggested that both preference and skill were continuously distributed variables. Kilshaw and Annett (1983) reported that left-handers were faster than right-handers in hand-movement time, and the greater slowness of the left hand of the right-handers was very striking, while there was little evidence of extra speed for the right hand of the right-handers in comparison to the preferred hand of the other preference groups. Furthermore, Annett (1992a) gave five group Cortex, (2001) 37, 493-500