Exp Brain Res (2007) 183:417–423 DOI 10.1007/s00221-007-1148-0 123 RESEARCH NOTE Shift of manual preference by lateralized practice generalizes to related motor tasks Luis Augusto Teixeira · Victor Hugo A. Okazaki Received: 10 July 2007 / Accepted: 14 September 2007 / Published online: 2 October 2007  Springer-Verlag 2007 Abstract Previous investigation (Teixeira and Teixeira in Brain Cogn, in press, 2007) has evidenced a persistent shift of manual preference for a particular motor task following lateralized practice. In the present study, we assessed the extent to which shift of manual preference is generalizable to related motor tasks. Twenty right-handers were assigned to an experimental or to a control group. The former were provided with practice on a particular sequence of Wnger movements with their left hand only, while the latter remained inactive. Participants were assessed on manual asymmetry, indexed by movement time, and manual prefer- ence for the practiced and for other two sequences of Wnger movements (transfer tasks). Assessment was made before, immediately after, and 30 days following (retention) prac- tice sessions. Results showed that lateralized practice led to signiWcant bilateral reduction of movement time, maintain- ing the symmetric performance observed before practice following task acquisition. Regarding manual preference, before task acquisition, all participants in the experimental group were right-handed for the main task; immediately after practice their predominant manual preference shifted to the left hand, a proWle that was maintained in retention. This persistent shift of manual preference was also observed for one of the transfer tasks requiring the same sequence of transitions between Wnger movements. Indices of correlation between manual asymmetry and manual preference were non-signiWcant across tasks and phases, suggesting that manual preference was not deWned by lat- eral asymmetry of performance. We propose that manual preference is established by automatic sensorimotor pro- cessing and/or increased conWdence on a single hand from previous experiences. Keywords Handedness · Lateralization · Manual asymmetry · Generalization · Motor training Introduction Lateralization of human motor function has been proposed as a dynamic and multifaceted process contingent upon individual related determinants (Serrien et al. 2006). One such individual determinant of human lateralization has been shown to be systematic motor experiences using a sin- gle limb, heretofore named lateralized practice (LP). Research has indicated that LP has a role in shifting manual preference (preference of a single hand to perform motor tasks). Evidence has been presented that as right-handed children (Singh et al. 2001) and adults (Teixeira 2007) advance in age, their preference for the right hand becomes stronger. Furthermore, left-handed children are frequently enforced to shift their manual preference to the right hand (Zverev 2006), and in many cases this environmental pres- sure is successful. Meng (2007) reported that in a large group of left-handed children, social eVort to shift manual preference produced the desired eVect in approximately 60% of the cases (see also Porac et al. 1986). Both strength- ening of manual preference in right-handers and shift of manual preference in left-handers seem to be due to exten- sive lateralized motor experiences in diVerent activities, modulating previous tendencies of use of the hands. In agreement with this interpretation, Mikheev and colleagues (2002) showed that judo athletes prefer more frequently than other individuals to perform certain movements with L. A. Teixeira (&) · V. H. A. Okazaki Department of Biodynamics, University of Sao Paulo, Sao Paulo, Brazil e-mail: lateixei@usp.br