The temporal locus of transfer of training between hands: an interference study.

Two experiments are presented which used a dual-task interference procedure to examine the temporal locus of lateral transfer of training. In Experiment 1, 120 undergraduates practised a sequential tapping task with either the left or the right hand, and then switched to the opposite, untrained hand for the test trials. Performance of an unrelated bulb-gripping task with the opposite hand during test trials but not during training trials effectively eliminated transfer of training between the hands for this skill. Because this contradicted the findings of Hicks, Frank and Kinsbourne (J. Gen. Psychol., 107 (1982) 277-281), we then attempted to replicate their study in a second experiment, with 48 subjects. Subjects who gripped a table leg during training trials performed as well during test trials as subjects who did not. We concluded (a) that transfer of training between the hands (cerebral hemispheres) occurs relatively late, when the individual switches to the untrained hand, and (b) that motor overflow is not critical to lateral transfer of training. These data are compatible with a callosal access model of interhemispheric interaction.