HAND-MOVEMENT PROFILES IN A TACTUAL-TACTUAL MATCHING TASK - EFFECTS OF SPATIAL FACTORS AND LATERALITY

We examined the effect of spatial factors and hemispheric lateralizati on upon hand-scanning strategies in 14 right-handed men tested in a ta ctual-tactual matching task. The experiment involved comparisons (judg ments of same or different) between two objects sequentially touched b y the fingertips of the left or right hand. Stimuli were made of smoot hly joined cubes whose junctions were not haptically discernible. Expl oratory strategies were inferred from the durations and locations of h and contacts with any of the cubes composing the stimuli. Accuracy was greater when the same stimulus was touched twice by the same hand tha n when different hands were used to feel it. With regard to strategies , both hands touched the upper parts of the object longer than the low er parts. Subjects also inspected more portions of the objects ipsilat eral to the hand used. Overall differences in time spent touching cube s were greater for the right hand than for the left hand, showing that touch times were less evenly distributed on object parts for the form er than for the latter. In this study, the process of information gath ering by touch appears to be determined by the intertwining integratio n of contextual factors (e.g., stimulus position in space), biomechani cal constraints on hand movements, and such cognitive factors as hemis pheric differences on the ability to encode spatial pattern informatio n.