Anatomical vs. external response coding in space-size associations in a reaching task
Mon-B21-Talk III-04
Presented by: Christian Seegelke
The spatial-size association of response code (SSARC) effect refers to the finding that (right-handed) participants respond faster and more accurate with the left hand to a small stimulus and with the right hand to a large stimulus. In the present study, we examined whether the crucial spatial response code refers to the anatomical side of the effector (i.e., left and right hand) or to the external spatial response position (i.e., where the hands are positioned in space). In separate blocks, participants performed planar reaching movements either with their left hand to small and with their right hand to large stimuli or with their left hand to large and with their right hand to small stimuli. To dissociate anatomical and external response coding, participants performed the reaches with their arms held in parallel or crossed. Regardless of arm posture, right-handed participants responded faster with their left hand to small stimuli and with their right hand to large stimuli. Left-handed participants exhibited the reversed pattern: faster responses with their left hand to large stimuli and with their right hand to small stimuli. Together, these results indicate the dominance of hand-related (anatomical) coding, rather than position-related (external) response coding in the SSARC effect.
Keywords: SR-compatibility, Reference frames, Physical stimulus size, Reaching, Response location