Covert unimanual response preparation triggers attention shifts to effectors rather than goal locations

The premotor theory of attention postulates that during response preparation, attention shifts are elicited towards the goal of a prepared movement. Support for this claim comes from research demonstrating enhanced performance at the location of upcoming saccades. To investigate whether attention shifts occur towards effectors or goal locations during the covert preparation of unimanual movements, we recorded event related brain potentials (ERPs) to task-irrelevant tactile probes that were presented while participants prepared to move one hand towards the index finger of the other hand, as directed by visual response cues presented at the start of each trial. These cues specified either the effector or the goal location of an upcoming movement. The somatosensory N140 component was enhanced when probes were presented to the effector hand relative to the goal hand, regardless of cue instructions. Analogous modulations of the N80 component were only present with effector cues. These results demonstrate a close link between covert response preparation and attention shifts, and strongly suggest that attention shifts are directed to the effector, and not to the goal location of manual movements