Abstract
Many studies show that if one is asked to produce a motion while observing another's motion, action production is influenced by the overlap in spatial position/direction (spatial congruency) and overlap in type of bodily motion (anatomical congruency) between observed and executed motions. In the present study, we examine this effect more closely by modifying the paradigm established by Brass, Bekkering, & Prinz (2001). We asked whether congruency between the kinematics of observed and executed up/down finger motions produces an anatomical effect even when the executed motions (key pressing and key lifting) involve different object-specific goals than the observed motions (downward or upward finger motions). To isolate spatial and anatomical effects, finger motions were presented with the observed hand in both an upright and inverted orientation. Furthermore, half of our participants saw a uniform gray background behind observed finger motions and half saw a table image below the hand with a blank wall behind (providing a goal object for downward, but not upward motions). We find that only key presses (not lifts) showed main effects of spatial and anatomical congruency. We suggest that when a salient familiar goal state for an alternative action is part of a more novel response sequence (e.g. having a key depressed as the starting position for a lift response), the congruency between observed goals and the novel and familiar goal states of responses yield conflicting facilitatory and inhibitory effects. In addition, congruency effects were influenced by the background presented. Specifically, our results show that when participants initially saw upright finger motions above a table, congruency effects were absent when the motions (and background) were subsequently inverted. However, this was not the case if upright or inverted motions were presented on a gray background or if inverted motions were first presented with a table background.