Implied Directionality Redefines Sidedness Effect

In this study we investigated whether implied motion in static photograph of hands may convey information about intended actions and whether this interacts with their automatic coding in generating the Sidedness effect (Ottoboni et al., 2005). A modified Simon task was used showing a hand with a colored circle in the centre. In the first experiment we replicated the Sidedness effect. In the second experiment, hands were rotated along their vertical axes in order to give the sense of motion and to test whether the direction of the implied action might interact with the sidedness effect. Both non-athletes and volleyball players were tested. Results showed a normal Sidedness effect for the back views in both groups. A Sidedness effect emerged in non athletes, but directionality contrasted the sidedness effect only in the volleyball players for the back views. Thus, action directionality seems to be coded only under special expertise requirement.