Sidedness coding is stimulus but not response dependent

The aim of the present paper is to provide further evidence for an effect related to early hand recognition processing, i.e. the sidedness effect (Ottoboni, Tessari, Cubelli & Umiltà, 2005). Little is known about the sidedness effect as it has only been reported in relation to a single set of stimuli and responses. For this reason, we decided to investigate the role of the posture of the hand stimulus in Experiment 1 by presenting pictures of hands rotated upside-down, and, in Experiment 2, the role of response hand posture by moving the response plane behind the participants’ back. The results indicate that the sidedness effect manifests itself in an inverted form when the stimuli, but not the response plane, are rotated. We conclude that ultimately the effect must be based on a structural representation of the body and not on the body schema because of its dependence on stimulus posture but not on response posture.