Social Inhibition of return: Causes and properties

The present thesis was dedicated to examining individuals’ performance on a low-level reaching task conducted under social-interactive conditions. In this paradigm named Social Inhibition of Return (social IOR) two individuals, sitting opposite each other take turns to respond to targets appearing on either side of a visual display. Typical results reveal that reaction times are longer when responses are directed to where the co-actor just responded. Despite being fairly simple, this task is intriguing to examine as it potentially incorporates features of both an inhibition of return (IOR) effect and, a joint-action phenomenon, due to its interactive nature. Indeed, the results of the standard social IOR paradigm where participants sit opposite are consistent with both explanations as the potential involvement of attentional inhibition and/or action co-representation cannot be disentangled. The present work examined the causes and properties of this intriguing effect over the course of four empirical chapters. First, Chapter 2 revealed that social IOR possesses a number of properties, characteristic of traditional IOR. Second, Chapter 3 convincingly demonstrated that action co-representation does not seem to contribute to the phenomenon. Furthermore, Chapter 4 confirmed these findings by revealing that social IOR does not depend on the socialness of the co-actor. Finally, Chapter 5 showed that it could even bias a range of free choice decisions which revealed another novel property of the effect. Taken together these findings were interpreted as mostly consistent with a low-level inhibitory account as opposed to a theory, advocating an involvement of action imitation/co-representation in the effect. The present work had a number of theoretical and methodological implications for the better understanding of social IOR. In more general terms, it also contributed to the quickly developing, alternative literature to the action co-representation account, advocating a bottom-up basis of some joint-action effects.