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

When Your Decisions Are Not (Quite) Your Own: Action Observation Influences Free Choices

A growing number of studies have begun to assess how the actions of one individual are represented in an observer. Using a variant of an action observation paradigm, four experiments examined whether one person's behaviour can influence the subjective decisions and judgements of another. In Experiment 1, two observers sat adjacent to each other and took turns to freely select and reach to one of two locations. Results showed that participants were less likely to make a response to the same location as their partner. In three further experiments observers were asked to decide which of two familiar products they preferred or which of two faces were most attractive. Results showed that participants were less likely to choose the product or face occupying the location of their partner's previous reaching response. These findings suggest that action observation can influence a range of free choice preferences and decisions. Possible mechanisms through which this influence occurs are discussed

The Role of Attention in a Joint-Action Effect

The most common explanation for joint-action effects has been the action co-representation account in which observation of another's action is represented within one's own action system. However, recent evidence has shown that the most prominent of these joint-action effects (i.e., the Social Simon effect), can occur when no co-actor is present. In the current work we examined whether another joint-action phenomenon (a movement congruency effect) can be induced when a participant performs their part of the task with a different effector to that of their co-actor and when a co-actor's action is replaced by an attention-capturing luminance signal. Contrary to what is predicted by the action co-representation account, results show that the basic movement congruency effect occurred in both situations. These findings challenge the action co-representation account of this particular effect and suggest instead that it is driven by bottom-up mechanisms

Mean RTs to localise targets as a function of effector and movement congruency in Experiment 1.

<p>Error bars represent standard errors of the mean.</p

An illustration of the standard condition in the movement congruency paradigm used in Experiments 1 and 2.

<p>Each person takes turns to reach out and touch one of two targets presented on the left or right. In the figure shown, one person is reaching to their right where the target has illuminated.</p

Trial sequence in Experiment 2.

<p>Trial sequence in Experiment 2.</p

Mean RTs to localise targets as a function of partner and movement congruency in Experiment 2.

<p>Error bars represent standard errors of the mean.</p

Percentage ‘same’ responses for each participant in all four experiments.

<p>Percentage ‘same’ responses for each participant in all four experiments.</p

Schematic representation of the paradigm employed in the four experiments.

<p>In Experiment 1 participants take turns to freely select and reach out to one of the two squares. In Experiment 2 the squares were replaced by images of products and participants asked to decide which of the two they preferred (or least preferred). In Experiments 3 and 4 pairs of faces were presented and participants asked to decide which of the two they thought most people would consider to be most (or least) attractive.</p

Action or attention in social inhibition of return?

When two individuals alternate reaching responses to targets located in a visual display, reaction times are longer when responses are directed to where the co-actor just responded. Although an abundance of work has examined the many characteristics of this phenomenon it is not yet known why the effect occurs. In particular, some authors have argued that action representation mechanisms are central to the effect. However, here we present evidence in support of an account in which the representation of action is not necessary. First, the basic effect occurs even when participants cannot see their co-actor’s movement but, importantly, have their attention shifted to a target side via an attentional cue. Second, its time course is too short-lasting to function effectively as a component of action planning. Finally, unlike other joint action phenomena, the effect is not modulated by higher order mechanisms concerned with the personal attributes of a co-actor. Taken together, these results suggest that this particular joint action phenomenon is due to attentional rather than action mechanisms