How social is social inhibition of return?

A number of studies have shown that the motor actions of one individual can affect the attention of an observer. In one notable example, "social inhibition of return," observers are relatively slow to initiate a response to a location where another individual has just responded. In the present article we examine the degree to which this phenomenon can be considered a social effect. We find that unlike the related social, or "joint," Simon effect, social inhibition of return is not influenced by competitive versus cooperative interaction, nor by live versus recorded interaction. We do find however that co-actors need to turn-take in order for the effect to occur. Thus, so-called "social" inhibition of return only reaches a minimal threshold to be considered a social phenomenon.