Affective processes appraise the salience of external stimuli preparing the agent for action. So far, the relationship between stimuli, affect, and action has been mainly studied in highly controlled laboratory conditions. In order to find the generalization of this relationship to social interaction, we assess the influence of the salience of social stimuli on human interaction. We constructed reality ball game in a mixed reality space where pairs of people collaborated in order to compete with an opposing team. We coupled the players with team members with varying social salience by using both physical and virtual representations of remote players (i.e., avatars). We observe that, irrespective of the team composition, winners and losers display significantly different inter- and intrateam spatial behaviors. We show that subjects regulate their interpersonal distance to both virtual and physical team members in similar ways, but in proportion to the vividness of the stimulus. As an independent validation of this social salience effect, we show that this behavioral effect is also displayed in physiological correlates of arousal. In addition, we found a strong correlation between performance, physiology, and the subjective reports of the subjects. Our results show that proxemics is consistent with affective responses, confirming the existence of a social salience effect. This provides further support for the so-called law of apparent reality, and it generalizes it to the social realm, where it can be used to design more efficient social artifacts. (Contains 10 figures and 4 tables.)