How Social and Refractory Is the Social Psychological Refractory Period?

The social psychological refractory period (PRP) effect refers to an increase in RT to the second of two successive stimuli when another person responds to the first stimulus (shared dual-task condition) rather than when a single person responds to both stimuli (individual dual-task condition). We investigated (a) whether a social PRP effect would occur without explicit instruction concerning task priority and (b) whether there are crosstalk effects in the shared dual-task situation. We observed a strong PRP effect together with a small crosstalk effect in the individual dual-task condition, but in the shared dual-task condition both effects were absent. These findings suggest that the explicit instruction to perform responses in a fixed order is necessary to obtain the social PRP effect. In the individual dual-task condition, sequential processing can be seen as a means to reduce or prevent crosstalk effects, which is not necessary in the shared dual-task condition.