Investigating the characteristics of "not responding": backward crosstalk in the PRP paradigm with forced vs. free no-go decisions.

Have you ever thought about what it means not to act? Basically, most people think about nonactions (or "not responding") as depending on the existence of a pre-activated response which is then inhibited. The main problem when investigating the characteristics of such no-go responses is that they do not provide reaction times. Importantly, Miller (Psychol Res 70:484-493, 2006) recently showed that in a dual-task paradigm, forced go/no-go decisions in the secondary task lead to a backward crosstalk effect (BCE) in the reaction times of the primary task. Based on this experimental setup, we conducted three experiments to investigate the characteristics of "not responding." The goal of Experiments 1 and 2 was to compare forced-choice and free-choice no-go responses. In both experiments, we only found a BCE when participants were forced not to respond. We interpret these findings as a first hint that the BCE is not due to an active inhibition of a pre-activated response tendency. Rather, we assume that it is caused by an automatic activation of specific response features when merely perceiving the secondary stimulus (Hommel, J Exp Psychol Hum Percept Perform 24:1368-1384, 1998). In the forced-choice condition, the stimulus unambiguously announces a no-go response. By contrast, this is not the case in the free-choice condition as here the stimulus only signals participants to freely decide to "go" or "not to go." Therefore, we tested in Experiment 3 rather directly if merely perceiving a stimulus unambiguously announcing a "no-go" causes a BCE. The results confirmed this. Overall, our results suggest that no-go responses do not differ conceptually from go responses.