Effects of a neutral warning signal on spatial two-choice reactions

Abstract

Posner et al. reported that, at short fixed foreperiods, a neutral warning tone reduced reaction times (RTs) in a visual two-choice task while increasing error rates for both spatially compatible and incompatible stimulus–response mappings. Consequently, they concluded that alertness induced by the warning does not affect the efficiency of information processing but the setting of a response criterion. We conducted two experiments to determine the conditions under which the trade-off occurs. In Experiment 1, participants performed the same two-choice task as in Posner et al.’s study without RT feedback. Results showed that the warning tone speeded responses with no evidence of speed/accuracy trade-off. In Experiment 2, RT feedback was provided after each response, and a speed/accuracy trade-off was found for the 50-ms foreperiod. However, better information-processing efficiency was evident for the 200-ms foreperiod. We conclude that the foreperiod effect of a 50-ms foreperiod is a result of response criterion adjustment and that providing trial-level RT feedback is critical for replicating this pattern. However, fixed foreperiods of 200 ms or longer benefit both speed and accuracy, implying a more controlled preparation component that improves response efficiency.