The time course of the verbal prediction effect

Choice reaction times following correct verbal predictions of the presented stimulus are faster than after incorrect predictions. Two experiments examined the influence of the time interval (PSI) between the prediction and the stimulus on the magnitude of the prediction effect. Experiment 1 used equiprobable stimuli and showed a smaller prediction effect at a 2-sec PSI than at a 0- or .5-sec PSI. Experiment 2 used unequal-probability stimuli and showed that the prediction effect was independent of PSI when the more frequent stimulus was predicted. When the less frequent stimulus was predicted, however, the magnitude of the prediction effect was smaller at .75- and 2-sec PSIs than at a 0-sec PSI. These results were discussed in terms of a prediction substitution hypothesis.