96 undergraduates in 5 groups performed 4 simultaneous probability learning tasks under either speed or accuracy instructions, each having 1 task with the probability of 1 of 2 alternative events (E1) given a cue (C1) equal to .7. Compared with a single task, P(E1) = .7, control, the multiple task resulted in more overshooting when (E1) = .7, less when P(E1) < .7. It is suggested that the multiple task disrupts sequential information, resulting in more overshooting, but that this effect is counteracted by cue generalization when P(E1) < P(E1 INFINITYC1). Ss with prior knowledge of probabiltiy or probability learning were found to (a) show more overshooting, and (b) more often approximate the "best strategy" for the particular situation. While the instructions were found to affect response speed, they did not seem to affect p(A1 INFINITYC1), where A1 is the prediction of E1. (21 ref.) (PsycINFO Database Record (c) 2006 APA, all rights reserved)