Effects of different acquisition procedures on response variability

In three experiments with college students, the effects of different acquis ition procedures on response variability were studied. The computer keypres sing task involved learning a sequence with a minimum number of presses on a subset of the keyboard. Procedures differed in type of training and in th e number, size, and sequence of training steps. Experiment 1 showed that in structions and shaping in three steps generated less variability in the num ber of responses made in each keypress sequence than shaping in six steps. Subsequent experiments showed that a large increase in the response require ment early in shaping increased variability. Postacquisition variability re mained unchanged in the number of responses per sequence-the aspect of resp onding on which reinforcement was contingent-but declined in location and t iming of keypressing. The results are discussed in tenus of the implicit re inforcement of variability and how the acquisition of qualitatively differe nt response strategies could influence variability.