The effects of introtacts on hypothesis testing in kindergarten and first-grade children.

Kindergarten and first-grade children were trained against their initial dimensional preference in a 2-dimensional simultaneous discrimination learning task. One third of the children received pretraining in using a sequential hypothesis-testing strategy, one third received pretraining in which they experienced solutions to tasks of the same type, and one third received no pretraining. Half of the children received introtact probes prior to each trial in the criterion task. Introtact probes had no effect on the performance of kindergarten children but facilitated the performance of first-grade children who received pretraining. Performance was generally better in the pretraining conditions than in the control condition and was generally better for first graders than for kindergarten children. Indices of the use of the sequential hypothesis-testing strategy were obtained from the responses to introtact probes. 75% of the first graders who received pretraining in hypothesis testing showed high proficiency in using the strategy, whereas only 38% of the kindergarten children did so. A strong tendency to become fixated on the irrelevant dimension was evident at both age levels.