THE STRATEGY-SPECIFIC NATURE OF IMPROVEMENT - THE POWER-LAW APPLIES BY STRATEGY WITHIN TASK

If strategy shifts speed up performance, learning curves should show d iscontinuities where such shifts occur Relatively smooth curves appear consistently in the literature, however To explore this incongruity, we examined learning when multiple strategies were used. We plotted po wer law learning curves for aggregated data from four mental arithmeti c experiments and then plotted similar curves separately for each part icipant and strategy. We then evaluated thefts achieved by each group of curves. In all four experiments, plotting separately by strategy pr oduced significantly better fits to individual participants' data than did plotting a single power function. We conclude that improvement of solution time is better explained by practice on a strategy than by p ractice on a task, and that careful assessment of trial-by-trial chang es in strategy can improve understanding of the effects of practice on learning.