Figure 3.

The relationship between the pretest threshold and the amount of improvement. Pretest thresholds (abscissa) and pretest minus post-test thresholds (ordinate) for individual learners (filled squares), non-learners (open circles), and controls (open triangles) are shown for each of the seven tested conditions (panels). On each condition, the number of the regression lines fitted is based upon the results of between-group comparisons (see text): one line (all listeners, dashed lines), two lines (learners, solid lines; controls and non-learners, dashed lines), and three lines (learners, solid lines; non-learners, dashed lines; controls, short-dashed lines). The dotted lines represent zero improvement.