Fig 4. Forward differences in response rates on the rich schedule (squares and solid lines) and on the lean schedule (triangles and dotted lines) as a function of component number for each rat.

The late-session curves of Figure 3 were smoothed before computing rate differences, the first two and last two data points of each data series being excluded (see text for an explanation of the smoothing method). In each panel, and as in Figure 3, the zero of the horizontal axis coincides with the earlier of the two response peaks. Notice the different vertical scales for each rat.