Figure 2: Average response rates of pigeons in two components of a multiple VI VI schedule with 60 reinforcers per hour in one component and 20 per hour in the other, showing the effects of the rate of free food presentations during timeout periods between components. The upper panel shows response rates during the last hour of baseline training and the first hour of disruption by timeout food across four conditions. In the lower panel, these data are reexpressed as log ratios of response rates with free food to response rates in the immediately preceding baseline and plotted as functions of timeout food rate. Adapted from Nevin (1974, Experiment 1).