Fig 7.

For the three amount ratios: length (presses per visit) of the first visit following a series of continuing food deliveries or following a series of continuing food deliveries ending with a discontinuation as a function of number of food deliveries. Group data are shown for visits following each of the nine food deliveries. Filled symbols represent visits following continuations, and unfilled symbols visits following a discontinuation. L stands for the left lever, R for the right lever, Con for continuation, and Dis for discontinuation.