Figure 9.

Summary of the shifts in the position of the reward-mountain produced by increasing the train duration from 0.25 to 1 s. Increasing the train duration reduced the pulse frequency required to produce a half-maximal reward in all rats (upper panel). In contrast, there was no change, in three cases, in the price at which time allocation for a maximal reward fell halfway between TA_max and TA_min, whereas lengthening the train duration reliably increased the value of this position parameter in the remaining three rats (lower panel). ^*Indicates that the 95% confidence interval does not include zero.