The average choice behavior across sessions ( Figure 2B) was computed by subtracting the log indifference point from the log of the offer ratios for each session. The relative offer ratios were then binned into the intervals shown in Figure 2B. A probit regression was then performed on the aligned and averaged choice **data** for visual comparison. To test the effect of inactivation of medial OFC on the indifference point and the inverse slope, a fully balanced design was implemented with fibertype (blocked/patent) and laser (on/off) as the factors in a two-way ANOVA. The number of repetitions of the design (n = 50) was used to match our previous paper of inactivation of lateral OFC . As noted above, some sessions (n = 4) were dropped due to IPs exceeding a 6:1 ratio. Repetitions of the design were also used as a blocking factor due to the wide range of subjective indifference points for each rat and pellet-pair. This block factor had a main effect of p<0.01 in all cases. This test was repeated on a subset of the sessions in which rats showed a significant preference for one of the pellets. In order to determine the threshold for indifference points sufficiently far from the 1:1, trials from sessions with the blocked fiber were randomly split into two separate groups. A bootstrap on the difference between the log of the indifference point for each group was used to determine a significance threshold (a = 0.05) for indifference point shifts.