Forced trials can influence the relationship between actual consumption and indifference points, especially in the case of low indifference points and high trial number. Percentage of forced trials may be a measure of behavioral rigidity or perseveration. Although we did observe some line differences in the proportion of trials that were forced, this was seen only at the 0-second delay, in which low preference mice had more forced trials (see Table 2). To assess whether there were group differences in this dependent variable, we conducted a mixed Experiment (1 or 2) × Sex × Alcohol Preference (High or Low) × Delay (0, 1, 2, 4, or 8) ANOVA on average percentage of forced trials. A main effect of Delay was detected F(4,240) = 20.52, p < 0.001, but Sex (p = 0.07), Experiment (p = 0.27), and Alcohol Preference (p = 0.56) were not. An interaction of Delay × Alcohol Preference was also detected F(4,240) = 3.61, p = 0.007, but interactions with Sex (ps > 0.17), and Experiment (ps > 0.27) were not. Therefore, data were collapsed across Sex
