(A) An example of the change in choice behavior (mean ±SEM) in relation to chocolate milk concentration, obtained from a single rat.

(B) The shift of choice function (mean ±SEM) across variable levels of motivational conflict, observed in a single rat performing cost-benefit conflict, benefit-benefit and non-conflict cost-benefit tasks. Error bars indicate SEM.

(C) Performance of benefit-benefit task by 11 individual rats, each with different psychometric functions, but all exhibiting clear dependence of their choice behavior on the concentration of chocolate milk.

(D) Acclimation to aversive light. Cost-benefit conflict task sessions were separated by at least three sessions of benefit-benefit task. Light intensity was increased over successive sessions.

(E) Measurement and reduction of side bias. Side bias to enter either the left or the right end-arm was reduced through two sessions of a bias-breaking training.

(F) Average running times (mean ±SEM) from click to the first lick were comparable across the different tasks and choices.

(G) Current choice is influenced by previous choice. For each task type, conditional probability of choosing pure chocolate milk (or, in the cost-cost task, dim light) in current trial (t) given choice of pure chocolate milk in previous trial (t−1), two trials before (t−2), three trials before (t−3), four trials before (t−4), or five trials before (t−5) was calculated. Change in probability was calculated by subtracting the unconditional probability of choosing pure chocolate milk (or dim light) and expressing as a percentage. Error bars indicate SEM. ∗p < 0.001 (2-tailed z-test comparing the conditional probability given choice in previous trial (t−1) with that given choice in two to five trials before (i.e., t−2, t−3, t−4 and t−5)).