Figure 1.

Schematic representation of the “indifferent” points. Arrows represent nose-poking tested under the PDT protocol: nose-poking in “Small & Sure” (SS) hole resulted in the certain delivery of 1-2 pellets, whereas nose-poking in “Large & Luck-Linked” (LLL) hole resulted in the delivery (or not) of 5-6 pellets, according to the level of probability “p,” which was decreased progressively over days. Thus, if the ratio between large and small reward size was 5-fold (upper part of the scheme), then the indifferent point was at p = 20%. By contrast, if the ratio between large and small reward size was 3-fold (lower part of the scheme), then the indifferent point was at p = 33%. TO: timeout.