Figure 1.

Schematic diagram showing the trial structure of the rCET. Trials began when the food-tray light illuminated. A nosepoke response in the food-tray extinguished the light and extended the levers. Each lever was permanently designated to initiate either low-effort/low-reward (LR) or high-effort/high-reward (HR) trials. When animals pressed one of the levers, both levers retracted and a 5-s ITI began. Following the ITI, 1 of the 5 stimulus lights briefly illuminated, 1.0 s for an LR trial and 0.2 s for an HR trial. If animals nosepoked in the previously illuminated aperture within 5 s (a correct response), they were rewarded 1 sugar pellet for an LR and 2 sugar pellets for an HR trial. A number of behaviors led to a 5-s timeout, signaled by house-light illumination: failure to make a lever response (choice omission), failure to withhold responding during the ITI (premature response), nosepoke in an unlit hole following the stimulus (incorrect response), and failure to make a nosepoke response following the stimulus (response omission). Figure reprinted with permission from Cocker, Hosking et al. (2012).