Figure 1.

Schematic diagram showing the trial structure of the rCET. The task began with illumination of the tray light. A nose-poke response in the food tray extinguished the tray light, commencing a new trial and extending the levers. These levers were permanently designated to initiate either low-effort/LR or high-effort/HR trials. If one of the two levers was pressed, the levers retracted and a 5-s ITI would begin. Following the ITI, one of five stimulus lights would be briefly illuminated: 1.0 s for a LR trial and 0.2 s for a HR trial. A nose-poke response in the illuminated hole (ie, correct response) led to a sugar reward—one pellet for a LR trial and two pellets for a HR trial—and the tray light would illuminate, indicating the opportunity to start the subsequent trial. A number of behaviors led to a 5-s time-out, signaled by house-light illumination: failure to make a lever response (choice omission); failure to withhold responding during the ITI (premature response); nose poke in an unlit hole following the stimulus (incorrect response); failure to make a nose-poke response following the stimulus (response omission).