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. Author manuscript; available in PMC: 2023 Mar 1.
Published in final edited form as: Behav Processes. 2022 Jan 13;196:104584. doi: 10.1016/j.beproc.2022.104584

Fig. 1.

Fig. 1.

Illustration of trial progression. Trials started with a blackout period and proceeded to (A) a forced-LL trial with only the LL associated lever available (e.g., left lever), (B) free-choice trial with both levers available or (C) a forced-SS trial with only the SS lever available (e.g., right lever). (D) After an LL lever press or (E) an SS lever press, the alternative lever retracted, the light above the lever illuminated, and a response initiated FI delay started. If the LL lever was chosen (D), then the next response after the LL delay resulted in (F) the light above the lever extinguishing and two pellets being delivered. If the SS lever was chosen (E), then the next response after the SS delay resulted in (G) the light above the lever extinguishing and one pellet being delivered. After a pellet delivery, (H) an ITI in blackout (both levers retracted) proceeded until the start of a new trial.