The Probabilistic Discounting Task222 also requires rats to choose between two levers. The small/certain lever guarantees the delivery of one food reward pellet, while the large/risky lever may deliver four pellets with a given probability. Typically, the probability of reward delivery for the large/risky lever descends across four trial blocks from certain (100%) to unlikely (12.5%), producing a shift in optimal choice across the session and allowing for a parametric assessment of risky decision-making.
