Replacement of goal-tracking by sign-tracking under reward uncertainty, and impairment by dopamine antagonism in the rat

Hypothesis: uncertainty influences Pavlovian reward prediction by arousing incentive motivation for reward (or ‘wanting’), expressed as sign-tracking (ST) or goal-tracking (GT) responses in an autoshaping paradigm. Here we investigated the effect of 3 types of uncertainty: 1) reward probability (UCS occurred after CS+ under 50% probability), 2) uncertainty about reward magnitude (UCS was 1, 2, or 3 sucrose pellets), and 3) uncertainty resulting from a combination of both conditions. We also tested the effects of reversal learning (shift in reward probability from 100 to 50%) and systemic dopamine blockade under uncertainty (flupenthixol, i.p.) on acquisition of autoshaping.