Affect-congruent attention modulates generalized reward expectations

Positive and negative affective states are respectively associated with optimistic and pessimistic expectations regarding future reward. One mechanism that might underlie these affect-related expectation biases is attention to positive- versus negative-valence features (e.g., attending to the positive reviews of a restaurant versus its expensive price). Here we tested the effects of experimentally induced positive and negative affect on feature-based attention in 120 participants completing a compound-generalization task with eye-tracking. We found that participants' reward expectations for novel compound stimuli were modulated in an affect-congruent way: positive affect induction increased reward expectations for compounds, whereas negative affect induction decreased reward expectations. Computational modelling and eye-tracking analyses each revealed that these effects were driven by affect-congruent changes in participants' allocation of attention to high- versus low-value features of compounds. These results provide mechanistic insight into a process by which affect produces biases in generalized reward expectations. Positive affective states are associated with optimistic future expectations, and negative affect is associated with pessimistic future expectations. However, the cognitive mechanisms that underpin these affect-congruent shifts in reward expectations remain unclear. To investigate this question, we focused on feature-based attention, the process by which attention to the different features of a stimulus influences the estimated value of that stimulus. We formulated a new compound generalisation paradigm to investigate how individuals allocate attention to high- versus low-value components of novel compound stimuli, and adopted a multi-method approach combining eye-tracking and computational modelling of behavioural data. Crucially, our central experimental manipulation was a controlled between-subjects laboratory affect induction during the generalisation phase of the task. The results of this study clearly identify feature-based attention as a cognitive mechanism by which affective states influence reward expectations: in positive affective states, participants attended more strongly to high-value cues within compound stimuli (and therefore formed more optimistic reward expectations for the compounds). In negative affective states, the converse was true: participants attended more strongly to low-value cues within compound stimuli, and therefore formed more pessimistic reward expectations for the compounds. These behavioural and modelling findings were separately corroborated by evidence from eye-tracking data.