Spontaneous Eye-Blink Rate as an Index of Reward Responsivity

Extensive research supports the role of striatal dopamine in pursuing and responding to reward, and that eye-blink rate is a valid indicator of striatal dopamine. This study tested whether phasic changes in blink rate could provide an index of reward pursuit. This hypothesis was tested in people with bipolar I disorder (BD; a population with aberrations in reward responsivity) and in those without BD. A total of 31 adults with BD and 28 control participants completed a laboratory task involving effort toward monetary reward. Blink rate was recorded using eye tracking at baseline, reward anticipation, and postreward. Those in the BD group completed self-report measures relating to reward and ambition. Results showed that across all participants, blink rates increased from reward anticipation to postreward. In the BD group, reward-relevant measures were strongly correlated with variation in blink rate. These findings provide validation for phasic changes in blink rate as an index of reward response.