Abstract
The ability to adaptively shift between exploration and exploitation control states is a critical component in the optimization of behavioral performance (Cohen, McClure, & Yu, 2007). Converging evidence from primate electrophysiology and computational neural modeling have indicated that changes in exploratory versus exploitive control state may be mediated by the broad noradrenergic projections emanating from the Locus Coeruleus (LC). The synthesis of these findings has resulted in the development of a theory of LC function (adaptive gain theory, Aston-Jones & Cohen, 2005) in which the LC modulates the gain of cortical units to facilitate either exploration or exploitation in response to current assessments of task utility. The pupillary response is strongly correlated with LC activity in primates (Rajkowski et al.,1993) and can be used as a non-invasive proxy to assess fluctuations in LC activity in humans. Ten participants completed fourteen visual analogies from Raven's Advanced Progressive Matrices Test while pupillary response and verbal protocols were recorded. Pupil diameter was measured continuously using an Eyelink 1000 eye tracker at a sampling rate of 250 Hz. Think aloud verbal protocols were used to identify periods of exploration within each trial. The results showed that during periods of high exploration there was a larger pupillary response compared to other periods. These findings are consistent with the LC's role in modulating exploration-exploitation tradeoffs as postulated by adaptive gain theory. Moreover, our results suggest that the human pupillary response may be able to serve as a useful tool for identifying shifts in control state during online processing.
Meeting abstract presented at VSS 2013