Poster E133, Monday, March 27, 2:30 – 4:30 pm, Pacific Concourse
Pupillometry and Frontal Theta Reflect Decision Threshold Increases During Evidence Accumulation
Daniel Barto1, James F. Cavanagh1; 1University of New Mexico
The process of making a decision during uncertainty requires cognitive control resources that are not apparent during easy decisions. For instance, a decision during uncertainty requires an accumulation of sensory evidence culminating in a discrete choice determined by a decision threshold. While much is known about mechanisms that resolve uncertainty in sensory accumulation, much less is known about the resolution of uncertainty by decision threshold adjustment. Pupil dilation, previously implicated in a variety of cognitive and affective states, has been shown to index decision threshold adjustment during selection of valued options. In this study, pupil dilation was collected while subjects performed a sensory discrimination task. Subjects were required to indicate the coherent directional movement of a group of dots against a background of random dot movement. Conflict was operationalized by varying the angle of dot movement, creating high (e.g. 11:55 vs. 12:05 on a clock) and low (e.g. 10:00 vs. 2:00) conflict conditions. Hierarchical Drift Diffusion Modelling indicated that the decision threshold (and not the evidence accumulation rate) was selectively altered by this manipulation. In conditions of high conflict, there was a significant increase in pupil dilation change from baseline as compared to conditions of low conflict. Additionally, time frequency decomposition of EEG waveforms revealed frontal theta and delta activity in conditions of high conflict compared to conditions of low conflict. These results indicate that pupil dilation and EEG can predict decision threshold adjustment in the presence of noisy sensory evidence.
Topic Area: THINKING: Decision making