Pupil Dilation as a Measure of Cognitive Effort During Memory Reconsolidation

Abstract

The pupil is known to dilate in response to numerous cognitive processes, thereby making it a sensitive measure of cognitive effort. While evidence from previous pupilometry studies demonstrates that the pupil dilates during memory encoding and retrieval, the present study aims to determine how pupil dilation reflects the amount of cognitive effort exerted at encoding and retrieval for correctly-recognized and updated information. Ten consenting, volunteer subjects from the University of Arizona completed a classic reconsolidation paradigm that spanned the course of one week, in which subjects were exposed to a total of 68 objects. The paradigm included a directed-forgetting manipulation, in which subjects were instructed to remember or forget certain objects. During encoding and retrieval, pupil diameter was measured using an SMI remote eye tracker. Of these ten subjects, five subjects met procedural protocol and had sufficient data present for analysis. One-way ANOVAs determined there was no significant difference at either encoding or retrieval between correctly-recognized and updated information, regardless of whether subjects were instructed to remember or forget an object at encoding.