The Use of Task-Evoked Pupillary Response as an Objective Measure of Cognitive Load in Novices and Trained Physicians

A New Tool for the Assessment of Expertise

Abstract

Purpose 

Task-evoked pupillary responses (TEPRs), or changes in pupil size, correlate with changes in cognitive processing demands. The magnitude of this change is a reliable marker of cognitive load. The authors used TEPRs to compare cognitive load between novices and trained physicians as they answered clinical knowledge questions.

Method 

In 2013, 20 emergency medicine trainees were recruited and divided into novice (n = 10) and trained physician (n = 10) groups. The authors used mobile eye-tracking glasses to assess changes in pupil diameter as participants answered arithmetic questions, general knowledge questions, and clinical emergency medicine questions in a controlled setting. Questions were categorized by difficulty a priori.

Results 

Difficult arithmetic questions caused greater changes in TEPRs than easy ones (P = .024). TEPRs were similar between groups when answering general knowledge questions (P = .383) but were significantly greater for novices than trained physicians when answering clinical questions (P < .001). TEPRs in trained physicians were significantly greater when answering difficult clinical questions than easy ones (P < .001), whereas TEPRs in novices were similar (P = .291). For those clinical questions answered correctly by both groups, TEPRs in novices were greater than those in trained physicians despite all participants answering correctly (P < .001).

Conclusions 

Novices require more mental effort to answer clinical questions than trained physicians, even when both respond correctly. Measuring TEPRs has the potential to be a valuable assessment tool by providing objective measures of expertise and is worthy of further study.