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

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.