Engagement and cognitive load of upper-year medical trainees during mixed reality-enhanced dissection

Mixed reality (MR) offers a way to visualize and manipulate complex digital objects in three dimensions, which is particularly beneficial for human anatomy. However, implementing MR effectively requires a deep understanding of its effects on cognitive processes. The purpose of this study was to evaluate cognitive markers of students' engagement and cognitive load while they used MR technology to overlay donor-specific diagnostic imaging onto the corresponding body donors in a fourth-year medical elective course. During two separate dissection sessions, each participant (n = 12) used the imaging on (1) a head-mounted Microsoft HoloLens and (2) an Apple iPad to examine the underlying anatomy of their body donor before beginning dissection. During each activity, participants wore portable five-lead electroencephalographic (EEG) devices to collect cognitive processing data. Separate indexes were calculated from those data to quantify engagement (engagement index; EI) and cognitive load (theta-alpha ratio; TAR), which were compared between HoloLens and iPad usage. Mean EI calculated from EEG data collected while using the HoloLens (0.499 ± 0.038) was significantly higher than the mean EI while using an iPad (0.297 ± 0.037; p = 0.002). Conversely, the mean TAR calculated from EEG data collected while using the HoloLens (1.508 ± 0.047) was significantly lower than that collected while using an iPad (1.813 ± 0.071; p = 0.012). These results indicate that the use of HoloLens to superimpose radiographic images onto a human body donor during dissection is significantly more engaging and requires less cognitive effort than the same task on an iPad.