OC10.02: Task‐evoked pupillary response as an index of cognitive workload of sonologists undertaking fetal ultrasound


Objectives: Pupillometry (eye pupil diameter measurement) is a well‐established, objective modality correlated with Cognitive Workload (CW). Pupillary dilation is related to increases in CW via increased sympathetic nervous system activity. We wanted to test the hypothesis that CW, as measured by pupillometry, differs during different parts of a routine fetal ultrasound examination. Methods: Using a Tobii Eye Tracker 4C (Tobii, Sweden) fitted just below the screen of a standard ultrasound system (GE Voluson E8), we observed and measured the pupil size of sonologists undertaking routine fetal ultrasound examinations. The eye tracker provides pupil size information for each eye at 90 Hz. Task‐evoked pupillary Response (TEPR), the stimulus‐induced increase in pupil diameter relative to a pre‐stimulus baseline period, was computed. Comparisons were made between “easy” tasks (fetal biometric measurement, maternal uterine artery and 3D mode) and “difficult” tasks (fine‐tuning and assessment of fetal brain, abdomen, femur, heart and spine). This was done by matching sonographer TEPR with events captured in second trimester scan videos that were labelled. Results: There were 14 participating sonographers undertaking 518 second trimester scans. We found a significant difference in TEPR between easy and difficult ultrasound tasks with TEPR values of 20.6% and 21.9%, respectively. Higher TEPR in difficult compared to easy tasks was observed in 13 of the 14 sonographers. In addition, sonologists with less expertise (< 2 years) compared to more expertise (> = 2 years) exhibited higher TEPR (22.2% vs. 21.3%), suggesting a higher CW. Conclusions: Preliminary results suggest that CW, as measured by pupillometry, differs between ultrasound tasks, and between expert and novice sonologists. It is known that high CW can lead to information overload, mental fatigue and errors in decision‐making; the ability to objectively measure CW is a first step towards understanding how this may affect operator performance.

Ultrasound in Obstetrics & Gynecology


author = {Sharma, H. and Drukker, L. and Droste, R. and Chatelain, P. and Papageorghiou, A.T. and Noble, J.A.},
title = {OC10.02: Task-evoked pupillary response as an index of cognitive workload of sonologists undertaking fetal ultrasound},
journal = {Ultrasound in Obstetrics \& Gynecology},
volume = {56},
number = {S1},
pages = {28-28},
doi = {10.1002/uog.22266},
url = {https://obgyn.onlinelibrary.wiley.com/doi/abs/10.1002/uog.22266},
eprint = {https://obgyn.onlinelibrary.wiley.com/doi/pdf/10.1002/uog.22266},
year = {2020}