Using mobile eye tracking to measure cognitive load through gaze behavior during walking in lower limb prosthesis users: A preliminary assessment

Sabina Manz; Thomas Schmalz; Michael Ernst; Thomas Maximilian Köhler; Jose Gonzalez-Vargas; Strahinja Dosen

doi:10.1016/j.clinbiomech.2024.106250

Using mobile eye tracking to measure cognitive load through gaze behavior during walking in lower limb prosthesis users: A preliminary assessment

Clin Biomech (Bristol, Avon). 2024 Apr 12:115:106250. doi: 10.1016/j.clinbiomech.2024.106250. Online ahead of print.

Authors

Sabina Manz¹, Thomas Schmalz², Michael Ernst², Thomas Maximilian Köhler², Jose Gonzalez-Vargas³, Strahinja Dosen⁴

Affiliations

¹ Department of Health Science and Technology, Aalborg University, Aalborg, Denmark; Ottobock SE & Co. KGaA, Global Research, Duderstadt, Germany.
² Ottobock SE & Co. KGaA, Clinical Research & Services, Research Biomechanics, Göttingen, Germany.
³ Ottobock SE & Co. KGaA, Global Research, Duderstadt, Germany.
⁴ Department of Health Science and Technology, Aalborg University, Aalborg, Denmark. Electronic address: sdosen@hst.aau.dk.

PMID: 38657356
DOI: 10.1016/j.clinbiomech.2024.106250

Abstract

Background: Lower limb amputation does not affect only physical and psychological functioning but the use of a prosthetic device can also lead to increased cognitive demands. Measuring cognitive load objectively is challenging, and therefore, most studies use questionnaires that are easy to apply but can suffer from subjective bias. Motivated by this, the present study investigated whether a mobile eye tracker can be used to objectively measure cognitive load by monitoring gaze behavior during a set of motor tasks.

Methods: Five prosthetic users and eight able-bodied controls participated in this study. Eye tracking data and kinematics were recorded during a set of motor tasks (level ground walking, walking on uneven terrain, obstacle avoidance, stairs up and ramp down, as well as ramp up and stairs down) while the participants were asked to focus their gaze on a visual target for as long as possible. Target fixation times and increase in pupil diameters were determined and correlated to subjective ratings of cognitive load.

Findings: Overall, target fixation time and pupil diameter showed strong negative and positive correlations, respectively, to the subjective rating of cognitive load in the able-bodied controls (-0.75 and 0.80, respectively). However, the individual correlation strength, and in some cases, even the sign, was different across participants. A similar trend could be observed in prosthetic users.

Interpretation: The results of this study showed that a mobile eye tracker may be used to estimate cognitive load in prosthesis users during locomotor tasks. This paves the way to establish a new approach to assessing cognitive load, which is objective and yet practical and simple to administer. Nevertheless, future studies should corroborate these results by comparing them to other objective measures as well as focus on translating the proposed approach outside of a laboratory.

Keywords: Cognitive load; Eye tracking; Lower limb amputation; Pupil diameter; Target fixation time.