Using a lower-limb prosthetic device can lead to increased cognitive demands, and since measuring cognitive load objectively can be challenging, most studies use questionnaires that are easy to apply but can suffer from subjective bias. As a result, researchers conducted a study to investigate whether a mobile eye tracker can be used to objectively measure cognitive load by monitoring gaze behavior during a set of motor tasks.
Five people with lower-limb amputations and eight able-bodied people participated in the 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. Participants were asked to focus their gaze on a visual target for as long as possible while performing the tasks. Target fixation times and increase in pupil diameters were determined and correlated to subjective ratings of cognitive load.
Overall, the researchers found that 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.
The study concluded that a mobile eye tracker may be used to estimate cognitive load in prosthesis users during locomotor tasks. While this paves the way to establish a new approach to assessing cognitive load, future studies should corroborate the results by comparing them to other objective measures as well as in translating the proposed approach outside of a laboratory, the authors wrote.
The open-access study “Using mobile eye tracking to measure cognitive load through gaze behavior during walking in lower limb prosthesis users: A preliminary assessment” was published in the journal ScienceDirect.
