Don't watch your step: gaze behavior adapts with practice of a target stepping task.

Vision plays a vital role in locomotor learning, providing feedback information to correct movement errors, and feedforward information to inform learned movement plans. Gaze behavior, or the distribution of fixation locations, can quantify how visual information is used during the motor learning process. How gaze behavior adapts during motor learning and in response to changing motor performance is poorly understood. This study examines if and how an individual's gaze behavior adapts during a sequence learning, target stepping task. We monitored the gaze behavior of 12 healthy young adults while they walked on a treadmill and attempted to precisely step on moving targets that were separated by variable distances (80%, 100%, and 120% of preferred step length). Participants completed a total of 11 trial blocks of 102 steps each. We hypothesized that both mean fixation distance would increase (participants would look farther ahead), and step error would decrease with experience. Following practice, participants significantly increased their fixation distance ( < 0.001) by 0.27 ± 0.18 steps and decreased their step error ( < 0.001) by 4.0 ± 1.7 cm, supporting our hypothesis. Our results suggest that early in the learning process, participants gaze behavior emphasized gathering visual information necessary for feedback motor control. As motor performance improved with experience, participants shifted their gaze fixation farther ahead placing greater emphasis on the visual information used for feedforward motor control. These findings provide important information about how gaze behavior changes in parallel with improvements in walking performance. People consistently vary how they use visual information to inform walking. However, what drives this variation and how sampled visual information changes with locomotor learning is not well understood. Here, we find that gaze fixation locations moved farther ahead while step error decreases as participants practice a target stepping task. The results suggest that participants increasingly used a feedforward locomotor control strategy with practice.