Optimal phase for central and peripheral visual detection differs within the stride-cycle

It is important to investigate perception in the context of natural behaviour in order to reach a holistic account of how sensory processes are coordinated with actions. In particular, the effect of walking upon perceptual and cognitive functions has recently been investigated in the context of how common voluntary actions may dynamically impact upon visual detection. This work has revealed that walking can enhance peripheral visual processing, and that during walking, performance on a visual detection task alternates through good and bad periods within the phases of the stride-cycle. Here, we extend this work by examining whether modulations in visual detection performance are uniform across the visual field while walking. Participants monitored parafoveal (∼3.7 d.v.a) and peripheral (∼7 d.v.a) locations left/right of fixation for the onset of targets while walking at a natural pace in wireless virtual reality. For targets at all locations, hit rate, reaction times and response likelihood modulated within each individual’s stride-cycle, at primarily 2 or 4 cycles per stride. Importantly, modulations in hit rate and reaction time shared the same frequency at both locations but had opposing modulation features between performance measures; increasing in amplitude and phase-lagged for hit rate and decreased in amplitude and leading for response times when analysing for peripheral targets revealing an interaction between visual field locations and modulations in performance. Together, these results demonstrate that modulations in visual performance entrained by the stride-cycle occur with unique amplitudes and phases across the visual field.