Visual demands of walking

The cognitive demands of natural behavior in ecologically valid environments are difficult to grasp with neurocognitive methods. While mobile amplifiers may allow EEG to be robustly measured outside controlled laboratory settings, it remains a challenge to extract meaningful event-related EEG activity, which is commonly used to index cognitive demands. The reason for this lies in the fact that the natural world, unlike a laboratory experiment, does not provide discrete and repetitive events to segment continuous EEG activity into interpretable epochs. This study investigates the viability of eye-blink-related activity as a method to enable investigating event-related EEG activity. Here, we report on blink-related EEG measures of participants that either stood, walked on a natural grass surface, or completed an obstacle course while performing auditory tasks. Blink-related EEG activity discriminated for different levels of mental load during walking. Both, behavioral parameters (e.g., blink duration or head motion) and blink-related EEG activity varied with walking conditions. While the occipital N1 was sensitive to selective adjustment of visual demands, later and more cognitively driven components (N2, P3) showed changes indicative of an overall narrowing of attention. This was also evident in blink-event related Alpha, and Theta power with functionally plausible patterns of increases and decreases in line with the demands of the walking task. Thus, eye blink-related EEG activity turned out to be a valuable tool for investigating visual demands during natural behavior.