Abstract
Useful Field of View (UFOV) is defined as the visual area from which information can be extracted at a brief glance. UFOV has been shown to correlate with vehicular crash risk, obstacle collisions, and propensity for falls. UFOV is normally tested while seated. This research examined the effects of both a change in posture and locomotion on UFOV performance. Ten participants were tested on a modified UFOV selective attention task while seated, standing, and stepping in place. The test consisted of a 67 ms simultaneous presentation of a letter (E, F, H or L) in the center of the screen and a black dot located at 57 degrees of eccentricity in one of eight possible locations encircling the central target (23 black rings were presented as distracters). This was followed by a 1 s masking field. The participants were then prompted for the letter identity and dot location. Participants were instructed to maintain central fixation throughout. Across all conditions participants had no difference in central target accuracy. However, a main effect of condition on peripheral target accuracy was found (p = .037). The mean accuracy reduced from 80.5% (standing) to 74% (seated) to 56.3% (stepping). Our findings show that a dynamic posture can affect UFOV selective attention performance in the periphery. Central processing was stable across all conditions, indicating that the decrease in peripheral accuracy while stepping was not due to inappropriate eye movements away from fixation. It does however indicate that whilst stepping, the size of the useful field of view significantly decreases, which affects peripheral performance. This finding has important implications for how the results of a UFOV test are used to evaluate the general size of the UFOV during varying activities, as the traditional seated test procedure may overestimate the size of the UFOV during locomotion.