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Matthew Rizzo, Johnson Moon, Mark Wilkinson, Kirk Bateman, Julie Jermeland, Tom Schnell; Ocular search of simulated roadway displays in drivers with constricted visual fields. Journal of Vision 2002;2(7):162. doi: 10.1167/2.7.162.
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Purpose: Ocular search depends on vision and attention; so does the useful field of view (UFOV).This pilot study aimed to test how UFOV reduction affects visually guided eye movements.
Methods: 34 licensed drivers participated in driving scenarios enacted in the Simulator for Interdisciplinary Research in Ergonomics and Neuroscience (SIREN), which has a 150#730; forward FOV. Driver eye movements were measured with an infrared system (ISCAN Model ETL 500) mounted in SIREN. Eye scanning measures (including frequency and duration of fixations and total scan path length) were recorded for a 166s span across the same geographic location in the drive. 13 drivers had reduced UFOV scores due to cognitive aging (5), retinitis pigmentosa (5), and other causes (3); 21 drivers had normal visual fields. UFOV measurements used the Vision Attention Analyzer 3000(Vision Resources, Chicago). We hypothesized that reduced UFOV would lead to greater fixation duration and lesser total number of fixations, distance between successive fixations, and total scan path length.
Results: Eye movement measures were extracted from the electronic data stream in all drivers. Drivers with visual field constriction did not differ from controls with respect to any of the eye scanning measures (P>0.05). Correlations between eye movement measures and the UFOV scores were low (Spearman r's from −0.178 to 0.217; P>0.34 all cases).
Conclusions: The UFOV task depends on speed of processing, divided attention and selective attention and taps abilities that contribute to the driving task at attentive and pre-attentive levels. However, reduced UFOV scores did not affect ocular search as predicted. Drivers with severely impaired UFOV did not change their visual scanning strategy to compensate for this loss, raising potential safety concerns. These drivers show decreased ability to extract information from a cluttered scene, even if they visit all scene locations, suggestive of “looking but not seeing.”
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