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Optical Engineering

Human search with a limited field of view: effects of scan speed, aperture size, and target conspicuity
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Paper Abstract

We investigate how human visual search performance with field of view (FOV) restrictions depends on scan speed, zoom factor, target location, and conspicuity. First, observers search a FOV that moves at a constant speed along a predefined path over a visual search scene (the field of regard, or FOR), and we measure the effects of scan speed, zoom factor, FOV size, target location, and conspicuity on search performance (detection time and probability). Then observers search either visual or thermal scenes by freely moving a joystick-controlled FOV over the FOR, while freely selecting the zoom factor in some conditions, and we measure the effects of the scan path characteristics and the use of different strategies on search performance. Search performance depends on the effective FOV size (the area where targets are expected to occur), but is largely independent of the display area. Both for visual and thermal imagery, various search performance measures correlate with target conspicuity. The results of both experiments suggest that observers can optimize their performance by adjusting their scanning behavior both to their visual limitations and to the expected target conspicuity. We present the outlines of a simple search model based on these current findings.

Paper Details

Date Published: 12 February 2013
PDF: 14 pages
Opt. Eng. 52(4) 041106 doi: 10.1117/1.OE.52.4.041106
Published in: Optical Engineering Volume 52, Issue 4
Show Author Affiliations
Maarten A. Hogervorst, TNO Defence, Security and Safety (Netherlands)
Alexander Toet, TNO Defence, Security and Safety (Netherlands)
Piet Bijl, TNO Defence, Security and Safety (Netherlands)

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