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Alyssa Hess, Andrew Wismer, Pooja Patel, Kirsten Orlandella, Corey Bohil, Mark Neider; Hide and Seek: Searching for Poorly Defined Camouflaged Targets. Journal of Vision 2013;13(9):692. doi: 10.1167/13.9.692.
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© ARVO (1962-2015); The Authors (2016-present)
Visual search in the real world often involves locating objects that blend in with the surrounding environment. In extreme cases, such as when the search target is intentionally camouflaged, observers might seek small background discontinuities, as opposed to discrete objects, to indicate a target’s presence. In two experiments, we characterized search behavior under these conditions by having participants search for a target discontinuity in natural forest scenes. Importantly, the targets were created directly from a portion of each corresponding background image, creating a camouflaged target. In Experiment 1, participants searched for randomly placed target discontinuities of varying sizes (40, 50, 60, and 70 pixel diameters). In all trials, participants received a 1s preview of the target prior to searching. Reaction times were fastest at the largest target size (~5.4s) and slowest at the smallest size (~7.3s), indicating that search became more difficult as target size decreased. Success rates in target present trials followed a similar pattern (~86% in the largest target size and ~78% in the smallest target size). Interestingly, fixation durations did not differ significantly across target sizes, indicating that information was extracted from the scene at a similar rate regardless of target difficulty. In Experiment 2, we examined whether search for discontinuities was affected by the availability of a visual target template by eliminating the target preview; observers were instructed to simply search for a camouflaged target in the background. The data were broadly consistent with Experiment 1 (reaction times of ~5.6s and ~7.1s in the largest and smallest target sizes, respectively). Overall, our data suggest that the human visual system is proficient at searching for targets that are not discrete objects. Additionally, when searching for camouflaged targets, observers are able to locate environment inconsistencies without a perfect visual representation of the target.
Meeting abstract presented at VSS 2013
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