Academic journal article Attention, Perception and Psychophysics

Training and Transfer of Training in the Search for Camouflaged Targets

Academic journal article Attention, Perception and Psychophysics

Training and Transfer of Training in the Search for Camouflaged Targets

Article excerpt

How do observers become proficient at finding camouflaged targets? Does gaining proficiency in locating a target in one camouflage search situation improve performance in novel camouflage situations? We examined these questions by having participants first perform a difficult camouflage search task for three sessions and, in the last session, search for novel camouflaged targets. Near-perfect transfer of training was observed, with participants finding targets in novel camouflage situations almost as quickly as in highly familiar search situations. Previous research has suggested that an "object search" strategy rather than a "background search" strategy is one reason camouflage search can be slow and inaccurate. Eye movement analyses suggest that a more background-focused strategy was not necessary for improved performance and was not responsible for transfer. Another experiment explicitly instructed participants to search background regions, rather than regions containing salient objects, and provided participants feedback regarding the location of their own fixations. Surprisingly, even in this condition, participants did not devote more oculomotor attention to background regions. Theoretical and practical implications are discussed. Supplemental figures for this article can be downloaded from app.psychonomic-journals.org/content/supplemental.

How do humans go about finding a search target when, through design (e.g., a military tank in the desert) or evolution (e.g., a lion in a savanna), it blends in with the background? Visual search has been extensively studied and a great deal has been learned about the guidance of attention during search, including how attention is controlled by bottom-up factors (e.g., Proulx, 2007; Theeuwes, 1992, 2004; Yantis & Jonides, 1984), top-down guidance (e.g., Bacon & Egeth, 1994; Chen & Zelinsky, 2006; Folk, Remington, & Johnston, 1992), and various memory mechanisms (e.g., Boot, McCarley, Kramer, & Peterson, 2004; Brockmole & Henderson, 2006; Chun & Jiang, 1998; Klein & MacInnes, 1999; Neider & Zelinsky, 2006b). Much of what we know about search has been derived from experiments in which target and distractors are easy to segment from the background (see Wolfe, 1994, for a review). However, many real-world search situations contain items that need to be segmented from the background to some degree to allow for efficient visual search. This is especially true in the search for camouflaged targets.

As outlined by Wolfe, Oliva, Horowitz, Butcher, and Bompas (2002), the visual system faces a number of potentially important challenges when target and distractor objects are placed within the context of a visually complex background. These problems include more difficult preattentive segmentation of objects from the background and the creation of "illusory objects" by noise in the background. Additionally, if segmentation is imperfect, attentional selection may be more difficult and time consuming. Imperfect segmentation might also result in noisy object representations being passed along to higher visual stages, such as those responsible for object recognition. Through a series of cleverly designed search experiments, Wolfe and colleagues found that the main cost of background complexity was associated with delayed information accrual affecting later target recognition stages. However, in extreme cases of item-background similarity, item-by-item selection was slowed. Importantly to the present context, background complexity had a negative impact on search performance in all experiments, highlighting the difficulties associated with complex searches in which the search items are not easily distinguished from the background.

To follow up on the findings of Wolfe et al. (2002), Neider and Zelinsky (2006a) directly examined the effect of target-background similarity. Neider and Zelinsky (2006b) had participants search through displays containing many children's toys and asked them to indicate whether or not a specific toy was present. …

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