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Sandra Utz, Claus Christian Carbon; Does the direction of dimensional changes influence reaction time costs in visual search?. Journal of Vision 2013;13(9):688. doi: 10.1167/13.9.688.
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© ARVO (1962-2015); The Authors (2016-present)
In traditional visual search experiments, participants are required to detect the presence of a predefined target item (e.g., a red bar) surrounded by varying numbers of irrelevant distractor items (e.g., green bars). Müller and his colleagues (e.g., Müller, Heller, Ziegler, 1995) observed that reaction times (RTs) are significantly faster when the target was defined within the same dimension in consecutive trials (e.g., red -> red; red ->green) compared to when the dimension of the target changed (e.g., red -> left-tilted). Aim of this study was to systematically investigate if the direction of dimensional changes plays a significant role in RT costs to develop a model of RT prediction under such conditions, which also comprises specific RT costs for dimension changes from color to orientation vs. orientation to color. 11 participants had to search for targets defined by either their color (red or blue) or orientation (right- or left-tilted) and the target dimension either stayed the same or changed on consecutive trials. Results showed the typical results pattern of remarkably higher RTs in dimensional change conditions (M = 470.4ms; SD = 49.6ms) in comparison to within dimensional conditions (M = 417.5ms; SD = 37.0ms; t(10) = -7.87; p <.001, d = 2.37). The closer look to the dimensional change trials revealed significantly higher RT costs if the change was from a target defined in the color dimension to a target defined in the orientation dimension in comparison to a change from orientation to color (t(10) = 2.32; p = .04, d = .71). A possibly stronger pre-activation of the color dimension and differences in the time necessary for shifting the attentional focus from color to orientation or from orientation to color could explain our results. Further experiments will have to extend the used paradigm by integrating further dimensions such as size, to reveal further asymmetries in RT costs.
Meeting abstract presented at VSS 2013
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