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Grayden Solman, Daniel Smilek; Zooming in and out: Global-local shifts in large scale visual search. Journal of Vision 2012;12(9):731. doi: https://doi.org/10.1167/12.9.731.
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© ARVO (1962-2015); The Authors (2016-present)
Search outside of the laboratory often involves movement within the search environment, dynamically engaging the visual array in order to bring a particular region of space into view, or to change the size of an object’s image in the visual field. In three experiments, we introduce a novel search task in which participants search through displays containing up to 128 items arranged on a search ‘canvas’ – potentially much larger than the physical display depending on zoom. To search, participants used the mouse scroll wheel to zoom in and out, and a click-drag interface to move the canvas within the display frame at that zoom level. Detection of the unique target item was signaled by clicking on the location of the item. Throughout each trial we recorded the magnification level and position of the frame in order to reconstruct search characteristics in terms of shifts in magnification and shifts in position. Here, we focus in particular on the number of transitions between global (zoomed out) and local (zoomed in) views during search. In Experiment 1, we manipulated item density. In Experiment 2, we replaced the typical homogeneous distribution of items with discrete clumps of items, and manipulated the number of clumps, density of items within clumps, and density of clumps within the entire search field. In Experiment 3, we varied the relative sizes of the items within individual displays, manipulating the number of distinct sizes (1, 2, or 4), and at which level of size the target was presented. We report increased numbers of global-local transitions with decreasing density, with increasing numbers of clumps, and as the number of distinct item sizes in each display increases. These results are consistent with global-local transitions during search being driven by the need to acquire different information from different levels of zoom.
Meeting abstract presented at VSS 2012
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