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Attila Farkas, Alen Hajnal; Fractal Dynamics of Visual Search as a Function of the Gestalt Law of Proximity. Journal of Vision 2013;13(9):1210. doi: 10.1167/13.9.1210.
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© ARVO (1962-2015); The Authors (2016-present)
The current project examined the effect of the Gestalt Law of proximity on visual cognition. Proximity can be directly quantified as the distance between adjacent objects in a visual array. Recent studies on eye movements have revealed the interactive nature of self organizing dynamic processes in visual cognition (Stephen & Mirman, 2010). Aks, Zelinsky, and Sprott (2002) found that visual search patterns are not randomly distributed, and that a simple form of temporal memory exists across the sequence of eye movements. We quantified the law of proximity using long-term autocorrelations of the time series of successive gaze locations, fixations, and response times. Eye movements were recorded during a typical visual search task (find a T shape among distracters). The stimuli were distributed either as equidistant elements, as rows with small horizontal inter-element distances, or as columns with smaller vertical inter-element distances. Long reaction times and large number of fixations were associated with increased task difficulty. More fixations were used for vertically organized stimuli in nonhomogenous trials, as compared to horizontal organization. Localizing targets was easier for horizontally organized stimuli, as indicated by quicker reaction times and fewer fixations. During the transition from homogenous to horizontally organized patterns participants made more fixations, and invested more time localizing targets than during the transition toward vertical organization (columns). This was also reflected in a more dynamic, nonrandom search process that alternated between short and long reaction times during the transition toward horizontal row structure, as revealed by antipersistent fractal structure of reaction time fluctuations with an average Hurst exponent less than 0.5. We concluded that the preference toward, and facilitation of horizontal organization patterns is consistent with previous findings that showed greater ease and frequency of vertical compared to horizontal eye movements in visual search tasks (Aks et al, 2002; Oyama, 1961).
Meeting abstract presented at VSS 2013
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