Abstract
Abstract: The ubiquity of apparently random behavior in visual search (e.g., Horowitz & Wolfe, 1998) has led to our proposal that the human oculomotor system has subtle deterministic properties that underlie its complex behavior (Aks, Zelinsky & Sprott, in press). We report the results of one subject's performance in a challenging search task in which 10,215 fixations were accumulated. A number of statistical and spectral tests revealed both fractal and 1/f structure. First, scaling properties emerged in differences across eye positions and their relative dispersion (SD/M)-both decreasing over time. Fractal microstructure also emerged in an Iterated Function Systems test and delay plot. Power spectra obtained from the Fourier analysis of fixations produced brown (1/f^2) noise and the spectra of differences across eye positions showed 1/f (pink) noise. Thus, while the sequence of absolute eye positions resembles a random walk, the differences in fixations reflect a longer-term dynamic of 1/f pink noise. These results suggest that memory across eye-movements may serve to facilitate our ability to select out useful information from the environment. The 1/f patterns in relative eye positions together with models of complex systems (e.g., Bak, Tang & Wiesenfeld, 1987) suggest that our oculomotor system may produce a complex and self-organizing search pattern providing maximum coverage with minimal effort.
AksD. J.ZelinskyG.SprottJ. C.(2002). Memory Across Eye-Movements: 1/f Dynamic in Visual Search. Nonlinear dynamics, Psychology and Life Sciences, 6 (1).
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