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Paul G. Lovell; Manipulating contour smoothness: Evidence that the association-field model underlies contour integration in the periphery. Journal of Vision 2005;5(8):469. doi: 10.1167/5.8.469.
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© ARVO (1962-2015); The Authors (2016-present)
Field et al. (1993) proposed that an association field model underlies performance in path-paradigm tasks. The association field integrates dynamically the outputs of filters with different orientation preferences. In the current study, simulations examined whether path-paradigm tasks could be solved by a simple-filter model (SFM) which posits that 2AFC decisions are based upon the maximum length of zero-bounded regions after convolution of stimuli with elongated filters. For the SFM, integration only occurs between the outputs of co-oriented filters. In contrast to Hess and Dakin (1999), initial simulations found that manipulations of Gabor patch phase were an inadequate control for the contribution of the SFM towards path-paradigm performance. In a further simulation, the angular difference between neighbouring elements was held constant, while the global smoothness of contours was varied. The SFM favoured jagged contours and was relatively impaired in the detection of smoother contours. Conversely, human observers favoured smoother contours in the fovea and parafovea (13°). Whilst the SFM could account for the detection of jagged and randomly structured contours, it is inadequate as an account of the detection of smooth contours. Consequently, the association field may provide a parsimonious account of contour integration across the whole visual field.
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