Abstract
In this study we examined the relative contribution of two perceptual grouping principles, namely proximity and collinearity, to the perception of a global orientation. For this purpose, we used Gabor lattices, two-dimensional patterns of regularly placed Gabor patches aligned in a sheared grid with two different principal directions (its axes). The distance between Gabor elements along each axis of the grid and the local orientation of the Gabor elements with respect to the grid were manipulated, in order to examine the effects of proximity and collinearity, respectively. We also examined whether the presentation time of the Gabor lattice had an influence on which grouping principle dominated the participants' percept. We found that proximity and collinearity interacted with each other to determine which axis was seen to be the global orientation. We found a relative preference for grouping based on collinearity for Gabor lattices in the short duration condition, whereas there was a relative preference for grouping based on proximity for Gabor lattices in the long duration condition. We will explain the pattern of results in terms of first- and second-order filters tuned to different orientations and scales.