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Lynn Olzak; Do cigars feed into contour integration mechanisms?. Journal of Vision 2015;15(12):994. doi: 10.1167/15.12.994.
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© ARVO (1962-2015); The Authors (2016-present)
Collinear facilitation and contour integration are often attributed to facilitative interactions among low-level, V1 mechanisms with neighboring receptive fields. There are conflicting reports as to whether facilitation is polarity (phase) specific (e.g., . Williams & Hess, 1998 vs Yu & Levi, 1997 ). The latter conflict may be resolved by the existence of more than one type of mechanism. Evidence from experiments measuring orientation bandwidths with full annular surrounds suggests that at least two mechanisms exist, one narrowly tuned and the other broadly tune. In many previous works, we have described complex orientation-signaling mechanisms that sum over a large range of superimposed spatial frequencies but only over a very tight range of orientations (cigars). These mechanisms essentially signal the average orientation present. They have also been shown to be phase-independent. We have previously suggested (Persike, M, Olzak, L. A. and Meinhardt, G. , 2009) that at least one type of contour detector sums over wide ranges of frequencies; thus, contour integration may also be accomplished by cigars. Here, I tested this hypothesis directly by creating complex Gabor packets containing two gratings of very different frequency. Distractor frequencies were iso-oriented around random axes. Target components were both tilted either together (left or right) or in opposition (high-left, low-right and vice versa), relative to the line of the contour at each given location. Observers performed a two-alternative temporal forced-choice between a display containing only distractors and the one containing the contour. If contour integration occurs before the component summing stage, or is not mediated by cigars, performance will be equal in the two conditions. If the output of cigars feeds into the contour integrating mechanism, performance will be better in the opposition condition. Preliminary results suggest that performance with contours containing the components in opposition was superior.
Meeting abstract presented at VSS 2015
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