Processing bimodal stimuli: integrality/separability of color and orientation

Bimler, David L. and Izmailov, Chingis A. and Paramei, Galina V. (2013) Processing bimodal stimuli: integrality/separability of color and orientation. Frontiers in Psychology, 4 (759). pp. 1-11. ISSN 1664-1078


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We examined how two distinct stimulus features, orientation and color, interact as contributions to global stimulus dissimilarity. Five subjects rated dissimilarity between pairs of bars (N = 30) varying in color (four cardinal hues, plus white) and orientation (six angles at 30° intervals). An exploratory analysis with individual-differences multidimensional scaling (MDS) resulted in a 5D solution, with two dimensions required to accommodate the circular sequence of the angular attribute, and red-green, blue-yellow and achromatic axes for the color attribute. Weights of the orientation subspace relative to the color subspace varied among the subjects, from a 0.32:0.61 ratio to 0.53:0.44, emphasis shifting between color and orientation. In addition to Euclidean metric, we modeled the interaction of color and orientation using Minkowski power metrics across a range of Minkowski exponents p, including the city-block (p = 1), Euclidean (p = 2) and Dominance metric (p → ∞) as special cases. For averaged data, p ~ 1.3 provided the best fit, i.e., intermediate between separable and integral features. For individual subjects, however, the metric exponent varied significantly from p = 0.7 to p = 3.1, indicating a subject-specific rule for combining color and orientation, as in Tversky and Gati's variable-weights model. No relationship was apparent between dimensional weights and individual p exponents. Factors affecting dimensional integrality are discussed, including possible underlying neural mechanisms where the interaction of the low-level vision attributes orientation and color might shift between uncorrelated (p = 1) or correlated (p ≥ 2) forms.

Item Type: Article
Additional Information and Comments: This document is protected by copyright and was first published by Frontiers. All rights reserved. It is reproduced with permission.
Keywords: color, orientation, bimodal stimuli,feature integration, multidimensional scaling, Minkowski metric, integral dimensions, separable dimensions
Faculty / Department: Faculty of Science > Psychology
Depositing User: Galina Paramei
Date Deposited: 18 Apr 2016 08:40
Last Modified: 24 Nov 2017 15:13

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