Age and gender effects on perceptual color scaling using triadic comparisons.

We examined age and gender as possible determinants of individual differences in triadic judgments of color dissimilarity. Seventy triads were constructed from 21 equal-lightness Munsell samples, at equal hue steps, forming a rough ellipse in the CIE-LAB plane, and presented to 51 males and 53 females (half young, half elderly adults) who indicated each triad's "odd one out." Principal component analysis followed by multidimensional scaling (MDS) revealed group differences in judgment reliability, with better performance for female and younger groups.

Perceptual color spacing derived from maximum likelihood multidimensional scaling.

The canonical application of multidimensional scaling (MDS) methods has been to color dissimilarities, visualizing these as distances in a low-dimensional space. Some questions remain: How well can the locations of stimuli in color space be recovered when data are sparse, and how well can systematic individual variations in perceptual scaling be distinguished from stochastic noise? We collected triadic comparisons for saturated and desaturated sets of Natural Color System samples, each set forming an approximate hue circle. Maximum likelihood MDS was used to reconstruct the configuration of stimuli more accurately than the standard "vote-count" approach.

Color vision: Introduction by the feature editors.

This feature issue of the Journal of the Optical Society of America A (JOSA A) stems from the 22nd Biennial Symposium of the International Colour Vision Society (ICVS) and reflects the basic and applied research interests of members of the color vision community. A profile is included of the 2013 Verriest Medal recipient.

Hue discrimination, unique hues and naming.

The hue discrimination curve (HDC) that characterizes performances over the entire hue circle was determined by using sinusoidally modulated spectral power distributions of 1.5 c/300 nm with fixed amplitude and twelve reference phases. To investigate relationship between hue discrimination and appearance, observers further performed a free color naming and unique hue tasks.

Color naming and categorization in inherited color vision deficiencies.

Dichromatic subjects can name colors accurately, even though they cannot discriminate among red-green hues (Jameson & Hurvich, 1978). This result is attributed to a normative language system that dichromatic observers developed by learning subtle visual cues to compensate for their impoverished color system. The present study used multidimensional scaling techniques to compare color categorization spaces of color-vision deficient (CVD) subjects to those of normal trichromat (NT) subjects, and consensus analysis estimated the normative effect of language on categorization.

Amodal completion as reflected by gaze durations.

In two experiments amodal completion of partly occluded shapes was investigated by recording eye movements in a directed visual-search task. Participants searched arrays of shapes in a prescribed order for target figures that could partly be occluded. Longer gaze durations were found on occlusion patterns than on truncated control patterns for targets but not for non-targets.

Color vision in the comb frequency domain.

In 1982, Horace Barlow considered the question of human trichromacy in the context of information theory: according to the Sampling Theorem, three types of receptors covering the visible spectrum (400-700 nm) might be sufficient to reconstruct the color signal. Although Barlow was led to reject the direct application of the Sampling Theorem to explain color dimensionality, the theoretical framework offers a fresh point of view for analyzing the color system in conjunction with the physical characteristics of natural color signals. This review aims to illustrate that if the strict mathematical reconstruction (as implied by the Sampling Theorem) is replaced by a pragmatic approximation of color signals, then trichromacy, with its subsequent opponent-color process, could be regarded as an optimization of color constancy abilities in the spectral environment of primates.