Color spaces of color-normal and color-abnormal observers reconstructed from response times and dissimilarity ratings

With multidimensional scaling analysis, color spaces were reconstructed from reaction times (RTs) required to make same-different judgements of pairs of 15 equiluminant colors and from dissimilarity ratings between them. In addition to normal trichromats, observers with red-green color deficiency were tested. Two main purposes were served by this study: (1) to compare spatial representations of colors derived from discriminative RTs with those derived from dissimilarity measures and (2) to examine whether the task may selectively affect the dimension reflecting, in color-abnormal spaces, the deficient red-green mechanism. Contradicting our hypothesis of lower dimensionality of RT spaces, as compared with rating spaces, no consistent differences in solution dimensionality were found. However, configurations derived from the two measures diverged. The rating procedure yielded the most logical results for recovering color space. The RT configuration revealed contraction in the tritanopic direction, indicating longer color processing when the short-wavelength mechanism is involved, and in addition, for color-abnormal observers, clustering in the protanopic and deuteranopic directions, indicating even longer processing by the deficient red-green mechanism. This finding implies that RTs are suitable for detecting temporal differences in color processing but, for that very same reason, rather ill-suited for reconstructing color spaces.     

先天性红-绿色觉异常者的非彩色表色色差辨别研究

该文就先天性红－绿色觉异常者对非彩色系表色色差的辨别展开了研究。结果表明,先天性红－绿色觉异常者色差识别的量值△Ｅ随目视评价的等级不同而异;先天性红－绿色觉异常者与色党正常者在非彩色表色辨别上存在一定的差异;同一明度等级上、下限的变化对先天性红－绿色觉异常者的非彩色表色辨别存在影响,这种影响与明度的级别有关。     

Multidimensional scaling of subjective colors by color-blind observers

Temporal coding theories of color vision suggest explanations of flicker-induced subjective colors such as those that appear on Benham’s disk. If color blindness were due simply to photopigment anomalies, then subjective colors might be elicited by central patterns of neural activity in color-blind observers that mimic those which the cones normally produce in colornormal observers. We had color-normal and color-blind observers scale subjective colors like those on Benham’s disk for similarity. The inferred color spaces for six normal observers resembled the familiar hue circle, but the spaces for five red-green-deficient observers were compressed along the red-green axis. This is consistent with the position that flicker colors are due to retinal processes, and suggests that color blindness may involve variations of the central nervous system in addition to photopigment anomalies.     

Escher in color space: Individual-differences multidimensional scaling of color dissimilarities collected with a gestalt formation task

The structure of color perception can be examined by collectingjudgments about color dissimilarities. In the procedure used here, stimuli are presented three at a time on a computer monitor and the spontaneous grouping of most-similar stimuli into gestalts provides the dissimilarity comparisons. Analysis with multidimensional scaling allows such judgments to be pooled from a number of observers without obscuring the variations among them. The anomalous perceptions of color-deficient observers produce comparisons that are represented well by a geometric model of compressed individual color spaces, with different forms of deficiency distinguished by different directions of compression. The geometrical model is also capable of accommodating the normal spectrum of variation, so that there is greater variation in compression parameters between tests on normal subjects than in those between repeated tests on individual subjects. The method is sufficiently sensitive and the variations sufficiently large that they are not obscured by the use of a range of monitors, even under somewhat loosely controlled conditions.     

Escher in color space: individual-differences multidimensional scaling of color dissimilarities collected with a gestalt formation task.

The structure of color perception can be examined by collecting judgments about color dissimilarities. In the procedure used here, stimuli are presented three at a time on a computer monitor and the spontaneous grouping of most-similar stimuli into gestalts provides the dissimilarity comparisons. Analysis with multidimensional scaling allows such judgments to be pooled from a number of observers without obscuring the variations among them. The anomalous perceptions of color-deficient observers produce comparisons that are represented well by a geometric model of compressed individual color spaces, with different forms of deficiency distinguished by different directions of compression. The geometrical model is also capable of accommodating the normal spectrum of variation, so that there is greater variation in compression parameters between tests on normal subjects than in those between repeated tests on individual subjects. The method is sufficiently sensitive and the variations sufficiently large that they are not obscured by the use of a range of monitors, even under somewhat loosely controlled conditions.     

Infants are trichromats.

Two experiments were conducted to demonstrate that human infants 3 months of age perceive color in a normal, trichromatic manner. In the first experiment, the visual attention of 30 infants was monitored in a habituation-dishabituation paradigm that used spectral and white lights with brightness factors eliminated. Infants discriminated white from monochromatic light in a region of the spectrum (490–500 nm) where color-normal adults can but color-deficient adults cannot. In the second experiment which also used a habituation paradigm, eight infants showed good discrimination between hues in a region of the spectrum (560–580 nm) where color-deficient adults typically show no hue discrimination. Results from these studies of the neutral zone and hue discrimination evidence trichromatic vision in infancy and are discussed in the context of their several clinical, social, and intellectual implications.     

MULTIDIMENSIONAL SCALING OF LARGE CHROMATIC DIFFERENCES BY NORMAL AND COLOR-DEFICIENT SUBJECTS

The following two articles offer a glimpse at current experimental psychology in the Soviet Union, normally screened from the English-speaking world by all but impenetrable language barriers. The accompanying Commentary by Tarow Indow helps place these contributions in the framework of contemporary work on the psychophysics of color perception.   Abstract —
Fifteen normal trichromatic subjects, two protanopes, and two deuteranopes judged pairs of successively presented foveal color stimuli. Multidimensional scaling of the data yielded estimates of a three-dimensional space with axes interpreted as red–green, blue-yellow, and white-black. For color-deficient subjects, the average radius of the space differed from that of normals, being smaller for the protanopes and larger for the deuteranopes. For both types of color deficiency, the blue-yellow axis was stretched relative to the red-green, more strongly in the protanopes. The findings are taken to support the generality of a "spherical" model.     

Coding of luminance and color differences on neurons in the rabbit's visual system

The neuronal activity in the rabbit's visual cortex, lateral geniculate nucleus and superior colliculus was investigated in responses to 8 color stimuli changes in pairs. This activity consisted of phasic responses (50-90 and 130-300 Ms after stimuli changes) and tonic response (after 300 Ms). The phasic responses used as a basis for the matrices (8 x 8) constructed for each neuron included the average of spikes/sec in responses to all stimuli changes. All matrices were treated by factor analysis and the basic axes of sensory spaces were revealed. Sensory spaces reconstructed from neuronal spike discharges had a two-dimensional (with brightness and darkness axes) or four-dimensional (with two color and two achromatic axes) structure. Thus it allowed us to split neurons into groups measuring only brightness differences and the measuring of color and brightness differences between stimuli. The tonic component of most of the neurons in the lateral geniculate nucleus showed linear correlation with changes in intensities; therefore, these neurons could be characterized as pre-detectors for cortical selective detectors. The neuronal spaces demonstrated a coincidence with spaces revealed by other methods. This fact may reflect the general principle of vector coding (Sokolov, 2000) of sensory information in the visual system.     

Color sensation of normal and anomalous trichromats measured by magnitude estimation

Summary Colors perceived by normal, protanomalous, and deuteranomalous trichromats were scaled by magnitude estimation. As a result, opponent-colors functions were obtained which show the hue sensations produced by spectral lights. For color-normal observers, the loci of maximal hue sensations were different in some aspects from those expected from current opponent-colors theories.The results obtained from the anomalous observers confirm the view that the causes of prot- and of deuteranomalous vision consist in reverse shifts of the long- and middle-wavelength cone sensitivities respectively. It was found that anomalous trichromats perceive less red in the violet spectrum than do normal subjects. This finding may be explained by the hypothesis that short-wave-length red is produced by a secondary maximum of the long-wavelength cone excitation. In the experiment, the main defect of anomalous trichromats, compared with normal subjects, consisted in the high instability of hue perception and hue recognition. This instability may be explained by an unfavorable signal/noise relation created by the similarity of the two long-wavelength receptor sensibilities in the anomalous red/green systems.     

Evolutionary models of color categorization based on discrimination

Specifying the factors that contribute to the universality of color categorization across individuals and cultures is a longstanding and still controversial issue in psychology, linguistics, and anthropology. This article approaches this issue through the simulated evolution of color lexicons. It is shown that the combination of a minimal perceptual psychology of discrimination, simple pragmatic constraints involving communication, and simple learning rules is enough to evolve color-naming systems. Implications of this result for psychological theories of color categorization and the evolution of color-naming systems in human societies are discussed.     

A maximum motion technique for assessment of color vision defects

Several luminance-matching methods, such as flicker fusion and the minimum motion technique (MMT), are capable of detecting certain forms of abnormal color vision. We present evidence that the heterochromatic fusion nystagmus (HFN) luminance matching technique can discriminate among normal trichromats, protanopes, and deuteranomals. The HFN luminance matching technique has the advantage that it provides a positive indication of isoluminance (maximization of motion) as opposed to the MMT and flicker fusion methods, which indicate isoluminance by the minimization of motion and flicker, respectively. We tested 16 normal trichromats, 6 protanopes, and 4 deuteranomals with the HFN technique. Results indicate that HFN is a useful tool for examining color vision. Because the HFN stimulus elicits reflexive eye movements (optokinetic nystagmus) that follow the apparent motion of the stimulus, HFN luminance matching will be particularly useful in animal and infant research, where other color vision tests are difficult to implement.     

The color-vision approach to emotional space: Cortical evoked potential data

A framework for accounting for emotional phenomena proposed by Sokolov and Boucsein (2000) employs conceptual dimensions that parallel those of hue, brightness, and saturation in color vision. The approach that employs the concepts of emotional quality, intensity, and saturation has been supported by psychophysical emotional scaling data gathered from a few trained observers. We report cortical evoked potential data obtained during the change between different emotions expressed in schematic faces. Twenty-five subjects (13 male, 12 female) were presented with a positive, a negative, and a neutral computer-generated face with random interstimulus intervals in a within-subjects design, together with four meaningful and four meaningless control stimuli made up from the same elements. Frontal, central, parietal, and temporal ERPs were recorded from each hemisphere. Statistically significant outcomes in the P300 and N200 range support the potential fruitfulness of the proposed color-vision-model-based approach to human emotional space.     

Children's Perception of Munsell Colors

This study examined perception of Munsell notation color by seven third-graders and three college adults (both with normal color vision) and three children (from the same family) who were red-green color blind. The stimuli varied in terms of Munsell Hue (red, green, and purple), Munsell Value (brightness), and Munsell Chroma (saturation). Each S judged the dissimilarity of 325 color pairs (from 26 stimuli). The data were analyzed via individual difference multidimensional scaling that defined a common perceptual space for the group. The results indicated that the third-graders’ color perception was like that of the adults. The color circle was reproduced, as were dimensions based on Munsell Value and Chroma. The color deficient children's data did not fit into that common space. Their perception was guided primarily by the brightness of the stimulus. In sum, the data indicated that, for the domain of Munsell colors, results obtained from adults concerning the dimensionality of the color space could be applied to young children (as long as they have normal color vision).     

The Color-Vision Approach to Emotional Space: Cortical Evoked Potential Data

A framework for accounting for emotional phenomena proposed by Sokolov and Boucsein (2000) employs conceptual dimensions that parallel those of hue, brightness, and saturation in color vision. The approach that employs the concepts of emotional quality. intensity, and saturation has been supported by psychophysical emotional scaling data gathered from a few trained observers. We report cortical evoked potential data obtained during the change between different emotions expressed in schematic faces. Twenty-five subjects (13 male, 12 female) were presented with a positive, a negative, and a neutral computer-generated face with random interstimulus intervals in a within-subjects design, together with four meaningful and four meaningless control stimuli made up from the same elements. Frontal, central, parietal, and temporal ERPs were recorded from each hemisphere. Statistically significant outcomes in the P300 and N200 range support the potential fruitfulness of the proposed color-vision-model-based approach to human emotional space.     

What Employment Counselors Need to Know About Employment Discrimination and the Civil Rights Act of 1991

Under Title VII of the Civil Rights Act of 1964 there are two theories of liability for employment discrimination: disparate treatment and disparate impact. While disparate treatment deals with the adverse treatment of a specified employee, disparate impact deals with discrimination against a class of individuals. The Civil Rights Act of 1991 modified the law to allow plaintiffs to more readily bring a discrimination case. This article reviews the major components of the Civil Rights Act of 1964, the Civil Rights Act of 1991, and a proactive approach to using equal opportunity law in employment counseling.     

COLOR PERCEPTION REQUIREMENTS OF 4,000 JOBS

Tabulation of the color discrimination requisites of a representative sample of 4,000 jobs revealed that the great majority of jobs require little or no color perception aptitude. The 2 percent of jobs requiring above-average color discrimination were listed by Dictionary of Occupational Titles classifications for the use of counselors in the guidance of clients with defective color vision.     

Time course analysis of the Stroop phenomenon

Dyer (1971) investigated the response competition hypothesis of the Stroop phenomenon by temporally separating the color and word components of single stimuli (incongruent, control, and congruent). This line of research was continued in a series of five experiments that generalized Dyer's study: (a) In addition to the color-naming task, a reading task was included; (b) the irrelevant stimulus component was presented before and after the relevant one; (c) the probabilities of congruent and incongruent stimuli were varied; (d) besides color-word/color stimuli, color-color and word-word stimuli were used; and (e) the functional discrimination (color naming or reading) was compared with a sequential discrimination task. The data suggest the following temporal relations: (a) a slow facilitation due to response bias; (b) its inhibitory counterpart; and (c) a fast, strong inhibition with no facilitatory complement that seems to correspond to the usual Stroop conflict but that seems to occur earlier than the response execution stage.     

Errorless transfer of a discrimination across two continua

A procedure developed earlier (Terrace, 1963) successfully trained a red-green discrimination without the occurrence of any errors in 12 out of 12 cases. Errorless transfer from the red-green discrimination to a discrimination between a vertical and a horizontal line was accomplished by first superimposing the vertical and the horizontal lines on the red and green backgrounds, respectively, and then fading out the red and the green backgrounds. Superimposition of the two sets of stimuli without fading, or an abrupt transfer from the first to the second set of stimuli, resulted in the occurrence of errors during transfer. Superimposition, however, did result in some “incidental learning”. Performance following acquisition of the vertical-horizontal discrimination with errors differed from performance following acquisition without errors. If the vertical-horizontal discrimination was learned with errors, the latency of the response to S+ was permanently shortened and errors occurred during subsequent testing on the red-green discrimination even though the red-green discrimination was originally acquired without errors. If the vertical-horizontal discrimination was learned without errors, the latency of the response to S+ was unaffected and no errors occurred during subsequent testing on the red-green discrimination.     

中国人眼对非彩色系表色色差辨别的实验研究

报道了中国人眼对表色色差辨别的实验研究中非彩色系列实验研究结果,并与国外有关结果进行了比较。结果表明,非彩色的明度特性变化,对人眼色差辨别无显著影响,色差值仅随目视评价的感觉等级不同而异。此结果与国外有关报道的结果基本一致。实验结果为中国颜色体系的非彩色系颜色样品提出了色差宽容度：△Ｅ＜１．５。此色差宽容度已被全国颜色标准化技术委员会认定为ＧＳＢＡ２６００３—９４《中国颜色体系》国家标准中颜色样品色差宽容度的技术参数。