Richer color experience in observers with multiple photopigment opsin genes

Traditional color vision theory posits that three types of retinal photopigments transduce light into a trivariate neural color code, thereby explaining color-matching behaviors. This principle of trichromacy is in need of reexamination in view of molecular genetics results suggesting that a substantial percentage of women possess more than three classes of retinal photopigments. At issue is the question of whether four-photopigment retinas necessarily yield trichromatic color perception. In the present paper, we review results and theory underlying the accepted photoreceptor-based model of trichromacy. A review of the psychological literature shows that gender-linked differences in color perception warrant further investigation of retinal photopigment classes and color perception relations. We use genetic analyses to examine an important position in the gene sequence, and we empirically assess and compare the color perception of individuals possessing more than three retinal photopigment genes with those possessing fewer retinal photopigment genes. Women with four-photopigment genotypes are found to perceive significantly more chromatic appearances in comparison with either male or female trichromat controls. We provide a rationale for this previously undetected finding and discuss implications for theories of color perception and gender differences in color behavior.     

The colors seen behind transparent filters

How do the colors and lightnesses of surfaces seen to lie behind a transparent filter depend on the chromatic properties of the filter? A convergence model developed in prior work (D'Zmura et al, 1997 Perception 26 471-492; Chen and D'Zmura, 1998 Perception 27 595-608) suggests that the visual system interprets a filter's transformation of color in terms of a convergence in color space. Such a convergence is described by a color shift and a change in contrast. We tested the model using an asymmetric matching task. Observers adjusted, in computer graphic simulation, the color of a surface seen behind a transparent filter in order to match the color of a surface seen in plain view. The convergence model fits the color-matching results nearly as well as a more general affine-transformation model, even though the latter has many more parameters. Other models, including von Kries scaling, did not perform as well. These results suggest that the color constancy revealed in this task is described best by a model that takes into account both color shifts and changes in contrast.     

Test of a convergence model for color transparency perception

Models of color transparency suggest that a region in which colors of surfaces converge in color space will appear transparent. The convergence is described by a transparency parameter alpha and a target of convergence. To test such models psychophysically, observers were presented a display with four colored areas. The colors of three of the areas were chosen in advance by the experimenter. The task of the observer was to choose the color of the fourth area to make a central region appear transparent. Settings for the fourth color were collected for a total of twenty-four color combinations chosen from three planes in color space. Observers' settings agreed well with the model, which predicts that choices for the fourth color lie along a line segment in color space that is parameterized by alpha. The results suggest further that color discriminability and color opponency also influence transparency judgment.     

Transfer of matching-to-sample in pigeons

In Experiment I, pigeons were first trained on simultaneous matching-to-sample with either color stimuli or form stimuli, and then shifted to stimuli on the other dimension. Matching performance in the first session with stimuli on a given dimension was not affected by prior matching training with stimuli on the other dimension. However, in the first six color-matching sessions pooled, birds with prior form-matching training performed significantly better than birds without any prior matching training. In Experiment II, birds with experience matching both colors and forms in separate sessions were tested with novel stimulus configurations involving either novel stimuli or novel combinations of familiar colors and forms. Matching performance was not affected by novel stimulus configurations, except that performance dropped to a chance level or below when the standard stimulus was novel. In Experiments II, III, and IV, three of four tests did not show any effect of prior reinforcement of pecks at a novel stimulus, presented alone, on subsequent matching of that stimulus. The results were interpreted as indicating that matching performance in pigeons depends on the learning of stimulus-response chains involving the specific stimuli employed during training. An incidental observation in Experiments I and II was that there were typically more excess pecks at the standard stimulus during form-matching sessions than during color-matching sessions, which may be related to the fact that form matching is more difficult than color matching.     

Lateralization differences for color-naming and color-matching in men and women

The relationship between accuracy of color-naming and color-matching in both visual fields (LVF and RVF) as a function of sex was investigated. Subjects were 19 men and 15 women who ranged in age from 18 to 32 yr. Each subject was tested on both a color-naming task and a color-matching task presented tachistoscopically. Accuracy measures for each task were obtained separately for both left and right visual fields. A two-factor analysis of variance with repeated measures on one factor followed by a t test for simple main effects showed significant right visual-field advantage for the color-naming task, a significant sex main effect for the color-matching task (in the left visual field only), and a significant interaction of sex by visual field for the matching task. Men performed in a more strongly lateralized fashion on the color-matching task than did women, supporting the notion of greater lateralization among males.     

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.     

Color logic of apparent motion

Two shapes of either the same or different color will seem to be in smooth apparent motion with like-colored mates, at proper conditions of flash timing and spacing. An experiment is reported in which the condition was tested for unlike-colored pairs, for example red-green alternated with green-red. The question of interest was how the visual system would resolve the disparity of color. An 'intelligent' solution would rotate the shapes in three dimensions. Like-colored and unlike-colored parts were found to move and transform similarly, however, the resolution being dependent more upon timing than upon color. The motion of intelligence as it might be applied to vision is discussed in light of these results.     

Organizational Justice Dimensions: Validation of an Arabic Measure

There is a continued debate regarding the dimensions of organizational justice. The present project investigated the dimensionality of organizational justice and the validity of an Arabic measure of organizational justice for a Kuwaiti samples. The first study sample consisted of 1,184 Kuwaitis (619 males and 565 females) from two groups: 728 employees and 456 teachers working in the public sector. The second study sample consisted of 373 participants (190 employees and 183 teachers). The instrument items were based on a careful review of the organizational justice literature to ensure relevance to the sample culture. Confirmatory factor analyses (CFA) using WLSMV estimator is used. WLSMV method is more appropriate for our data because variables are measured on an ordinal scale. WLSMV is considered a less bias estimator compared with the standard maximum likelihood in case of ordinal data. CFA analyses identified the four distinctive factors of distributive, procedural, interpersonal, and informational organizational justice. The four‐factor model fit the data significantly better than one‐, two‐ or three‐factor models. Moreover, the study revealed that these four dimensions of organizational justice were significantly correlated with the four relevant outcomes of instrumentality, organizational commitment, organizational citizenship behavior, and collective esteem. Using the Arabic version of Colquitt's ( 2001 ) instrument (Fischer et al., 2011 ), the second study presented an evidence of concurrent validity of the new Arabic scale. The present study confirmed the four‐factor dimensionality of organizational justice. Results of the current study may raise the issue of development of scales versus translation of well‐ developed ones. Theoretical and practical implications of the results are discussed.     

COLOR SPACE OF NORMALLY SIGHTED AND COLOR-DEFICIENT OBSERVERS RECONSTRUCTED FROM COLOR NAMING

Abstract— An experimental procedure based an the color-naming method introduced by Boynton, Schafer, and Neun (1964) was used to study the color appearance of equilumtnant spectral stimuli in observers with congenital red-green color deficiencies, as well as in normal trichromats. Subjects' responses (choice of one or more labels from the set red, yellow, green, blue, and white) were converted to numeric scores, which were used to estimate subjective difference between pairs of colors Individual subjects' matrices were processed by means of multidimensional scaling. As in the direct rating of color dissimilarities in normal trichromats. (Sokolov & Izmatlov, 1983), and color-deficient observers (Paramei Izmailov, & Sokolov, 1991), these indirectly obtained measures yielded a color space in which three dimensions appear to be necessary and sufficient. The dimensions are interpreted as evidence for red-green, Mae-yellow, and achromatic (saturation) sub-systems. Based on the color-naming technique, three-dimensional spaces were reconstructed for the color-deficient observers. These results were compared with those obtained by Helm (1964). It is argued that retaining more than one (blue-yellow) dimension in the color spaces of such observers provider additional information indicating preservation of residual red-green discrimination accompanied by finer discrimination of chroma than in normal trichromats. The spherical model of color discrimination developed for normal trichromats (lzmailov & Sokolov, 1991) is shown to be valid for color-deficient subjects as well and may be useful as a framework for differentiating proton and deutan types of color deficiency. Color-naming functions, which seem not to reveal a differentiation between protans and deutans, provide results form which this differentiation can be extracted in reconstructed color spaces.     

On the prediction of confusion matrices from similarity judgments

Three observers viewed visual representations of eight complex sounds in both a pairwise similarity-judgment task and an identification task. A multidimensional scaling procedure applied to the similarity judgments yielded a three-dimensional perceptual space and the relative positions of the stimuli in that space. A probabilistic decision model based on weighted interstimulus distances served to predict well the confusion matrices of the identification task. Three conditions of the identification task, calling for identification of different subsets of the eight stimuli, led the observers to vary the weights they placed on the dimensions; they apparently adjusted the weights to maximize the percent correct identification. An additional group of 14 subjects, participating only in the similarity-judgment task, manifested the same three dimensions as the observers (corresponding to the locus of low-frequency energy, the locus of midfrequency energy, and visual contrast), and also a fourth dimension (corresponding to the periodicity, or waxing and waning, of the sound). Although not evident in the scaling analysis for the three observers, our utilization of the additional dimension increased significantly the variance accounted for in their identification responses. The overall accuracy of the predictions from a perceptual space to identification responses supplies a substantial validation of the use of multidimensional scaling procedures to reveal perceptual structure in demonstrating the ability of that structure to account for behavior in an independent task. The empirical success of this approach, furthermore, suggests a relatively simple and practical means of predicting, and possibly enhancing, identification performance for a given set of visual or auditory stimuli.     

Approximated Penalized Maximum Likelihood for Exploratory Factor Analysis: An Orthogonal Case

The problem of penalized maximum likelihood (PML) for an exploratory factor analysis (EFA) model is studied in this paper. An EFA model is typically estimated using maximum likelihood and then the estimated loading matrix is rotated to obtain a sparse representation. Penalized maximum likelihood simultaneously fits the EFA model and produces a sparse loading matrix. To overcome some of the computational drawbacks of PML, an approximation to PML is proposed in this paper. It is further applied to an empirical dataset for illustration. A simulation study shows that the approximation naturally produces a sparse loading matrix and more accurately estimates the factor loadings and the covariance matrix, in the sense of having a lower mean squared error than factor rotations, under various conditions.     

How retaining objects containing multiple features in visual working memory regulates the priority for access to visual awareness

The content of visual working memory influences the access to visual awareness. Thus far, research has focused on retention of a single feature, whereas memoranda in real life typically contain multiple features. Here, we intermixed a delayed match-to-sample task to manipulate VWM content, and a breaking Continuous Flash Suppression (b-CFS) task to measure prioritization for visual awareness. Observers memorized either the color (Exp. 1), the shape (Exp. 2) or both the features (Exp. 3) of an item and indicated the location of a suppressed target. We observed that color-matching targets broke suppression faster than color-mismatching targets both when color was memory relevant or irrelevant. Shape only impacted priority for visual awareness through an interaction with color. We conclude that: (1) VWM can regulate the priority of visual information to access visual awareness along a single feature dimension; (2) different features of a memorandum vary in their potency to impact access to visual awareness, and the more dominant feature may even suppress the effect of the less dominant feature; (3) even stimuli that match an irrelevant feature dimension of the memorandum can be prioritized for visual awareness.     

An evaluation of the construct of body image

The two studies reported in this paper were designed to evaluate the efficacy of a multidimensional model of body image that incorporated the dimensions of perception, affect, cognition, and behavior. Study 1 selected items from established measures that were judged to reflect these four dimensions. This four-factor model was then tested in Study 2. The participants for Study 2 were 175 females. The results did not support the hypothesized four-factor model. An exploratory factor analysis revealed a model that consisted of three factors: Cognitions and Affect Regarding Body, Body Importance and Dieting Behavior, and Perceptual Body Image. Below-average-weight respondents rated the Cognitions and Affect Regarding Body factor as more important than did above-average-weight respondents. Below-average-weight respondents overestimated their body size, whereas average-weight and above-average-weight respondents made underestimates, with above-average-weight respondents underestimating their body size to a greater extent than average-weight respondents. The results highlight the multidimensionality of the body image construct and the difficulty in attempting to simplify this construct. Implications of these findings for better understanding problems among people with disturbed body image are discussed.     

Segregation by color and stereoscopic depth in three-dimensional visual space

Two experiments were conducted to investigate how color and stereoscopic depth information are used to segregate objects for visual search in three-dimensional (3-D) visual space. Eight observers were asked to indicate the alphanumeric category (letter or digit) of the target which had its unique color and unique depth plane. In Experiment 1, distractors sharing a common depth plane or a common color appeared in spatial contiguity in thexy plane. The results suggest that visual search for the target involves examination of kernels formed by homogeneous items sharing the same color and depth. In Experiment 2, thexy contiguity of distractors sharing a common color or a common depth plane was varied. The results showed that when target-distractor distinction becomes more difficult on one dimension, the other dimension becomes more important in performing visual search, as indicated by a larger effect on search time. This suggests that observers can make optimal use of the information available. Finally, color had a larger effect on search time than did stereoscopic depth. Overall, the results support models of visual processing which maintain that perceptual segregation and selective attention are determined by similarity among objects in 3-D visual space on both spatial and nonspatial stimulus dimensions.     

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.     

Selective weighting of action-related feature dimensions in visual working memory

Planning an action primes feature dimensions that are relevant for that particular action, increasing the impact of these dimensions on perceptual processing. Here, we investigated whether action planning also affects the short-term maintenance of visual information. In a combined memory and movement task, participants were to memorize items defined by size or color while preparing either a grasping or a pointing movement. Whereas size is a relevant feature dimension for grasping, color can be used to localize the goal object and guide a pointing movement. The results showed that memory for items defined by size was better during the preparation of a grasping movement than during the preparation of a pointing movement. Conversely, memory for color tended to be better when a pointing movement rather than a grasping movement was being planned. This pattern was not only observed when the memory task was embedded within the preparation period of the movement, but also when the movement to be performed was only indicated during the retention interval of the memory task. These findings reveal that a weighting of information in visual working memory according to action relevance can even be implemented at the representational level during maintenance, demonstrating that our actions continue to influence visual processing beyond the perceptual stage.     

The control of visual attention using multiple target features

An experiment was conducted to determine how visual attention is allocated in response to pairwise combinations of location, color, and size cues. Subjects viewed displays of eight letters arranged into an 'X' pattern emanating from a central fixation point. The letters varied on the dimensions of location (foveal or parafoveal positions), size (large or small), and color (red or blue). Seven of the letters were 'X's and the remaining, critical letter was either an 'R' or an 'L'. Subjects were given advance cues about characteristics of the critical letter on two of the three dimensions (location size, and color). The cues varied in their validity such that on any trial either both dimensions were validly cued, one dimension was validly cued while the other was invalidly cued, or both cues were invalid. Subjects were instructed to try to use the cues to find the critical letter, and response times to identify it as an 'R' or an 'L' served as the main dependent measure. Two models were evaluated against the data; in one, location cues are viewed as having distinct effects on an early stage of attention whereas color and size cues operate only in a later, selection stage. In the other model, all cues are used in a similar way to select display items for serial, focal attention. In general, the serial processing model provides a more complete account of the data.     

Pigeons (<Emphasis Type="Italic">Columba livia</Emphasis>) show change blindness in a color-change detection task

Change blindness is a phenomenon whereby changes to a stimulus are more likely go unnoticed under certain circumstances. Pigeons learned a change detection task, in which they observed sequential stimulus displays consisting of individual colors back-projected onto three response keys. The color of one response key changed during each sequence and pecks to the key that displayed the change were reinforced. Pigeons showed a change blindness effect, in that change detection accuracy was worse when there was an inter-stimulus interval interrupting the transition between consecutive stimulus displays. Birds successfully transferred to stimulus displays involving novel colors, indicating that pigeons learned a general change detection rule. Furthermore, analysis of responses to specific color combinations showed that pigeons could detect changes involving both spectral and non-spectral colors and that accuracy was better for changes involving greater differences in wavelength. These results build upon previous investigations of change blindness in both humans and pigeons and suggest that change blindness may be a general consequence of selective visual attention relevant to multiple species and stimulus dimensions.     

Configural processing of faces in the left and the right cerebral hemispheres

This study investigates the rules by which the component features of faces are combined when presented in the left or the right visual field, and it examines the validity of the analytic-holistic processing dichotomy, using concepts elaborated by Garner (1978, 1981) to specify stimulus properties and models of similarity relations as performance criteria. Latency measures of dissimilarity, obtained for the two visual fields, among a set of eight faces varying on three dimensions of two levels each, were fitted to the dominance metric model, the feature-matching model, the city-block distance metric model, and the Euclidean distance metric model. In addition to a right-visual-field superiority in different responses, a maximum likelihood estimation procedure showed that, for each subject and each visual field, the Euclidean model provided the best fit of the data, suggesting that the faces were compared in terms of their overall similarity. Moreover, the spatial representations of the results revealed interactions among the component facial features in the processing of faces. Taken together, these two findings indicate that faces initially projected to the right or to the left hemisphere were not processed analytically but in terms of their gestalt.     

The genetic structure of personality I. Phenotypic factor structure of the EPQ in an Australian sample

The Eysenck Personality Questionnaire was completed by 4874 female and 2746 male Australian adults from the Australian Twin Register. Tetrachoric correlations between item responses were computed by maximum likelihood, and factor analysed. Stable Extraversion, Neuroticism and Social desirability (‘Lie’) factors were identified. In the four-factor solution, the fourth factor was clearly a Psychoticism factor, which had loadings greater than 0.2 on all but two of the items of the P scale. When more than four factors were estimated, however, this factor progressively split into Unconventional/impulsive behavior, suspiciousness, cruelty and punctuality factors. These P factors were stable across sexes and, in an oblique rotation, only moderately correlated. The factorial heterogeneity of the P scale is overlooked because of under-extraction of factors in the conventional 4-factor solution.