Natural images have a characteristic spatial structure, with amplitude spectra that decrease with frequency roughly as 1/f. We have examined how contrast (pattern-selective) adaptation to this structure influences the spatial sensitivity of the visual system. Contrast thresholds and suprathreshold contrast and frequency matches were measured after adaptation to random samples from an ensemble of images of outdoor scenes or of synthetic images formed by filtering the amplitude spectra of noise over a range of spectral slopes. Adaptation selectively reduced sensitivity at low-to-medium frequencies, biasing contrast sensitivity toward higher frequencies. The pattern of aftereffects was similar for different natural image ensembles but varied with large changes in the slope of the noise spectra. Our results suggest that adaptation to the spatial structure in natural scenes may exert strong and selective influences on perception that are important in characterizing the normal operating states of the visual system.
Early postreceptoral color vision is thought to be organized in terms of two principal axes corresponding to opposing L- and M-cone signals (LvsM) or to S-cone signals opposed by a combination of L- and M-cone signals (SvsLM). These cone-opponent axes are now widely used in studies of color vision, but in most cases the corresponding stimulus variations are defined only theoretically, based on a standard observer. We examined the range and implications of interobserver variations in the cone-opponent axes. We used chromatic adaptation to empirically define the LvsM and SvsLM axes and used both thresholds and color contrast adaptation to determine sensitivity to the axes. We also examined the axis variations implied by individual differences in the color matching data of Stiles and Burch [Opt. Acta6, 1 (1959)]. The axes estimated for individuals can differ measurably from the nominal standard-observer axes and can influence the interpretation of postreceptoral color organization (e.g., regarding interactions between the two axes). Thus, like luminance sensitivity, individual differences in chromatic sensitivity may be important to consider in studies of the cone-opponent axes.
Ishihara Pseudoisochromatic Plates have been known to be one of the best screening tools for red-green color vision deficiencies. Although majority of the normal trichromats read all the plates correctly, it has been known that some normal trichromats make mistakes in reading the plates. The purpose of this study was to obtain reading results of Ishihara plates by normal trichromats and analyze the misreading patterns to seek potential explanations. Methods. Reading data on Ishihara plates (abbreviated version, 2001) and the anomaloscope setting were obtained from 249 normal trichromats as part of color vision screening procedure for psychophysical experiments. The spectral reflectance of each color of dots in the Ishihara plates was measured by GretagMacbeth Spectrolino Spectrophotometer and plotted in the DKL cone-excitation space. Each plate was scanned into a digital image file and colored dots were put into separate layers to simulate various combinations of reading patterns. Results. Out of 249 normal trichromats, 111 individuals (45%) misread at least one plate. The common misreading patterns generally followed the reading behavior of color vision defectives. Otherwise, the misreading patterns appear to originate in the cognitive aspect. For instance, the plate number 13 that should read “73” was misread as none (response by color defectives), 7, 13, 18, 23, 28, or 78. These misreading patterns cannot be predicted by chromaticity coordinates of the colored dots. Rather, the interpretation of “7” (can be read as 1 or 2 due to the unique Ishihara style) or “3” seem to induce various misreading patterns.
This study is an empirical investigation of the extent to which focal colors and unique hues of red, green, blue, and yellow are related. 40 young adults were asked to pick focal colors and unique hues from 100 color patches printed on white paper. Their saturation was varied in four levels. Analysis showed mean focal colors and mean unique hues were almost identical for the four color terms.
We examined individual differences in the color appearance of nonspectral lights and asked how they might be related to individual differences in sensitivity to chromatic stimuli. Observers set unique hues for moderately saturated equiluminant stimuli by varying their hue angle within a plane defined by the LvsM and SvsLM cone-opponent axes that are thought to characterize early postreceptoral color coding. Unique red settings were close to the +L pole of the LvsM axis, while green, blue, and yellow settings clustered along directions intermediate to the LvsM and SvsLM axes and thus corresponded to particular ratios of LvsM to SvsLM activity. Interobserver differences in the unique hues were substantial. However, no relationship was found between hue settings and relative sensitivity to the LvsM and SvsLM axes. Moreover, interobserver variations in different unique hues were uncorrelated and were thus inconsistent with a common underlying factor such as relative sensitivity or changes in the spectral sensitivities of the cones. Thus for the moderately saturated lights we tested, the unique hues appear largely unconstrained by normal individual differences in the cone-opponent axes. In turn, this suggests that the perceived hue for these stimuli does not depend on fixed (common) physiological weightings of the cone-opponent axes or on fixed (common) color signals in the environment.
Purpose. To evaluate the separate contributions of chromaticity and luminance to the perception of color from motion (Cicerone et al., Perception & Psychophysics, 1995). Methods. The stimulus consisted of 12 frames, each a 5° white square containing 900 randomly placed dots (each 3' of arc, red or green). Dots falling within a 1.2° circular region, assigned to the test, were of one chromaticity and of one luminance, either 4, 8, or 16 cd/m2. Outside the test region, dots were fixed at 8 cd/m2 and were either all red or all green. The test region was displaced vertically from frame to frame by reassignments of chromaticity and luminance while keeping dot locations fixed. When the frames were presented in quick succession (effective speed 3.3 deg/sec), the test region was perceived as a moving disk with color spreading within its boundaries. As chromaticity and luminance of the test dots and chromaticity of the surround dots were systematically varied, six color normals and one deuteranope were asked to rate apparent motion, subjective contour, and color spread on a 5-point scale and with color matching. Results. If the test and the surround were of different chromaticities and equiluminant, color normals perceived apparent motion and color spread, but no clear subjective contour. Adding luminance differences enhanced the perception of color spread and of a subjective contour. Luminance differences in the absence of chromaticity differences produced color spread. Adding chromaticity difference enhanced color spreading for all test-surround luminance contrasts. Under conditions with chromatic and luminance differences, the deuteranope performed as the color normals would if only luminance differences were present. Conclusions. Chromaticity differences in the absence of luminance differences between test and surround are sufficient for the perception of color from motion. Adding luminance can enhance perceived color spread.
Chromatic discriminations were measured on two critical axes: one on tritan lines where the excitation level of S-cones varied at fixed L/M cone ratios, and the other along lines radiating from the point (1, 0) in CIE coordinates, in which the L/M ratio varied at fixed S-cone excitation levels. Color discrimination thresholds were measured on a color monitor for 20 starting colors with a dark surround or with an equiluminant white or yellow surround. Discriminations on L/M cone lines were best when the color was near the L/M cone excitation balance and were not affected by S-cone excitation level. The level of L/M cone excitation had no effect on discriminations by S-cones. When the S-cone discriminations were plotted as a function of the S-cone excitation of the starting color, the curve for the dark surround showed a basic TVI template. Discrimination with the yellow or white surrounds was better than discrimination for a dark surround when the S-cone excitation level of the starting color was near that of the surround. A further experiment indicated that S-cone discrimination for the colors whose S-cone excitation level was the same as the white surround was impaired when a gap was introduced between the starting colors and the white surround.
The construct of Negative Mood Regulation expectancies (NMRE) is sufficiently different between Japanese and American cultures to require going beyond literal translation of the American scale to include items that assess ways Japanese may attempt to regulate mood that differ from how Americans do. We collected data from two samples of Japanese college students. Data support the reliability and initial validity of the new Japanese NMR Scale. 概要 負の感情に対する態度(NMR)の複合概念は日本と アメリカの文化では異なるため、アメリカの心理測定尺度を逐 語的に訳すだけではなく、アメリカ人とは違った 日本人独特の感情規制を測るための項目を加えることが 必要である。本研究では、日本の大学生を対象に二か所の大学 で調査を実施した。 調査の結果、日本人を対象としたNMR 尺度(NMRJ)の信頼性と妥当性が確認された。 Catanzaro and Mearns (1990) defined negative mood regulation expectancies (NMRE) within Rotter's (1954) social learning theory as people's beliefs that, when they experience an unpleasant mood, they can do something to make themselves feel better. Over 20 years of research support the validity of the NMR Scale that measures these expectancies (Mearns, Patchett & Catanzaro, in press). Stronger NMRE are associated with better adjustment, more adaptive coping, and fewer symptoms of emotional and physical distress (Catanzaro & Mearns, 1999). Recent research suggests raising NMRE is an important aspect of psychotherapeutic success (e.g., Backenstrass et al., 2006; Cloitre, Stovall-McClough, Miranda, & Chemtob, 2004). The NMR Scale consists of 30 items, completing the stem, When I'm upset, I believe that.... Each item represents a statement about the potential outcome of employing a cognitive or behavioral strategy for regulating one's mood. A German language NMR Scale has been published (Backenstrass, Pfeiffer, Schwarz, Catanzaro, & Mearns, 2008), which was a direct translation of the American scale. Many Japanese psychological measures are literal translations of English language scales, following an imposed-etic approach (Benet-Martinez, 2007). Because of differences between Japanese and American cultures, we went beyond direct translation to create a culturally relevant Japanese NMRE measure, integrating an emic approach. A bi-cultural, bi-lingual team translated the original 30 NMR Scale items, and generated an additional 25 new items representing ways Japanese may regulate mood that differ from how Americans do. These included items about social obligations and concerns about social judgment related to negative mood. Items were backtranslated; discrepancies and ambiguities in wording were corrected. Method: We tested two samples of Japanese college students. Sample 1: 315 freshman at an urban university (50% female; mean age = 18.84); Sample 2: 359 students at a rural university (56% female; mean age = 19.86). In addition to the 55-item Japanese NMR Scale (NMR-J), Sample 1 completed measures of depression, incidence of self-injury, and suicidal intention. Sample 2 completed additional measures of coping; symptoms of depression, anxiety and somatic complaints; and social approval motivation (socially desirable responding). Results: The NMR-J had an overall alpha of .87. Table 1 presents intercorrelations of scale totals for Sample 2. The NMR-J correlated positively with coping (r=.34, p<.01) and social approval motivation(r=.19, p<.05), and negatively with depression (r=-.51, p<.01), anxiety (r=-.35, p<.01) and somatic complaints (r=-.29, p<.01). We also calculated correlations separately for males and females (see Table 1). ANOVA analyses showed significant sex differences for all variables except coping. The level of difference for the NMR-J was similar to that found for the American NMR Scale (males: mean=170.09; females: mean=163.50; F(1, 357)=7.33, p<.01). We next correlated individual items with the criterion measures. Based on these results, we deleted 15 items that had weak corrected item-whole correlations or did not correlate with criterion measures. The resulting 40-item scale had a Cronbach's alpha of .88, correlated very highly with the original 55-item measure (r=.98, p<.01), and maintained significant correlations with other scales. We conducted a factor analysis, which revealed a single factor that accounted for a large portion of variance. Two other factors had eigenvalues above 2.0. These appeared to assess (a) social methods for mood regulation, and (b) concerns about social obligations or criticism by others related to negative moods. Discussion: Results support the initial reliability and validity of the 40-item Japanese language NMR Scale. The scale showed strong internal consistency, significant correlations with criterion measures of coping and distress, and a modest correlation with socially desirable responding. Results support the utility of assessing the NMRE construct in the Japanese population, and reinforce the appropriateness of an emic approach that seeks to create a Japanese measure that is culturally relevant. The disadvantage of this emic approach is that comparisons of scores between U.S. and Japanese measures will be impossible. The advantage is that the NMR-J will be culturally accurate. Further research should examine non-college student populations, use non-self-report criteria and incorporate longitudinal designs. Also examination of NMRE's role in psychotherapy in Japan will be illuminating. Table 1 Intercorrelations of Scales NMRJ coping total Hopkins Somatic Hopkins Depress. Hopkins Anxiety MLAM SD NMRJ revised NMRJ -.34** .33** .33** -.29** -.32** -.23** -.51** -.53** -.46** -.35** -.34** -.35** .19** .11 .25** coping total -.07 -.07 .00 -.03 Hopkins Somat. -.59** .63** -.04 Hopkins Depres. -.73** -.26** Hopkins Anxiety --.19**
The magnitude of the Müller-Lyer illusion was investigated using the Brentano figure by varying the chromaticities of the shaft and the fins along the cone-excitation axes and by varying the occlusion status of the shaft by the fins. 72 college students participated using the staircase method. The stimuli whose shaft and the fin chromaticities were the same produced larger illusions than stimuli with different chromaticities regardless of the luminance contrast between the figure and the surround. When the shaft appeared in front of the fins, the illusion effect was stronger than when the shaft was occluded by the fins.
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