Categorical Perception Of Color Research Articles

Color Perception in Children with Autism

This study examined whether color perception is atypical in children with autism. In experiment 1, accuracy of color memory and search was compared for children with autism and typically developing children matched on age and non-verbal cognitive ability. Children with autism were significantly less accurate at color memory and search than controls. In experiment 2, chromatic discrimination and categorical perception of color were assessed using a target detection task. Children with autism were less accurate than controls at detecting chromatic targets when presented on chromatic backgrounds, although were equally as fast when target detection was accurate. The strength of categorical perception of color did not differ for the two groups. Implications for theories on perceptual development in autism are discussed.

Categorical perception of color is lateralized to the right hemisphere in infants, but to the left hemisphere in adults

Both adults and infants are faster at discriminating between two colors from different categories than two colors from the same category, even when between- and within-category chromatic separation sizes are equated. For adults, this categorical perception (CP) is lateralized; the category effect is stronger for the right visual field (RVF)-left hemisphere (LH) than the left visual field (LVF)-right hemisphere (RH). Converging evidence suggests that the LH bias in color CP in adults is caused by the influence of lexical color codes in the LH. The current study investigates whether prelinguistic color CP is also lateralized to the LH by testing 4- to 6-month-old infants. A colored target was shown on a differently colored background, and time to initiate an eye movement to the target was measured. Target background pairs were either from the same or different categories, but with equal target-background chromatic separations. Infants were faster at initiating an eye movement to targets on different-category than same-category backgrounds, but only for targets in the LVF-RH. In contrast, adults showed a greater category effect when targets were presented to the RVF-LH. These results suggest that whereas color CP is stronger in the LH than RH in adults, prelinguistic CP in infants is lateralized to the RH. The findings suggest that language-driven CP in adults may not build on prelinguistic CP, but that language instead imposes its categories on a LH that is not categorically prepartitioned.

The effect of Stroop interference on the categorical perception of color

In two experiments, we examined the effects of Stroop interference on the categorical perception (CP; better cross-category than within-category discrimination) of color. Using a successive two-alternative forced choice recognition paradigm (deciding which of two stimuli was identical to a previously presented target), which combined to-be-remembered colors with congruent and incongruent Stroop words, we found that congruent color words facilitated CP, whereas incongruent color words reduced CP. However, this was the case only when Stroop interference was presented together with the target color, but not when Stroop stimuli were introduced at the test stage. This suggests that target name, but not test name generation, affects CP. Target name generation may be important for CP because it acts as a category prime, which, in turn, facilitates cross-category discrimination.

Neural basis of categorical perception of colour

Neural basis of categorical perception of colour

Categorical perception of colour in the left and right visual field is verbally mediated: Evidence from Korean

In this study we demonstrate that Korean (but not English) speakers show Categorical perception (CP) on a visual search task for a boundary between two Korean colour categories that is not marked in English. These effects were observed regardless of whether target items were presented to the left or right visual field. Because this boundary is unique to Korean, these results are not consistent with a suggestion made by Drivonikou [Drivonikou, G. V., Kay, P., Regier, T., Ivry, R. B., Gilbert, A. L., Franklin, A. et al. (2007) Further evidence that Whorfian effects are stronger in the right visual field than in the left. Proceedings of the National Academy of Sciences 104, 1097–1102] that CP effects in the left visual field provide evidence for the existence of a set of universal colour categories. Dividing Korean participants into fast and slow responders demonstrated that fast responders show CP only in the right visual field while slow responders show CP in both visual fields. We argue that this finding is consistent with the view that CP in both visual fields is verbally mediated by the left hemisphere language system.

Color category influences heterogeneous visual search for color

Many previous studies have revealed chromatic characteristics of visual search using relatively simple stimuli. They suggested that color difference between a target and distractors was a crucial factor. However, it may not be applicable to natural environments that contain numerous colors. This study demonstrates the existence of a color-category effect on heterochromatic visual search. Color differences between a target and distractors were constant in the OSA uniform color scales; however, the search times varied widely. This suggests that color differences alone do not explain search performance. To clarify the mediation of a higher-order categorical color process, search times were analyzed using 11 basic colors. When the color category of a target was shared by a larger number of distractors, the search performance declined. However, when the color category of a target was not shared with distractors, the target was easily detected. The results suggest that heterochromatic stimuli could be segregated by categorical color perception.

ニューラルネットワークによる照明光の変化を考慮したカテゴリカル色知覚モデル

We developed a model that can operate similarly to human categorical color perception. The color of an object is not exclusively determined by the reflection spectrum from the surface of the object but is greatly affected by the ambient environmental conditions and depends upon color constancy, The mechanism of color constancy, however, is not explained in detail so acquiring the cognition of the categorical color name of objects under different illuminations is difficult. To that end, the relationship between the chromaticity and the categorical color perception of colored chips under different illuminations is the product of a categorical color-naming experiment was learned by using a neural network. The results showed that the obtained neural network has similar characteristics to those of human vision system.

Color term knowledge does not affect categorical perception of color in toddlers

Categorical perception of color is shown when colors from the same category are discriminated less easily than equivalently spaced colors that cross a category boundary. The current experiments tested various models of categorical perception. Experiment 1 tested for categorical responding in 2- to 4-year-olds, the age range for the onset establishment of color term knowledge. Experiment 2 tested for categorical responding in Himba toddlers, whose language segments the color space differently from the way in which the English language does so. Experiment 3 manipulated the conditions of the task to explore whether the categorical responding in Experiments 1 and 2 was equivalent to categorical perception. Categorical perception was shown irrespective of naming and was not stronger in those children with more developed color term knowledge. Cross-cultural differences in the extent of categorical perception were not found. These findings support universalistic models of color categorization and suggest that color term knowledge does not modify categorical perception, at least during the early stages of childhood.

Acquisition of categorical color perception: A perceptual learning approach to the linguistic relativity hypothesis.

Color perception can be categorical: Between-category discriminations are more accurate than equivalent within-category discriminations. The effects could be inherited, learned, or both. The authors provide evidence that supports the possibility of learned categorical perception (CP). Experiment 1 demonstrated that observers' color discrimination is flexible and improves through repeated practice. Experiment 2 demonstrated that category learning simulates effects of "natural" color categories on color discrimination. Experiment 3 investigated the time course of acquired CP. Experiment 4 found that CP effects are acquired through hue- and lightness-based category learning and obtained interesting data on the dimensional perception of color. The data are consistent with the possibility that language may shape color perception and suggest a plausible mechanism for the linguistic relativity hypothesis.

Acquisition of categorical color perception: A perceptual learning approach to the linguistic relativity hypothesis.

Acquisition of categorical color perception: A perceptual learning approach to the linguistic relativity hypothesis.

The categorical perception of colors and facial expressions: the effect of verbal interference.

A series of five experiments examined the categorical perception previously found for color and facial expressions. Using a two-alternative forced-choice recognition memory paradigm, it was found that verbal interference selectively removed the defining feature of categorical perception. Under verbal interference, there was no longer the greater accuracy normally observed for cross-category judgments relative to within-category judgments. The advantage for cross-category comparisons in memory appeared to derive from verbal coding both at encoding and at storage. It thus appears that while both visual and verbal codes may be employed in the recognition memory for colors and facial expressions, subjects only made use of verbal coding when demonstrating categorical perception.

Effects of Stimulus Size on Categorical Color Perception in the Peripheral Visual Field

Effects of Stimulus Size on Categorical Color Perception in the Peripheral Visual Field

色空間の分類数に応じて現れる階層的なカテゴリカル色知覚

We generally express color as some categorical color even though we have the ability to discriminate millions of colors. Most studies of categorical color perception have been based on color naming, so they have been affected by vocabulary. We have identified the locations of categorical color perception without the effect of a vocabulary by using a color space classification method. Five observers classified a set of 424 OSA color samples and an additional 6 JIS-munsell chips into several (2-14) groups. The locations of the classified categories were similarly arranged in color space across the observers. The classified categories had at least four stages, probably corresponding to multi-stage categorical color perception. Some classified categories had regions dissimilar to the categories derived with a color naming method.

低照度レベルにおける周辺視野でのカテゴリカル色知覚の特性

We measured the characteristics of categorical color perception in the peripheral visual field under low illumination conditions and compared with those under 2000 lx illuminance in our previous study [J. Illum. Engng. Inst. Jpn. 83 (1999)]. OSA color chips, simulated by the LCD projector, were presented at the fovea (0 deg), at eccentricities of 30 and 50 deg in the nasal visual field, and at 30, 50, 70, and 80 deg in the temporal visual field. A large gray surrounding field, made with a hemisphere, was illuminated by D65 fluorescent lamps at 5 or 0.1 lx. The stimulus was subtended 4 deg and presented for 3 s. The observer reported the color appearance of the stimulus with 1 of 11 basic color terms. The response of color categories at the fovea showed almost no difference to the 50 deg temporal under 5 lx illuminance. Beyond the 30 deg nasal and the 70 deg temporal, the response of achromatic categories increased, and that of green, purple, and pink categories decreased. Under 0.1 lx the response of achromatic categories dominated. Our results show that categorical color perception in the central visual field is constant across a large visual area under a wide range of illumination conditions.

低照度レベルにおける周辺視野でのカテゴリカル色知覚に関する個人差についての検討

低照度レベルにおける周辺視野でのカテゴリカル色知覚に関する個人差についての検討

Categorical perception effects induced by category learning.

The authors report a series of studies designed to determine whether effects similar to those observed in the innate categorical perception of color and phonemes are induced during the learning of simple unidimensional categories and more complex multidimensional ones. In Experiment 1 no evidence was found for such effects when stimuli varied on 1 dimension. Experiments 2 and 3 demonstrated a within-category compression effect but no between category expansion effect for stimuli varying in 2 dimensions. Compression only was also shown in Experiment 4, which used pictures of actual objects. Multidimensional scaling analyses illustrate how within-category compression without expansion was sufficient to produce categorical clustering of items in the similarity space. These analyses also show that learning changed the dimensional structure of similarity space. Results are compared with those from other studies exploring similar phenomena and with neural network simulations.

カデゴリカル色知覚に基づく各種光源下での色の見え

カデゴリカル色知覚に基づく各種光源下での色の見え

Neuronal mechanisms of color categorization in areas V1, V2 and V4 of macaque monkey visual cortex

A landmark study conducted by Berlin and Kay ( Basic Color Terms, University of California Press, Berkeley, 1969, pp. 1–12) demonstrates that well-developed languages contain exactly 11 basic color terms. The basic colors (8 chromatic and 3 achromatic) are situated in specific locations of color space, suggesting a fixed relationship between specific hue and luminance. To determine the physiologic origins of the basic colors, we have studied the responses of cells in visual cortical areas V1, V2 and V4 of the behaving macaque monkey, using chromatic and achromatic stimuli of varying luminance. A total of 569 cells (291 from V1, 205 from V2, 73 from V4) were obtained, and classified as ‘B’ (bright; 43–50% of the total cells in each area), ‘D’ (dark; 6–12% of the total), and ‘ B D ’ (bright/dark; 27–28% of the total) color or non-color cells according to each cell's color/luminance preference in relation to the neutral gray background. About two thirds of ‘B’ cells in each area were color specific, whereas the proportion of color cells in ‘ B D ’ and ‘D’ categories was lower. In all three areas (V1, V2, V4), color cells with preferences for midspectral colors (such as yellow, lime and green) also preferred high luminance levels, while color cells with preferences for endspectral colors (such as red and blue) responded preferentially to luminance levels closer to background. The data provide evidence for categorical color perception within the visual system, as well as providing a physiological basis for the increased saliency of endspectral contours observed at equiluminance in psychophysical studies.

Category effects in color memory

AbstractCategorical color perception has previously been tested using a naming method, and the data from 27 subjects so examined in several experiments have been combined to yield a “categorical color difference index” (CCDI) that can be computed for any pair of colors in the OSA set of 424 samples. A new experiment is performed in which categorical color perception is encouraged without the explicit use of names by allowing 10 seconds to elapse between the presentation of two stimuli before they are judged same or different. All of the colors being compared are either identical or nearest neighbors in the orange region of the OSA space. Nearest neighbors, which are separated by 2 OSA units, clearly differ when presented simultaneously; with the delay, errors (“same” responses) sometimes occur. These errors decrease as CCDI increases, suggesting that categorization occurs when colors must be remembered. Response time, on the other hand, is independent of CCDI and therefore may reflect color differences based upon discrimination, rather than identification.

Influence of achromatic surrounds on categorical perception of surface colors

Color samples selected from the OSA Uniform Color Scales set were seen isolated in a dark field, illuminated by hidden projectors. These appeared as self-luminous aperture colors when thus isolated. We employed a categorical color-naming procedure to assess color appearance. Achromatic surrounds of 33 min width, if adjacent to samples subtending about 2.2 deg, were sufficient to render normal categorical surface-color perception. As the size of surrounds decreased, color naming shifted from that normally observed in the surface-color mode to that appropriate to the aperture-color mode. For isolated samples, brown was almost never seen, being most often replaced by orange; a white border less than one-sixtieth the width of the color samples was sufficient to restore its perception in an otherwise dark field. The reflectance of the surround and the gap between test and surround stimuli were also examined and found to be important factors in surface color perception, whereas the overall luminance level was not.