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The Berkeley Color Project The Berkeley Color Project is a large-scale study of color perception and aesthetics. We argue that this complex domain, replete with marked individual differences and emotional overtones, is best approached using a massive repeated measures (MRM) design in which the same subjects evaluate the same set of colors over a wide range of tasks, including preferences (for single colors, color pairs, colors in different contexts), colorimetric assessments (red/green, yellow/blue, light/dark, and saturation), and associations (with various emotional dimensions and classical music). Forty-eight participants balanced for both gender and artistic experience, performed 32 tasks with 37 colors sampled from color space: 8 hues (unique red, green, blue, and yellow plus their approximate angle bisectors: orange, purple, cyan, and chartreuse) at 4 brightness/saturation levels (light, dark, saturated, and medium), plus 5 matched achromatic colors. Color Preferences In this portion of the Berkeley Color Project we investigate preferences for single colors and color combinations. Average preferences for single colors yielded a relatively smooth function of hue with a peak at blue and a trough at chartreuse, for which rated blueness/yellowness explained 88% of the variance. Preferences were largely invariant across saturation and lightness levels, except that (a) dark yellow and dark orange (browns) were less preferred than their lighter counterparts, (b) dark red was more preferred. Preference for color combinations could only weakly be predicted by preference for individual colors in each pair. Adding participants' ratings of color harmony, however, dramatically increased the amount of variance explained. Individuals differed in the degree to which they preferred combinations that they found harmonious (correlations raging from -0.11 to 0.74). Originally when this poster was presented we concluded that these individual differences could be accounted for by measures of personality (BFI), but this was no longer true once we had our full set of data. Artistic experience does, however relate to preference for harmony: people with no artistic experience and people with a lot of artistic experience are less influenced by harmony than people who have a moderate amount of artistic experience. The Color of Music We investigated the relations among color, music, and emotion for the 37 colors of the Berkeley Color Project: saturated, desaturated, light, and dark shades of red, orange, yellow, yellow-green, green, blue-green, blue, and purple, plus white, black, and 3 grays. To study color/music relations, participants viewed all 37 colors while listening to 18 orchestral selections in major and minor keys by Bach, Mozart, and Brahms that had slow, moderate, and fast tempos. For each selection, participants chose the five most-consistent and the five least-consistent colors. Across composers, faster tempos and major keys were both associated with brighter, warmer, more saturated colors than slower tempos and minor keys. To determine whether affective responses might mediate these color/emotion associations, we also studied the relation between the color samples and emotion words and between the musical selections and emotion words. Participants produced color/emotion associations by rating the consistency between 16 emotion words and each of the 37 colors. Strong associations were found between many emotion words and colorimetric dimensions: e.g., happy, lively, and enthusiastic with light-warm-saturated colors; sad, dreary, and unenthusiastic with dark-cool-desaturated colors; strong and aggressive with warm-saturated colors; and weak and shy with cool-desaturated colors. Participants also produced music/emotion associations by rating the consistency between each emotion word and each of the 18 musical selections. We found a strong link between the affective response to musical selections and the affective response to the corresponding chosen colors. Specifically, there was a strong positive correlation between the ratings of emotional associations to the 18 musical selections and the ratings of emotional association to the colors people chose as most/least consistent with the same musical selection. This finding suggests that affective response may mediate the relations we found between color and music. Preference for Three-Color Combinations in Varying Proportions Previous research on preference for color combinations investigated pairs of colors (Schloss & Palmer, VSS-07; Ou & Luo, 2006). The current project investigated preference for combinations of three colors in varying proportions. The full set of 37 colors included eight hues (red, orange, yellow, chartreuse, green, cyan, blue and purple) at four saturation/lightness cuts through color space (high-saturation, medium-saturation, light, and dark), as well as five grays. In Experiment 1, displays were 45-degree-rotated checkerboards whose two colors were always adjacent high-saturation hues. When a third color of any of the remaining six hues was present, it formed squares of four different sizes (large, medium, small and absent) at the intersections of the checkerboard. Observers rated their preferences for each display. Later they also rated their preferences for the individual colors in isolation. The results showed that displays containing no third color were most preferred, and preference decreased as the area of the third color increased (p < .05). When the third color was present, the display was most preferred when the third color was closest in hue to the other two colors, consistent with prior studies of color harmony (Schloss & Palmer, VSS-07). A regression model accounted for 62% of the variance with the following predictors: size of the third color square, average preference for the two individual checkerboard colors, distance in hue between the third color and the checkerboard colors, and redness/greenness of the checkerboard colors. Further experiments examined cases in which adding the third color increased the harmony of the two-color combination, and in which combinations of colors in other cuts of the color space were investigated. The Role of Spatial Composition in Preference for Color Pairs In this project we investigated the role of spatial composition in preference for color pairs. Our 37 colors included: 8 hues (red, orange, yellow, chartreuse, green, cyan, blue, purple) x 4 brightness/saturation levels (saturated, desaturated, light, dark) plus five grays. In the first experiment, displays contained two figure-ground pairs (small squares on larger squares), side-by-side. Both pairs contained the same two colors in opposite spatial locations (e.g., yellow figure on blue ground and blue figure on yellow ground). Participants were asked whether they preferred the left, right, or neither pair. A regression model showed that 32% of the variance was explainable by difference in preference for figure and ground colors when rated in isolation: pairs in which the ground color was more preferred than the figure color were more preferred overall. An additional 33% of the variance, however, was explainable by yellowness/blueness and lightness darkness: pairs with yellower, lighter figures and bluer, darker grounds were more preferred. In the second experiment we tested whether relative area, surroundedness or shared perimeter size influenced how spatial composition affected pair preference. In figure-ground displays we varied the area (and perimeter) of the figure; in bipartite displays we varied the relative size of the left and right regions; and in "plus sign" displays we varied the perimeter of the figure and held area constant. Results show that relative area was the most important factor influencing preference. For both figure-ground displays participants preferred color combinations in which the smaller region was yellower and the larger region was bluer. This was also true for bipartite displays, showing that surroundedness was not an important factor. Changes in perimeter when area was held constant had no effect on preference. Preference for color-pairs within finely sampled color space In previous research we found that preference for color pairs increased as a function of color similarity (Schloss & Palmer, VSS07). The 37 colors we used were only coarsely sampled within color space, however: 8 hues (red, orange, yellow, chartreuse, green, cyan, blue and purple) x 4 brightness/saturation levels (saturated, light, muted and dark) plus five grays. In this experiment, we tested whether preferences for color pairs remained monotonic when sampled more finely between the colors previously examined. Four equally spaced colors were interpolated between (a) adjacent saturated hues (hue change), (b) saturated and muted colors of the same hue (saturation change), (c) light and muted colors of the same hue (lightness change), and (d) muted and dark colors of the same hue (darkness change). We used checkerboard displays rather than figure-ground pairs with a central square on a larger ground square to avoid potential artifacts due to relative depth. Half of the displays contained narrow gaps between the squares of the checkerboard and half did not, but this factor did not matter. If preference were simply a function of color similarly, then there should be a monotonic increase in preference as color similarity increased. This was not the case: preference increased as similarity in saturation and lightness decreased (p < .001), and it was not significantly affected by similarity in hue (p > .05). In addition, checkerboards with differences in lightness/darkness were always more preferred than those with differences in hue or saturation (p < .001), regardless color similarity. These findings support the hypothesis that very similar colors "clash" more than less similar colors within a finely sampled color space, especially for differences in saturation and lightness. Further experiments will examine the relation between color discriminability and color preference. The Relationship between Color and Form in Judgments of Preference and Harmony In this study we investigated how the shapes and colors of lines influenced both preference and harmony ratings. We used two types of lines, irregularly jagged and smoothly curved, which were each presented in isolation as well as in side-by-side pairs: both jagged, both curved, and jagged + curved. Colors included eight saturated hues (unique-red, orange, unique-yellow, chartreuse, unique-green, cyan, unique-blue and purple). Single lines appeared in each of the eight colors. Pairs of lines appeared in one of three color relationships: same hue (identity), adjacent hues (analogous), or opposite hues (complementary). Average preference ratings were only affected by line type: curved single lines were preferred to jagged single lines, and pairs containing same-shaped lines (both curved or both jagged ) were preferred to pairs that contained one line of each type. In contrast, harmony ratings were strongly influenced by both line type and color relationship. Single curved lines were judged more harmonious than single jagged lines, curved pairs were more harmonious than jagged pairs, and pairs with different lines types were judged least harmonious. For all line pair types, harmony ratings increased as a function of hue similarity, consistent with Schloss and Palmer's (VSS-07) findings that color harmony for figure ground pairs is largely driven by hue similarity. Cross-Cultural Differences in Color Preference: Japan vs. the USA We studied cross-cultural color preferences for the 37 colors of the Berkeley Color Project: 8 hues (unique-red, orange, unique-yellow, chartreuse, unique-green, cyan, unique-blue, and purple) x 4 brightness/saturation levels (saturated, desaturation, light, and dark) plus five grays. Forty observers in Tokyo, Japan, and 48 observers in Berkeley, USA, rated aesthetic responses to all 37 colors using a line-mark ratings scale. The hue preference functions (averaged over brightness/saturation levels) were very similar for Japanese and American observers, with a broad peak around blue and a trough around yellow-chartreuse. Reliable differences were present in preferences for brightness/saturation levels, however. In particular, Japanese observers had a greater relative preference for light colors, rating light colors higher than Americans did and rating dark colors lower than Americans did. Japanese observers also liked desaturated (muted) colors less than American observers for warm colors (chartreuse, yellow, orange, red, and purple) but not for cool colors (green, cyan, and blue). Some gender effects were similar in the two cultures, but others were different. Males in both cultures tended to prefer saturated colors more than females, whereas females in both cultures tended to prefer desaturated colors more than males. Japanese females also preferred relatively lighter colors more than Japanese males, rating light colors more highly and dark colors less highly than their male counterparts. No similar interaction was present in the American observers, however. A colorimetric model based on yellowness/blueness, saturation, and brightness/darkness explained 79% of the Japanese group variance, versus 60% for the American data. An ecological-valence model, based on the assumption that people like colors that remind them of positive things (sky, trees) and dislike colors that remind them of negative things (vomit, feces), will also be fit to the data to determine whether the cultural differences we found can be predicted by this model. An Ecological Valence Theory of Human Color Preferences We studied color preferences for 37 colors: 8 hues x 4 brightness/saturation levels plus five grays. Average color preference for saturated, desaturated, and light colors was a relatively smooth function of hue with a strong peak at blue and a trough at chartreuse. The hue function differed for dark colors: dark orange and yellow were much less preferred, and dark red and green were somewhat more preferred. Males preferred saturated colors to desaturated ones, whereas females preferred desaturated colors to saturated ones. Male-female differences were highly correlated with rated activeness/passiveness of colors (r=0.73), with males preferring active colors. People with greater color expertise preferred chromatic colors more than novices, but both preferred achromatic colors equally. Despite enormous individual differences, hue preference was relatively stable within observers across brightness/saturation levels (average r=0.35). Hue preference was also relatively stable across contextual objects: walls, trim, couches, pillows, shirts/blouses, ties/scarves (average r=0.65). A colorimetric model based on yellowness/blueness, saturation and brightness/darkness explained 60% of the group variance, whereas an emotional-association model based on calmness, courageousness, and frustratedness of colors explained 79%. We also tested an ecological-valence model, hypothesizing that people like colors that remind them of positive things (sky, trees) and dislike colors that remind them of negative things (vomit, feces). We asked participants to name all the objects that came to mind for each presented color and later obtained ratings of how positive/negative they felt about each object. We then weighted the average valence for each object by the frequency with which it was reported for each color. Color preference was strongly related to this weighted object valence measure (r=0.83), suggesting that color preference may be analogous to taste in food: a heuristic designed to help guide us toward potentially beneficial objects and situations and away from potentially harmful ones. All of the above research is funded in part by NSF Grant BCS-0745820 to Stephen E. Palmer and by a gift from Google, Inc. |
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