as described in the Methods section, a MDS was calculated for all the colors and for all the shapes, respectively (see Figure 4). The results of the MDS are consistent with what was found with the Chi-square tests. This figure clearly shows that black, green, pink, and white are situated far away from each other in the MDS, consistent with the results of the Chi-square tests that they are strongly associated with four different tastes. On the other hand, the MDS figure shows one close cluster comprising the cloud, heart, and stars, and another tightly distributed cluster consisting of the cross, rectangle, and square. These results are consistent with the results of the Chi-square tests that cross, rectangle, and square are associated with bitter, whereas the cloud, heart, and star are associated with sweet instead.
FIGURE 4. Multi-dimensional scaling of distances among colors (upper panel) and shapes (lower panel). The thumbnails of the targets (color patches in the upper panel and shapes in the lower panel) were arranged in the way that their distance between each other reflects their dissimilarity in taste-patterns. Data from all countries combined, weighted by the confidence rating.
Cross-Cultural Similarities and Differences in the Taste-Patterns
In order to examine the cross-cultural difference in the taste-patterns, we first performed a log-linear analysis, using Stimulus (28 color-, shape-, and texture-stimuli) × Taste (bitter, salty, sour, sweet, and umami) × Country (China, India, Malaysia, and the USA) as the variables. The final model retained all effects. The likelihood ratio of this model was χ2(0) = 0, p = 1.00, indicating that the 3-way interaction of Stimulus × Taste × Country was significant, χ2 = 860.34, p < 0.001. In order to interpret this term, we then performed 2-way log-linear analyses for each stimulus with Taste and Country as variables. As can be seen in Table 2, the interaction between Taste and Country was significant for eight of the colors (blue, green, gray, orange, purple, red, white, and yellow), five of the shapes (asymmetrical star, drop, heart, moon, and star), and one of the textures (smooth). The effects of country on the taste-patterns for these stimuli are demonstrated in Figure 5.
FIGURE 5. The taste-patterns for stimuli with which cross-cultural differences were found. Note that the percentage of the bitter, salty, sour, sweet, and umami taste terms chosen for the visual stimuli are represented by the fill-in colors black, white, green, pink, and blue, respectively.
Representational dissimilarity matrices were also calculated as a function of the culture (see Figure 6). First, the blue color displays similar taste-patterns as the color white for the Malaysian participants. The Chinese and Indian groups also showed the same trends; whereas participants from the USA did not. Second, the Indian participants exhibited similar taste-patterns for the colors green, orange, pink, purple, red, and yellow; whereas the Chinese group might further divide these colors into two sub-groups, each one having similar taste taste-patterns, including (1) green, orange, and purple, and (2) red, yellow, and pink. By contrast, the participants from Malaysia and the USA did not show any such pattern of results. By contrast, some cross-cultural similarities can be found in the shape-taste associations across the four cultural groups. That is, they all had a sub-group of shapes with similar taste-patterns, including the square, rectangle, and cross shapes. On the other hand, the Indian, Malaysian, and USA groups all had a sub-group of star, moon, and heart with similar taste-patterns, whereas the Chinese group did not clearly show such a pattern. As for the asymmetrical star shape, drop shape, and rough shape, all the four groups showed different patterns from each other.
FIGURE 6. The RDMs for color-shape-texture-taste associations for each group of participants. The color of each cell stands for the dissimilarity between the taste-associated patterns of the objects in the respective row and column, wit