Categorical perception of color (CCP) refers to the phenomenon by which the discrimination of between-category (BC) colors (i.e., colors that fall into different color categories) is faster and more accurate than the discrimination of within-category (WC) colors (i.e., colors that belong to the same category). Theoretical controversy exists regarding the influence of perception and language on CCP. The perception-based view holds that, although different lexical codes may be used, language does not affect CCP. In contrast, the language-based view suggests that language can influence the speaker’s thought, and thus, language exerts an influence on CCP. Several studies of CCP have provided evidence supporting both views. In recent years, a new theory, the categorical/verbal label comparisons (VLC) model, has been developed in which it is argued that cognitive conflict between a combination of semantic and perceptual processes leads to CCP, and thus, this effect is essentially one of cognitive processing rather than perceptual recognition or lexical codes. This study attempts to investigate the role of perception and language in CCP by changing participants’ ability to process information regarding either color vision or semantics.
In this study, participants were required to perform a visual search task to find the only chip (object) that was different in color from 12 other chips (background) around a fixation point. The participants were asked to press “f” when the object was presented to the left of the fixation point and “j” when the object was presented to the right of the fixation point. In Experiment 1, color vision fatigue was used to disturb the color vision of 26 university students who were randomly selected to perform a shape discrimination task unrelated to CCP. In the fatigued condition, two colors belonging to the same category flickered on the screen at 50 Hz for 15 s, and then, 12 trials of the visual search task were performed. In the nonfatigued condition, a constant gray background was presented on the screen lasting 15 s, followed by the visual search task. In Experiment 2, semantic satiation was used to disturb the semantic processing of 22 university students who were randomly selected to perform a meaning-judgment task unrelated to CCP, in which the meaning of a word on the screen was either that of a color or a facial expression. In the high-satiation condition, 60 equivalent color words and 6 noncolor words were judged, and then, 12 trials of the visual search task were performed. In the low-satiation condition, 60 equivalents facial expression words and 6 color words were judged, followed by the visual search task.
A 3-way repeated measures ANOVA was performed on the RT data from Experiment 1 (category type x degree of color vision fatigue x visual field). The results indicated that the interaction between category type and the degree of color vision fatigue was significant, F(1, 25) = 49.250, p < 0.001, ηp 2 = 0.663. Color vision fatigue was associated with increased RTs for within-category colors (not significant) and with significantly decreased RTs for between-category colors, F(1, 25) = 6.760, p = 0.015, ηp 2 = 0.213. A 2-way repeated measures ANOVA was performed on CCP effects (the RTs for the within-category condition minus the RTs for the between-category condition), and the results indicated that the main effect of the degree of color vision fatigue was significant, F (1, 25) = 13.183, p = 0.001, ηp 2 = 0.345, such that the fatigued condition (41 ms) produced stronger CCP effects than the nonfatigued condition (17 ms). These results indicated that color vision fatigue increased the effect of CCP in participants. In Experiment 2, since semantic satiation only disturbs the word being satiated without disturbing the others, the two types of stimuli in the WC condition may have been affected differently. Based on whether the meaning of the two colors in the WC condition was identical to the meaning of the satiating word, the WC condition was split into two conditions: identical-WC and nonidentical-WC. A 3-way repeated measures ANOVA was performed on the RT data from Experiment 2, and the results indicated that the interaction between category and the degree of semantic satiation was significant, F(1, 20) = 4.674, p = 0.022, ηp 2 = 0.330. A simple effects analysis found that the RTs in the two WC conditions were not significantly different from the RTs in the low-satiation condition (287 ms for identical vs 283 ms for nonidentical, p = 0.377), but both WC condition RTs were slower than those in the BC condition (263 ms, p < 0.001). The RT for the identical-WC condition (291 ms) was slower than both those in the nonidentical-WC condition (279 ms, p = 0.004) and those in the BC condition (261 ms, p < 0.001). A 3-way repeated measures ANOVA was performed on CCP effects (condition x degree of satiation x visual field), and the results indicated that the interaction between identical type conditions and the degree of satiation was significant, F(1, 20) = 8.471, p = 0.009, ηp 2 = 0.298. A simple effects analysis found that the identical-WC condition (30 ms) produced a stronger CCP effect than the nonidentical-WC condition (18 ms) in the high-satiation condition, F(1, 20) = 10.772, p = 0.004, ηp 2 = 0.350, but this comparison was not significant in the low-satiation condition (23 ms vs 19 ms), F(1, 20) = 0.773, p = 0.390. These results indicated that semantic satiation increased CCP effects in participants in the identical-WC condition. In sum, the results of these experiments indicated that semantic processing was not influenced by color vision fatigue, but it was influenced by semantic satiation.
Linguistic relativism cannot explain the perceptual effects found in Experiment 1, and linguistic universalism cannot explain the semantic effects found in Experiment 2; only the VLC model can explain all the results of this study. Therefore, this study supports the VLC model. Participants’ color vision was disturbed by color vision fatigue, such that the role color vision information played in visual search task performance was decreased, and the effect of semantic information was increased. As a result, the effect of CCP increased in Experiment 1. In Experiment 2, the participants’ semantic processing of the satiated word was disturbed by semantic satiation, leading to difficulty in extracting the meaning of the satiated word. Therefore, the RT in the identical-WC condition was slowed, and the effect of CCP was increased.