| Faster or more accurate performance is able to be achieved during the discrimination to between-category colors (e.g. comparing blue to green) than within-category colors (e.g. comparing two different shades of blue). This is defined as categorical perception (CP) of color.A great deal of research on the CP of color supports the idea that it is related to human language processes. But for the question of how language leads to the color CP, current researches have not yet given a thorough explanation and experimental results. Some of the studies think that the color CP is caused by the improvement of language to the discrimination of between-category colors. Once the participants try to complete the task of discriminating the colors via visual encoding, the language encoding process is automatically activated. And the judgment is depended on the verbal label to the stimulus. When the two kinds of colors belong to the different color categories, those two will be given different labels such as green and blue in the discrimination, which is easier to discriminate; when the two kinds of colors are from the same color category, what the participants can depend on is only the physical difference of colors. This theory of improvement focuses on the participation of language in the discrimination on between-category colors rather than the discrimination on the within-category colors. However, the processing of language happens automatically, unconsciously and implicitly. The suggestion that language can optionally participate in the discrimination of between-categorical colors rather in the discrimination of within-categorical colors couldn’t stand by itself. In addition, the ERP experimental results of Liu et al. showed that the discrimination of within-category colors elicited a more conflict-related negative N2component, compared to the discrimination of between-category colors, which could prove that besides the conflict caused by the visual difference there was an effect of conflict caused by language. Therefore, the theory of improvement can’t comprehensively explain the mechanism of color CP caused by language and lack of evidence to prove itself. Thus, in terms of the discrimination of within-category colors, more studies should be done to find out whether verbal label has effect on it and what kind of effect it has. Moreover, a new theory should be explored to thoroughly explain the color CP.Therefore, based on the previous researches and the new neuron evidence, our study comes out a new theory-Verbal Label Comparison Model. This model emphasizes that, during the judgment of whether two kinds of colors are the same or not, two accesses of information processing can be used to make a judgment: the visual perception code and the verbal labels which are implicitly, automatically, and unconsciously compared. And the output of verbal label comparison would influence the response to the output of perception comparison, suggesting the color CP could happen at the response stage. When to discriminate a color pair in within-category, the output of visual comparison is different colors while the output of verbal comparison is the same one. A conflict will be triggered by the incongruent outputs. So the comparison of verbal label slows down the response to the visual comparison. In contrast, for between-categorical color pair, the comparisons of visual perception and verbal labels are linked to the same response-they are the "different" colors. Therefore, the responses are congruent.In order to prove the VLC model, this study took use of the classic conflict-laden paradigm and the conflict adaptation effect paradigm, and tried to gain the behavioral results to prove the reliability of VLC model through the angle of adopting color same-different judgment task to imitate the conflict adaptation effect paradigm and the angle of exploring the correlation between the delayed response times caused by the control to the conflict in the incongruence trials of arrow Flanker task and the response times difference of within-category colors and between-category colors in the color same-different judgment task.In experiment1, the independent variable of interest was pair type (within-category vs. between-category) and trial order (previous trials vs. Current trials).The dependent variable was response times. By imitating the conflict adaptation effect paradigm and controlling the order of former and current trials to avoid the repetition effect, we gained the conflict adaptation effect in the color same-different judgment. RTs to the within-category stimulus (W)following a W stimulus is faster than that following a between-category stimulus(B), while RTs to a B stimulus following a W stimulus is slower than that following a B stimulus. A significant interaction of RTs was found between previous trials and current trials. Based on the results and the explanation of conflict monitoring theory to the conflict adaptation effect, we could conclude that there were incongruence trials, namely, conflict trials, in the color same-different judgment task. Specifically in experiment1. the conflict trial was within-category trial. Therefore, during the discrimination of within-category colors, there is a conflict, which was in line with the VCL model that the outputs of visual encoding and verbal label are incongruent lead to a conflict. In experiment2, the independent variable was task type (arrow Flanker task vs. color same-different judgment task) and the dependent variable was response times. According to the results, in arrow Flanker task, there was a significant difference between the incongruence condition and the congruence condition, and the significant difference also exited in the discrimination between within-category colors and between-category colors. After the Person correlation test between the delayed response times caused by the control to the conflict in the incongruence trials of arrow Flanker task and the response times difference of within-category colors and between-category colors in the color same-different judgment task, we could conclude that there was a moderate correlate between these two kinds of difference of response times. And because the conflict controlling ability of each participant should be stable according to each participant’s spatiality.Therefore, we can conclude that in the color same-different judgment task, the difference of response times between within-category colors and between-category colors is the difference caused by controlling conflict in the discrimination of within-category colors. So, we can prove that the VLC model is reliable.The two experiments of this study gave behavioral evidence to prove that there was a conflict in the discrimination of within-category colors, which was in line with the explanation of the VLC model to the color CP. |
