Short-term Trained Lexical Categories Cause a Shift of Color Categorical Perception from Right Hemisphere to Left Hemisphere

Abstract

Zhou et al.(2010) demonstrated that newly trained lexical categories produced lateralized categorical perception(CP) of color, suggesting that color CP can be a result of learned categories. However, since the way in which participants learned the name of a color in their study different from the one in actual life, the ecological validity of this study can be challenged. In actual life, a color name is connected with a color category. For example, the word "blue" refers to all kinds of blue. Can the training used by Zhou et al.(2010) induce participants to learn such a connection between the color name and a color and therefore produce color CP? In order to reveal the relationship between lexical categories and color CP more exactly, the present study probed into this question. Moreover, the present study also aimed at investigating the cognitive mechanism in acquired category effects. Six colors were used in the present study. B1 and B2 were light blue and dark blue. By making B1 and B2 lighter and darker, we obtained B11 and B12, B21 and B22 respectively. B11,B12, B21 and B22 formed a graded series from light to dark blue. Participants were trained to name B1 and B2 with two meaningless syllables duān and kěn, respectively, in six training phases. Given that participants may connect the color name to a color category after training, we expected B12B21 to be between-category color, but B11B12 and B21B22 to be within-category color pairs. Participants also completed a visual search task before and after the training, in which they were asked to search a target color from a ring of 12 colored squares surrounding a fixation marker, and indicated whether the target was on the left or right side of the circle by making button-press responses. The data showed that, in the visual search task before training, reaction times to targets were faster for between-category color pair candidate than for within-category color pair candidates. Moreover, this effect was more significant when the targets were presented in the left visual filed. In the visual search task after training, reaction times to targets were also faster for between-category color pair candidate than for within-category color pair candidates, but the effect was more significant when the targets were presented in the right visual filed. In conclusion, the findings of the present study suggested that(1) when perceiving different colors shared the same lexical category, participants may distinguish them into different sub-categories, which produced a right hemisphere color CP;(2) trained lexical categories can produce a left hemisphere color CP, and also cause a shift of color CP from right hemisphere to left hemisphere;(3) participants can learn a connection between color name and color category even when only a specific color was presented;(4) category learning may occur automatically even when participants learn only one example.