A delayed discrimination task yields categorical perception of color not only in the right but also in the left visual field

Whether categorical perception of color is lateralized in the left cerebral hemisphere (e.g., Gilbert, Regier, Kay, & Ivry, 2006) or not (e.g., Witzel & Gegenfurtner, 2011) is still controversial. This ongoing debate, however, has been studied with visual search tasks, which seemed to produce residual laterality effects. The present study assessed whether a delayed discrimination task with divided visual field method, rather than visual search tasks, yields lateralized or bilateral categorical perception of color. The results showed an advantage for between-category discrimination relative to within-category discrimination. Such an advantage, importantly, was obtained in the left visual field as well as in the right visual field. These results suggest categorical perception of color is bilateral and not lateralized. Combining recent studies with visual search tasks (e.g., Witzel & Gegenfurtner, 2011), our results would provide further evidence for bilateral categorical perception, and thus throw doubt on the laterality effects of categorical perception.