A DISSOCIATION IN NAMING DIGITS AND COLORS FOLLOWING COMMISSUROTOMY

Pairs of red and green digits were flashed in the opposite visual fiel ds of L.B., a man with complete forebrain commissurotomy. He was highl y accurate in naming both digits, the green ones alone, or the red one s alone, regardless of field. In contrast, he was relatively poor at n aming the colors of the digits in the left visual field, and in compar ing colors between fields. This dissociation suggests either (a) that information about shape was tagged by color and transferred from right to left hemisphere, but information about color itself was not transf erred, or, more likely (b) that L.B.'s right hemisphere has acquired t he ability to overtly name highly familiar stimuli, such as digits, bu t not colors.