The ability of 24 infants between 15 and 70 days of age, at the beginning of experimentation with them, to discriminate between combinations of red, yellow-green, green, and blue-green was studied. Combinations of the color filters were made up so that two colors were projected upon a screen above the infant's head as he lay on his back. It was then determined whether the infant could detect movement when the filter was moved back and forth in the projection machine. The appearance on the screen of the two colors was such that one color was surrounded by the other color. When the filter was moved, the center color appeared to move within the field of the other color. If movement could be detected discrimination between the two colors by the infant could be assumed. By observing the following of the infants' eyes in relation to the moving color stimuli, it was found that they could discriminate between the color combinations red and yellow-green, red and green, red and blue-green, yellow-green and green, yellow-green and blue-green, and green and blue-green. Control experiments showed that the discriminations had not been made upon the basis of a brightness difference or of some mechanical aspect of the experimental situation. (PsycINFO Database Record (c) 2006 APA, all rights reserved)