Selective attention between words, shapes and colors in speeded classification and vocalization tasks.

The presence of irrelevant words (incongruent color and shape names) substantially slowed the sorting of shapes and colors. This interference was maintained over four sessions of practice for color sorting, but essentially vanished for shape classification and color classification using stimuli in which the word and color were physically separated. Interference with oral naming was maintained over 4 days of practice for all types of stimuli, demonstrating that spatial selectivity of attention is highly dependent upon the response requirements of the task.