THE PHENOMENOLOGY OF ATTENTION .2. BRIGHTNESS AND CONTRAST

The effect of attention on perceived brightness and contrast was in in vestigated in eight experiments. Attention was manipulated by engaging observers in an attention-demanding concurrent task (letter detection ) or by directing attention to a location with a peripheral cue, In ai l of the dual-task manipulations, attention reduced the variability of responses. However, attention did not affect the brightness of stimul i, nor did it affect the amount of simultaneous brightness contrast. R esults with peripheral location cues were similar; however, tile effec t of attention in these experiments could be attributed to nonperceptu al factors, The metaphorical ''spotlight'' of attention reduces observ ers' uncertainty about the brightness of a stimulus, but it does not ' 'illuminate'' in terms of brightness or contrast. (C) 1997 Academic Pr ess.