The study investigates whether attention alters the perceived appearance of stimuli, a question that has been debated for over a century. Using a psychophysical method, the authors demonstrate that attention increases the apparent contrast of stimuli, enhancing their perceived salience. This effect is consistent with neurophysiological findings showing that attention increases neuronal contrast sensitivity (contrast gain). The experiments involve observers performing orientation discrimination tasks while covertly attending to either a peripheral or central cue. Results show that when attention is directed to a peripheral cue, the cued stimulus appears more contrasted than it actually is, improving performance in the discrimination task. The findings suggest that attention changes the strength of a stimulus by boosting its 'effective contrast' or salience, enhancing its perceived intensity. This research contributes to the understanding of how visual attention optimizes the limited capacity of the visual system.The study investigates whether attention alters the perceived appearance of stimuli, a question that has been debated for over a century. Using a psychophysical method, the authors demonstrate that attention increases the apparent contrast of stimuli, enhancing their perceived salience. This effect is consistent with neurophysiological findings showing that attention increases neuronal contrast sensitivity (contrast gain). The experiments involve observers performing orientation discrimination tasks while covertly attending to either a peripheral or central cue. Results show that when attention is directed to a peripheral cue, the cued stimulus appears more contrasted than it actually is, improving performance in the discrimination task. The findings suggest that attention changes the strength of a stimulus by boosting its 'effective contrast' or salience, enhancing its perceived intensity. This research contributes to the understanding of how visual attention optimizes the limited capacity of the visual system.