Attention biases decisions but does not alter appearance

Cross-modal attention enhances perceived contrast

“…Crucially, the cueing of attention enhanced neural processing in the same ventral regions of the visual cortex, which, as the authors confirm, are responsive to physical differences in contrast. These results are consistent with the proposal that attention increases perceived contrast by boosting early sensory processing in visual cortex (9,(12)(13)(14), and they contradict the hypothesis that the effect of attention is due to a decisional bias (20).…”

“…However, the issue continues to be debated (19,20). Schneider (19) reported that peripheral cues increase perceived brightness only at levels near detection threshold, more so for white than black cues.…”

Are the effects of attention on speed judgments genuinely perceptual?

“…In two experiments, Schneider and Komlos (2008) replicated the findings in Carrasco et al (2004) with comparative contrast judgments, but when similarity judgments were used (with the same stimuli), the participants' responses did not show any sign of a cuing effect. The authors concluded that the effect of exogenous cues on forced choices about apparent contrast emerges at the decision stage and is not genuinely perceptual.…”

“…Finally, a nonperceptual account of the effect of spatial cuing on judgments of contrast intensity was recently introduced by Schneider and Komlos (2008). In particular, the authors suggested that the effect of spatial attention on judgments of contrast intensity is the consequence of the prioritization of the cued information, which biases the decision process.…”

“…Given Schneider and Komlos's (2008) demonstration of decision biases, rather than modulation of perceived contrast, the question arises as to whether the reported modulation of other perceptual attributes is also due to decision biases. First of all, it should be noted that there are examples of effects produced by exogenous cues that are genuinely perceptual-specifically, those in which exogenous cues have been shown to reduce the intensity of a visual attribute.…”