Attention induces conservative subjective biases in visual perception.

Although attention usually enhances perceptual sensitivity, we found that it can also lead to relatively conservative detection biases and lower visibility ratings in discrimination tasks. These results are explained by a model in which attention reduces the trial-by-trial variability of the perceptual signal, and we determined how this model led to the observed behavior. These findings may partially reflect our impression of 'seeing' the whole visual scene despite our limited processing capacity outside of the focus of attention.