The Effects of Feature-Based and Memory-Driven Attention on Appearance
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Recent evidence suggests that, in addition to improving performance, spatial attention alters the perceptual experience of visual stimuli. We investigated whether two other forms of attention – feature-based attention, and memory-driven attention – also produce an increase in the perceived contrast of stimuli. Perceived contrast was measured by requiring participants to report which of two Gabor stimuli appeared higher in contrast, under different attentional or memory conditions. In Experiment 1, our results indicated that participants indeed allocated attention in a feature-based manner, but no increase in perceived contrast when attending to a given colour was found. Instead, feature-based attention appears to have produced a response bias, such that a stimulus was selected more often when it was attended. In Experiment 2, no change in perceived contrast due to the memory task was observed. A subsequent experiment indicated that our memory task may not have succeeded in causing an attentional shift, which limits the scope of our conclusions on the relationship of memory to perception, but is informative for the development of effective memory manipulations. Overall, our results have provided evidence that the mechanisms of feature-based attention may not be identical to those of spatial attention, but have left the effects of memory-driven attention to be determined.