Cuing interacts with perceptual load in visual search.

We tested the strong form of the perceptual-load hypothesis, which posits that the amount of perceptual load is the only factor determining whether attention can be effectively focused. Participants performed a visual search task under conditions of low and high load and with either a 100% valid spatial cue or no spatial cue. With no cue, participants showed evidence of processing to-be-ignored stimuli when perceptual load was low but not when it was high, consistent with the perceptual-load hypothesis. However with a 100% valid spatial cue, participants showed little evidence of processing to-be-ignored stimuli, even when perceptual load was low. These results suggest that although perceptual load may be an important factor in attentional selectivity, load alone is not sufficient to explain how and when selective attention is effective.