Target specificity improves search, but how universal is the benefit?

Pictorial cues generally produce stronger search performance relative to categorical cues. We asked how universal is the benefit of a pictorial cue? To test this, we trained observers to categorize sinusoidal gratings in which categories were distinguished by spatial frequency or orientation. Next, participants completed a search task in which targets were pictorially and categorically cued. Measures of target and distractor processing that primarily rely on foveal processing showed universal benefits; however, the benefit was larger in the orientation condition. Importantly, an index of the direction of spatial attention (i.e., target guidance) showed that the orientation condition produced a pictorial benefit but the spatial frequency condition did not. Experiment two replicated the spatial frequency results and also included conditions that increased the discriminability, lowered the spatial frequencies, or both increased the discriminability and decreased the spatial frequencies of the categories. We found that only categories utilizing lower spatial frequencies produced a pictorial guidance benefit. This demonstrates that pictorial cues do not universally improve search performance above categorical cues; it depends on the features that distinguish the categories. Additionally, the increased discriminability condition improved guidance but failed to produce a pictorial benefit, suggesting an interesting disassociation between the amount of target guidance and the existence of a pictorial benefit. Given that perception is known to progress from low/coarse to high/fine spatial frequencies, this suggests that the pictorial guidance benefit acts on early low spatial frequency processing only, but foveal object recognition processes utilize both early and late spatial frequency processing.