The effects of spatial and temporal cueing on metacontrast masking

We studied the effects of selective attention on metacontrast masking with 3 different cueing experiments. Experiments 1 and 2 compared central symbolic and peripheral spatial cues. For symbolic cues, we observed small attentional costs, that is, reduced visibility when the target appeared at an unexpected location, and attentional costs as well as benefits for peripheral cues. All these effects occurred exclusively at the late, ascending branch of the U-shaped metacontrast masking function, although the possibility exists that cueing effects at the early branch were obscured by a ceiling effect due to almost perfect visibility at short stimulus onset asynchronies (SOAs). In Experiment 3, we presented temporal cues that indicated when the target was likely to appear, not where. Here, we also observed cueing effects in the form of higher visibility when the target appeared at the expected point in time compared to when it appeared too early. However, these effects were not restricted to the late branch of the masking function, but enhanced visibility over the complete range of the masking function. Given these results we discuss a common effect for different types of spatial selective attention on metacontrast masking involving neural subsystems that are different from those involved in temporal attention.