Can anticipating distractors influence visual object recognition accuracy?

One of the factors known to influence visual crowding, the reduced ability to recognise a peripheral object in clutter, is attention. For example, cuing the target location reduces crowding. Another way to modulate attention is by influencing expectation. Previously it has been shown that expectation, driven by differences in flanker frequency, can affect target recognition accuracy in an un-crowded flanker-task. Here we tested if flanker-frequency influences orientation discrimination thresholds for tilted clock-like stimuli under crowded conditions. Finding an effect of expectation on crowding would add to the growing number of studies suggesting that crowding cannot be fully explained as a purely feature integration problem. We manipulated crowding (spacing: wide or narrow) and expectation (flanker-frequency: either 25% or 75%) in a block-wise design. As expected, we found that orientation discrimination thresholds increased for flanked compared to un-flanked trials and this increase was more pronounced when the flankers were closer to the target. However, we found no effect of flanker frequency, for either the close or the far flankers. This suggests that, at least in our paradigm, expectation does not influence object recognition, implying that crowding is driven by bottom up signals and is not easily influenced by top down processes. However, we failed to replicate previous results demonstrating an effect of flanker frequency for un-crowded targets; our results, although suggestive, are therefore not the last nail in the coffin for effects of distractor anticipation on visual crowding.