Attention switching between global and local elements: Distractor category and the level repetition effect

When selecting information at global and local levels of hierarchical stimuli, there is a robust effect of level repetition in which performance is more efficient when a target is presented at the same level as the previous target. Moreover, the effect is symmetrical; it affects global and local processing equally. Evidence exists to suggest the effect may be automatic; however, we show here that the level repetition effect requires some amount of competition from the ignored level, and that the nature of the irrelevant information can determine whether the level-repetition effect is symmetrical (global and local responses are affected equally) or asymmetrical (global responses are more greatly affected than local responses). In Experiment 1, the level-repetition effect was eliminated when information at the distracting level was invariant across trials; effects of hemisphere bias and level repetition were observed only when suppression or filtering of distractor information was required. Experiment 2 demonstrated that simple featural variance is sufficient to produce the level repetition effect and that the symmetry of the level-repetition effect is sensitive to Garner-type interference that affects global processing to a greater extent than local processing. In Experiment 3, we showed that the absence of a level-repetition effect in the invariant distractor condition persists when the position of relevant stimuli is random within a block, a manipulation which should greatly reduce the contribution of controlled attention. We conclude that simple featural variance at the ignored level is critical to produce the advantage of level repetition, and that the size of the effect can be asymmetrical.