Flexibility in resizing attentional breadth: Asymmetrical versus symmetrical attentional contraction and expansion costs depends on context.

One of the core ways that attentional resources can be regulated is the breadth of attention: the tendency to concentrate one's attentional resources over a small region of space (i.e., "narrow scope"), or to spread them over a larger region of space (i.e., "broad scope"). It has long been understood that humans have a preference towards the broad or global level of processing. More recently, beyond any static preference, researchers have increasingly appreciated the importance of rapid rescaling of attentional breadth to meet task demands, especially for real-world tasks such as driving. Here, we examined whether there was any asymmetry in the human capacity to resize attention from a narrow to broad scale (expansion) versus a broad to narrow scale (contraction). In Experiment 1, we found remarkable symmetry in expansion and contraction efficiency, even under conditions where the global stimuli were demonstrably more salient. This indicates that humans can flexibly adapt to the attentional demands of the context. However, in Experiment 2, an asymmetry was revealed, whereby attentional expansion was more efficient than contraction. The key difference between Experiments 1 and 2 was whether or not the initial baseline block demanded frequent attentional resizing, suggesting that recent experience can impact attentional flexibility. We also found reliable individual differences in participants' ability to resize their attentional breadth, identifying a group of high-flexibility individuals who excelled at both attentional expansion and contraction.