Jans, B., Peters, J. C., & De Weerd, P. (2010)
Psychological review, 117(2), 637.
Although in traditional attention research the focus of visual spatial attention has been considered as indivisible, many studies in the last 15 years have claimed the contrary. These studies suggest that humans can direct their attention simultaneously to multiple noncontiguous regions of the visual field upon mere instruction. The notion that spatial attention can easily be split is counterintuitive in the light of current neurocognitive models of attention. We examined studies on divided attention against 4 methodological criteria that should be satisfied in order to convincingly demonstrate divided attention, and we found no studies in the current literature that pass this test. On the basis of current theories of attention, we argue that dividing attention may not be easily achievable by naive human observers and that, instead, it is a skill that may be acquired only through training.
Contribution to the field
This very extensive literature review gave counter-weight to an in our view unfounded hypothesis that attention can be split to monitor stimuli fully simultaneously in various locations without appreciable costs. We suggested that studies making such claims had methodological flaws. Following the publication of this review, a number of studies from the groups of P. Fries and S. Kastner have shown that the attending of multiple locations leads to discrete attentional sampling of those locations, rather than to a parallel attentional split (also in line with the view of R. VanRullen and others).