Spatial attention and feature-based attention are differentially sensitive to individual working memory capacity and perceptual load

A central and long-standing topic of interest to both psychologists and neuroscientists has been the capacity limited nature of perception, cognition and action. Most often, attention is the term invoked to label the mechanism by which a limited cognitive system can prioritize and select a subset of task-relevant sensory inputs and actions amongst a seemingly unbounded set of possible representations and behaviour. This selective mechanism is often modelled as a unitary and domain-general capacity-limited resource that is dynamically shifted to meet the processing demands invoked by the context. The present work offers a test of the unitary attention hypothesis using a variant of a classic validity manipulation [(Posner, M. I. (1980). Orienting of attention. Quarterly Journal of Experimental Psychology, 32, 3-25)] and the inferential logic of Sternberg (2001. Separate modifiability, mental modules, and the use of pure and composite measures to reveal them. Acta Psychologica, 106, 147-246). The results stand as evidence for at least two modular visual attention systems split according to a spatial and feature-based reference.