How to exploit diversity for scientific gain: Using individual differences to constrain cognitive theory

People often show considerable systematic variability in their ability to perform many different cognitive tasks. In this article, we argue that by combining an individual-differences approach with an experimental-cognitive-neuroscience approach one can often further constrain potential theories of the underlying cognitive mechanisms. In support of this proposal, we outline three basic benefits of using an individual-differences approach: validating neurophysiological measures, demonstrating associations among constructs, and demonstrating dissociations among apparently similar constructs. To illustrate these points, we describe recent work by us and other researchers that utilizes each of these techniques to address specific questions within the domain of visual working memory. It is our hope that some of these techniques for utilizing individual variability may be applied to other domains within cognitive neuroscience.