The N-Back Task: What Does It Measure?

Some of the most practically useful findings in the discipline of cognitive psychology are the relationships between working memory capacity (WMC) important cognitive abilities and the way WMC is critical for a variety of different psychological constructs (Engle & Kane, 2004).  However, one problem that is frequently neglected is that researchers use different cognitive tasks to measure and study WMC. For the present study, subjects completed two complex span tasks (Operation Span and Symmetry Span), two measures of fluid intelligence (Raven’s Advanced Progressive Matrices and Number Series), and two measures of n-back. One of the n-back measures used verbal stimuli (digits, letters, and words) and the other measure of n-back used visuospatial stimuli (Faces, Wingdings, and Kanji). Additionally, we manipulated the amount of interference there was in the n-back tasks. The present study has three critical research questions. First, are complex span tasks and n-back tasks correlated highly enough to infer that they measure the same cognitive ability? Second, do the complex span tasks and n-back tasks predict the same variance in fluid intelligence measures or do they predict unique variance in this important cognitive ability. Last, does our interference manipulation change how the n-back tasks correlate with the complex span tasks and the measures of fluid intelligence?