Although a number of theories of intelligence have been created in the past century, Horn and Cattell's (1966) Theory of Fluid and Crystallized Abilities has reigned as one of the more popular theories of intelligence with the Raven's Progressive Matrices being the most used assessment of fluid intelligence. Fluid intelligence is the ability to solve novel problems with minimal involvement from prior training or strategies retrieved from memory. In general, fluid intelligence cannot be improved through training. But, recent studies have shown that working memory capacity and visuospatial abilities have a strong relationship with fluid intelligence. Based on the knowledge that working memory capacity can improve with training, a recent study by Jaeggi, Buschkuehl, Jonides, and Perrig (2008) claimed to have improved fluid intelligence by having participants complete a four week training program using the dual n-back task. The dual n-back task is a working memory task that presents auditory and visual stimuli simultaneously. A concern of Jaeggi et al.'s study was whether they improved fluid intelligence as the construct is defined by Horn and Cattell, or if the improvement in test performance was due to improved visuospatial abilities. The current study replicated and expanded Jaeggi et al.'s study by having participants complete variations of the dual n-back task as training. Participants were assessed with four tests of Gf and four cognitive tests.

The current study was successful in replicating Jaeggi et al.'s (2008) results. However, the current study also observed improvements in scores on the Raven's Advanced Progressive Matrices for participants who completed a variation of the dual n-back task or a short-term memory task training program. Participants' scores improved significantly for only two of the four tests of GJ, which raises the issue of whether the tests measure the construct Gf exclusively, as defined by Cattell (1963), or whether they may be sensitive to other factors. The concern is whether the training is actually improving Gf or if the training is improving attentional control and/or visuospatial skills, which improves performance on specific tests of Gf. The findings are discussed in terms of implications for conceptualizing and assessing G f.