I have pointed out in an earlier post how training young children to increase their working memory capacity will increase their IQ. This same phenomenon has now been demonstrated in young adults (mean age = 25.6 years).
Subjects were pre-tested on an IQ test involving visual analogy problems of increasing difficulty. Each problem presented a matrix of patterns in which one pattern was missing. The test was to identify the missing pattern from a set of alternatives. After training or a control without training, the test was repeated and scores compared.
The working memory task consisted of presenting at the same time two short series of stimuli, one visual and one auditory. The visual stimuli consisted of a small white square positioned at one of eight locations on a black screen and presented sequentially every three seconds. After seeing the series, the subject was tested with a test screen and asked to say if it matched the screen that was presented some n-number of screens earlier. This is a standard n-back paradigm often used to test working memory capacity. The n was adjusted to performance level and increased as subjects became proficient at remembering 2, then 3, etc. prior screens. A similar protocol was used for the auditory task, which involved hearing a recording of the sounds of a sequence of alphabet letters, with subjects asked to tell if a target test sound was the same as one they had heard 2, 3, or more sounds earlier.
Both working memory capacity and IQ improvements were seen in as little as 8 daily training sessions, and subjects steadily improved as training was extended to 19 days of training.
Jaeggi, S. M. et al. 2008. Improving fluid intelligence with training on working memory. Proc. Natl. Acad. Science. www.pnas.org/cgi/doi/10.1073/pnas.0801268105