Individual differences in working memory capacity: more evidence for a general capacity theory.

The causes of the positive relationship between comprehension and measures of working memory capacity remain unclear. This study tests three hypotheses for the relationship by equating the difficulty, for 48 individual subjects, of processing demands in complex working memory tasks. Even with difficulty of processing equated, the relationship between number of words recalled in the working memory measure and comprehension remained high and significant. The results favour a general capacity view. We suggest that high working memory span subjects have more limited-capacity attentional resources available to them than low span subjects and that individual differences in working memory capacity will have implications for any task that requires controlled effortful processing.