Stocks and losses , items and interference : A reply to Oberauer and

Results of a recent study of spatial working memory are presented in support of the claim by Jenkins and her colleagues (Jenkins, Myerson, Hale, & Fry, 1999) that secondary tasks produce larger interference effects in individuals with higher simple spans than in individuals with lower simple spans. Because spans and interference effects were assessed independently, this study refutes the claim by Oberauer and Süß (2000) that the relation between span and interference effect size is merely an artifact of regression to the mean. In contrast with the present findings, Oberauer and Süß did not find evidence of larger interference effects in higher span individuals, but the reason for this may be straightforward: The secondary tasks that they used did not produce significant interference. Recent findings by Logie and his colleagues indicate that phonological similarity and word length effects are larger in individuals with higher word spans (Logie, Della Sala, Laiacona, Chalmers, & Wynn, 1996). These results, those of Jenkins, Myerson, et al. (1999), and the results reported here suggest that, across individuals, the absolute effect size for many manipulations that decrease memory span is an increasing function of simple span.