Working memory and interference: A comment on Jenkins, Myerson, Hale, and Fry (1999)

Jenkins, Myerson, Hale, and Fry (1999) showed that slopes relating complex spans to simple spans were considerably smaller than one, indicating that p ersons with higher simple spans suffered more interference when the span ta sk teas combined with a processing demand. They argued that this finding ru led out accounts of working memory based on interference and/or inhibition of interfering information. We demonstrate that the effect is mainly an art ifact from regression to the mean, owing to the low reliability of span sco res as used by Jenkins et al. Data from 133 young adults for two verbal and two spa tial span tasks show that the slopes, elating complex to simple pe rformance are considerably higher for sum scores than for span scores. Furt hermore, an adequate test for an interference or an inhibition account of w orking memory is to predict interference from complex span tasks, not from simple span tasks. Interference effects in the verbal span tasks were negat ively correlated with an independent measure of working memory capacity, co nsistent with the interference/inhibition account.