The role of interference in memory span

In two experiments, we investigated the possibility that susceptibility to proactive interference (PI) affects performance on memory span measures. We tested both younger and older adults (older adults were tested because of the suggestion that they are differentially susceptible to PI). We used two different span measures and manipulated testing procedures to reduce PI fo r these tasks. For older adults, span estimates increased with each PI-redu cing manipulation; for younger adults, scores increased when multiple PI ma nipulations were combined or when PI-reducing manipulations were used in pa radigms in which within-task PI was especially high. The findings suggest t hat PI critically influences span performance. We consider the possibility that interference-proneness may influence cognitive behaviors previously th ought to be governed by capacity.