Storage interference in working memory cannot be removed by attention

In the present study, we examined the hypothesis that the storage interference in working memory can be removed by attention. A dual-task paradigm was employed in Experiment 1 and 2, in which participants performed a color memory task and an RSVP letter detection task concurrently. The cognitive load of the RSVP letter detection task and the storage interference caused by the RSVP letter detection task was manipulated independently. That is, the produced storage-interference difference between the low and high interference conditions was comparable between the low and high cognitive load conditions, whereas the available attentional resources were different under the two cognitive load conditions. Since there were more attentional resources in the low load condition, the removal hypothesis predicts that differences in recall performance between the low and high interference conditions should be larger in high load than in low load, i.e., there would be an interaction between load and interference. However, the results of the two experiments did not show such an interaction. In Experiment 3, we manipulated the time available for the removal mechanism to work while inducing both the storage interference and processing interference. The results showed no sign of interference removal. Thus, the present results provided solid evidence to challenge the removal hypothesis.