Further evidence that the speed of working memory consolidation is a structural limit

It has been proposed that the typically slow consolidation of information from vision to working memory (WM) is under flexible control, and thus can be speeded based on task demands. Recently (Carlos et al., 2023, doi: 10.3758/s13414-023-02757-7), we showed that consolidation is not sped even when it is prioritized over a subsequent competing decision task (T2). However, other research (Nieuwenstein et al., 2015, doi: 10.1167/15.12.739; Woytaszek, 2020) has manipulated the proportion of trials with T2 present and suggested that anticipated interference from competing tasks can lead to speeding of consolidation. Here, we present evidence against speeding of consolidation even when interference can be anticipated, providing an additional line of evidence against flexible control of WM consolidation. Using a within-subjects manipulation, participants completed blocks of a WM task with T2 presented at varying delays from the WM sample, on either 50% or 100% of trials. Retroactive interference from T2 onto WM was similar regardless of block (i.e., T2 probability). In another manipulation, we also varied the delay from T2 response to WM probe and found that this second delay’s duration had no effect on WM reports. Importantly, this suggests that changes in WM performance with sample-T2 delay measure only the interruption of WM consolidation and are not contaminated by proactive interference from T2 onto the report of information from WM. In sum, the present results are consistent with the transfer of information from vision to WM being a slow process that is not under flexible control—either from explicit volitional prioritization, or implicit demands to counter anticipated interference.