crows control working memory before and after stimulus encoding erica fongaro & Jonas Rose * the capacity of working memory is limited and this limit is comparable in crows and primates. to maximize this resource, humans use attention to select only relevant information for maintenance. Interestingly, attention-cues are effective not only before but also after the presentation of to-beremembered stimuli, highlighting control mechanisms beyond sensory selection. Here we explore if crows are also capable of these forms of control over working memory. two crows (Corvus corone) were trained to memorize two, four or six visual stimuli. comparable to our previous results, the crows showed a decrease in performance with increasing working memory load. Using attention cues, we indicated the critical stimulus on a given trial. these cues were either presented before (pre-cue) or after sample-presentation (retro-cue). on other trials no cue was given as to which stimulus was critical. We found that both pre-and retro-cues enhance the performance of the birds. these results show that crows, like humans, can utilize attention to select relevant stimuli for maintenance in working memory. importantly, crows can also utilize cues to make the most of their working memory capacity even after the stimuli are already held in working memory. This strongly implies that crows can engage in efficient control over working memory. Working memory (WM) refers to the ability to memorize information over short periods and, importantly, to process this information. This makes WM a core component of cognition that is critical for decision making, planning, goal directed behavior and many other cognitive abilities 1,2. It is well established that WM is not a passive storage but that it requires active maintenance of information 3. Consequentially, WM is not only vulnerable to distraction but also limited in duration and in capacity 4-6. It was estimated that healthy humans can maintain about three to five items in working memory 7-11. Capacity-limitation is a critical bottleneck of cognition and has recently been coined the 'bandwidth of cognition' 12,13. In light of these limitations, it is evident that WM must rely on effective top-down control 14. This control can occur in different ways. Attention can act as a 'gatekeeper' that prioritizes the encoding of relevant sensory stimuli and filters out irrelevant information 14-18. While this mechanism is highly effective, it requires prior knowledge about the relevance of upcoming sensory events. If this information is not available at the time of encoding, the system also needs to control the maintenance of information that is already held in WM. In humans, both mechanisms are well established-attention is used to gate stimuli for WM and executive control selects from information already maintained in WM. Pioneering work from Posner and Cohen 19 demonstrated that visual cues facilitate target detection if a location is cued prior to the presentation of the target. Likewise, such 'pre-cues' facil...