What you don't know can't hurt you: Retro-cues benefit working memory regardless of prior knowledge in long-term memory.

Knowledge stored in long-term memory (LTM) impacts working memory (WM) overall, but it is unclear whether LTM facilitates focusing or switching attention in WM. We addressed this question using the retro-cue paradigm: Briefly presented arrays of individually calibrated numbers of shapes (concrete or abstract) were followed by a blank retention interval (no-cue) or a retro-cue to focus participants' attention to the to-be-probed shape. Experiment 3 included double retro-cue trials that required participants to switch their attention to a different shape. Participants recalled the color (Experiments 1) or location (Experiment 2) of the probed shape, or recognized the target shape among two other options (Experiment 3). Confirming the overall LTM effect on WM, fewer abstract shapes were needed to match the performance of concrete shapes during the calibration phase. Most importantly, retro-cues benefitted performance regardless of the nature of the shape, suggesting that LTM impacts WM overall without moderating attention.