Introspective judgments predict the precision and likelihood of successful maintenance of visual working memory.

Working memory serves as an essential workspace for the mind, allowing for the active maintenance of information to support short-term cognitive goals. Although people can readily report the contents of working memory, it is unknown whether they might have reliable metacognitive knowledge regarding the accuracy of their own memories. We investigated this question to better understand the core properties of the visual working memory system. Observers were briefly presented with displays of three or six oriented gratings, after which they were cued to report the orientation of a specific grating from memory as well as their subjective confidence in their memory. We used a mixed-model approach to obtain separate estimates of the probability of successful memory maintenance and the precision of memory for successfully remembered items. Confidence ratings strongly predicted the likelihood that the cued grating was successfully maintained, and furthermore revealed trial-to-trial variations in the visual precision of memory itself. Our findings provide novel evidence indicating that the precision of visual working memory is variable in nature. These results inform an ongoing debate regarding whether this working memory system relies on discrete slots with fixed visual resolution or on representations with variable precision, as might arise from variability in the amount of resources assigned to individual items on each trial.