Long-term representational costs of overloading working memory.

Can learning too much information at once impair long-term retention of its meaning? Emerging evidence suggests that encoding too many items into working memory (WM) limits subsequent long-term memory (LTM) retrieval of their details and gist. These findings highlight a boundary condition for theories positing relatively automatic gist encoding. But how expansive is this boundary? Experiment 1 shows that it extends to older adults, despite their generally enhanced reliance on gist memory. In two older adult samples (n = 40 each), LTM gist retrieval was reduced for objects encoded in sets exceeding WM capacity. Experiment 2 shows that this boundary holds even when retaining items in LTM is essential. Under intentional long-term learning, young (n = 81) and older (n = 40) adults' LTM gist retrieval remained affected by overloading WM at encoding. Results invite leading memory theories to reconsider the universality of relatively automatic gist encoding.