Interference Across Memory Systems: Disrupting Long-Term Memories Through Working Memory

Forgetting is a fundamental feature of human memory, yet important questions remain about how long-term memories become vulnerable to interference. While previous research has focused on interference between intentionally learned long-term memory traces, it is less known whether such interference can be induced via working memory. The present study addressed this question across two experiments using a novel paradigm combining a long-term and a working memory task. Participants first encoded object–location associations into long-term memory, then completed a working memory task in which the same objects reappeared in the same or shifted locations (60° or 120°), or were absent, before performing a final long-term memory test. Interference induced through the working memory task impaired long-term memory retrieval. This effect was driven by swap errors: participants occasionally reported the task-irrelevant working memory location instead of the long-term memory one. Experiment 2 further showed that both maintenance and test of interfering information in working memory disrupted long-term memory, with testing producing the strongest effects. These findings demonstrate that long-term memories can be disrupted via working memory, suggesting that intentional encoding into long-term memory is not required for interference to occur. We discuss these findings in light of an asymmetric gate between working and long-term memory.