Proceedings of the Annual Meeting of the Cognitive Science Society

Pattern separation enables discrimination between similar experiences and relies on hippocampal function. The Mnemonic Similarity Task (MST) indexes this process using the Lure Discrimination (LDI). Recent studies, on the other hand, suggest MST performance is influenced by perceptual processing. We investigated the extent of mnemonic processes in MST performance across increasing delays between encoding and retention phases (0 minutes, 30 minutes, 8 hours, 24 hours). LDI declined in the 8-hour and 24-hour groups, with significantly worse lure discrimination especially for low similarity lures. Response patterns revealed a bias, shorter delays showed an "Old" response bias, whereas longer delays were characterized by a "New" response bias. Additionally, decreasing lure similarity was associated with increased "New" responses. Together, these findings suggest that the MST is sensitive to mnemonic processing over short delays, however performance at longer delays is constrained and may reflect non-mnemonic factors.