Short-term false memories vary as a function of list type

False memories have primarily been investigated at long-term delays in the Deese-Roediger-McDermott (DRM) procedure, but a few studies have reported meaning-based false memories at delays as short as 1-4 s. The current study further investigated the processes that contribute to short-term false memories with semantic and phonological lists (Experiment 1) and hybrid lists containing items of each type (Experiment 2). In Experiment 1, more false memories were found for phonological than for semantic lists. In Experiment 2, an asymmetrical hyper-additive effect was found such that including one or two phonological associates in pure semantic lists yielded a robust increase in false alarms, whereas including semantic associates in pure phonological lists did not affect false alarms. These results are more consistent with the activation-monitoring account of false memory creation than with fuzzy trace theory that has not typically been referenced when describing phonological false memories.