We tested the hypothesis that common stimuli are stored in memory bett
er than bizarre stimuli are. Subjects memorized a series of noun pairs
embedded within 20 common or bizarre sentences. By using a between-li
st design, free and cued recall, and intentional-learning instructions
, we were able to obtain a commonness effect (i.e., a recall advantage
for the common sentences). Riefer and Rouder's (1992) multinomial pro
cessing-tree model for measuring storage and retrieval was applied to
the data, which revealed that the recall advantage for common sentence
s was due to storage and not retrieval processes. We propose a two-fac
tor theory: that common items are stored better in memory, but that bi
zarre items are retrieved better from memory. This storage-retrieval e
xplanation does a good job of accounting for a number of findings asso
ciated with the bizarreness effect.