Episodic memory encoding is pervasive across many kinds of task and often a
rises as a secondary processing effect in tasks that do not require intenti
onal memorization. To illustrate the pervasive nature of information proces
sing that leads to episodic encoding, a form of incidental encoding was exp
lored based on the "Testing" phenomenon: The incidental-encoding task was a
n episodic memory retrieval task. Behavioral data showed that performing a
memory retrieval task was as effective as intentional instructions at promo
ting episodic encoding. During fMRI imaging, subjects viewed old and new wo
rds and indicated whether they remembered them. Relevant to encoding. the f
ate of the new words was examined using a second, surprise test of recognit
ion after the imaging session, fMRI analysis of those new words that were l
ater remembered revealed greater activity in left frontal regions than thos
e that were later forgotten-the same pattern of results as previously obser
ved for traditional incidental and intentional episodic encoding tasks. Thi
s finding may offer a partial explanation for why repeated testing improves
memory performance. Furthermore, the observation of correlates of episodic
memory encoding during retrieval tasks challenges some interpretations tha
t arise from direct comparisons between "encoding tasks' and "retrieval tas
ks" in imaging data. Encoding processes and their neural correlates may ari
se in many tasks, even those nominally labeled as retrieval tasks by the ex
perimenter.