Prior training
Participants were trained on speaking with minimal head movement
in a dummy scannerwhile listening to recorded EPI sound. Under conditions
of loud noise participants tend to increase the intensity of their
voice by speaking louder and for longer, causing major and prolonged
movements (Tourville et al., 2008), which affect the quality ofMRI measurements
during vocalization. In order to limit artefacts due to overt
speech production, participants were trained to speak with minimal
facial muscular activity. Post-hoc analysis of actual headmovementmeasures
during the acquisition of the data showed no significant difference
in volume-to-volume displacement during the first two volumes of nonspeech
(encoding) and (recall/monitoring) speech trials.
Participants were also trained in using visual strategies to encode
word pairs. Interactive imagery has shown to be a valid technique for
word pair tasks (Dunlosky and Hertzog, 2001). They practised in making
up an image or scene involving the two words during the 6 s of presentation
and to rest afterwards