Before starting the actual experiment, subjects were given a brief 20-trial practice session to test the volume of the headphones and to habituate to the scanner noise. To ensure a balanced design, the cue words were randomly assigned to the conditions for each individual subject. Moreover, to ensure a sufficient number of trials in each of the four conditions, we used 132 trials for the auditory imagery trials because of expected difficulty, and 108 trials for the other conditions. The order of presentation of the stimuli was pseudorandomized in such a way that no two consecutive trials were of the same condition. Participants were instructed to keep their eyes open during imagery trials to match Ext-Enc and were not told about the memory retrieval task the next day.
