Example of stimuli from the Digit-Symbol Verification Task. Participants in the present study completed the digit-symbol verification task while fMRI data were collected. On each trial, a key containing nine digit-symbol pairs and a single digit-symbol probe-pair appeared simultaneously for 3.5 s, and participants were to judge whether the probe-pair was in the key (A) or not (B). The digit-symbol pairings in the key and the probe-pair varied across trials. On half of the trials, the probe-pair matched a digit-symbol pair in the key, and on half of the trials, the probe-pair did not match a digit-symbol pair in the key. There were 52 trials in a run, and inter-stimulus intervals varied from .5 to 16.5 s.