Sequential memory scanning during sternberg memory task regardless of the different presentation style

Previous EEG/MEG studies with the Sternberg memory scanning task revealed a serial memory scanning process independent of what was to be memorized. The present study explored for the first time event related potentials (ERPs) during both the memory maintenance and retrieval phases of the Sternberg task with simultaneous or successive presentation of a memory set, posing the question whether the type of presentation of stimuli to be memorized affects the memory process. A difference in P300 amplitude between two presentation types during the maintenance phase was considered to reflect a difference in stimulus evaluation and the onset of the memory maintenance process. During the retrieval phase, the duration of P300 in the parietal area increased with memory load, indicating a serial scanning process regardless of the presentation type. These results suggest converging dynamics from a presentation type - dependent maintenance phase toward a memory retrieval phase that is independent of the presentation types of the memory set.