Mahsa Alizadeh Shalchy (UC Riverside)
P300 Morphology and Behavioral Differences during Variations of N-back Task

Although working memory (WM) is part of many cognitive functions, its mechanism is still elusive. A popular way to assess WM function is using the N-Back task: subjects are asked to report whether the current stimulus matches one presented N stimuli earlier. While the basic structure of the N-back task is consistent across literature, the type of stimulus used and task features vary considerably in terms of duration, inter stimulus interval (ISI), feedback, and response contingencies. Little is known about the effect of these variations on the neural and behavioral correlates of WM. To investigate the possible effect of these factors on the neural and behavioral outcomes, 9 healthy UCR undergraduates were recruited to perform different versions of the N-back task while simultaneously recording their EEGs: Three different experimental set-ups with distinct stimulus durations, ISI, feedback response contingencies, and three different stimuli types (colored circles, pictures, and syllables), crossed into nine different task/stimuli combinations. Preliminary results suggest that neural and behavioral data differ for different versions of the N-Back task. Within each set-up, task type seems to play an independent role in modulating the P300 event-related potential (ERP) component morphology, accuracy and reaction time (RT). These results show that care must be taken when comparing N-back study outcomes particularly when it comes to task paradigms.