General proactive interference and the N450 response.
Strategic repetition of verbal stimuli can effectively produce proactive interference (PI) effects in the Sternberg working memory task. Unique fronto-cortical activation to PI-eliciting letter probes has been interpreted as reflecting brain responses to PI. However, the use of only a small set of stimuli (e.g., letters and digits) requires constant repetition of stimuli in both PI and baseline trials, potentially creating a general PI effect in all conditions. We used event-related potentials to examine general PI effects by contrasting the interference-related frontal N450 response in two Sternberg tasks using a small versus large set size. We found that the N450 response differed significantly from baseline during the small set-size task only for response-conflict PI trials but not when PI was created solely from stimulus repetition. During the large set-size task N450 responses in both the familiarity-based and response-conflict PI conditions differed from baseline but not from each other. We conclude that the general stimulus repetition inherent in small set-size conditions can mask effects of familiarity-based PI and complicate the interpretation of any associated neural response.
Tays
William J
WJ
Psychology Department, Brock University, St. Catharines, Ontario, Canada.
Dywan
Jane
J
Segalowitz
Sidney J
SJ
D000293:Adolescent; D003220:Conflict, Psychological; D004569:Electroencephalography; D005074:Evoked Potentials, Visual; D005260:Female; D005625:Frontal Lobe / Q000502:physiology*; D006801:Humans; D008297:Male; D008570:Memory, Short-Term; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation; D021641:Recognition, Psychology; D014705:Verbal Behavior; D055815:Young Adult