title: The N1 hypothesis and irrelevant sound: evidence from token set size effects.
abstract: This study investigated how increases in the number of different types of sound (token set size) within a heard but ignored sequence influence brain activity and performance in a serial recall task (the irrelevant sound effect). We tested the hypothesis that brain processes affected by the refractory state of the neuronal populations involved in generating the auditory N1 play a role in the memory disruption produced by irrelevant sound. Auditory event-related potentials (ERPs) were recorded when volunteers performed a serial recall task that required remembering lists of visually presented numbers that were followed by a distractor-filled retention interval. The results showed that both increments in set size from 1 to 2 and from 2 to 5 elicited an increase of the N1 amplitude. Furthermore, increases in set size from 2 to 5, but not from 1 to 2, caused a significant decrease of the serial recall performance. This result suggested that, if N1 were to play a role in the disruption produced by irrelevant sound, the processes underlying the N1 wave may only serve as a necessary rather than a sufficient condition for disruption.
authors.affiliation: Cognitive Brain Research Unit, University of Helsinki, Helsinki, Finland.
authors.forename: Tom
authors.initials: T
authors.lastname: Campbell
authors.forename: István
authors.initials: I
authors.lastname: Winkler
authors.forename: Teija
authors.initials: T
authors.lastname: Kujala
authors.forename: Risto
authors.initials: R
authors.lastname: Näätänen
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000293:Adolescent; D000328:Adult; D004569:Electroencephalography / Q000379:methods*; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006801:Humans; D012153:Retention, Psychology / Q000502:physiology*