ERP evidence for hemispheric asymmetries in exemplar-specific explicit memory access.
The right cerebral hemisphere (RH) appears to be more effective in representing visual objects as distinct exemplars than the left hemisphere (LH) which is presumably biased towards coding objects at the level of abstract prototypes. As of yet, relatively little is known about the role that asymmetries in exemplar-specificity play at the level of explicit memory retrieval. In the present study, we addressed this issue by examining hemispheric asymmetries in the putative event-related potential (ERP) correlates of familiarity (FN400) and recollection (LPC). In an incidental study phase, pictures of familiar objects were presented centrally. At test, participants performed a memory inclusion task on identical repetitions and different exemplars of study items as well as new items which were presented in only one visual hemifield using the divided visual field technique. With respect to familiarity, we observed exemplar-specific FN400 old/new effects that were more pronounced for identical repetitions than different exemplars, irrespective of the hemisphere governing initial stimulus processing. In contrast, LPC old/new effects were subject to some hemispheric asymmetries indicating that exemplar-specific recollection was more extensive in the RH than in the LH. This further corroborates the idea that hemispheric asymmetries should not be generalized but need to be distinguished not only in different domains but also at different levels of processing.
Aging Group, Leibniz Research Centre for Working Environment and Human Factors, Dortmund, Germany; Brain & Cognition Group, Department of Psychology, Saarland University, Saarbrücken, Germany. Electronic address: kueper@ifado.de.
Kristina
K
Küper
Brain & Cognition Group, Department of Psychology, Saarland University, Saarbrücken, Germany.
Hubert D
HD
Zimmer
D000293:Adolescent; D000328:Adult; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D014794:Visual Fields / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology; D055815:Young Adult
Exemplar-specificity; FN400; Hemispheric asymmetry; LPC; Laterality effects; Recognition memory