title: Profound retroactive interference in anterograde amnesia: What interferes?
abstract: OBJECTIVE
  Anterograde amnesia is characterized by a profound inability to retain new information. Recent research suggests that at least some of this severe memory impairment may be the product of retroactive interference. What exactly interferes with memory in amnesic patients, however, remains unknown. The aim of the present study was to examine whether or not postlearning material which is highly dissimilar from the material to be remembered would interfere with amnesic patients' memory.
  
  
  METHODS
  Prose retention was tested in 10 densely amnesic patients and 10 controls following a 10 minute delay period, which was either unfilled (minimal interference) or filled with a tone detection task in which participants were required to listen for piano notes (nonspecific interference).
  
  
  RESULTS
  A significant nonspecific retroactive interference effect was observed in the amnesic patients (p < 0.004): Whereas 7 out of the 10 amnesic patients were able to recall some prose material following the unfilled delay period, only 1 of them was able to recall any material after the tone detection delay.
  
  
  CONCLUSIONS
  The data reveal that some amnesic patients have the capacity to retain new material for much longer than usual but that apparently any new postlearning information profoundly interferes with such retention. This nonspecific retroactive interference effect deviates from the item-specific interference effect that is typically assessed in clinical practice and which is frequently observed in patients with executive impairment. We hypothesize that these interference effects are qualitatively different, occurring during distinct memory processes, namely retrieval (item-specific interference) and consolidation (nonspecific interference).
authors.affiliation: Human Cognitive Neuroscience, Psychology, University of Edinburgh, Edinburgh EH8 9JZ, United Kingdom. m.dewar@ed.ac.uk
authors.forename: Michaela
authors.initials: M
authors.lastname: Dewar
authors.forename: Sergio
authors.initials: S
authors.lastname: Della Sala
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Beschin
authors.forename: Nelson
authors.initials: N
authors.lastname: Cowan
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D020324:Amnesia, Anterograde / Q000473:pathology / Q000523:psychology*; D001921:Brain / Q000473:pathology; D004493:Education; D056344:Executive Function / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008570:Memory, Short-Term / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010897:Pitch Discrimination / Q000502:physiology; D055815:Young Adult