The hippocampus supports recognition memory for familiar words but not unfamiliar faces.
Bilateral damage to the human hippocampus profoundly impairs the ability to form long-term, consciously accessible memories, producing a classic amnesic syndrome. However, the effect of hippocampal damage on our ability to recognize items via a feeling of familiarity is hotly disputed. Dual-process theory predicts no effect, whereas declarative memory theory predicts impairment of all types of recognition memory. Here, we demonstrate a striking material specificity in the effect of focal hippocampal damage: Recognition memory is impaired for words but intact for faces. The latter finding is incompatible with declarative memory theory, whereas the former constrains dual-process theory by revealing the limitations of postulated extrahippocampal familiarity-based processes. We suggest that the hippocampus boosts recognition of well-known stimuli (high-frequency words) by activating pre-experimental associations that enrich the context of their presentation. By contrast, recognition memory for some kinds of previously unfamiliar stimuli (unfamiliar faces) may be supported by extrahippocampal familiarity-based processes, at least over short intervals.
Bird
Chris M
CM
Institute of Cognitive Neuroscience, University College London, London, UK. chris.bird@ucl.ac.uk
Burgess
Neil
N
D001307:Auditory Perception / Q000502:physiology; D016022:Case-Control Studies; D005145:Face; D005260:Female; D006624:Hippocampus / Q000293:injuries / Q000502:physiology* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology*; D008959:Models, Neurological; D008960:Models, Psychological; D009483:Neuropsychological Tests; D013061:Speech Acoustics; D014796:Visual Perception / Q000502:physiology