Going, going, gone . . . ? Implicit and explicit tests of conceptual knowledge in a longitudinal study of semantic dementia

Patients suffering from semantic dementia provide important constraints on theories of the structure and organisation of semantic memory. In this article we report one such patient, AM, whose progressive deterioration of semantics enables us to address the much-debated issue of whether conceptual structure is hierarchically organised. The hierarchical account predicts that brain damage should impair lower levels of the hierarchy (property information) before affecting higher level (category) information (Warrington and Shallice, Q. J. Exp. Psychol. 1975, 27, 635-657). We evaluate this prediction by repeated testing of AM in two studies--a semantic priming task and a verification task--over an 18 month period, contrasting the progressive deterioration of properties (functional and perceptual) and category relations (category co-ordinates and category labels). Properties were preserved longer than category information, arguing against a hierarchical account of semantic memory. In addition, functional properties were most robust to brain damage, supporting our claim that functional information plays a special role in semantic representations (Durrant-Peatfield et al., Proc. 19th Ann. Conf. of the Cognitive Science Society. Erlbaum, Mahwah, NJ, 1997. pp. 193-198. Tyler et al., Cognitive Neuropsychol. 1997, 14, 511-545).

[1]  R. Nebes,et al.  Integrity of Semantic Fields in Alzheimer's Disease , 1988, Cortex.

[2]  L. Tyler,et al.  Functional Properties of Concepts: Studies of Normal and Brain-damaged Patients , 1997 .

[3]  L. K. Tyler,et al.  Automatic Access to Lexical Semantics in Aphasia: Evidence from Semantic and Associative Priming , 1993, Brain and Language.

[4]  Matthew A. Lambon Ralph,et al.  The relationship between naming and semantic knowledge for different categories in dementia of Alzheimer's type , 1997, Neuropsychologia.

[5]  E. Funnell.  Objects and properties: a study of the breakdown of semantic memory. , 1995, Memory.

[6]  E. Warrington.  Quarterly Journal of Experimental Psychology the Selective Impairment of Semantic Memory the Selective Impairment of Semantic Memory , 2022 .

[7]  W. Marslen-Wilson,et al.  The temporal structure of spoken language understanding , 1980, Cognition.

[8]  A. Young,et al.  Face Recognition and Awareness After Brain Injury , 1992 .

[9]  Karalyn Patterson,et al.  Lexical and Semantic Binding Effects in Short-term Memory: Evidence from Semantic Dementia , 1997 .

[10]  Lorraine K. Tyler,et al.  The Time Course of Activation of Semantic Information during Spoken Word Recognition , 1997 .

[11]  James L. McClelland,et al.  A computational model of semantic memory impairment: modality specificity and emergent category specificity. , 1991 .

[12]  J. Hodges,et al.  Semantic dementia. Progressive fluent aphasia with temporal lobe atrophy. , 1992 .

[13]  Myrna F. Schwartz,et al.  Of cabbages and things: Semantic memory from a neuropsychological perspective—A tutorial review. , 1994 .

[14]  Lorraine K. Tyler,et al.  Exploring the Loss of Semantic Memory in Semantic Dementia: Evidence from a Primed Monitoring Study , 2022 .

[15]  M. Ross Quillian,et al.  Retrieval time from semantic memory , 1969 .

[16]  Erminio Capitani,et al.  Perceptual and Associative Knowledge in Category Specific Impairment of Semantic Memory: A Study of two Cases , 1993, Cortex.

[17]  G. Humphreys,et al.  The Fractionation of Visual Agnosia , 1987 .

[18]  D. Neary,et al.  Semantic dementia: a form of circumscribed cerebral atrophy , 1995 .

[19]  L. Tyler.  The Distinction Between Implicit and Explicit Language Function: Evidence from Aphasia , 1992 .

[20]  A. Caramazza,et al.  General to specific access to word meaning: A claim re-examined , 1989 .

[21]  Lorraine K. Tyler,et al.  Loss of Semantic Memory: Implications for the Modularity of Mind , 1994 .

[22]  T. Shallice,et al.  Category specific semantic impairments , 1984 .

[23]  G. Gainotti,et al.  Neuroanatomical correlates of category-specific semantic disorders: a critical survey. , 1995, Memory.

[24]  D. Schacter.  Consciousness and Awareness in Memory and Amnesia: Critical Issues , 1992 .

[25]  A. Marcel.  Conscious and unconscious perception: Experiments on visual masking and word recognition , 1983, Cognitive Psychology.

[26]  J. Mandler.  How to build a baby: II. Conceptual primitives. , 1992, Psychological review.

[27]  Joseph P. Levy,et al.  The distinctiveness of form and function in category structure: A connectionist model , 1997 .

[28]  A. Marcel.  Conscious and unconscious perception: An approach to the relations between phenomenal experience and perceptual processes , 1983, Cognitive Psychology.

[29]  J. Hodges,et al.  Differentiating the roles of the hippocampal complex and the neocortex in long-term memory storage: evidence from the study of semantic dementia and Alzheimer's disease. , 1997, Neuropsychology.

[30]  S. Johansson,et al.  Word Frequencies in British and American English , 1985 .

[31]  J R Hodges,et al.  Nonfluent progressive aphasia and semantic dementia: A comparative neuropsychological study , 1996, Journal of the International Neuropsychological Society.

[32]  Julie S. Snowden,et al.  Semantic dementia: autobiographical contribution to preservation of meaning , 1994 .

[33]  J. Hodges,et al.  Is semantic memory consistently impaired early in the course of Alzheimer's disease? Neuroanatomical and diagnostic implications , 1995, Neuropsychologia.

[34]  Lorraine K. Tyler,et al.  When leopards lose their spots: knowledge of visual properties in category-specific deficits for living things , 1997 .

[35]  Helen Moss,et al.  Birkbeck Word Association Norms , 1996 .

[36]  James L. McClelland,et al.  Why there are complementary learning systems in the hippocampus and neocortex: insights from the successes and failures of connectionist models of learning and memory. , 1995, Psychological review.

[37]  T. Shallice.  From Neuropsychology to Mental Structure: Converging Operations: Specific Syndromes and Evidence from Normal Subjects , 1988 .

[38]  Lorraine K Tyler,et al.  Real-time comprehension processes in agrammatism: A case study , 1985, Brain and Language.