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Neuropsychological inference with an interactive brain: A critique of the locality assumption

Farah, Martha J. (1994) Neuropsychological inference with an interactive brain: A critique of the locality assumption.

Short Abstract:

When cognitive neuropsychologists make inferences about the functional architecture of the normal mind from selective cognitive impairments they generally assume that the effects of brain damage are local, that is, that the nondamaged components of the architecture continue to function as they did before the damage. This assumption follows from the view that the components of the functional architecture are modular, i.e., informationally encapsulated. In this target article it is argued that this "locality" assumption is probably incorrect. Inferences about the functional architecture can nevertheless be made from neuropsychological data with an alternative set ofassumptions, according to which human information processing is graded, distributed, and interactive. These claims are supported by three examples of neuropsychological dissociations and a comparison of the inferences obtained from these impairments with and without the locality assumption. The three dissociations involve selective impairments in knowledge of living things, disengaging visual attention, and overt face recognition. In all three, the neuropsychological phenomena lead to more plausible inferences about the normal functional architecture when the locality assumption is abandoned. Also discussed are the relations between the locality assumption in neuropsychology and broader issues, including Fodor's modularity hypothesis and the choice between top-down and bottom-up research approaches.

Long Abstract:

When cognitive neuropsychologists make inferences about the functional architecture of the normal mind from selective cognitive impairments they generally assume that the effects of brain damage are local, that is, that the nondamaged components of the architecture continue to function as they did before the damage. This assumption follows from the view that the components of the functional architecture are modular, i.e., informationally encapsulated. In this target article it is argued that this "locality" assumption is probably incorrect. Inferences about the functional architecture can nevertheless be made from neuropsychological data with an alternative set ofassumptions, according to which human information processing is graded, distributed, and interactive. These claims are supported by three examples of neuropsychological dissociations and a comparison of the inferences obtained from these impairments with and without the locality assumption. The three dissociations involve selective impairments in knowledge of living things, disengaging visual attention, and overt face recognition. In all three, the neuropsychological phenomena lead to more plausible inferences about the normal functional architecture when the locality assumption is abandoned. Also discussed are the relations between the locality assumption in neuropsychology and broader issues, including Fodor's modularity hypothesis and the choice between top-down and bottom-up research approaches.

Keywords:	cognitive architecture, face recognition, lesions, localization, modularity, neural nets, neuropsychology, semantics, vision
Subjects:	Psychology: Cognitive Psychology Computer Science: Neural Nets Neuroscience: Neuroanatomy Neuroscience: Neural Modelling Neuroscience: Neurophysiology
ID code:	bbs00000561
Deposited by:	Martha Farah on 02 May 2001