The Neuropsychology of Imagery Processing
Final technical rept. Dec 1987-Nov 1990,
HARVARD UNIV CAMBRIDGE MA
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High-level visual processes make use of stored information, and are invoked during object identification, navigation, tracking, and visual mental imagery. The present work has resulted in a theory of the component processing subsystems used in high-level vision. This theory was developed by considering neuroanatomical, neurophysiological, and computational constraints. This theory had lead to two kinds of empirical work First, specific hypotheses about individual processing subsystems have been tested. For example, the analysis of the representation of spatial relations lead to the prediction that two subsystems are used to encode this information, and a set of experiments was conducted that provided support for this distinction. This work has involved a combination of divided-visual-field experiments with normal subjects and detailed examinations of patients with focal brain damage. Second, the subsystems have been implemented in a large computer simulation model, which has been used to generate predications about specific neurological syndromes. The model can be damaged in a variety of ways, and its performance on a set of tasks then observed. Predictions from the model have been tested, the results generally support its underlying assumptions and specific claims. In addition, individual subsystem have been implemented as neural network simulation models, which have been related directly to properties of the neural substrate assumed to underlie processing. The experiments conducted to date are summarized in the context of the theory in this report, and the utility of the theory for understanding the effects of brain damage as illustrated by reviewing a single case study in detail.