In recent years, there has been a resurgence of interest in the topic for several reasons. One is the development of more sophisticated and nuanced models of “recognition” according to which perception is taken to be a multi-stage interactive process; on such accounts, the distinction between perceptual disorders and agnosia is seen not as dichotomous but rather as a process in which sensory inputs give rise to progressively more elaborated representations in which different types of information (e.g., shape, color, location) may be emphasized (Heinke and Humphreys 2003; Ellis and Young 1988). Second, in light of the increasingly complex and interactive models of recognition, the heuristic value of data from patients with agnosia has proven to be substantial. As illustrated by the influential contributions of Farah (2004), Riddoch and Humphreys (1987), and others, data from agnosic subjects may serve to indicate the fault lines in the process of recognition and offer important constraints for accounts based on animal work, modeling, and studies of normal subjects.
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