Systematicity and Specialization in Semantics: A Computational Account of Optic Aphasia

Modality-specific naming deficits, such as optic aphasia, have been taken as evidence that semantics is organized into distinct modality-specific subsystems. We adopt an alternative view in which semantics is a learned, internal representation within a parallel distributed processing system that maps between multiple input and output modalities. We show that the robustness of a task to damage depends critically on its systematicity, and that modality-specific naming deficits can arise because naming is an unsystematic task.