Evaluating the Trace Deletion Hypothesis and Processing Deficit Accounts: A Computational Modeling Approach

Caplan et al. (2007) have proposed that the sentence processing deficit in agrammatic aphasia is a consequence of intermittent deficiency (ID) in the capacity to carry out syntactic, semantic, and task-related computations. We operationalize ID as a specific impairment in a cognitive architecture for sentence processing. We also implement a complementary hypothesis of slowed processing (SP), which ascribes the deficit to a pathological slowdown (Hanne et al., 2011). We contrast these processing deficit accounts with a representational deficit account, the Trace Deletion Hypothesis (TDH) (Grodzinsky, 2000), which claims that patients suffer from impairment in their syntactic representation.