On processing lexical meanings in aphasia and Alzheimer's disease: some (re)considerations.

The time course of lexical inferences during language comprehension is discussed according to a Lexical Inference Model (LIM). It distinguishes among three types of lexical inferences, respectively generated from semantic, conceptual, and strategic representations. Following discussion of the model, data from lexical priming studies conducted with aphasic patients as well as with Alzheimer's Disease patients are (re)considered in light of the LIM. The view that "word-level priming" (WLP) is not a sufficient task to tap in the time course of lexical activation during online processing is favored. Since most lexical priming studies on aphasia and Alzheimer's Disease used the WLP paradigm with an interstimulus interval larger than 100 ms, initial claims regarding automatic or modularized lexical processing are shown to be premature. However, the deficient lexical access or integration processes found in aphasias of the Broca and Wernicke types and in the dementia of the Alzheimer type are predicted by the LIM.