Effects of Verb Bias and Syntactic Ambiguity on Reading in People with Aphasia

The Lexical Bias Hypothesis (Gahl, 2002) claims that people with aphasia have difficulty understanding sentences when the verb's argument structure bias conflicts with the sentence structure. This hypothesis can account for comprehension deficits that affect simple sentences, but the role of verb bias has not been clearly demonstrated in temporarily ambiguous sentences.

This study examined how verb bias affects comprehension of temporarily ambiguous and unambiguous sentences using self-paced reading.

People with aphasia and controls read sentences that contained sentential complements (e.g., The talented photographer accepted (that) the fire could not have been prevented.). The main verb was biased to take a direct object (e.g., accepted) or a sentential complement (e.g., admitted). In addition, the sentential complement was either introduced by the complementizer that (i.e., unambiguous) or unmarked (i.e., ambiguous).

The people with aphasia's reading times were affected more by verb bias than by the presence of the complementizer, whereas the control group's reading times were more affected by the presence or absence of the complementizer.

The results were generally consistent with the Lexical Bias Hypothesis, and showed that a mismatch between verb bias and sentence structure affected processing of unambiguous and temporarily ambiguous sentences in people with aphasia.