Purpose: There is a lot of evidence that people with aphasia have more difficulty understanding structurally complex sentences (e.g., object clefts) than simpler sentences (subject clefts). However, subject clefts also occur more frequently in English than object clefts. Thus, it is possible that both structural complexity and frequency affect how people with aphasia understand these structures. Method: Nine people with aphasia and 8 age-matched controls participated in the study. The stimuli consisted of 24 object cleft and 24 subject cleft sentences. The task was eye tracking during reading, which permits a more fine-grained analysis of reading performance than measures such as self-paced reading.Results: As expected, controls had longer reading times for critical regions in object cleft sentences compared with subject cleft sentences. People with aphasia showed the predicted effects of structural frequency. Effects of structural complexity in people with aphasia did not emerge on their first pass through the sentence but were observed when they were rereading critical regions of complex sentences. Conclusions: People with aphasia are sensitive to both structural complexity and structural frequency when reading. However, people with aphasia may use different reading strategies than controls when confronted with relatively infrequent and complex sentence structures. P eople with aphasia often have difficulty understanding complex sentences, especially sentences that do not follow the canonical, or typical, word order for their language (e.g., Dick et al., 2001). In English, sentences typically follow subject-verb-object word order. Sentences with noncanonical word order are both more syntactically complex and less common than sentences with canonical word order (e.g., Roland, Dick, & Elman, 2007). Studies of sentence comprehension impairments in people with aphasia have focused on the contributions of structural complexity (e.g., Caplan, Waters, DeDe, Michaud, & Reddy, 2007;Dick et al., 2001;Grodzinsky, 2000;Thompson & Choy, 2009). However, research from adults without brain damage suggests that the relative frequency of syntactic structures also influences processing difficulty (e.g., Levy, 2008;Staub, 2010). Thus, it is possible that people with aphasia have trouble understanding sentences with noncanonical word order at least in part because such sentences occur relatively infrequently compared with sentences with canonical word order. The purpose of the present study was to determine whether sentence comprehension impairments in people with aphasia reflect sensitivity to the frequency of the structure as well as structural complexity.A lot of evidence regarding effects of structural complexity comes from studies investigating how people with aphasia process sentences with object and subject relative clauses, such as the object and subject clefts in examples 1 and 2: Sentences 1 and 2 both convey the idea "the boy hugged the girl," but object clefts such as in sentence 1 are more difficult to process than su...
