Mild reading difficulties are a pervasive symptom in aphasia, but are little researched. Eye tracking research with neurologically healthy participants has demonstrated that reading is influenced by a number of information sources that are related to our experience with language. Two of these sources of influence, frequency and context, demonstrate that more probable words and structures are processed more quickly than those that are less probable. However, not much is known about probabilistic influences on the reading of people with aphasia at the sentence level. Two eye tracking experiments were conducted to establish whether or not frequency and context influence reading for people with aphasia in a way that is parallel to that of neurologically healthy participants. The first experiment examined the influence of word frequency and context on visual word recognition at the sentence level. The second experiment examined the influence of argument structure frequency on the reading of temporarily ambiguous sentences. Specifically, target sentences appeared after a context that cued a specific verb meaning and probabilistically associated argument structure. The target sentence was either consistent with or at odds with that context. The analysis of eye movements from both experiments revealed that people with aphasia have prolonged fixation durations and an increased proportion of regressions (backward fixations), indicative of their reading difficulties. Results from the first experiment demonstrated large effects of word frequency and context on both first pass and second pass eye movement measures by both groups. This suggests that frequency and context are related to both early and late processing stages of reading. However, differences were found between groups in a later processing stage where the aphasia group relied more on the context (top-down processing support) than the control group. The second experiment revealed that participants from both groups were sensitive to argument structure frequency when they read sentences that were temporarily ambiguous. Context cues facilitated the access of verb meaning and probabilistically associated argument structure, even though the individuals with aphasia showed delayed reading patterns. The context effect was found for both first pass and second pass eye movement measures, and was particularly strong for total fixation durations, which indicate re-reading behaviour. Overall, the outcome suggests the importance of considering multiple factors in sentence reading. Reading and sentence decoding by neurologically healthy individuals as well as individuals with aphasia are not only influenced by syntactic factors, but are also sensitive to factors relating to our language exposure. Results from the aphasia group are consistent with constraint-based theories of sentence comprehension and with slowed or reduced processing accounts.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:683776 |
| Date | January 2016 |
| Creators | Huck, Anneline |
| Publisher | City University London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://openaccess.city.ac.uk/14516/ |
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