Recovery in a letter-by-letter reader: more efficiency at the expense of normal reading strategy

Variations in Eye-Gaze Behaviors Evident When Five Adults With Aphasia-Based Alexia Read Multisentence Passages

PURPOSE

The problems that people with aphasia encounter when reading passages are poorly understood. This study's purpose was in-depth examination of eye-gaze behaviors exhibited by five people with aphasia-based alexia.

METHOD

Five adults with aphasia-based alexia and five neurotypical adults (NAs) read paragraphs while having their eye movements recorded. Acquired data included descriptive characterization of overall eye-gaze behaviors and determination of the (a) percent of fixated words, (b) average fixation duration, (c) average initial and total summed fixation durations of processing attempts on individual words, and (d) effects of word length and frequency on fixation durations. Careful examination of these data allowed examination of consistencies and discrepancies among people with aphasia and supported speculation about underlying deficits.

RESULTS

Case participants exhibited unique fixation behaviors in comparison to one another and to neurotypical adults. Case participants' total reading time, percent of fixated words, average fixation duration, and average initial and total summed fixation durations on passage words exceeded those of neurotypical adults. Four of five exhibited positive word length and negative word frequency correlations with fixation durations.

CONCLUSIONS

People with aphasia display eye-gaze behaviors unique to them and differing from those of NAs when reading texts. Better understanding of the connection between specific eye-gaze behaviors and problems decoding words, linking them with lexical-semantic information, and constructing meaning from written content is necessary to further progress in developing effective assessment tools and treatments.

The determinants of saccade targeting strategy in neurodevelopmental disorders: The influence of suboptimal reading experience

Whether eye-movements deficits are causal in reading disorders (RD) or rather a consequence of linguistic processing difficulty experienced by disabled readers has been extensively debated.Since RD are frequently comorbid with the Neurofibromatosis type1 (NF1), children with NF1 were used as a comparison group for children with dyslexia in this study.Eye movements were recorded while 21 dyslexic, 20 NF1, and 20 typically developing children performed an oculomotor lateralized bisection task. In this experiment, we manipulated the type of stimulus - discrete (words and strings of hashes) versus continuous (solid lines) - and the visual field where the stimulus was displayed (left vs right). The results showed that (1) only proficient readers (TD and NF1 without RD) showed fully developed oculomotor mechanisms for efficient reading, with a clear preferred viewing location located to the left of the word's centre in both visual fields, and fine-tuned saccade targeting guided by the between-character space information and (2) NF1 poor readers mirrored the dyslexic eye movement behaviour, with less accuracy and more variability in saccadic programming, no sensitivity to the discreteness of the stimuli, particularly in the left visual field. We concluded that disruption to oculomotor behaviour reflectsthe fact that many of the processes involved in reading are not yet automatized for children with RD, independently of NF1. This suggests that the differences in saccade targeting strategy between children with and without RD would be secondary consequences of their reduced reading experience.

Diverging receptive and expressive word processing mechanisms in a deep dyslexic reader

We report on KJ, a patient with acquired dyslexia due to cerebral artery infarction. He represents an unusually clear case of an "output" deep dyslexic reader, with a distinct pattern of pure semantic reading. According to current neuropsychological models of reading, the severity of this condition is directly related to the degree of impairment in semantic and phonological representations and the resulting imbalance in the interaction between the two word processing pathways. The present work sought to examine whether an innovative eye movement supported intervention combining lexical and segmental therapy would strengthen phonological processing and lead to an attenuation of the extreme semantic over-involvement in KJ's word identification process. Reading performance was assessed before (T1) between (T2) and after (T3) therapy using both analyses of linguistic errors and word viewing patterns. Therapy resulted in improved reading aloud accuracy along with a change in error distribution that suggested a return to more sequential reading. Interestingly, this was in contrast to the dynamics of moment-to-moment word processing, as eye movement analyses still suggested a predominantly holistic strategy, even at T3. So, in addition to documenting the success of the therapeutic intervention, our results call for a theoretically important conclusion: Real-time letter and word recognition routines should be considered separately from properties of the verbal output. Combining both perspectives may provide a promising strategy for future assessment and therapy evaluation.

An eye movement based reading intervention in lexical and segmental readers with acquired dyslexia

Due to their brain damage, aphasic patients with acquired dyslexia often rely to a greater extent on lexical or segmental reading procedures. Thus, therapy intervention is mostly targeted on the more impaired reading strategy. In the present work we introduce a novel therapy approach based on real-time measurement of patients' eye movements as they attempt to read words. More specifically, an eye movement contingent technique of stepwise letter de-masking was used to support sequential reading, whereas fixation-dependent initial masking of non-central letters stimulated a lexical (parallel) reading strategy. Four lexical and four segmental readers with acquired central dyslexia received our intensive reading intervention. All participants showed remarkable improvements as evident in reduced total reading time, a reduced number of fixations per word and improved reading accuracy. Both types of intervention led to item-specific training effects in all subjects. A generalisation to untrained items was only found in segmental readers after the lexical training. Eye movement analyses were also used to compare word processing before and after therapy, indicating that all patients, with one exclusion, maintained their preferred reading strategy. However, in several cases the balance between sequential and lexical processing became less extreme, indicating a more effective individual interplay of both word processing routes.

Eye movements in reading: some theoretical context

The study of eye movements has proven to be one of the most successful approaches in research on reading. In this overview, it is argued that a major reason for this success is that eye movement measurement is not just a methodology--the control of eye movements is actually part and parcel of the dynamics of information processing within the task of reading itself. Some major developments over the last decade are discussed with a focus on the issue of spatially distributed word processing and its relation to the development of reading models. The survey ends with a description of two newly emerging trends in the field: the study of continuous reading in non-Roman writing systems and the broadening of the scope of research to encompass individual differences and developmental issues.