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| Identifier |
000407820 |
| Title |
Evaluation of fixations during reading |
| Alternative Title |
Αξιολόγηση των σημείων προσήλωσης κατά την ανάγνωση |
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Author
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Αγιοργιωτάκης Μιχαήλ
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Thesis advisor
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Πλαϊνης, Σωτήρης
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Reviewer
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Τσιλιμπάρης , Μιλτιάδης
Ταρουδάκης, Μιχαήλ
Σίμος, Παναγιώτης
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| Abstract |
Purpose
The main purpose of this study was to evaluate fixations recorded during reading in two different luminance conditions, with an emphasis on their duration and spatial distribution (fixation stability). Οther characteristics of fixations, such as number of microsaccades and their characteristics have been also analyzed.
Methods
In this study a group of 14 people participated with a mean age of 30,6 years (25-36), native Greek speakers, with habitual refractive correction, VA better than 0.0 logMAR in each eye. They have been asked to read a paragraph, consisted of 141 words, in high and low luminance conditions. Eye movement data have been recorded under two conditions of luminance using a video eyetracker (EyeLink II by SR Research Ltd.) at a sampling rate of 500 Hz at a distance of 40 cm. We have developed an algorithm to analyze the recorded data, to detect forward and regressive saccades and obtain information about the characteristics of fixations, such as fixation duration, 68% BCEA and also to detect and analyse microsaccades.
Results
There was not any statistical significant difference in the number of fixations in high and low luminance conditions. Luminance had an effect on the percentage distribution of saccades, as the percentage of regressive fixations was lower and the percentage of forward fixations was higher in low luminance. We also showed that the median fixation duration and median 68 % BCEA were higher in low luminance conditions. For both forward and regressive fixations, we found a weak positive statistical significant correlation between 68% BCEA and fixation duration, in high and low luminance conditions. The average number of microsaccades per fixation was higher in low luminance conditions and the average microsaccades rate (N/sec) was higher in high luminance conditions for both forward and regressive fixations. We also showed that the average number of microsaccades increases as a function of fixation duration, while the average microsaccades rate decreases. The majority of the detected microsaccades are oriented to the opposite direction of the previous saccade.
Conclusions
Ex-Gaussian analysis was proved a useful tool to understand the effect of luminance in the distributions of fixation duration, 68% BCEA, and the microsaccades’ characteristics (peak velocity and amplitude). The separation of forward and regressive fixations lead to a better understanding of their characteristics during reading. The analysis presented in this study could be helpful for future studies to unveil the effect of other factors on fixations, such as contrast, print size, personality characteristics and other cognitive factors.
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| Language |
English |
| Issue date |
2017-03-29 |
| Collection
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School/Department--School of Medicine--Department of Medicine--Post-graduate theses
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Type of Work--Post-graduate theses
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| Permanent Link |
https://elocus.lib.uoc.gr//dlib/5/7/d/metadata-dlib-1491987103-793100-21240.tkl
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| Views |
267 |
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