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Web Usability or Accessibility: Comparisons between people with and without intellectual disabilities in viewing complex naturalistic scenes using eye-tracking technology

Date

2009-07-02T19:18:45Z

Authors

Bazar, Nancy Sceery

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Abstract

The purpose of this primarily quantitative study was to compare how young adults with and without intellectual disabilities examine different types of images. Two experiments were conducted. The first, a replication and extension of a classic eyetracking study (Yarbus, 1967), generated eye gaze patterns and data in response to questions related to the famous painting, The Unexpected Visitor. Both groups exhibited goal-directed behavior based on the judgment of eight independent raters, an extension to the original study, but there was a statistically significant difference between the two groups, based on the judgment of two cooperating raters. Raters could not differentiate between the scan paths of the young adults with and without intellectual disabilities. Yarbus' study was also extended by the inclusion of an interview with the participants. There was a statistically significant difference in the word count and recollection of major elements from The Unexpected Visitor between the groups. The second experiment used eye-tracking technology and a current saliency model that predicted salient points in images (Walther & Koch, 2006) under two sets of saliency features. Participants rapidly viewed 30 images of Web sites and other natural scenes from three different sources. This study found no statistically significant differences between people with and without intellectual disabilities for teacher created pictures from a fourth grade geomorphology course and award winning Web sites, leading to a strong recommendation of a usability rather than accessibility for people with intellectual disabilities. Finally, the relative merits of two methods of saliency prediction were compared. The more recently developed Walther model (Walther & Koch) proved to produce similar results as the computationally intensive Itti model (Itti, Koch, & Niebur, 1998), under the conditions of this experiment. This suggests that researchers may use the simpler model in the future to compare groups.

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Keywords

Disabilities, Eye – tracking, Saliency, Web accessibility, Section 508, Yarbus

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