Psychophysics of Reading: XIX. 1
PSYCHOPHYSICS OF READING: XIX. HYPERTEXT SEARCH AND
RETRIEVAL WITH LOW VISIONa

HUGO BRUGGEMAN and GORDON E. LEGGE

Abstract-Low vision is any chronic form of visual impairment, not correctable by glasses or
contacts that adversely affects performance of important everyday visual tasks. Most people with
low vision need magnified text to read. On a fixed-size computer screen, the magnification of
text trades off against the proportion of the entire screen visible. To read hypertext, simultaneous
access to the full-screen page is important for skimming text and for locating hyperlinks.
Therefore, people with low vision using magnified text might encounter difficulties reading
hypertext, especially when hyperlinks are placed at unpredictable locations (true for most
webpages). We investigated hypertext information retrieval as the time taken and number of
nodes traversed to answer a series of questions. In Experiment 1, low-vision performance for
reading prose and hypertext was compared to normal performance: low-vision performance
deficits in hypertext retrieval were predictable from deficits in conventional prose reading.
Experiment 2 evaluated the effect of web-page layout on low-vision performance: retrieval
performance was severely affected when hyperlinks had unpredictable locations. This extra
deficit was eliminated when users were provided with simultaneous access to full-screen layout.
Based on these findings, we discuss the accessibility of the Internet by people with low vision.

Mini review of other papers in this series

This paper is part of an ongoing series of research publications dealing with the psychophysics of
reading in normal and low vision. These publications report findings at the University of
Minnesota’s Laboratory for Low-Vision Research by G. E. Legge and his colleagues, supported
by the National Institutes of Health. Citations with links to the abstracts for the 20 papers in the
series can be found at http://vision.psych.umn.edu/www/people/legge/series.html. For
convenience, the 20 citations are listed in the Appendix in Roman numeral order and will be
referred to by Roman numerals in this mini review (e.g., XIX for the current paper, the
nineteenth in the series).

The two main goals of this research are to understand how visual information is used in reading
by people with normal and low vision and to understand how different forms of low vision affect
reading. One application of this work has been to guide the design of text displays including low-
vision reading aids (cf., III).

Our primary measure of reading performance is reading speed in words per minute (Wpm).
Reading speed can be measured objectively, is reproducible, and is sensitive to visual
parameters. We have developed several methods for measuring reading speed including
video/computer-based methods (I, VIII, XIV) and a chart-based method, the MNREAD acuity
chart (XV). We have also used the rapid serial visual presentation (RSVP) method (XVI, XVIII,
XX). We have shown that reading speed is a more sensitive performance measure than
comprehension for assessing effects of visual factors (VII).


a Reprinted from Proceeding of the IEEE, Vol. 90, No. 1, pp. 94-103, 2002.