Increased Word Spacing Improves Performance for Reading Scrolling Text with Central Vision Loss

Hannah Harvey, Stephen Anderson, Robin Walker

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Significance: Scrolling text can be an effective reading aid for those with central vision loss. Our results suggest that increased inter-word spacing with scrolling text may further improve the reading experience of this population. This conclusion may be of particular interest to low vision aid developers and visual rehabilitation practitioners.
Purpose: The dynamic, horizontally scrolling text format has been shown to improve reading performance in individuals with central visual loss. Here, we sought to determine whether reading performance with scrolling text can be further improved by modulating inter-word spacing to reduce the effects of visual crowding: a factor known to impact negatively on reading with peripheral vision.
Methods: The effects of inter-word spacing on reading performance (accuracy, memory recall and speed) was assessed for eccentrically-viewed single sentences of scrolling text. Separate experiments were used to determine whether performance measures were affected by any confound between inter-word spacing and text presentation rate in words per minute (wpm). Normally-sighted participants were employed, with a central vision loss implemented using a gaze-contingent scotoma of 8o diameter. In both experiments, participants read sentences that were presented with an inter-word spacing of one, two or three characters. 
Results: Reading accuracy and memory recall were significantly enhanced with triple-character inter-word word spacing (both measures P < 0.01). These basic findings were independent of the text presentation rate (in wpm). 
Conclusions: We attribute the improvements in reading performance with increased inter-word spacing to a reduction in the deleterious effects of visual crowding. We conclude that increased inter-word spacing may enhance reading experience and ability when using horizontally scrolling text with a central vision loss.
Original languageEnglish
Pages (from-to)609-616
Number of pages8
JournalOptometry and vision science : official publication of the American Academy of Optometry
Issue number8
Early online date16 Jul 2019
Publication statusPublished - 1 Aug 2019


  • Reading
  • macular degeneration
  • dynamic text
  • scrolling text
  • vision loss
  • perceptual crowding

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