PSYCHOPHYSICS OF READING - XVII - LOW-VISION PERFORMANCE WITH 4 TYPESOF ELECTRONICALLY MAGNIFIED TEXT

Most people with low vision Bleed magnification to read. Page navigati on is the process of moving a magnifier during reading. Modern electro nic technology can provide many alternatives for navigating through te xt. This study compared reading speeds for four methods of displaying text. The four methods varied in their page-navigation demands. The cl osed-circuit television (CCTV) and MOUSE methods involved manual navig ation. The DRIFT method (horizontally drifting text) involved no manua l navigation, but did involve both smooth-pursuit and saccadic eye mov ements. The rapid serial visual presentation (RSVP) method involved no manual navigation, and relatively few eye movements. There were 7 nor mal subjects and 12 low-vision subjects (7 with central-field loss, CF L group, and 5 with central fields intact, CFI group). The subjects re ad 70-word passages at speeds that yielded good comprehension. Taking the CCTV reading speed as a benchmark, neither the normal nor low-visi on subjects had significantly different speeds with the MOUSE method. As expected from the reduced navigational demands, normal subjects rea d faster with the DRIFT method (85% faster) and the RSVP method (169%) . The CFI group read significantly faster with DRIFT (43%) and RSVP (3 8%). The CFL group showed no significant differences in reading speed for the four methods.