Benefits of rapid serial visual presentation (RSVP) over scrolled text vary with letter size

We previously reported that low vision readers do not benefit from a rapid serial visual presentation (RSVP) display relative to a scroll display. Each reader in those studies was presented with only one letter size, and it was the same for both displays. In the current study, we systematically varied the size of the letters and compared reading rates from the 2 displays for letters that were 2, 4, 6, 8, and 10 times each reader's acuity threshold. Using this paradigm, we found that subjects with normal vision (n = 12) read faster with RSVP for all text sizes. Low vision subjects (N = 20) showed no benefit of RSVP until the text was at least 8x their acuity threshold. As in our prior studies, there was a great deal of variability within the low vision group, and for a small number of subjects (25%), reading was faster from the scroll than from the RSVP display.