Reading quickly in the periphery — the roles of letters and sentences

In the periphery, crowding obscures the internal letters of words, yet peripheral reading is no faster when letters are spaced far enough apart to escape crowding. To resolve this paradox, we measured reading rate as a function of eccentricity and letter spacing for ordered and unordered words using Rapid Serial Visual Presentation (RSVP). When words are in sentence order, reading rate is independent of letter spacing. When words are out of order, peripheral reading rate falls at the small letter spacings at which crowding occurs. Words degraded to simulate crowding are read foveally at similar rates as intact words in the periphery, with a similar effect of word order. Previous authors have noted large discrepancies in peripheral reading rate between studies. We show that reading rates for unordered words are strikingly consistent across observers and labs. The discrepancies in reading rate for sentences represent individual differences in the benefit that observers gain from the sentence context, which may reflect differences in print exposure. Readers normally use both word order and word content. Our results show that removing word order reveals a much more homogeneous reading rate and exposes the effects of crowding on word content.