The Role of Perceptual and Word Identification Spans in Reading Efficiency: Evidence From Hearing and Deaf Readers

Theories of reading posit that decisions about "where" and "when" to move the eyes are driven by visual and linguistic factors, extracted from the perceptual span and word identification span, respectively. We tested this hypothesized dissociation by masking, outside of a visible window, either the spaces between the words (to assess the perceptual span, Experiment 1) or the letters within the words (to assess the word identification span, Experiment 2). We also investigated whether deaf readers' previously reported larger reading span was specifically linked to one of these spans. We analyzed reading rate to test overall reading efficiency, as well as average saccade length to test "where" decisions and average fixation duration to test "when" decisions. Both hearing and deaf readers' perceptual spans extended between 10 and 14 characters, and their word identification spans extended to eight characters to the right of fixation. Despite similar sized rightward spans, deaf readers read more efficiently overall and showed a larger increase in reading rate when leftward text was available, suggesting they attend more to leftward information. Neither rightward span was specifically related to where or when decisions for either group. Our results challenge the assumed dissociation between type of reading span and type of saccade decision and indicate that reading efficiency requires access to both perceptual and linguistic information in the parafovea. Public Significance Statement Our work shows that reading efficiency requires access to both perceptual and linguistic information in the upcoming text. In addition, skilled deaf readers have a unique reading profile hallmarked by faster reading rates, fewer skipped words, and less rereading of text without loss of comprehension. Deaf readers also attend more to information to the left of fixation, perhaps due to changes in visual attention that occur with early deafness and/or sign language experience.