Effect of letter spacing on visual span and reading speed

Abstract

S. T. L. Chung (2002) has shown that rapid serial visual presentation (RSVP) reading speed varies with letter spacing, peaking near the standard letter spacing for text and decreasing for both smaller and larger spacings. In this study, we tested the hypothesis that the dependence of reading speed on letter spacing is mediated by the size of the visual span-the number of letters recognized with high accuracy without moving the eyes. If so, the size of the visual span and reading speed should show a similar dependence on letter spacing. We tested this prediction for RSVP reading and asked whether it generalizes to the reading of blocks of text requiring eye movements. We measured visual-span profiles and reading speeds as a function of letter spacing. Visual-span profiles, measured with trigrams (strings of three random letters), are plots of letter-recognition accuracy as a function of letter position left or right of fixation. Size of the visual span was quantified by a measure of the area under the visual-span profile. Reading performance was measured using two presentation methods: RSVP and flashcard (a short block of text on four lines). We found that the size of the visual span and the reading speeds measured by the two presentation methods showed a qualitatively similar dependence on letter spacing and that they were highly correlated. These results are consistent with the view that the size of the visual span is a primary visual factor that limits reading speed.

The effects of interletter spacing in visual-word recognition

“…Chung (2002), using a rapid serial visual presentation task in which reading speed was taken as the speed that corresponded to 80% reading accuracy, found that reading speed in peripheral vision with a slightly wider interletter spacing (1.4 times the default spacing) was the same as the reading speed with the default spacing (e.g., vs. ) -while (unsurprisingly) it decreased slightly with large interletter spacings (2 times the default interletter spacing; as in ; see also Yu et al 2007, for a similar finding). However, we must keep in mind that Chung focused on peripheral rather than on foveal vision, so that these data may not generalize to foveal presentations.…”

Extra-large letter spacing improves reading in dyslexia

“…20 and 21). Recognition is impaired when letters are closer than a critical spacing (19), which is proportional to eccentricity but independent of print size (22).…”

“…* However, very little research has investigated the potential effects of such manipulations (12,13). Here, we pursue this approach, which is motivated by behavioral evidence showing that dyslexics are abnormally affected by crowding (14)(15)(16)(17), a perceptual phenomenon with detrimental effects on letter recognition that is modulated by the spacing between letters (18,19). Crowding refers to the interference of flanking letters on the recognition of target letters (review in refs.…”

“…Parsing of a letter string into its constituent graphemes is a key component of phonological decoding (28), which in turn, is fundamental for reading acquisition (29). Crowding might not only slow down reading speed (19,22) but also induce reading errors, because crowding is accompanied by a jumbled percept that is thought to reflect pooling of features from the target and the flankers (21). These findings lead to the prediction that extra-wide interletter spacing in words should reduce crowding and ameliorate reading performance in dyslexics.…”

Evaluation of video browser features and user interaction with VAST MM

“…Depending on the user's cognitive abilities, the content of a keyframe can be visually processed in less than 100 milliseconds. According to the empirical evaluation reported in [10], a person can read as many as 600 words per minute in a flashcard setting, which, on average, is one word every 100 ms. Similar results were found in [11] for recognizing objects in scenes, e.g.…”