Fonts of wider letter shapes improve recognition in peripheral vision

Designing legible fonts often involves balancing various trade-offs. While the added negative space that surrounds light-weight fonts enhances legibility by mediating the effects of crowding from nearby letters (Dobres, Reimer, & Chahine, 2016), it also impedes legibility at small visual angles by taking up the black space needed for letter recognition at low spatial frequencies (Beier & Oderkerk, 2019). Given the dependence of crowding on visual complexity (Bernard & Chung, 2011) and that stroke frequency has been shown to be a predictor of spatial frequency channels, here, we facilitated letter recognition at small visual angles by increasing the letter width in order to decrease visual complexity by way of the stroke frequency, defined as the number of lines crossed by a horizontal slice through a letter, divided by the width of that letter (Majaj, Pelli, Kurshan, & Palomares, 2002). To investigate the effect of width on letter recognition, we tested three variations of Helvetica (Condensed, Roman, and Expanded). We employed a short exposure single report trigram paradigm in which a string of three letters were presented left or right of the center in the fovea at 1.3° eccentricity. Participants were instructed to report the middle letter while maintaining fixation on the fixation cross. We used an adapted accelerated staircase procedure to determine individual stimulus x-heights and used backward masking to control the exposure duration. A repeated-measures ANOVA indicated a main effect of font width. Bonferroni corrected post hoc t-tests showed that recognition performance decreased significantly with width. Specifically, mean recognition for Roman was significantly higher than for Condensed, while recognition for Expanded was significantly higher than both Roman and Condensed. The findings indicate that wider letter shapes improve reading at small visual angles.