Effects of Increased Letter Spacing on Digital Text Reading Comprehension, Calibration, and Preferences in Young Readers

In educational technology environments, the ability to customize digital text presentation offers opportunities to enhance learning experiences through typographical adjustments. This study investigated how digital letter spacing (LS) manipulations affect reading comprehension (RC), reading speed, calibration of comprehension (CoC), and preferences in emergent readers. We examined 163 second graders and 126 third graders as they read digital texts in Hebrew under two conditions: standard LS (100%) and increased LS (150%). The results revealed developmental differences in response to spacing manipulations: increased LS significantly improved RC in second graders, whereas it showed an opposite trend for third graders. Reading rate remained stable across conditions for both groups. Children also demonstrated more accurate CoC under their individually optimal LS condition, suggesting that their comprehension monitoring was responsive to typographical features that supported reading. Preferences analysis indicated a higher numerical proportion of participants favoring the standard LS condition over the increased LS condition in both grades. These findings imply that by integrating adaptive typographical features into educational technology, educators can enhance performance in developing readers, supporting differentiated instruction in increasingly digital learning environments.