Bionic Reading in L2 academic contexts: An eye-tracking study

Bionic Reading, a text-presentation format that bolds the initial portion of each word while leaving the remaining letters in regular font weight, has attracted considerable public attention and has been promoted as a means of enhancing reading performance. However, its effects on the online processing of academic texts by second language (L2) readers remain poorly understood. Using eye-tracking methodology, the present study extended research on Bionic Reading to the relatively underexplored context of L2 academic reading and investigated how different bolding positions and visual salience patterns affect reading. Participants read texts presented in five conditions: Regular Text, Bold Start, Bold End, Bold to Gray, and Gray to Bold. The standard Bionic Reading format (Bold Start) produced no reliable facilitative effects on either reading efficiency or comprehension accuracy relative to Regular Text. Changing the bolding position alone, as in the Bold End condition, likewise produced no reliable facilitative effects. By contrast, the Bold to Gray and Gray to Bold conditions, both involving stronger within-word visual salience, reduced reading efficiency without improving comprehension accuracy. Exploratory individual-difference analyses further indicated that readers with greater academic word knowledge showed greater processing demands in the Gray to Bold condition. By systematically examining different bolding positions and visual salience patterns, this study shows that Bionic Reading does not facilitate L2 academic reading and that stronger within-word visual salience may instead interfere with reading efficiency. These findings extend the empirical evaluation of Bionic Reading beyond L1 reading and general text types, and clarify how different forms of within-word visual salience influence L2 academic reading.