Microsaccades during reading.

Recent research has shown that microsaccades contribute to high acuity vision. However, little is known about whether microsaccades also play a role in daily activities, such as reading, that do not involve stimuli at the limit of spatial resolution. While the functions of larger saccades in reading have been extensively examined, microsaccades are commonly regarded as oculomotor noise in this context. We used high-resolution eyetracking and precise gaze localization to investigate fine oculomotor behavior during reading. Our findings show that microsaccade characteristics differ from those measured during sustained fixation: microsaccades are larger in size and primarily leftwards during reading, i.e. they move the line of sight backward on the text. Analysis of how microsaccades shift gaze relative to the text suggests that these movements serve two important functions: (1) a corrective function, by moving the gaze regressively within longer words when the preceding saccade lands too far toward the end of these words, and (2) an exploratory function, by shifting the gaze on adjacent words to gain additional information before the execution of the next saccade. Thus, microsaccades may benefit reading by enhancing the visibility of nearby words. This study highlights the importance of examining fine oculomotor behavior in reading, and calls for further research to investigate the possible roles of microsaccades in reading difficulties.