This study investigates the effective stimulus span during fixation in reading, using a computer-based eye-movement controlled display system. The researchers modified the text display based on the reader's eye position, creating "windows" of normal text for the reader while varying the peripheral text patterns. The results indicate that skilled readers acquire word-length pattern information at least 12 to 15 character positions to the right of the fixation point, primarily influencing saccade lengths. Specific letter and word-shape information are acquired no further than 10 character positions to the right. The study also found that reducing the window size significantly increased reading time due to more fixations and longer fixations, but did not affect comprehension test scores. These findings suggest that fluent reading relies on a relatively narrow region for visual information acquisition, supporting the idea that eye movements are guided by peripheral visual patterns.This study investigates the effective stimulus span during fixation in reading, using a computer-based eye-movement controlled display system. The researchers modified the text display based on the reader's eye position, creating "windows" of normal text for the reader while varying the peripheral text patterns. The results indicate that skilled readers acquire word-length pattern information at least 12 to 15 character positions to the right of the fixation point, primarily influencing saccade lengths. Specific letter and word-shape information are acquired no further than 10 character positions to the right. The study also found that reducing the window size significantly increased reading time due to more fixations and longer fixations, but did not affect comprehension test scores. These findings suggest that fluent reading relies on a relatively narrow region for visual information acquisition, supporting the idea that eye movements are guided by peripheral visual patterns.