High refresh rate and oculomotor adaptation facilitate reading from video displays

Reading from a video display terminal (VDT) was tested at screen refresh rates of 500 Hz and 60 Hz. Reading was initially 8 words/min (3.05%) faster at 500 Hz. A hypothesis that reading rate on VDTs is limited by stimulus availability accounts for the difference. When the eye reaches a new fixation position, it 'parks' until a sample of text appears at the fovea. Then processing resumes in the normal way. This idea, combined with the 500-Hz reading data, can predict reading rate at any refresh rate, and is quantitatively confirmed by the reading rate at 60 Hz. The difference in reading rates disappeared for the second half of the text, as a result of differences between frequencies of eye movements in the two refresh conditions. From the first half to the second, subjects at 60 Hz made more large forward saccades and fewer small reverse saccades. Both changes make sampling of the text more sparse, compensating for the dead time between samples. Subjects were unaware of refresh conditions, differences in their reading rates, and types of eye movements they generated. Reading from a continuously illuminated active-matrix display is slightly faster than from a comparable VDT.