How low can you go? Tracking eye movements during reading at different sampling rates.

Eye-movement research has revolutionized our understanding of reading, but the use of eye-tracking techniques in investigating the reading process is still limited by the cost of high-precision eye-tracking, which limits research to laboratories with sufficient resources. It is important to evaluate to what extent cognitive processes during reading can be measured with less expensive eye-tracking devices. One such way may be to use devices with a lower sampling rate, which are much less expensive than high-sampling rate eye-trackers. We recorded readers' eye movements during reading at different sampling rates and show that it is possible to measure the classic effect of word frequency on fixation duration, reflecting ongoing cognitive processing during reading, at sampling rates ranging from 250 to 2000 Hz. We simulate even lower sampling rates and show that, with a sufficiently large sample size, it is possible to detect the effect of word frequency even at very low sampling rates (30-125 Hz). Our results demonstrate that, in principle, low sampling rates are not an obstacle to studying the effects of cognitive processing during reading.