Abstract
Across languages, the speech signal is characterized by a predominant modulation of the amplitude spectrum at ~4-5 Hz, reflecting the processing of linguistic information chunks (i.e., syllables or words) approximately every 200 ms. Interestingly, ~200 ms is also the typical duration of eye fixations during reading. Prompted by this observation, we estimated the frequency at which German readers sample text, and demonstrate that they read sentences at a rate of ~5 Hz. We then examined the generality of this finding in a meta-analysis including 14 languages. We replicated the empirical result for German and observed that fixation-based sampling frequencies vary across languages between 3.9 and 5.2 Hz. Remarkably, we identified a systematic rate reduction from easy to difficult writing systems. Finally, we directly investigated in a new experiment the association between speech spectrum and eye-movement sampling frequency at a person-specific level and found a significant correlation. Based on this evidence, we argue that during reading, the rate of our eye movements is tuned to supply information to language comprehension processes at a preferred rate, coincident with the typical rate of speech.
Significance Statement Across languages, speech is produced and perceived at a rate of ~4-5Hz. When listening to speech, our brain capitalizes this temporal structure to segment speech. We show empirically that while reading our eyes sample text at the same rate, and generalize this finding in a meta-analysis to 14 languages. Reading rates vary between 3.9 and 5.2Hz – i.e., within the typical range of the speech signal. We demonstrate that the difficulty of writing systems underpins this variance. Lastly, we also demonstrate that the speech rate between persons is correlated with the rate at which their eyes sample text. The speech rate of spoken language appears to act as a driving force for the voluntary control of eye movements during reading.