The phonological trace of perceived words starts fading away in short-term memory after a few seconds. Spoken utterances are usually 2-3 s long, possibly to allow the listener to parse the words into coherent prosodic phrases while they still have a clear representation. Results from this brain potential study suggest that even during silent reading, words are organized into 2-3 s long "implicit" prosodic phrases. Participants read the same sentences word by word at different presentation rates. Clause-final words occurring at multiples of 2-3 s from sentence onset yielded increased positivity, irrespective of presentation rate. The effect was interpreted as a closure positive shift (CPS), reflecting insertion of implicit prosodic phrase boundaries every 2-3 s. Additionally, in participants with low working memory span, clauses over 3 s long produced a negativity, possibly indicating increased working memory load. (Contains 5 figures and 1 supplementary data.)