Lexical processing and text integration of function and content words: evidence from priming and eye fixations.

The results of two experiments comparing processing of function words and content words are reported. In Experiment 1, priming was present for both related function and related content word pairs, as measured in lexical decision response times. In Experiment 2, participants' eye movements were monitored as they read sentences containing either a high- or a low-frequency function or content target word. Average word length and word frequency were matched across the function and content word conditions. Function words showed frequency effects in first-fixation and gaze duration that were similar to those seen for content words. Clear differences in on-line processing of function and content words emerged in later processing measures. These differences were reflected in reading patterns and reading time measures. There was inflated processing time in the phrase immediately following a low-frequency function word, and participants made more regressions to the target word in this condition than in the other three conditions. The priming effects in lexical decision and the word frequency effects in initial processing measures in silent reading for both word types were taken as evidence of common lexical processing for function and content words. The observed differences in later processing measures in the eye-movement data were taken as evidence of differences in the role that the two word types have in sentence processing beyond the lexical level.