Effects of contextual predictability and transitional probability on eye movements during reading.

In 2 eye-movement experiments, the authors tested whether transitional probability (the statistical likelihood that a word precedes or follows another word) affects reading times and whether this occurs independently from contextual predictability effects. Experiment 1 showed early effects of predictability, replicating S. A. McDonald and R. C. Shillcock's (2003a) finding that words with a high transitional probability (defeat following accept) are read faster than words with a low transitional probability (losses following accept). However, further analyses suggested that the transitional probability effect was likely due to differences in predictability rather than transitional probability. Experiment 2, using a better controlled set of items, again showed an effect of predictability, but no effect of transitional probability. The authors conclude that effects of transitional probability are part of regular predictability effects. Their data also show that predictability effects are detectable very early in the eye-movement record and between contexts that are weakly constraining.