Stem and whole-word frequency effects in the processing of inflected verbs in and out of a sentence context

Abstract

The relationship between stem and whole-word frequency was investigated by simultaneously manipulating both frequency measures in a set of inflected verbs. In Experiment 1, these verbs were presented in isolation as part of a lexical decision task, and an effect of stem frequency only was observed. In Experiment 2, the same verbs were presented in sentences in a self-paced reading task, and an interaction between stem and whole-word frequency was observed. These findings contradict “either–or” models of morphological processing that assume two separate and independent processing routes for morphologically complex words, and also provide further evidence that the relationship between stem and whole-word frequency effects is context-sensitive.

Keywords:

• Morphology
• Frequency
• Context
• Inflection

Acknowledgements

The authors thank the members of the Educational Psychology Psycholinguistics Lab at the Beckman Institute for their assistance in running participants and Dick Anderson and Peter Golato for their helpful comments and suggestions. This research was supported in part by a University of Illinois Campus Research Board Grant to K. Christianson.

Notes

¹Stem frequency has also been called base frequency, cumulative root or root frequency (Niswander et al., 2000) or stem-cluster frequency (Alegre & Gordon, 1999), while whole-word frequency is sometimes called word frequency (Alegre & Gordon, 1999; Niswander et al., 2000) or surface frequency (Baayen et al., 2007). For consistency's sake, and because the present research concerns inflected words exclusively, the terms stem and whole-word frequency will be used throughout.

²Some of these verbs share an “e” with their suffix (e.g., blamed, seized). Conceivably, this could make decomposition less likely, but McCormick, Rastle, & Davis (2008) provide evidence that it does not.