The processing of derived and inflected suffixed words during reading

The encoding of suffixed words (both derivations and inflections) was assessed by monitoring eye movements during reading English sentences in which the target words were embedded. The target words were derived words in Experiment 1 and inflected words in Experiment 2. In each experiment, whole-word frequency and root frequency were independently manipulated, where pairs of words differing on one variable and matched on the other were inserted into the same sentence frame. For derived words, root morpheme frequency affected processing earlier than did whole-word frequency: it affected the duration of the first fixation, whereas whole-word frequency affected processing only beginning on the second fixation. In contrast, for (the regular) inflected words, word frequency had significant effects beginning on the first fixation, whereas root frequency had significant effects beginning with the first fixation duration only for plural nouns and not for inflected verbs. Subsequent regression analyses on the inflected words suggested that the usual part of speech for the stem may play a significant role in processing. The data thus indicate that in normal reading, both the whole word as a unit and the root morpheme play a significant role in processing.