Processing Inflectional and Derivational Morphology

Three lexical decision experiments were carried out to investigate the nature of morphological decomposition in the lexical system. The first of these experiments compares the priming effect of inflectionally and derivationally related forms on a simple inflected word. Italian derived words like mutevole (changeable) were as effective as non-derived inllected words like mutarono (they changed) in priming the related form mutare (to change). The design of the remaining experiments is based on the stem homograph paradigm (Laudanna, Badecker, & Caramazza, 1989, Journal of Memory and Language, 28, 531-546). When an unambiguous word like mute (mute) is primed by a stem homograph like mutarono (they changed)-a morphologically unrelated word with a homographic stem-there is a robust inhibitory effect when compared with unrelated prime conditions. Experiments two and three compared the effect on forms like mute of priming by an inflected stem homograph (mutarono) and priming by a derived “root homograph” like mutevole-a morphologically unrelated derived word with a homographic root (mut-). While there was a consistent inhibitory effect with the inflected primes, there was no such effect with the derived primes. These results indicate that there is a level of lexical representation in the input lexicon at which inflected and derived words are analyzed in terms of their inflectional stems and affixes, but not also in terms of their derivational roots and affiies. It is argued that the inhibitory effects found in experiments two and three and the facilitation effects found in experiment one and elsewhere support the notion that there are multiple representational levels at which morphological structure is represented. o 1992 AC&AC press, I~C.