Cross-Morphemic Predictability and the Lexical Access of Compounds in Mandarin Chinese

Chinese poses a challenge for models of compound processing, since the basic notions of morpheme, word and phrase are not consistently distinguished by native speakers. It is thus proposed that the mental lexicon consists of linked and overlapping listemes (in the sense of Di Sciullo and Williams 1987) which can potentially be of any size (morpheme, word, phrase). One implication of this approach for compound processing is that cross-morphemic predictability should play an important role: the more predictable one morpheme is from the other, the easier the compound should be to access. To study this implication, cross-morphemic predictability is quantified using the measure of Mutual Information from information theory, which divides the frequency of the constituent of interest (i.e. a compound) by the frequencies of the components (i.e. morphemes). This leads to two specific predictions: compound frequency should have a positive effect on lexical access, but morpheme frequency should have a negative effect. In Experiment 1, it is demonstrated that a very simple connectionist network, built according to the overlapping listeme approach, conforms to these two predictions. This suggests that separate effects of word and morpheme frequency need not require separate processing levels for words and morphemes. Experiment 2 then compares the network's behavior with Chinese native speakers in a lexical decision task involving spoken Mandarin Chinese compounds. As predicted, there was a positive effect of word frequency on response speed and accuracy, and a negative effect of morpheme frequency. Suggestions are made for reconciling these results with the more familiar positive or neutral morpheme frequency effects found in other studies.