What asymmetries within comprehension reveal about asymmetries between comprehension and production: The case of verb inflection in language acquisition

Two recent studies (Johnson et al., 2005; Perez-Leroux, 2005) found that English- and Spanish-learning children do not show the ability to use verb inflection as a cue to subject number before the age of 5 to 6 years. These findings suggest an asymmetric development as verb inflections are usually correctly produced before this age. In the present study we investigated whether German 3- to 4-year-olds take advantage of the information provided by the verb inflection in sentence comprehension. In a first study, children's looking behavior at two pictures was measured after presentation of a sentence in which the subject number was coded only by the verb inflection. The results from this study suggest that children's looks reflect correct interpretation of the sentences and thus show their ability to make use of verb inflection. In a second experiment, preferential looking was combined with an additional task in which the children had to point to the matching picture. In this case children did not perform above chance level. Our results underline the relevance that specific task demands have on the performance of children in comprehension testing. These have to be accounted for when interpreting findings on production and comprehension asymmetries in language acquisition.