The current study sought to assess development differences in children's learning of irregular nouns and verbs under conditions of negative and positive evidence. Fifty-five 3-, 4- and 5-year-old children learned nonsense nouns and verbs and were later asked to produce plural forms for the nouns and past tense forms for the verbs. Forms were constructed to be irregular, and half were provided through negative evidence and half through positive evidence. Age, form (noun vs. verb) and evidence type (negative vs. positive) interacted: 3-year-olds learned more nouns through negative evidence t(15) = 2.76, p = 0.014, r2 = 0.34, while 5-year-olds learned more verbs through negative evidence t(16) = 2.281, p = 0.04, r2 = 0.25. Four-year-olds showed equal learning across the two conditions. These results suggest developmental differences in the efficacy of negative evidence.

This study compared negative and positive evidence in adult word learning, predicting that adults would learn more forms following negative evidence. Ninety-two native English speakers (32 men and 60 women [M age = 20.38 years, SD = 2.80]), learned nonsense nouns and verbs provided within English frames. Later, participants produced plural and past tense forms for the irregular nouns and verbs following negative or positive evidence. As anticipated, correct production followed negative evidence, and errors followed positive evidence. Additionally, participants learned more verbs than nouns. Implications for first and second language learning are discussed.