• negative evidence;
  • positive evidence;
  • acquisition of irregular novel noun forms;
  • acquisition of irregular novel verb forms

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 [Mage= 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.