addition affect anxiety attention auxiliary verb avoidance behaviorism caleb gattegno catalan language chinese language cognition communication communication accommodation communicative competence community competence computer-assisted language learning contrastive analysis conversation copula critical period hypothesis critical period culture defense language institute dell hymes dictionary discourse education ellen bialystok english language eric lenneberg error analysis fear feedback formula fremdsprachen und hochschule french language gender role german language germans gibberish gloss group dynamics hardest language indo-european languages inference information input enhancement interdisciplinarity interlanguage italian language language acquisition language acquisition device language education language transfer learning by teaching lexicon linguistics measurement methodology mime artist mnemonics modern language aptitude test monitor theory morpheme motivation motivation in second language learning natural language navajo nation negative neurobiology neurolinguistics neurology noam chomsky omission phoneme phonetics phonology plural pragmatics private speech pro-form proficiency pronoun psycholinguistics psychology routine second language semantics silence society sociolinguistics sound spanish language substitution suffix syntax t-v distinction target language the silent way theory typology universal grammar variation vocabulary willingness to communicate word order writing