History of linguistics (20th century) ; History of linguistics (21st century) ; Lernmotivation; Affekt (Einfluss auf Zweitspracherwerb) ; Affect (influence on second language acquisition) ; Motivation research ; Multidisciplinary research ; Komplexes System; Complex system; Emergenztheorie; Emergence (theory of) ; Systems theory ; Soziokognition; Social cognition; Discursive psychology; Social psychology ; Interimsgrammatik (Spracherwerb) ; Lernervarietät (Spracherwerb) ; Learner variety (language acquisition) ; Interlanguage (language acquisition) ; Second language acquisition (psycholing.)