Self-knowledge; Selbsterkenntnis; Self concept ; Representation (of time) ; Time (notion of) ; Time indication ; Mental representation (language acquisition) ; Object individuation; Conceptual development; Konzept (Spracherwerb) ; Concept formation ; Spracherwerb und neurologische Entwicklung; Language acquisition and neurological development; Sprache und Denken (Ontogenese) ; Language and thought (ontogenesis) ; Cognitive development; Language acquisition and cognitive development ; Baby talk; Motherese; Child-directed speech; Ammensprache; Babysprache; Infant-directed speech; Fatherese; Language spoken to children