Relier Pairs Critical PeriodVersion en ligne Critical Period par Jenny Sanjuanita 1 The czech twins (1972) 2 Isabelle (1930) 3 Noam Chosmky 4 Genie (1970) 5 Universal Grammar Her deaf-mute mother as her only contact. She had no sense of language. They had been kept locked in insolation in a cellar with only each other for company. They little speech and communicated mostly in gestures. Languages need to have generalizable grammatical rules 1965. Proposed Language Acquisition Device (LAD) Her case served to study wheter language could be taught even after critical periods for language development had been missed.