Relier Pairs Critical PeriodVersion en ligne Critical Period par Jenny Sanjuanita 1 Universal Grammar 2 The czech twins (1972) 3 Noam Chosmky 4 Genie (1970) 5 Isabelle (1930) Her case served to study wheter language could be taught even after critical periods for language development had been missed. 1965. Proposed Language Acquisition Device (LAD) 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