In Los Angeles in 1970 a social worker made a routine visit to the home of a partially blind woman who had made an appeal for public assistance. The social worker discovered that the woman and her husband had kept their 13 year old daughter Genie locked away in almost total isolation during her childhood.
Genie could not speak or stand upright. She had spent every day bound naked to a child’s potty seat and could move only her hands and feet. At night she was placed in a kind of straightjacket and caged in a crib with wire mesh sides and a cover. Whenever Genie made a noise her father beat her. He never communicated with her in words; instead he growled at her and barked at her instead.
After she was rescued she spent a number of years in excessive rehabilitation programs including speech and physical therapy. She eventually learned to walk and to use the toilet. She also eventually learned to recognise many words and speak in basic sentences. Eventually she was able to string together two word combinations like ‘big teeth’ then three word ‘small two cup’. She didn’t however, learn to ask questions and didn’t develop a language system that allowed her to understand English grammar.
Four years after she began stringing word together, she is still unable to speak fluently. A san adult she speak in short, mangled sentences like ‘father hit leg’ ‘big wood’ and ‘Genie hurt’ which when pieced together can be understood.
This shows that children like Genie who are abandoned and abused and not exposed to language for many years, rarely speak normally. Some language experts have argued that cases such as these suggest the existence of a critical period for language development; but other issues can cloud these case
Is there a critical period for language learning?
Most babies learn a language by a certain age if they are to learn to speak at all. A critical period is a fixed time period on which certain experiences can have a long lasting effect on development. It is a time of readiness for learning, after which, learning is difficult or impossible. Almost all children learn one or more languages during their early years, so it is difficult to determine whether there is a critical period for language development.
In1967 Lenneberg proposed that language depends on maturation and that there is a critical period between about 18 months and puberty during which time a first language must be acquired. Lenneberg especially thought that the pre-school years were an important time frame as thisis whe language develops rapidly and with ease.
Although much language learning takes place during pre-school years, it continues into adulthood. Therefore, young children’s proficiency in language does not seem to involve a biologically critical period.