When a child produces words successfully s\he receives praise and encouragement, subsequently motivating the child to repeat the behaviour.
However there are problems with this theory:
All children pass through the same stages of language development regardless of the type and amount of adult reinforcement they receive. If acquisition were entirely dependent on parental reinforcement then there would be more variation between individual children.
Chomsky believes that children have an innate ability to extract the rules underlying language from the world around them. He said that children had, inside their brain, a Language Acquisition Device that becomes active as soon as a child is exposed to speech. The programmed patterns “primary linguistic data” are general and the child has to learn the rules by applying them. Experiments such as Jan Berko’s “Wug” testing help prove this. The experiment involved Burko showing children a picture of an animal he had made up. He called this animal a “Wug”. He then showed a picture with many wugs on it. He asked the children what was on the card now and they instinctively said “Wugs”. This helps to prove that plurals are inherent and not learnt, because all the children would not have heard the word wug before the experiment.
There are problems with this theory too:
The main criticism of Chomsky’s theory is that it underestimates the power and role of language as a social phenomenon. Cases such as Genie prove that social interaction is essential for language to occur.
Lenneburg developed Chomsky’s idea of LAD. He said there was a critical period within which a child must be exposed to language in order to develop normally. They must learn language before reaching puberty.
Piaget argues that children can only use a certain linguistic structure when they understand the concepts involved. Studies have been made of children whose mental development has been retarded but who can still speak fluently. It would appear that a child’s ability to grasp grammar and sentence structure is independent of cognitive development.
Genie was discovered age 13. She was found to be mentally retarded. Doctors did not know if she was born this way of if it occurred from years of abuse. This led to many problems.
It was evident that Genie had a ‘thirst’ for language. During her time with Susan Curtis she wanted everything names by pointing at them. She began stringing two words together. She said things like “big teeth” and “little marble”.
Genie stayed with the Ridler family for 4 years. During that time she learnt many words. By this time she had passed puberty.
Curtis believed they were on their way to disproving Lenneburg’s theory.
In 1975 Susan Curtis wrote up 4 years worth of research. She found that Genie had a good vocabulary but her grammar was not good at all. Genie could not form sentences. She also discovered that Genie’s performance had increased significantly over the years. On the Leiter International Performance Scale, which was developed for use with deaf children and does not require verbal instructions, she had an IQ of 38 in 1971, 53 in ’72, 65 in ’74 and 74 in ’77. On tests testing the different sides of the brain Genie scored incredibly low when having to use the left side of her brain, but normally for her age when suing her right side.
In 1977, the last time Genie was filmed, scientists found that without constant teaching Genie had regressed. She now barely said a word.
The case of Genie appeared to prove Lenneburg’s theory.
Lenneburg said that a child must have interaction with humans and learn to speak before puberty or they will never learn at all.
In other cases of feral children, some, who were discovered at a much younger age than Genie, learnt language and were eventually able to speak well. Cases such as Genie, or Wild Peter (found age 12) were unable to do more than string a few words together.
Genie failed to learn any kind of grammar. According to Chomsky this is what distinguishes the language of humans from the of animals. Genie could not grasp the difference between various pronouns or between active and passive verbs. In that sense she appeared to have passed the critical period.
The problem with the case of Genie and the validity of Lenneburg’s theory is that Genie was brain damaged. If she had had a normal functioning brain then the case would have proved Lenneburg’s theory without a doubt. As it stands, because of her brain damage we can never be sure.
