The Cognitive Approach

Diagnosis: HM was a patient with severe and frequent epilepsy. His seizures were based in a brain structure called the hippocampus. In 1953, doctors decided to surgically remove part of the brain around this area.

Results: The operation reduced his epilepsy, but led to him suffering memory loss. He could still form short-term memories, but was unable to form new long-term memories. For example, he could read something over and over without realising that he had read it before. He also moved house and had difficulty recalling the new route to his house. However, he could still talk and show previous skills (procedural memory). From tests, they found HM's episodic memory (for past events) and semantic memory (for knowledge, e.g. word meanings) was affected more than his procedural memory.

Method: Washoe, a chimpanzee, was raised like a human child and taught American Sign Language (ASL).

Results: By the end of the 22nd month of the project, Washoe had learnt at least 34 signs.

Conclusion: The development of language in the chimpanzee appeared to follow the same patterns as language development in children (both speaking children, and those using ASL). Washoe learnt language at similar rate to children of the same age. Additionally, language acquisition seemed to require interaction with caregivers and communication in everyday situations. However, she did not learn grammar.

Evaluation: There are ethical considerations, in that Washoe was taken from the wild and deprived of other chimpanzees for companionship. There are also issues of external validity - it is not possible to accurately generalise results from a chimp to human children.