Neuropsychological evidence for a distinction between STM and LTM

Some of the strongest evidence for a distinction between STM and LTM comes fromt he study of people who have suffered brain damage. The loss of memory among such people is usually selective, i.e. it affects one type of memory but not another.

There are several case studies of people with severe memory loss, including that of Clive Wearing. Milner (1966) has reported on another famous case study of a young man only known by his initials, HM. He suffered from severe epilepsy and underwent brain surgery to remove parts of his temporal lobes and hippocampus. The operation alleviated his epilepsy but left him with severe memory deficits although his IQ remained above average. He was able to reccall events in his early life but was unable to remember events for about ten years before the surgery and could not learn or retain new information. He could remember approximately 6 numbers in the order they had been presented suggesting that his STM was relatively intact. However, he repeatedly read the same magazine without realising that he had read it before and was unable to recognise the psychologists who spent long periods of time with him. This suggests that HM had a normal STM but that his LTM was now…