Case studies of brain-damaged patients related to research into memory, including the case of Henry Molaison (HM).
Case studies are very detailed investigations of an individual or small group of people, usually regarding an unusual phenomenon or biographical event of interest to a research field. Due to a small sample, researchers using the case study method can conduct an in-depth analysis of the individual/group under examination.
Case studies create opportunities for a rich yield of data, and the depth of analysis can in turn bring high levels of validity (i.e. providing an accurate and exhaustive measure of what the study is hoping to measure).
Studying abnormal psychology can give insight into how something works when it is functioning correctly, such as brain damage on memory (e.g. the case study of patient KF, whose short-term memory was impaired following a motorcycle accident but left his long-term memory intact, suggesting there might be separate physical stores in the brain for short and long-term memory).
he detail collected on a single case may lead to interesting findings that conflict with current theories, and stimulate new paths for research.
There is little control over a number of variables involved in a case study, so it is difficult to confidently establish any causal relationships between variables.
Case studies are unusual by nature, so will have poor reliability as replicating them exactly will be unlikely.
Due to the small sample size, it is unlikely that findings from a case study alone can be generalised to a whole population.
The case study’s researcher may become so involved with the study that they exhibit bias in their interpretation and presentation of the data, making it challenging to distinguish what is truly objective/factual.
Henry Molaison, known by thousands of psychology students as "HM," lost his memory on an operating table in a hospital in Hartford in August 1953. He was 27 years old and had suffered from epileptic seizures for many years.
William Beecher Scoville, a Hartford neurosurgeon, stood above an awake Henry and skilfully suctioned out the seahorse-shaped brain structure called the hippocampus that lay within each temporal lobe. Henry would have been drowsy and probably didn't notice his memory vanishing as the operation proceeded.
The operation was successful in that it significantly reduced Henry's seizures, but it left him with a dense memory loss. When Scoville realized his patient had become amnesic, he referred him to the eminent neurosurgeon Dr. Wilder Penfield and neuropsychologist Dr. Brenda Milner of Montreal Neurological Institute (MNI), who assessed him in detail. Up until then, it had not been known that the hippocampus was essential for making memories, and that if we lose both of them we will suffer a global amnesia. Once this was realized, the findings were widely publicized so that this operation to remove both hippocampi would never be done again.
Penfield and Milner had already been conducting memory experiments on other patients and they quickly realized that Henry's dense amnesia, his intact intelligence, and the precise neurosurgical lesions made him the perfect experimental subject. For 55 years, Henry participated in numerous experiments, primarily at Massachusetts Institute of Technology (MIT), where Professor Suzanne Corkin and her team of neuropsychologists assessed him.
Access to Henry was carefully restricted to less than 100 researchers (I was honored to be one of them), but the MNI and MIT studies on HM taught us much of what we know about memory. Of course, many other patients with memory impairments have since been studied, including a small number with amnesias almost as dense as Henry's, but it is to him we owe the greatest debt. His name (or initials!) has been mentioned in almost 12,000 journal articles, making him the most studied case in medical or psychological history. Henry died on December 2, 2008, at the age of 82. Until then, he was known to the world only as "HM," but on his death his name was revealed. A man with no memory is vulnerable, and his initials had been used while he lived in order to protect his identity.
Henry's memory loss was far from simple. Not only could he make no new conscious memories after his operation, he also suffered a retrograde memory loss (a loss of memories prior to brain damage) for an 11-year period before his surgery. It is not clear why this is so, although it is thought this is not because of his loss of the hippocampi on both sides of his brain. More likely it is a combination of his being on large doses of antiepileptic drugs and his frequent seizures prior to his surgery. His global amnesia for new material was the result of the loss of both hippocampi, and meant that he could not learn new words, songs or faces after his surgery, forgot who he was talking to as soon as he turned away, didn't know how old he was or if his parents were alive or dead, and never again clearly remembered an event, such as his birthday party, or who the current president of the United States was.
In contrast, he did retain the ability to learn some new motor skills, such as becoming faster at drawing a path through a picture of a maze, or learning to use a walking frame when he sprained his ankle, but this learning was at a subconscious level. He had no conscious memory that he had ever seen or done the maze test before, or used the walking frame previously.
We measure time by our memories, and thus for Henry, it was as if time stopped when he was 16 years old, 11 years before his surgery. Because his intelligence in other non-memory areas remained normal, he was an excellent experimental participant. He was also a very happy and friendly person and always a delight to be with and to assess. He never seemed to get tired of doing what most people would think of as tedious memory tests, because they were always new to him! When he was at MIT, between test sessions he would often sit doing crossword puzzles, and he could do the same ones again and again if the words were erased, as to him it was new each time.
Henry gave science the ultimate gift: his memory. Thousands of people who have suffered brain damage, whether through accident, disease or a genetic quirk, have given similar gifts to science by agreeing to participate in psychological, neuropsychological, psychiatric and medical studies and experiments, and in some cases by gifting their brains to science after their deaths. Our knowledge of brain disease and how the normal mind works would be greatly diminished if it were not for the generosity of these people and their families (who are frequently also involved in interviews, as well as transporting the "patient" back and forth to the psychology laboratory). After Henry's death, his brain was dissected into 2,000 slices and digitized as a three-dimensional brain map that could be searched by zooming in from the whole brain to individual neurons. Thus, his tragically unique brain has been preserved for posterity.
HM could not create any new declarative long term memories this suggests new information entering his STM was not transferred to LTM indicating there are two distinct stores that process information, so case studies benefit our understanding of memory function.
However, case studies are unique and HM was an individual with brain damage so his, and other case studies may not be representative of memory functions in all people, so case studies cannot be generalised to a wider population to help explain memory function.
The case study of KF indicated that the STM has both a visual and verbal processing ability which has broadened our understanding of memory and supports theories such as Baddeley and Hitch’s (1974) working memory model, so case studies increase our knowledge of memory function.
Analyse the use of case studies of brain damaged patients, such as the case of Henry Molaison (HM), as evidence of memory function. (6)
Discuss the use of case studies in cognitive psychology as a method to research memory. You must make reference to the context in your answer. (8) October 2017
Explain two ways that the case study of Henry Molaison (HM) demonstrates the difference between short-term memory and long-term memory. (4) January 2018