Patient HM

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Patient HM is an infamous case referenced throughout cognitive psychology and neuroscience. During his childhood, he suffered from severe epileptic seizures. The seizures were so debilitating that he had to quit his job at the age of 27. He underwent experimental surgery by surgeon William Beecher Scoville in 1953 to alleviate the seizures.

Let's take a look at how findings from Patient HM have allowed psychologists to understand more about Memory!

We will start by describing what exactly happened that caused the observed changes in Patient H.M.'s Memory.
Next, we will look at the different types of memory that were affected or remained intact after the surgery, with a focus on h.m. retrograde amnesia.
Whilst evaluating the case of Patient HM we will discuss the Patient H.M. controversy debate and Patient H.M. ethics.

Patient H.M Memory

Scoville localised his epilepsy as stemming from the medial temporal lobes and suggested removing these structures, including the hippocampus. Scoville had no idea what the function of the hippocampus was. After the surgery, HM no longer suffered from seizures, but his memory was significantly impaired.

Fig. 1 After surgery Patient HM developed retrograde amnesia but some other types of memory remained intact

H.M. Retrograde Amnesia

His short-term memory remained. However, his long-term memory became non-existent. He could not form any new memories of events, so for HM, time stopped in 1953, when he was 27. He could not remember anything about his daily life, such as where he lived, who cared for him, what he ate for his last meal, or how old he was.

HM had a form of retrograde amnesia. Retrograde amnesia is an illness characterised by the inability to recall past memories that occurred before the incident that caused memory loss.

For 55 years, HM participated in many experiments, mainly at the Massachusetts Institute of Technology. He learned some new motor skills, such as drawing a figure by looking at its reflection in a mirror. He never got tired of doing memory tests because they always seemed new to him. He enjoyed crossword puzzles and could repeat the same puzzle if the words were erased, as the puzzle was new to him each time.

Here are some examples of experiments in which HM participated:

Recall tasks to see if he could recall memories/events of childhood and adulthood (before the surgery).

It was found that HM could remember events from his youth, but there were some gaps in his memory, such as recalling events one to two years before his surgery or some events from when he was 16 years old onwards. He could remember some general events, such as the moon landings and the Kennedy assassination, which shows his semantic knowledge was still intact.

H.M. Impaired and Intact Types of Memory

Tests measure other cognitive skills such as IQ, general knowledge, and perception. It was found that his personality remained similar, his IQ was not impaired, and his language and perception skills were largely unaffected, except for his sense of smell which was slightly impaired.

Maze task: this is a task where you have to trace the correct route from the start to the finish point. HM attempted to do this task, using the same maze to see if he would be able to remember the correct route.

He tried the maze 252 times but never improved. Every time he figured out the right route, he immediately forgot it.

Mirror star tracing task: This is a task to trace a star. In this task, participants cannot look directly at their hands. Instead, they have to look into a mirror to see their hand. Multiple trials were done to see if he learned the skill after practising it numerous times. HM improved at star tracing, making fewer mistakes each time he attempted the task, even though he could not remember doing the task.

HM even learned how to play tennis, even though he could not remember learning. This and his improvement in the mirror star tracing task shows his procedural memory was still intact.

What can we learn from research on HM?

Patient HM's results support the following conclusions:

The hippocampus is vital for encoding short-term memories into long-term memories.
There are different systems for retrieving and making long-term memories.
There are different types of memories.
Different brain regions are responsible for procedural and semantic memories.

Evaluation of Research on Patient HM

Multiple tests were used to measure different types of memories and cognitive skills. The tasks HM was asked to do had high reliability as they were tried-and-tested memory puzzles. Also, HM showed consistent results in studies with different researchers. Major advancements in memory research could be achieved because of HM.

Patient H.M. Controversy

Although the tests used have been established as reliable tools, the surgery that H.M. had and never can be replicated therefore, it is difficult to establish how valid the results are. As the study cannot be replicated the reliability of the study are difficult to establish.

Since the original research has been published several books and articles have been published. These books and articles have been heavily criticised and have sparked controversy over H.Ms case, such as ethical issues.

Patient H.M. Ethics

HM gave consent to participate in the studies each time they were explained to him over the next 50 years. There is some controversy over the ethics of patient HM, such as whether HM was able to give proper informed consent. This is due to his memory impairments.

HM took part in an experiment that involved administering electric shocks. This was stopped because the researcher noted that he was tolerant of them. However, researchers were respectful of HM. His real name was not revealed to the public until after his death. This could have potentially caused psychological and physical harm.

Patient H.M - Key takeaways

HM suffered from severe epilepsy.
After the surgery, HM stopped having seizures, but his memory was largely affected.
HM took part in many memory experiments.
HM gave consent to participate in research every time this was explained to him.
There is some controversy over ethical issues in HM research.

Frequently Asked Questions about Patient HM

HM gave consent to participate in research every time this was explained to him. However, there is some controversy over ethical issues in this research. More specifically, he did not understand his situation due to his memory impairments.

HM had semantic knowledge, could recall childhood memories, and learn new skills such as playing tennis, even though he had no recollection of learning.

Patient HM is an infamous case referenced throughout cognitive psychology and neuroscience.

Researchers were respectful of HM. His real name was not revealed to the public until after his death.

The medial temporal lobes, including the hippocampus.

Final Patient HM Quiz

Patient HM Quiz - Teste dein Wissen

Question

What does bilateral mean?

Show answer

Answer

Front side of the brain.

Show question

Question

What type of memories was Schmolck et al. (2002) investigating?

Show answer

Answer

Hippocampus memories.

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Question

Which of the following variables Schmolck et al. (2002) investigated is the dependent variable?

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Answer

Scores on the semantic LTM tests Schmolck et al. created.

Show question

Question

Which of the following variables Schmolck et al. (2002) investigated is the independent variable?

Show answer

Answer

Scores on the semantic LTM tests Schmolck et al. created.

Show question

Question

What is a lesion?

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Answer

Lesions are brain regions damaged usually due to injury or disease.

Show question

Question

What is semantic memory?

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Answer

Semantic memories are long-term memories that do not stem from personal experiences, i.e., facts and knowledge we acquire.

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Question

Which of the following does not describe the procedure used in Schmolck et al. (2002)?

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Answer

Natural experiment.

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Question

Which statements do not match how patient HM performed?

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Answer

Worse than the MTL+ group.

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Question

What was the correlation found between mistakes made in tests and brain damage?

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Answer

A positive correlation was found between mistakes made and the amount of brain damage the participants had.

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Question

What type of tests did Schmolck et al. (2002) use?

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Answer

Self-constructed.

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Question

How did patients with damage near the hippocampus do in the semantic knowledge tests?

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Answer

Patients with damage near the hippocampus normally performed in semantic knowledge tests.

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Question

What did Schmolck et al. conclude?

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Answer

The findings indicate impairments in semantic knowledge are related to damage to the lateral temporal cortex. This finding implies different brain parts are responsible for semantic and episodic long-term memory.

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Question

What was removed from patient HM's brain?

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Answer

The medial temporal lobe which included the hippocampus was removed during H.Ms surgery.

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Question

Why did HM undergo surgery?

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Answer

HM had a lobotomy to alleviate severe epileptic seizures.

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Question

Which of the following has been found to lay a crucial role in memory?

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Answer

Hippocampus

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Question

What was HM asked to do in the mirror star tracing task?

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Answer

H.M was asked to trace a star. In this task, participants cannot look directly at their hands. Instead, they have to look into a mirror to see their hand.

Show question

Question

Which of the following tests measured visual and motor skills?

Show answer

Answer

Mirror star tracing task

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Question

Who was the main researcher that investigated H.M?

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Answer

Milner was the main researcher who investigated H.M.

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Question

Is the following statement true, "H.M's perception remained intact"?

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Answer

False

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Question

What type of amnesia did HM develop?

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Answer

Retrograde amnesia

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Question

Which type of memories could HM still recall?

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Answer

Semantic memories

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Question

Did HM performance improve throughout the trials of the mirror tracing task?

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Answer

Yes

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Question

Did HM performance improve throughout the trials of the maze test?

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Answer

Show question

Question

What are the conclusions that can be derived from the findings of HM?

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Answer

The following conclusions are supported by patient H.Ms results:

different brain regions store and retrieve short and long-term memories
there are different types of memories
different brain regions are responsible for procedural and visual and motor skills
the hippocampus is vital for encoding short-term memories into long-term memories
the fact that H.M. could still remember his childhood shows that there are different systems for retrieving long-term memories and making long-term memories
different brain regions are responsible for various cognitive skills

Show question

Question

What are the advantages of research on patient H.M?

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Answer

The advantages of research on patient HM are:

the tasks H.M. were asked to do had high reliability as they were tried-and-tested memory puzzles
the study used multiple tests to measure different types of memories and cognitive skills
major advancements in memory research could be achieved because of H.M
H.M. showed consistent results in studies with different researchers.

Show question

Question

What are the controversies surrounding research on HM?

Show answer

Answer

There is some controversy over the ethics of patient H.M, such as:

It is debated whether H.M was able to give proper informed consent. This is due to his memory impairments.
H.M took part in an experiment that involved administering electric shocks. This was stopped because the researcher noted that H.M was tolerant of them
- This could have potentially caused psychological and physical harm.

Show question

Question

Which of the options match the following description, 'the inability to form new memories'?

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Answer

Anterograde amnesia

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Question

At the time when H.M.'s hippocampus was removed, the function of this structure remained unknown.

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Answer

True

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Question

What type of memory remained intact after H.M.'s surgery?

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Answer

short-term memory

Show question

Question

What was the purpose of the recall tasks that HM participated in?

Show answer

Answer

To see if he could recall memories/events of childhood and adulthood that happened before the surgery.

Show question

Question

HM couldn't remember any events from his youth.

Show answer

Answer

False

Show question

Question

How do we know that HM's semantic knowledge was intact?

Show answer

Answer

He could remember general events, such as the moon landing and the Kennedy assassination.

Show question

Question

What did the tests measuring cognitive skills such as IQ, general knowledge, and perception show in HM's case?

Show answer

Answer

They showed that his personality remained similar, his IQ was not impaired, and his language and perception skills were largely unaffected, except for his sense of smell which was slightly impaired.

Show question

Question

What is the maze task?

Show answer

Answer

This is a task where you have to trace the correct route from the start to the finish point.

Show question

Question

What was the mirror star tracing task?

Show answer

Answer

This is a task to trace a star. In this task, participants cannot look directly at their hands. Instead, they have to look into a mirror to see their hand.

Show question

Question

HM even learned how to play tennis, even though he could not remember learning. This shows that his ______ memory was intact.

Show answer

Answer

procedural

Show question

Question

The case of HM shows us that different brain regions are responsible for procedural and semantic memories.

Show answer

Answer

True

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Question

Is the following statement true or false? Different parts of the brain are responsible for different types of memory.

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Answer

True.

Show question

Question

Why did the patient HM undergo brain surgery?

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Answer

To relieve him from severe epileptic seizures.

Show question

Question

What happened to patient HM after his surgery?

Show answer

Answer

His long-term memory was impaired.

Show question

Question

What is the role of the hippocampus?

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Answer

Hippocampus is an important structure for memory processes and the formation of memory.

Show question

Question

Schmolck et al. (2002) investigated which area of the brain is responsible for long-term episodic memory.

Show answer

Answer

False.

Show question

Question

Semantic memories are a type of ___.

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Answer

Short-term memory.

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Question

The order of the colours of the rainbow is an example of ______ memory,

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Answer

Semantic.

Show question

Question

Schmolck et al. (2002) investigated damage to what part of the brain in relation to semantic memory?

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Answer

Schmolck et al. (2002) wanted to investigate the relationship between damage to the lateral temporal cortex and performance on semantic tests.

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Question

Schmolck et al. (2002) was a ____ experiment.

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Answer

True.

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Question

Why was the study of Schmolck et al. (2002) considered a natural experiment?

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Answer

Because the independent variable was naturally occurring and wasn't manipulated by the researchers.

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Question

What was the sample in Schmolck et al. (2002) study?

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Answer

Six patients with brain damage and eight controls.

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Question

Schmolck et al. (2002) used a ______ measures design.

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Answer

Repeated measures.

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Question

Schmolck et al. (2002) found that the patients with hippocampus damage performed similarly to the control group. What does it tell us about the hippocampus and semantic memory?

Show answer

Answer

Hippocampus doesn't appear to play a significant role in semantic memory.

Show question

Flashcards in Patient HM56

Start learning

What does bilateral mean?

Front side of the brain.

What type of memories was Schmolck et al. (2002) investigating?

Hippocampus memories.

Which of the following variables Schmolck et al. (2002) investigated is the dependent variable?

Scores on the semantic LTM tests Schmolck et al. created.

Which of the following variables Schmolck et al. (2002) investigated is the independent variable?

Scores on the semantic LTM tests Schmolck et al. created.

What is a lesion?

Lesions are brain regions damaged usually due to injury or disease.

What is semantic memory?

Semantic memories are long-term memories that do not stem from personal experiences, i.e., facts and knowledge we acquire.

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Patient HM

Patient H.M Memory

H.M. Retrograde Amnesia

H.M. Impaired and Intact Types of Memory

What can we learn from research on HM?

Evaluation of Research on Patient HM

Patient H.M. Controversy

Patient H.M. Ethics

Patient H.M - Key takeaways

Frequently Asked Questions about Patient HM

Was HM's case study ethical?

What could Patient HM do?

What is HM in memory research?

What ethical principle was followed in the case of HM?

What was removed from patient HM brain?

Final Patient HM Quiz

Patient HM Quiz - Teste dein Wissen

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