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Discovering Psychology: Updated Edition

Remembering and Forgetting

Remembering and Forgetting is the ninth program in the Discovering Psychology series. This program looks at the complexity of memory: how images, ideas, language, physical actions, even sounds and smells are translated into codes that are represented in the memory and retrieved as needed.

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Essay: The Biology of Memory

Memory is defined as stored information. When we take in information — a lecture, for example — neurotransmitters in the brain are working to filter and store the information in memory. While it sounds simple, memory is a complex and dynamic process that relies on a series of factors.

At a very basic level, the process involves the hippocampus in the brain taking information from the environment, encoding it, and changing it into a form that the cerebral cortex can then store, retain, and retrieve. Through each step a memory neurotransmitter called acetylcholine transmits the needed nerve impulses.

What we know about memory is also instructive about why we forget. In chronic memory loss and dementia, the acetylcholine transmission is impaired. In the most severe cases of memory loss, like Alzheimer’s disease, not only is the acetylcholine connection devastated, but the cortex also gradually deteriorates and the brain acquires toxic substances.

Recent research into memory, forgetting, and the advancement of Alzheimer’s disease focuses on the ways the eye-blink classical conditioning tests, demonstrated in the program, can predict the earliest onset of dementia and Alzheimer’s disease. Because Alzheimer’s disease kills cells and its pathology is irreversible, early detection is the only hope for a cure or prevention.

Doctors and researchers are working to develop a vaccine for Alzheimer’s disease. The vaccine would block the toxins that accumulate in the brain and preserve the acetylcholine connection that is so vital to memory.

Visit Diana Woodruff-Pak’s home page at Temple University. The site includes a schematic of eye-blink classical conditioning, brain scans of the cerebellum and hippocampus, as well as a bibliography of books and articles.


Chunking: The process of taking single items of information and collecting them based on similarity, association, or other organizing principles, into larger wholes.

Classical Conditioning: A form of learning in which behavior or conditional response comes to be elicited by a stimulus that has acquired its power through an association with a biological stimulus, such as food, or repetition. Also called Pavlovian conditioning, after the Russian physiologist, Ivan Petrovich Pavlov, whose experiments with dogs revolutionized the concept of memory and response.

Engram: The hypothesized chemical change in the brain resulting from the storing of memory information; also called memory traces.

Functional Amnesia: A severe type of memory loss caused by psychological factors such as anxiety, hysteria, or repression.

Mnemonic: Technique or device used to aid in memorization.

Organic Amnesia: A permanent form of memory loss, resulting from biological devastation to the brain, such as disease, alcoholism, chemical poisoning, and senility.

Repression: Freudian theory of expelling or excluding painful thoughts or memories from conscious awareness by storing them in the subconscious.

Serial Position Effect: A characteristic of retrieval in which a person’s recall of first and last items in a list is better than recall of other items.