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Memory is one of the most fascinating aspects of human psychology. It's how we store and recall information about our experiences, knowledge and skills. Without memory, you wouldn't be able to remember your friends' names, how to ride a bike, or even who you are! Memory isn't just one thing it's a complex system with different parts working together.
Key Definitions:
In 1968, two psychologists named Richard Atkinson and Richard Shiffrin proposed a model to explain how our memory works. Their model, called the Multi-store Model (sometimes called the Atkinson-Shiffrin Model), suggests that memory consists of three separate stores or components:
The Multi-store Model proposes that information flows through three distinct memory stores:
According to the Multi-store Model, information flows through our memory system in a specific sequence:
Sensory memory is the first stage where information from our senses (sight, hearing, touch, etc.) enters our memory system.
Information in sensory memory lasts for a very brief time:
Sensory memory gives your brain a chance to decide what information is worth paying attention to. Without it, you'd miss important details as your attention shifts.
If we pay attention to information in sensory memory, it moves to short-term memory. This is where we actively work with information for a brief period.
George Miller's research (1956) showed that STM can hold about 7±2 items (5-9 items) at once. This is often called "Miller's Magic Number".
Without rehearsal, information in STM lasts for approximately 18-30 seconds before it's forgotten.
Information in STM is primarily encoded acoustically (by sound), though visual and semantic encoding can also occur.
Peterson and Peterson demonstrated the limited duration of STM in their classic study. Participants were shown trigrams (three-letter combinations like "GHK") and asked to count backwards in threes from a given number (to prevent rehearsal). When tested after intervals of 3 to 18 seconds, recall dropped dramatically. After just 18 seconds without rehearsal, recall accuracy fell to about 10%, supporting the idea that STM has a limited duration.
If information in STM is rehearsed or processed deeply, it can transfer to long-term memory, our permanent storage system.
LTM has virtually unlimited capacity. You can continue learning new information throughout your life without "running out of space".
Information can remain in LTM for a lifetime, though some memories may become harder to retrieve over time if not accessed regularly.
Information in LTM is primarily encoded semantically (by meaning), though other forms of encoding also occur.
Attention acts as a filter between sensory memory and short-term memory. We can only process a small amount of the information that enters our sensory memory, so attention helps us select what's important.
There are two main types of rehearsal that help transfer information from STM to LTM:
This involves repeating information over and over to keep it in STM (like repeating a phone number until you dial it). This type of rehearsal is less effective for transferring information to LTM.
This involves thinking about the meaning of information and connecting it to existing knowledge. This type of rehearsal is much more effective for transferring information to LTM.
Clive Wearing, a British musician, suffered brain damage from a viral infection in 1985. His case provides strong evidence for the Multi-store Model because his illness damaged his ability to transfer information from STM to LTM. As a result, he has severe anterograde amnesia he can't form new long-term memories. His STM functions normally (he can hold a conversation), but within minutes he forgets it ever happened. His case supports the idea that STM and LTM are separate systems, as the Multi-store Model suggests.
When people are asked to recall a list of words, they typically remember words from the beginning (primacy effect) and end (recency effect) better than words in the middle. This supports the Multi-store Model because:
The Multi-store Model provides a foundational framework for understanding how memory works. It proposes that memory consists of three stores: sensory memory, short-term memory and long-term memory. Information flows from sensory memory to STM through attention and from STM to LTM through rehearsal. While the model has limitations and has been expanded upon by more recent theories, it remains an important starting point for understanding memory processes.
In the next session, we'll explore more complex models of memory that address some of the limitations of the Multi-store Model.