Introduction
The stage model of memory, also known as the multi-store model, was proposed by Richard Atkinson and Richard Shiffrin in 1968. This influential model describes how information flows through three distinct stages of memory: sensory memory, short-term memory (STM), and long-term memory (LTM). Each stage is responsible for different aspects of memory processing, including the encoding, storage, and retrieval of information. This model laid the foundation for future research in cognitive psychology and memory studies.
The Three Stages of Memory
1. Sensory Memory
Sensory memory is the first stage where information from the environment is initially recorded. It holds sensory input for a very brief period—usually a fraction of a second. Sensory memory is modality-specific, which means it is divided based on the type of sensory input:
- Iconic memory: Visual sensory memory (lasts for about 0.5 seconds)
- Echoic memory: Auditory sensory memory (lasts for about 3–4 seconds)
Sensory memory acts as a buffer for incoming sensory data. Only information that receives attention moves forward to the short-term memory.
2. Short-Term Memory (STM)
Short-term memory is the next stage where selected information from sensory memory is temporarily held for processing. STM has the following features:
- Limited capacity: Can hold about 7±2 items (as per Miller’s Law)
- Short duration: Lasts for about 15 to 30 seconds without rehearsal
- Encoding: Primarily acoustic (based on sound), although visual and semantic encoding also occurs
To retain information in STM, individuals often use rehearsal techniques such as repetition. Without rehearsal, the information quickly decays or is displaced by new information.
3. Long-Term Memory (LTM)
Long-term memory is the final and most durable stage of memory. Information transferred from STM to LTM can last for days, years, or even a lifetime. Key characteristics include:
- Unlimited capacity: There’s no known limit to how much LTM can store
- Long duration: Information can be retained indefinitely
- Encoding: Primarily semantic (based on meaning)
Information in LTM can be retrieved and brought back into STM when needed. Retrieval may be influenced by cues and context.
Processes in the Model
The model also explains the mechanisms of memory through three processes:
- Encoding: Transforming sensory input into a format that can be stored
- Storage: Retaining information over time
- Retrieval: Accessing stored information when needed
Atkinson and Shiffrin emphasized that memory is not a passive storage system, but a dynamic process involving interaction between stages.
Strengths of the Stage Model
- Clear and simple structure to understand memory processes
- Led to extensive experimental research and testing
- Supported by evidence like the serial position effect (primacy and recency)
Criticisms of the Model
- Oversimplified – doesn’t explain the complexity of memory
- STM and LTM are not entirely separate; interaction is more dynamic
- Neglects the role of working memory (later developed by Baddeley and Hitch)
Despite these criticisms, the Atkinson-Shiffrin model remains a fundamental concept in cognitive psychology and serves as a foundation for more advanced models.
Conclusion
The stage model of memory by Atkinson and Shiffrin provides a basic yet powerful framework for understanding how we process and store information. By dividing memory into sensory, short-term, and long-term stages, the model has helped psychologists and educators understand learning, forgetting, and recall mechanisms. While it has been refined by later theories, its core concepts continue to influence memory research today.