Understanding Human Memory Through the Information Processing Model

Every day, your brain takes in an almost unimaginable flood of information – sights, sounds, conversations, and sensations – yet only a small fraction of it ever becomes a lasting memory. Why does some information stick while the rest fades almost instantly? The answer lies in how your brain processes, organizes, and stores what it encounters. The Information Processing Model of memory offers a structured explanation of this journey, tracing how a piece of information travels from a fleeting sensory impression to something you can recall years later.

The computer analogy: how it started 🔗

In the mid-twentieth century, cognitive psychologists began drawing a parallel between the human mind and the emerging technology of computers. Just as a computer has input, processing, and storage stages, the human brain was theorized to handle information in a similarly sequential way. Information processing theory became a foundational approach in cognitive psychology, framing the mind as a system that receives information from the environment, processes it, and stores it for later use. While the computer analogy has its limits – human memory is far more flexible and error-prone than any hard drive – it gave researchers a useful starting framework for studying cognition.

The Atkinson-Shiffrin model: three stages of memory 🔗

Psychologists Richard Atkinson and Richard Shiffrin proposed their landmark model in 1968, describing memory as a sequence of three distinct stores: sensory memory, short-term memory (STM), and long-term memory (LTM). Information moves through these stores sequentially in a linear process, via attention, rehearsal, and retrieval. Each stage has its own rules about how much information it can hold and for how long – and understanding those rules helps explain both why we remember some things and why we forget others.

Stage 1: sensory memory 🔗

The process begins the moment your senses pick up something from the world around you. Sensory memory stores information exactly how it’s received from your senses – images you see are stored visually (called iconic memory), and sounds you hear are stored as sounds (called echoic memory). The duration of iconic memory was found to be just 250 milliseconds, meaning people can hold visual information for only about a quarter of a second. Echoic memories, by contrast, can last as long as four seconds.

The sensory registers do not process the information carried by a stimulus but rather detect and hold information for milliseconds to seconds. Atkinson and Shiffrin also called them “buffers,” as they prevent immense amounts of information from overwhelming higher-level cognitive processes. Most of what enters sensory memory is never processed further – it simply decays and disappears.

Stage 2: short-term memory 🔗

When you pay attention to something in sensory memory, it gets transferred into short-term memory. This is the active, working stage – the mental workspace where you hold information while you use it. STM is the capacity to store and manipulate information for a short time, usually up to 30 seconds. Its capacity is also tightly limited. George Miller’s research found that people can only hold up to 7 plus or minus 2 items in working memory – he also created the term “chunking” to explain how to make the most of this short-term capacity.

STM is sometimes called working memory – a term that better captures its active, dynamic nature. Working memory describes whatever we are thinking about in a given moment – what our minds are currently working on. Information can enter working memory either from long-term memory (what we already know) or from sensory memory (what is happening in our environment at a given moment). Without active effort to retain information, it decays from STM rapidly – Peterson and Peterson (1959) showed that without rehearsal, material could be virtually gone within 18 seconds.

Stage 3: long-term memory 🔗

Long-term memory is the final destination for information that has been sufficiently processed. LTM has unlimited capacity and duration, allowing you to remember different events in your life and other important information, and memories that are given more meaning in STM can be transferred to LTM. Endel Tulving noted the importance of encoding specificity in long-term memory, distinguishing between episodic memories (memories of events), procedural memories (knowledge of how to do things), and semantic memories (general knowledge) – all stored differently.

The gatekeepers: attention and rehearsal 🔗

Information does not move through these three stages automatically. Two processes act as critical gatekeepers: selective attention and rehearsal. Without them, information stalls and fades before it can be stored permanently.

The role of selective attention 🔗

At any moment, your senses are receiving far more input than your brain can fully process. Selective attention is the mechanism that filters this flood, deciding what gets promoted from sensory memory into short-term memory. Attention and memory cannot operate without each other – dividing attention during encoding prevents the formation of conscious memories. Research published in the Journal of Neuroscience demonstrated that the information incorporated into a memory representation is selected, at least in part, by the manner in which attention is allocated at encoding – goal-directed attention to a particular feature of an event enhances the cortical activity responsible for processing that feature.

This has practical significance: when your attention is split – say, you’re trying to read while watching television – the brain’s encoding resources are divided, and memory for both tasks suffers. Research comparing selective and divided attention during the encoding stage found that participants who used selective attention had significantly higher memory accuracy scores than those under divided attention conditions.

Maintenance rehearsal vs. elaborative rehearsal 🔗

Once information is in short-term memory, rehearsal is what keeps it alive long enough to potentially move into long-term storage. But not all rehearsal is created equal. Psychologists distinguish between two types.

Maintenance rehearsal involves simple repetition – mentally repeating something over and over without adding any meaning to it. Maintenance rehearsal is what you use when you get a phone number and wish to retain it only long enough to make one call – and regardless of how long you keep repeating it, it’s not likely to lead to durable long-term memory.

Elaborative rehearsal, by contrast, goes deeper. In elaborative rehearsal, information is processed at a deeper level and has the ability to move to long-term memory. This type of rehearsal works by thinking about the meaning of the information and connecting it to other information already stored in memory. For example, instead of just repeating a new concept word by word, connecting it to something you already know – a personal experience, a related idea, a vivid image – creates richer, more durable memory traces.

Depth of processing: why meaning matters 🔗

The distinction between maintenance and elaborative rehearsal connects directly to an influential extension of the information processing model – the levels of processing framework proposed by Fergus Craik and Robert Lockhart in 1972. The levels of processing model focuses on the depth of processing involved in memory and predicts that the deeper information is processed, the longer a memory trace will last.

Craik and Tulving tested this directly, asking participants questions about words at different levels of depth – physical features (is it in capital letters?), sound (does it rhyme with “block”?), or meaning (does it fit this sentence?). Shallow processing involves basic features of the information, whereas deep processing engages with its meaning, leading to better retention. A key aspect of this model is the concept of elaboration – ongoing deep processing of information – which enhances long-term recall.

There is also a particularly powerful form of deep encoding called the self-reference effect. The self-reference effect is the tendency for an individual to have better memory for information that relates to oneself compared to material that has less personal relevance. When you link new material to your own experiences or identity, it becomes significantly more memorable – a finding with clear applications for studying and learning.

Limitations and extensions of the model 🔗

The Atkinson-Shiffrin model was groundbreaking, but it has not gone without criticism. Critics often cite that it is overly simplistic and too linear in nature – for example, the current understanding of short-term memory suggests that it is multidimensional. There are also rare occasions when STM is damaged but LTM is not, which the model struggles to explain, since it suggests that information unable to pass through STM should never be encoded in LTM.

These limitations led to important refinements. In 1974, Baddeley and Hitch proposed the working memory model, which replaced the single short-term store with a more complex system. In Baddeley and Hitch’s model, short-term memory has different forms – memories in visual-spatial form, spoken or written material, and an episodic buffer – all supervised by a central executive that controls the flow of information to and from long-term memory. Rather than replacing the original model, this should be understood as building upon it.

Importantly, a review published in the Journal of Memory and Language highlighted that much of the broader theoretical perspective proposed by Atkinson and Shiffrin in 1968 has been missing from the historical record – notably, they themselves described “working memory” as consisting of a verbal short-term store and a visual short-term store, and explained that some coding processes are more effective than others for transferring information to long-term memory, consistent with the later notion of depth of processing. In other words, the model was ahead of its time in ways that are still being appreciated.

What this means for how we learn 🔗

The information processing model is not just an academic framework – it has direct implications for how we study, teach, and retain knowledge. Paying focused attention, avoiding split-attention situations, and engaging in elaborative rather than rote rehearsal all directly improve the likelihood that new information will reach long-term memory. Connecting concepts to existing knowledge, generating personal examples, and thinking about meaning rather than surface features are all strategies grounded in decades of cognitive research. Understanding how your memory actually works is the first step to working with it more effectively – rather than against it.

What do you think? Knowing that elaborative rehearsal creates more durable memories than simple repetition, how might you change the way you approach studying or learning something new? And if selective attention is essential for encoding, what does that suggest about the environments we choose when we want to truly retain information?

References

1. https://en.wikipedia.org/wiki/Information_processing_theory
2. https://www.simplypsychology.org/multi-store.html
3. https://www.jneurosci.org/content/29/25/8270
4. https://www.simplypsychology.org/levelsofprocessing.html
5. https://pubmed.ncbi.nlm.nih.gov/32119438/
6. https://www.sciencedirect.com/science/article/pii/S0749596X23000700