The information processing theory compares the human brain to a computer or basic processor. It theorizes that the brain works in a set sequence, as does a computer. The sequence goes as follows, “receives input, processes the information, and delivers an output”. Once we encode information in our brain, we somehow have to retain it. Our brains take the encoded information and place it in storage.
In order for a memory to go into storage (i.e., long-term memory), it has to pass through three distinct stages: Sensory Memory, Short-Term Memory, and finally Long-Term Memory.
Sensory Memory
In the Atkinson-Shiffrin model, stimuli from the environment are processed first in sensory memory: storage of brief sensory events, such as sights, sounds, and tastes. We are constantly bombarded with sensory information. We cannot absorb all of it, or even most of it. And most of it has no impact on our lives. For example, what was your professor wearing the last time you saw them? Chances are, you don’t remember. Sensory information about sights, sounds, smells, and even textures, which we do not view as valuable information, we discard. For example, light reflecting off your cup of coffee hits your eye; the image is transferred through the optic nerve to the sensory register. If you do not attend to it, it fades from this memory store and is lost. In fact, your cup may be on your desk most of the time, and you see it without really “seeing” it many times during the day. If we view something as valuable, the information will move into our short-term memory system.
sensory memory
| Definition | Description | Example | |
| Sensory Memory | The initial stage of memory that lasts for a very short period of time (a fraction of a second to a few seconds). |
It is responsible for temporarily holding information that is received through the five senses—hearing, vision, taste, smell, and touch. |
If you walk into a room and see a red apple on a table, the image of the apple is briefly stored in your sensory memory. If you don’t attend to it, the image quickly fades away. |
Visual sensory memory is known as iconic memory (from the word icon or “image). Iconic memory was first studied by the psychologist George Sperling (1960). In his research, Sperling showed participants a display of letters in rows, similar to that shown in Figure X, “Measuring Iconic Memory.” However, the display lasted only about 50 milliseconds (1/20 of a second). Then, Sperling gave his participants a recall test in which they were asked to name all the letters that they could remember. On average, the participants could remember only about one-quarter of the letters that they had seen.
Auditory sensory memory is called echoic memory, named after the phenomenon of an echo. Unlike iconic memory that tends to fade quickly, echoic memories have a longer lifespan and can persist for up to four seconds (Cowan, Lichty, & Grove, 1990). This feature is beneficial in various ways, for instance, it enables you to recall the beginning of an extensive sentence when you reach its end, or to jot down your psychology professor’s last remark even after they’ve completed their sentence.
Short-term Memory
Short-term memory (STM) is a temporary storage system that processes incoming sensory memory. The terms short-term and working memory are sometimes used interchangeably, but they are not exactly the same. Short-term memory is more accurately described as a component of working memory. Short-term memory takes information from sensory memory and sometimes connects that memory to something already in long-term memory. Short-term memory storage lasts 15 to 30 seconds. Think of it as the information you have displayed on your computer screen, such as a document, spreadsheet, or website. Then, information in STM goes to long-term memory (you save it to your hard drive), or it is discarded (you delete a document or close a web browser).
short-term memory
| Definition | Description | Example | |
| Short-term Memory | Also known as working memory, it is responsible for briefly holding information that is currently in use. | It has a limited capacity and can hold information for a period of time ranging from seconds to minutes. | You are trying to remember a phone number that someone just gave you, so you begin repeating it to keep it in STM until you have a chance to write it down or dial it. This repetition is termed rehearsal. However, if someone interrupts you to ask you a question while you are rehearsing the number, responding interferes with rehearsal, and the phone number is lost. |
Note the longest string at which you got the series correct. For most people, the capacity will probably be close to 7 plus or minus 2. In 1956, George Miller reviewed most of the research on the capacity of short-term memory and found that people can retain between 5 and 9 items, so he reported the capacity of short-term memory was the “magic number” 7 plus or minus 2. However, more contemporary research has found working memory capacity is 4 plus or minus 1 (Cowan, 2010). Generally, recall is somewhat better for random numbers than for random letters (Jacobs, 1887) and also often slightly better for information we hear (acoustic encoding) rather than information we see (visual encoding) (Anderson, 1969).
Moving from Short-Term Memory to Long-Term Memory With Rehearsal
Rehearsal moves information from short-term memory to long-term memory.
rehearsal
Active rehearsal is a way of attending to information to move it from short-term to long-term memory. During active rehearsal, you repeat (practice) the information to be remembered. If you repeat it enough, it may be moved into long-term memory. For example, this type of active rehearsal is the way many children learn their ABCs by singing the alphabet song.
Alternatively, elaborative rehearsal is the act of linking new information you are trying to learn to existing information that you already know. For example, if you meet someone at a party and your phone is dead but you want to remember his phone number, which starts with area code 203, you might remember that your uncle Abdul lives in Connecticut and has a 203 area code. This way, when you try to remember the phone number of your new prospective friend, you will easily remember the area code.
Craik and Lockhart (1972) proposed the levels of processing hypothesis that states the deeper you think about something and the more meaning you can associate with it, the better you remember it.
When memories are encoded and stored in the brain, they have to be stored somewhere, so the brain biochemically alters itself and its neural tissue. Just like you might write yourself a note to remind you of something, the brain “writes” what’s called a memory trace, or engram, changing its own physical composition to do so. The basic idea is that events (occurrences in our environment) create a memory trace through a process of consolidation: the neural changes that occur after rehearsal to move a memory into long-term memory. Memory trace decay, when the physical record of a memory fades, and interference, memory obstruction caused by competing information, are two factors that affect short-term memory retention.
The Organization of Long-term Memory
long-term memory
| Definition | Description | Example | |
| Long-term memory | This holds information that is not in immediate use but needs to be remembered for an extended period of time. | It has a large, potentially unlimited, capacity and can hold information for a period of time ranging from minutes to a lifetime. | If you learn a new definition, it will first be stored in your short-term memory, but with repetition and practice, it will eventually be transferred to your long-term memory where you can recall it at a later time. |
Long-term memory (LTM) is the continuous storage of information. Unlike short-term memory, long-term memory storage capacity is believed to be unlimited. It encompasses all the things you can remember that happened more than just a few minutes ago.
What is the first word that comes to mind when you hear “peanut butter”? Did you think of jelly? If you did, you probably have associated peanut butter and jelly in your mind. It is generally accepted that memories are organized in semantic (or associative) networks (Collins & Loftus, 1975). A semantic network consists of concepts, and as you may recall from what you’ve learned about memory, concepts are categories or groupings of linguistic information, images, ideas, or memories, such as life experiences. Although individual experiences and expertise can affect concept arrangement, concepts are believed to be arranged hierarchically in the mind. Related concepts are linked, and the strength of the link depends on how often two concepts have been associated.
Importantly for memory, activating any part of a semantic network also activates the concepts linked to that part to a lesser degree. The process is known as spreading activation (Collins & Loftus, 1975). If one part of a network is activated, it is easier to access the associated concepts because they are already partially activated. When you remember or recall something, you activate a concept, and the related concepts come along with it. However, the activations do not spread in just one direction. When you remember something, you usually have several routes to get the information you are trying to access, and the more links you have to a concept, the better your chances of remembering.
Other Memory Models
Atkinson and Shiffrin’s model is not the only model of memory, but it was one of the first, and it laid the foundation for other memory models that were able to refine this model and more clearly articulate what constitute these different types of memories and what causes information to move from short-term memory to long-term memory.
Baddeley and Hitch Model of Working Memory
For example, psychologists Baddeley and Hitch (1974) proposed a model where short-term memory itself has different forms. In their model, storing memories in short-term memory is like opening different files on a computer and adding information. The type of short-term memory (or computer file) depends on the type of information received. There are memories in visual-spatial form, as well as memories of spoken or written material, and they are stored in corresponding short-term areas: in a visuospatial sketchpad (for the visual stuff), a phonological loop (for the audio stuff), and what Baddeley later coined the “episodic buffer”, which can store a mixture of visual, spatial, or verbal information for a short time, like a scene from a movie. According to Baddeley and Hitch, a central executive part of memory supervises or controls the flow of information to and from the three short-term systems.