7.1 The Two-Store Model of Memory: Types of Memory and Storage
Do you remember your very first day of school? What did it feel like when you were separated from your parents? Did you like your teacher? Did you make friends? The process of creating a new memory and bringing it back to mind years later is a complicated and abstract thing, yet we all do it every day. How does memory work? That’s what we’ll be discussing in this lesson.
The Two-Store Model of Memory
The most accepted theory in psychology for how memory works is called the two-store model of memory, which was developed by Atkinson and Shiffrin in 1968. This model states that we have three basic types of memory, and those are called the sensory register, short-term memory and long-term memory. Let’s go through each of these types of memory in more detail.
All memory works by first forming an impression of something that happens in your life. Let’s go back to that memory of the first day of school. The memory is based on things you saw, heard, smelled, touched or tasted. In other words, all memories start by using your five senses. That’s why this initial beginning to all memory is called the sensory register. The sensory register is a temporary mechanism that processes input from the five senses and transforms this input into meaningful ideas and concepts. In order to understand this idea better, let’s go through two examples.
Research says that the two primary ways your sensory register works are by processing things you see and things you hear. When your mind processes things you see, it’s called iconic memory, or iconic storage. Iconic memory is when you can picture an image for a split second after it has disappeared from view. Research says that this type of memory only lasts about one second. Look at this red dot. It’s moving in a circle, and you can easily track the dot’s progress. If the speed picks up, though, your sensory memory kicks in. It keeps the red dot in mind so that soon, it looks like a red circle rather than a single dot. This is an example of the way your iconic memory works. Even after the dot has moved on, an image of it remains in your head for a split second. Since the dot is moving so quickly, your sensory memory constructs a circle where none actually exists. You’ve probably seen this if you were playing with a toy top where if you spin the top, any image that appeared on it gets blurred and looks like something different. If you’ve ever played with a sparkler at night and drew pictures using the sparkler trail, you were making use of your iconic memory.
The other way our sensory register can work is using auditory information. This type of sensory memory is called echoic memory, or echoic storage. I’m sure you’ve yelled your name in a place where you could hear it come back in an echo; that’s where we get the name for this type of memory. Again, it’s very short; echoic memory only lasts about four seconds. But it’s the reason you can hear a sound, like a buzzing or an alarm, in your head for just a couple of seconds after the sound is turned off. Again, all memories start from this sensory information we get from our environment. On your first day of school, you were quickly taking in all the sights and sounds from your new classroom. What happens after the information goes through our five senses?
Short-Term and Long-Term Memory
The two-store model of memory is called that (‘two-store’) because it says that after information goes through the sensory register, there are two places where a memory can be stored. Those two places are called short-term memory and long-term memory. You can guess from the names, ‘short term’ and ‘long term’, what the difference is between these two types of memory. Theoretically, short-term memory only lasts about 30 seconds, and it’s where your mind works on forming new memories or goes over new information. In contrast, long-term memory is theoretically permanent. That’s where you store all the memories from your entire life, such as what happened on your first day of school. In a different lesson, we’ll go over the details of both short-term and long-term memory. For this lesson, all you need to know is that the two-store model of memory says that after information goes through the sensory register, it can go to either of these locations for processing.
Steps to Successful Memory
For this lesson, the last important idea you need to understand is that in addition to different types of memory, such as iconic versus echoic, there are three steps, or stages, that all memories must go through in order to be successfully used. Let’s go over these three stages. The first stage of all memories is called encoding. Encoding is when a memory is initially processed and understood. It’s the process of going through our five senses, through our sensory register and then being transformed in terms of what this information means. For example, let’s say that on your first day of school, you’re standing in the classroom and you hear a noise. What is the noise? Is it the sound of your new teacher’s voice? Is it a bell that signals the end of a class period? Is it the wheel turning in the hamster cage? In order for a new memory to be fully formed, the first step your mind has to go through is to process this sensory information into some kind of meaningful concept.
The second stage of memory is called storage. Storage is when a memory is permanently saved for future use. We’ve all had the experience where some things that happen to us are stored into our memory, and other things are not. When you meet someone new and he tells you his name, can you remember that name the next day? If the answer is yes, that means the memory was successfully stored. If not, there’s some reason the information was not stored. Maybe you were distracted, or maybe you couldn’t understand because he had a strong accent, or maybe you simply didn’t try to remember the information because you thought you’d never see this person again, so it wasn’t important. There are several reasons why storage might happen or might not, but in order for a memory to truly be formed, it must be first encoded, then stored. There’s one more step to the process.
The final stage to memory is called retrieval. Retrieval is when a memory is successfully brought out of storage to be used. In other words, when we actually remember something that happened to us, we have retrieved that memory. Can you retrieve your experience from the first day of school? It might be pretty hazy, but many people can at least retrieve some information about this experience. Try to retrieve information about a fun family vacation you had, or retrieve information about your favorite movie. Who were the actors? Can you retrieve some quotations you liked from the movie? In another lesson, we’ll talk about how retrieval works in long-term memory and how you can use certain tricks to help you retrieve information, such as when you’re studying for a test.
In order to really understand these three stages of memory, think about a computer. What steps do you need to go through to create and use a file? The first step we discussed for memory was encoding. Encoding is creating a new memory. This would be like taking the steps to turn on the computer, open a particular software package like a word processor and type in the words. The second step was storage. This would be saving your file to somewhere permanent inside the computer. The final step is that you need to find the file and open it back up later. This would be like retrieval of memory. In order for you to use a computer successfully, you need to create, save and open the file again later. These are the same steps for memory. If any of the steps don’t work, the memory can’t be used.
In summary, the two-store model of memory suggests that memory is made up of three parts: the sensory register, short-term memory and long-term memory. It’s called ‘two-store’ because once memories have gone through the sensory register, they can be stored in either short-term or long-term memory. The sensory register mainly uses either iconic memory for vision, which lasts about one second, or echoic memory for sound, which lasts about four seconds. The three stages all memories must go through in order to be successful are encoding, storage and retrieval. Other lessons will cover many of these ideas in more detail.
After watching this lesson, you should be able to:
- Define the two-store model of memory and its three parts
- Define sensory register, iconic memory and echoic memory
- Describe the three stages of memory: encoding, storage and retrieval