In this video I cover the first box in the 3-box model, sensory memory, in greater detail. I explain how this store refers to information from all of the senses, though individual senses can be specified using terms like iconic memory or echoic memory. I also describe how the brief duration of sensory memory relates to managing the constant flow of information from the senses. This also relates to the myth that the mind has some sort of detailed record of all of our experiences. Next I explain George Sperling’s work demonstrating the duration of sensory memory and how this relates to the role of selective attention in organizing our perceptions and moving information to the next box in our memory model, which is short-term memory.
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Video Transcript:
Hi, I’m Michael Corayer and this is Psych Exam Review. In this video I want to explain the first box of our box model of memory. So this is the sensory memory store. It’s also known as the sensory register. Now the sensory memory store is a highly detailed representation of the sensory information that’s coming in from all of our senses and it’s a very limited duration, it only lasts for about a second or so.
Now as I said, this refers to information from all of our senses so we can be more specific with sensory memory we can talk about specific types of sensory memory so for instance you could refer only to your visual sensory memory and that’s known as iconic memory. That’s visual. Or you could refer specifically to your auditory sensory memory and that’s known as echoic memory.
But for the most part we’re going to be referring to all of the senses at once when we talk about sensory memory. So why is sensory memory so limited, why is it so short? Less than a second, it’s like it barely exists. So why is that? Well it’s sort of because of necessity. If you think about it, you have all this information coming in from your senses and it’s immediately being followed by more information coming in from your senses right. It’s like this onslaught of information and so you can’t hold onto all of it for very long. You can imagine if you held onto all that sensory information, I mean you’d quickly be overwhelmed with the amount of information that’s coming in.
So it would be like setting a delay on a guitar. If you’ve ever used a delay pedal. So you play a note and it rings out for a long time after you’ve played it. If you set that delay really long and you keep playing notes you end up with this mishmash of sounds that doesn’t sound particularly good and that would be sort of an analogy for what would happen if you held onto your sensory memory for an extended period of time. You need to get rid of it because you’ve got more information coming in and that might be more relevant to you.
So this brings us to a myth that you may have heard I want to dispel this myth. This is the idea that you have a detailed memory of all of your experiences, that somehow your mind is able to keep a record of everything that’s ever happened to you and that if you could just find the right technique or use hypnosis or something that you could somehow have access to all of this information. That’s simply not true. The information isn’t there, it’s not locked away in your mind somewhere. It’s simply gone. It was in your sensory memory for about a second and then was essentially discarded.
Now this makes sense because most of the information that’s coming in is irrelevant. It doesn’t matter to you, you don’t need to recall it. There’s no reason for your mind to keep track of all of this minutia and detail of everything you’ve ever seen or everything you’ve ever heard. You can imagine the amount of information that that would be it would be, I mean, it’s unfathomable. And why would you want to hold onto all of that, particularly if it’s irrelevant? So it doesn’t really make sense that we would hold on to that information. This hasn’t been demonstrated. It’s not the case that you can recall things.
You might feel like you can recall them and when we talk about hypnosis in the future maybe we’ll come back to this idea. You might think you remember some experience from your fourth birthday party, under hypnosis you remembered what color shirt your mom was wearing or something but if we compare that to any actual evidence like we find a photograph from that party we see that a lot of times people think they remember it, it turns out they’re wrong. So they’re confident but they’re not accurate. Anyway, that’s a myth, hopefully you can forget about that idea.
So let’s go onto how do we prove that sensory memory exists? I mean it’s so short-lived how do we even know that it’s happening? Well you have personal experience of something like this like. For instance, you see a flash of lightning during a thunderstorm and you feel like, I mean it’s only there for less than a second, but you kind of have for a brief moment, this detailed picture of exactly what it looked like. But within about a second, it’s gone. If you try to draw it, by the time you went to write it down you wouldn’t remember it in that level of detail.
So you have this feeling that it exists and it’s the same thing with a sound that you hear. You can sort of replay it exactly in your mind as soon as you hear it but a few seconds later it’s gone, you don’t remember exactly what it sounded like. So how do we demonstrate that it even exists beyond just sort of this feeling?
Well this brings us to some research by a guy named George Sperling. Sperling designed a clever test to show that this sensory memory did in fact exist and the way that he did this was he used a device called a tachistoscope and what this was was that this was in 1960 before modern computer development that would probably be how you do this type of test now, but you looked through a little viewfinder and they flashed letters on the screen very very briefly, about a twentieth of a second. Sperling would flash an array of letters, so 12 letters arranged into three rows, four letters in each row. They would be there very briefly, less than a second, and then he would ask people to tell him what was on the top row or the middle row or the bottom row.
He found that people were able to do this. They were able to recall one of the rows if he asked immediately and the way that he asked was by ringing a tone. A high tone, a middle tone or a low tone and ringing the tone a quarter of a second after they saw the letters. So very briefly you see the letters and almost at the same time you hear this tone and you can sort of read the letters off of your mind.
It’s like they’re there in your sensory memory. But what Sperling found was if he waited just one second to ring that tone and ask for which row, within a second the letters were gone. People started making lots more mistakes. He also found people could recall, when he asked within a quarter of a second, people could recall any of the rows but they couldn’t recall all of the rows because by the time they thought about one of the rows, the others essentially disappeared.
So I can give you an idea of what this sort of felt like for the participants. Now I don’t have the timing set up to play a tone and we won’t go through this whole procedure but I’m just going to flash some letters on the screen and I’ll immediately, as I flash them, I’ll say either top, middle, or bottom and see if you can recall what was on that row. So I’ll try to do this, timing might not be perfect. We’ll see. So…top. Ok. Bottom. Even then, I probably delayed that was probably longer than a quarter of a second there. Top.
You can see, if you were, you might have had this experience that you’re sort of reading it off of your mind, off of your sensory memory. Where you had this store of it but if you didn’t read it right away, it was gone. This brings us to the idea of selective attention and that we can only attend to some of the things in our environment; some of the things that we see, some of the things that we hear, some of the things that we feel. We can only attend to so much at once right?
Our attention is by nature selective. We can’t attend to everything. So this means that in the next box that we look at, which is our short-term memory, we can only move some of the things from sensory memory to our short-term memory. There’s no way to move all of them, there’s simply too much information. It’s essentially infinite, the number of things that you could pay attention to and so what you choose to focus your attention on, what you deem as relevant is the only things that you can essentially move to your short-term memory.
So that’s the next box that we’ll look at in the next video. I hope you found this helpful, if so, please like the video and subscribe to the channel for more.
Thanks for watching
