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Praphob Sussangkarnunconfirmed user (Mechanical Engineering, Bristol University)

Published in psycho.philica.com

How the human memory determines our perception of the world

Article body



The thought which had me thinking about writing this paper came to me several years ago, during my gap year (A year break between high school and university), but I never quite got around to it.


One day while sitting in a car (back then I still could not drive) and looking out of the window, I noticed that the wheels on the car driving next to ours seems to be spinning backwards. This effect of course is nothing unusual, similar to when observing spinning helicopter blades and depending on its speed of rotation, it can either be seen moving one way or the other, or even not moving at all. Often when observing rapidly occurring events; we will be unable to keep up and process what exactly is going on.  This made me wonder what it is that is the limiting factor. It is it the maximum rate at which our sensory organs can detect the changes in the environment? Is it the maximum rate at which electronic signal pulses can be sent to the brain? Is it the maximum rate at which the brain can process the information? Or, since for us to realize that the wheels are spinning the brain must remember the previous positions of the wheel, could it be that the limiting factor was our memory. Any of these answers are possible, but it was this simple thought that started the idea for this paper.


The Memory Frame rate


As humans, we greatly rely on our ability to remember to perform tasks (The issues of different types of memories, for example, working or long term memory, will not be discuss here suffice to say that by one mechanism or the other the brain is able to store new data for use). Even as you are reading this paper, you are relying on the fact that you can remember the previous words read, in order to understand the meaning of the whole sentence. Without it we would not be able to accumulate information, make decisions on it, leaving us unable to "think". Everything would be done via action and pre-determined instinctive reactions.


Now consider a case where a ball is thrown towards us. As mentioned before, in order for us to know that the ball is moving towards us we must have remembered the previous positions of the ball. Consider now a situation where we are recording the path of the ball with a video camera. Lets say that it records one frame in a second, when the information is processed (played back), the path and movement of the ball can roughly be seen. This frame rate would surely however, not be adequate if for example, we wish to catch the ball. Increasing the video camera's frame rate to say, twenty four frames per second, should give enough detail so that when processed, the path of the ball could be anticipated and the ball caught. What happens however, if the ball was replaced with a bullet fired from a gun? To get good detail of the bullet path the frame rate of the video camera would need to be increase significantly and consider what would happen if we wish to observe something which was traveling faster still? The fact of the matter is, no matter how much the frame rate of the video camera was increased, there will always be gaps in between the frames where essentially, nothing is recorded. No matter how high the frame rate events will never be recorded "continuously", for that to happen the frame rate would have to be infinite. If that was possible there would still be another fundamental problem that is storage. To record events at an infinite rate even for just a nanosecond would require an infinite amount of film. As long as the amount of film available is finite, we can only record at a certain frame rate for a certain amount of time.


As with a video camera requiring film to store its footage, the human brain also physically requires space to store its memory. It is very likely that the human brain has a finite amount of memory (For working memory at least), and since it is also very likely that information are processed around the brain in a digital form (Our sensory organs are not "continuously" sending a signal to the brain) the frequency at which the brain record information must be finite. In effect that means that what we remember are simply a series of instances, or the states of inputs (sound or vision for example) into the memory at different, almost infinitely small duration of time. These inputs of course come mainly from different sensory organs, but also from the conscious mind itself, since to be able to think we must also remember our own thoughts. Our own thoughts in a way are nothing more than input signals generated by the mind itself, combined with information obtained from the working memory, they will always be in the same form as signals generated by our sensory organs. As you are thinking now what actually is generated in your mind? If you think of a person, you might "see" the image of their face. If you think of a piece of music, you might "hear" it in your mind, or "feel" some emotions. If you think of being pinch you might "feel" pain. Can you think in a form which is different from that of our sensory organs? In the end the information recorded in our memory is simply the input of our sensory organs being stimulated and the sensory input generated by our mind. With this in mind there are still different arrangements which could be possible, for example, those in the diagrams shown below.








The differences between these two models are not great but nevertheless it exists. If you look at a flower for example, your eyes will be sensing the image of the flower and you will also see the image. If while doing this however you try to think of another image, for example a bird, then although your eyes might still be sensing the image of the flower you no longer really "see" the flower. In your mind the image of the bird will be the dominant one. In this, and similar cases, the input into the working memory for the different models will be different.


Take the top model on for example, both the signal from the sensory organs and the input from the mind are directly sampled (recorded) by the working memory. So in the case above, both the image of the flower and of the bird will be recorded for later use. For the model on the bottom however this will be different. The working memory is sampling the state of mind, in this case the there is an input of the image of the flower into the mind from the eyes. There will also be the signal of the image of the bird from the working memory (Or possibly long term memory in this case) being access by the mind, and the image signal generated by the mind itself (For example, even if the memory only contain images of a blue bird, the mind could combine this with its memory of the color red and imagine a red bird instead). The combination and superimposition of these signals will form an overall image in the mind and it is only this image which is recorded. So in the top model, both the clear image of the flower and the bird will be stored. In the bottom model however this is not the case.


There are many other models possible, however, that issue is not the main focus of this paper. The main thing which should be considered is the limitations of the working memory and how it affects our perspective of the world. In a way memory essentially determines our experience of the world, since what we do not remember will simply have no significance on our conscious mind at all. To think about this, let us return to the example of the ball being thrown towards you. Let us say that another person is throwing a tennis ball towards you and it struck you in the eye. Suppose that in this time our working memory recorded three instances, one as the ball left the other person's hand, one as the ball is half way between the two of you and one just before the ball struck you in the eye. What you experience is essentially a tennis ball being thrown towards you and hitting you in the eye. However in between the three times that your memory recoded the state of input to it, the tennis ball could have done anything and your whole experience of what happened will be exactly the same. For example, the ball could changed color, changed shape or even turned into a bowling ball, but if for the three times that the sensory input is recorded the tennis ball was in the same state and position as it would be had it just traveled along normally, then your whole experience would have been exactly the same.


This is an issue which we should consider if our memory is limited in such ways. It is possible that because of our limitations we are unable to ourselves see our limitations. As we go about our daily life our experiences seems to be "continuous", however that could simply just be an illusions. Our experiences are simply a series of "snapshots" of the world. Built upon a series of instantaneous input states memorized, and the order in which they are recorded. The reason we do not notice the gaps in our memory is because when we retrieve the information from the memory, the missing parts are not recorded and therefore we have no way of knowing it was missing in the first place.


Perception of time

If this is indeed how our memories are recorded it could have several other implications, some of which are its effects on our speed of thought and possibly how we perceive time. As mentioned before, in order to think we must be able to remember our own thought. It is not possible to process everything at once and obtained the answer required in one instance. For example, trying to multiply relatively large values, let us say eighty seven times twenty four. Attempting to do this, we would usually form the image of the two values in our mind, and calculate parts of the equation at a time. Recording each new part which has been calculated, and building upon it. However, since the memory is only recording at a certain rate, an amount of time would pass between each recording. Since we can not build upon the part which we have already calculated until it is stored in the memory, the rate at which the memory is recorded will contribute to the overall processing time.


The memory could also be a factor we use in order to gauge the passing of time. How can tell how much time has passed? How do we know that one hour is longer than one minute? Or do we? In fact, this is not always necessary the case, for example, when waking up it is not possible to tell how long we have been asleep, whether it is a couple of hours or ten hours. Apart from of course using other factors like how tired you feel or how high the sun is in the sky. But of course there is an observation that, when we have woken up at the same time frequently using an alarm clock, after a while we no longer require the alarm clock to wake up at the right time and that our body have some kind of internal body clock mechanism. This of course is possible, but it could also be that waking up at a particular time has been worked into an instinctive reaction, like breathing, triggered by the conditions at that particular time of day without having anything to do with the time at all. In fact, this observation could also be use to argue that there is no body clock mechanism, since usually when we get into a habit of waking up at a particular time no matter when we go to sleep we will still wake up at the same time regardless of how many hours we have slept.


What ever the case, our perception of time could be looked at from another perspective. Lets for a moment go back to the example of the video camera. Let's say that we are recording an event at twenty four frames each second for one second. Let us say that we process (play back) the information at a certain speed, say twenty four frames per second. So in this case when we replay the event back we will essentially see it happening at its normal rate and the event will last one second. If we record the event for twice as long (two seconds), there would be twice the amount of frames, and if we process it back at the same rate then the event would last twice as long. Now, let us double the recording speed to forty eight frames each second and only record the event for one second. Processing this back at the same rate as before the event will seem to last for two seconds (twice that of reality), although we would observe that the event occurring would be half the speed as it was before.


The frame rate of the camera in this case is equivalent to the recording frequency of human memory and the play back speed is equivalent to the processing speed of the brain of the instances from the memory. Therefore, the brain could gauge time by assessing and processing through the number of instances recorded in the working memory. The larger the amount of instances, the longer the event will seem to have lasted. Many people have experienced situations in the past where, events that lasted a short time seem to have lasted much longer (usually these are exceptional and important situations), for example, a person experiencing a car accident. In these situations it is possible that the rate of memory recording frequency will be increase, possibly to enable the individual to think and react faster to the event. As a result, the event will appear to have lasted much longer than usual.

May 15th 2006

Praphob Sussangkarn


Information about this Article
Peer-review ratings (from 3 reviews, where a score of 100 represents the ‘average’ level):
Originality = 75.17, importance = 52.25, overall quality = 51.66
This Article was published on 23rd August, 2006 at 00:20:26 and has been viewed 6766 times.

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1 Peer review [reviewer #187confirmed user] added 2nd September, 2006 at 09:24:13

It is, of course, always interesting to see a fresh perspective on one’s own discipline, but here we have a good example of why people should not assume that just because psychology considers human experience, being human is qualification enough to discuss the subject at this level any more than having elbows qualifies one to talk about mechanical engineering.

The article raises questions that would quickly be answered with a working knowledge of memory research and, especially, visual neurophysiology, such as might be acquired from a good experimental psychology degree. The idea that we should skip over the question of different forms of memory is a worrying start, as all the examples about catching balls almost certainly involve a very different memory mechanism from most other tasks, in this case centred on low-level sensory analysis, probably using a form of neuron-level linkage to accomplish the task at such speed.

The idea of frame rate in the relationship between sensation and memory also doesn’t fit what we know about the cell-level processes on the retina. The processes are much more analogue than the author realises, with individual photoreceptors sending signals upon receiving sufficient stimulation such that the primary visual cortex is constantly receiving piecemeal information about the visual scene, rather than all the cells of the retina somehow sending snapshots of the visual scene in a co-ordinated way.

In fairness, this isn’t the first person to reify the video camera metaphor of perception and memory - there is plenty written on the reconstructive nature of memory, for example, which clearly shows that although we may feel as though we have a stream of visual information flowing into our heads which we can watch back later, this is far from what really happens.

Originality: 2, Importance: 2, Overall quality: 2

2 Peer review [reviewer #7116confirmed user] added 19th November, 2006 at 01:32:44

I believe the author’s initial observations, used as a metaphor for the essay, are drawn to a mistaken conclusion. The illusion that spinning objects stall or move in reverse is generally caused bya kind of moire between the object’s rotational speed and some environmental factor which imposes its own phase. The two common culprits, which I have no doubt are the ones in the author’s example, are fluorescent lighting and film. Under a steady light source like the sun, wheels do not appear to back-spin. This would suggest that there is no true “phase” mechanism in our optical capacity. (Pointedly, as a wheel speeds up it would eventually be observed to backspin even if we had an extraordinarily rapid “phase” in our eyes/brain.)

Originality: 4, Importance: 2, Overall quality: 2

3 Peer review [reviewer #2144unconfirmed user] added 19th November, 2006 at 07:29:39

I quote:”Often when observing rapidly occurring events; we will be unable to keep up and process what exactly is going on. “

Actually, even when the events are static, and not rapid, Man’s sense organs will often not be able to process exactly what is going on.

An example is that of optical illusions, using the famous cliched example of “Which arrow is longer?”. Even though the arrows are not moving, the eye also cannot process which arrow is longer without the help of a ruler.

Originality: 5, Importance: 4, Overall quality: 4

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