When an image gets on the retina of an eye it does not just disappear thereafter. Our brain continues to see the perceived image for some time. But it happens only in case the picture is not “blocked" by something else. If you disguise the picture you saw with another picture or even with 20 different pictures imposed on each other the effect of consecutive images will not be reached.
Therefore the so-called inertness of the visual analyze (also called iconic or sensory memory) is relative. Strictly speaking, the visual system is not inert but quite mobile. The illusion of inertness appears only in cases when perceived pictures are not blocked by something else.
To test it you will need a pocket flashlight and a dark room - for example a bathroom in your house or apartment.
Take your flashlight and enter the bathroom. Turn off the light. Give your eyes about five minutes to adjust to the darkness.
Lift your hand to your eye level and hold it with your palm facing you about 15" away.
Take the flashlight in your other hand and point at the palm.
Prepare for the experiment. Your eyes should be directed on the palm. In order to see the consecutive image, it is necessary to fix your eyes on one object. Get ready and do not move your eyes.
For a short time (one second is enough) light the palm with the flashlight. Lower the palm and continue to fix your eyes at the point where your palm was initially.
In some 2-3 seconds the consecutive imaging will start "to appear". You will see your hand hanging before your eyes. You will also see a part of the bathroom. The consecutive image will be the same as the photo laboratory when it is lit by the dim light of the photo lantern.
If you do not move your eyes the consecutive image will stay for about 5 seconds and then gradually disappear. If you try to register details of the bathroom the consecutive image will disappear once you start moving your eyes.
1. The consecutive image appears not at once but seconds after the light reaches the retina of an eye.
2. The consecutive image is seen for some seconds and then gradually fades away.
3. If your eyes move after the lighting of the flashlight the consecutive image will be indistinct and will quickly disappear.
4. The consecutive image moves along with your eyes. This means that the picture which you continue to see, after the flashlight is off, is actually in the retina of your eyes. If the consecutive image was the product of your brain it would not move together with your eyes.
5. Excited by the photons of light your eye receptors continue to generate electric impulses for a short time which causes the effect of the consecutive image.
6. The consecutive image is not kept in the brain and cannot be reproduced again after it has disappeared.
The above described phenomenon in psychology is referred to as sensory or iconic memory. Paying attention is a question of physiological memory. Therefore you should not confuse the iconic memory with the ability to remember and keep the information for its subsequent use.
Consecutive Images and Text
In this experiment you will see that consecutive images cannot be used for instant memorizing of a text. It is impossible to read information contained in a text from the consecutive image.
For the sake of the experiment you will need a book and a flashlight. A flashlight from a picture camera will do.
Attention! You do not need to do more than 2-3 experiments with the flashlight.
Open your book on any page with text. Take the book in your left hand and keep it with the text before your eyes at an arms' length. Fix your eyes in the middle of the page. Take the flashlight in the right hand and hold it by your right ear pointing it directly to the page with the text.
Turn the flashlight on. After exposing your retinas to the light close your eyes and try not to move your eyeballs.
In 2-3 seconds you will see the consecutive image. If you do not move your eyes the vision of the page will stay on for a few seconds. If you move your eyes the consecutive image will collapse.
Note that you will only see the general view of the page - maybe large letters (the heading). Instead of the text you will only see its location. It will be impossible to read it..
Even if the consecutive image was so precise that it would let you see even the small print you would still not be able to read it. The reason is that in order to read the text you would have to move your eyes but along with your eyes the text would move as well since the "picture" is in your eye retina.
* The consecutive image does not keep small details of the perceived image. If the small details were kept (the letters of the text) it would still be impossible to read them since the image would move together with your eyes where the consecutive image would collapse.
* The so-called photographic memory is impossible. It is impossible to look at a page with a text then close your eyes and read it off the registered image.
- M. Ruslans