Picture yourself sitting sideways in a train looking out of the window. You cannot get up from your seat and the train is moving at a constant speed. The window is 1 meter high and its width may vary from 1 to 1000 millimeter. Note this width is measured in the direction (dimension) parallel to the one the train is moving in . What do you see?
Regardless of the width of the window, the light reflected by the passing landscape will reach your eyes; You will see the same no matter how wide or narrow the window. Still, the wider, the better you will be able to comprehend what you are seeing. This is because with a wider window every detail will be visible for a longer period of time than with a narrower one.
The above is an analogon. Instead of sitting in a train, we are "being" and "moving forward" in time. Instead of a window, we have "awareness", which is in fact the perception of events in time, including ourselves and our own thoughts. Note that a dead unaware object would be analogous to a person sitting in the train without a window in front of him.
Like the window has a width in the direction the train is moving in, awareness has "extendedness" in time. Since the window is moving, the time interval of awareness is shifting forward in time. Like the window may vary in width, the time interval - let us call it "Time Window" - may vary. And the longer it is, the better we are able to comprehend what we perceive and experience.
Note that Time Windows of different entities are centered. Otherwise we would not perceive each other and the world.
We can likely extend our Time Window a little by concentrating to understand or solve something. And when unconscious or in a dreamless sleep it shrinks to almost nothing.
The size of our Time Window is probably below or in the order of our threshold of perception, which is on average somewhat below 100 milliseconds. It may even be related to this threshold. In this respect it should be mentioned that this threshold has been found to correlate with intelligence test scores; Arthur Jensen reports on this research in his book The g factor. The computer game Thinkfast measures, among other elementary cognitive tasks, this threshold.
The correlation of perceptual threshold with I.Q. however is negative, so that low thresholds go with high I.Q., which shows that this threshold itself is not the Time Window. At this moment (2008) I am not certain at all if the Time Window, if it exists, has size in the time dimension. I am considering it may have size in another dimension, which may be not a physical but a psychometric one, in which case it would not actually be a window in the physical sense as originally meant in this old article. My best current guess is that the Time Window is what I now call "awareness" or (in its outward expression) "creativity", being the synergy of conscientiousness, intelligence and associative horizon.