O.K. This is OT. Tongue in cheek, too! I can no disagree with you more. With your assertion to the facts, which can be asserted in the different fields of science involve with the perception of a the animal called a homo sapiens sapiens. First of all one must differential which systems are sub-system of which. Furthermore one should define what is meant by perception and the different kinds of perception and which perceptual systems interact and at what level this is controlled by a overlying perceptual systems. 1) The perception of its environment by a human being is governed by a cognitive process which takes place in its brain. This process has many sources of input which come for different sub-systems. In the case of a book from PG these are visual, tactile, olfactive, aural and taste. We can consider these to be external sub-systems of perception. 2) It perception of its environment is also governed by internal input which is stored in it brain. This input contain the experiences and emotional data. This we can consider to be internal sub-systems of perception. 3) It is also know that the amount of visual input, by itself, a human (to be more exact it brain) must process is more than can processed in real time. This data, as with all external input, is filtered. The filtering process thereof is governed by various other sub-systems both internal and external. Yet, as the visual input passes these filters it is no long purely visual, or at least no long belongs to the purely visual perception, but belongs to the cognitive perception process of the human. Now, the human body, as biological entity, and its system underlie the many variations. Thereby, these biological systems will pass the same stimulus, a PG book, input as different data. For example, a shade of green is not the same for me as it is to others as I have a color dysfunction that other do not. On the other side a human as a thinking entity, will process the same data differently as it thought process have been formed though out its life experiences and no two human share the exact same life experiences, partially also due to their biological differences. Yet, in order to discuss a particle system of human beings as a whole we must, idealize somewhat. What we have not done is defined exactly what a visual system is. If we consider visual as the perception of light the there are actually two biological systems involved. One optical and the other is tactile, as heat is another form of light energy. On the other side we have not defined what light is! If we define it just as that part of the electro-magnetical spectrum that the optical system that the human animal can take as input there is only one. To conclude: I have beyond any doubt shown that the human body has only one biological system for inputing visual data and thereby has only one visual system. The perception of this data is all together a different matter. Furthermore, it is clear that one can construe almost anything by choosing the definitions thereof in the most arbitrary way. Also, the introduction of other concepts and mixing them arbitrarily into the argument one can make a point, yet it leaves the realm of what was being discussed in the first place. Though this is somewhat tongue in cheek, I hope that you do understand that we agree on many views concerning the below mentioned. It is only a matter of which functionality one is discussing or which particular field one is interested in. regards Keith. ;-)) Am 20.11.2011 um 04:17 schrieb James Adcock:
The time I check a biology book the human has just one visual system.
The biology books lie, as do ophthalmologists and optometrists. How people read, and how they visually perceive varies greatly from person to person. As the very simplest, consider the wide variety of visual orthotics something more than half of all humans wear, and how varying various people's mental and emotional responses are to the same book -- the brain is part of the visual system.