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Information For Perception Does It Exist in The Environment Or Is It Just a Product of The Nervous System

In this article, I want to make two general points about perception. The first point is that information pickup involves the isolation of invariants in dynamic stimulation. This means that information pickup is much more than the output of particular sensory nerves at any given moment in time. The second point is that because the pickup of information involves the isolation of invariants in dynamic stimulation, there is equivalent information for different perceptual systems. I believe that an understanding of these two points will increase our understanding of perception and our understanding of blindness and its impact on perception.

One of the most persistent fallacies about blindness in popular culture and science is the notion that blind and sighted people perceive different worlds. The idea here is that what we perceive is a product of the sensory channels involved in perception. If the visual channels are not active, the assumption is that the perception of many physical attributes such as layout, size, distance, detail and salience is necessarily always incomplete because the products from the visual channels are absent. The assumption is that there is nothing a blind person can do to mitigate against this situation. The assumption is that the incompleteness in perception is a necessary consequence of the physiological deficiency and it affects almost every aspect of perception.

Much research in perception stems from this erroneous assumption. However, through the pioneering ideas and research of Dr. James J. Gibson and the more recent research of Drs. John M. Kennedy, Morty Heller and Paul Gabias, to name a few, an alternative view of perception is gaining acceptance in psychology. This view is called the ecological approach to perception. According to this approach, perception is not a product of the output of sensory channels to the brain. The brain does not construct the world out of sensations from the sensory channels. Instead, the brain, sensory and motor systems operating as an entire unit isolate invariants in dynamic stimulation which correspond to the physical properties of the world, as we know them. According to the ecological position, information is not the output of sensory nerves to the brain. Information is not to be considered the neural building blocks of the world for the brain. Instead, information is what the world has to offer. It is directly related to the physical properties of the world and not the physiological properties of nerves. This is because information pickup involves the isolation of invariants in dynamic stimulation, it is not restricted to the output of particular sensory nerves.

Because the pickup of information involves the isolation of invariants in dynamic stimulation, there can be equivalent information for different perceptual systems. This is an extremely important point. It is in fact a tenet of the ecological approach to perception. Support for the tenet is abundant. All you have to do is to observe blind people who have had training and opportunity going about their lives and competing with sighted people on absolute terms of equality. I will return to this point later, after I describe the properties of the different types of information available in the environment, appropriate for each perceptual system. Information about the world exists at the surfaces of rigid and nonrigid substances, and within nonrigid substances. Information about the world is inherent in the layout, and change in layout of rigid surfaces. Information is also inherent in the texture and pigment of surfaces.

Visual information about the world is embodied in structured light. This structured light is called the ambient optic array. It consists of nested sets of solid angles, each projecting to a point of observation. Of course, the environment is made up of an infinite set of points of observation and at least theoretically, an observer can be stationed at any point of observation and can move through multiple points of observation. The invariants in the structured light are directly related to the layout of surfaces in the environment including the surfaces of the observer's body. The changes in structured light correspond to changes in surface layout caused by displacements or changes in surface composition. Displacements of the observer's body are specified to the observer at points of observation within the field of view. Displacements in the environment which do not involve the observer's body are also specified as changes in the structured light. Yet, within these changes, there is still persistence of structure which specifies the permanent shape of objects moving through the environment.Auditory information is embodied in wave fronts with frequency trains specifying particular auditory events, and different arrival times and intensities of wave fronts at the two ears specifying location in space. With auditory events far away, head movements cause little change in intensity and arrival times of the wave fronts at the two ears. Practically speaking, this means that it is harder to localize a sound event in the distance. However, when auditory events are close by, they are much easier to localize. This is because head movements cause much larger changes in intensities and arrival times of the wave fronts at the two ears. The fact that differences between inputs to the two ears are much more detectable the closer the sound event is to the observer, and the fact that they are harder to detect the further away the sound event is from the observer, gives rise to what can be called auditory perspective. This auditory perspective is governed by the same geometrical principles as visual perspective. So, perspective is not just a visual principle, as is commonly thought. This is surprising to many people. It makes the point that there are often multiple sources of equivalent information.

Olfactory and gustatory information is embodied in the molecular structure of substances. Olfaction is carried through air. Our sense of smell is not at all bothered by the dynamic flow of air caused by wind, or of the flow of air caused by inhaling and exhaling. If anything, wind helps olfaction and so does sniffing. This reinforces the point that perception is best under dynamic conditions. Here again, with smell, the perception of odors involves extracting nonchange from change.

Haptic information, that is, information perceived through active touch, is embodied in the substances of solids and liquids and the layout of surfaces and the changing layout of surfaces. This haptic information is best picked up through active exploration of the substances and surfaces of the world. Active exploration can be accomplished through direct contact with substances and surfaces, by means of the hands. Other body parts can also be used but they are somewhat less efficient at information pickup, unless the person has no hands and the feet are used as substitutes. Active exploration can also be accomplished at a distance by means of instruments such as a white cane. Using a cane, a blind person can explore a large array of cluttered objects in complete safety. This can be a room, a home, a yard, an acreage, or an entire city. The important point here is that the perception of large layouts can occur despite and because of large changes in stimulation. The invariants in structure are perceived despite and because of dynamic stimulation to the perceiver. This fact is the riddle of perception. This is what makes perception so fascinating to study. I will take up this point again, later.

Now, I want to return to the idea that there can be equivalent information across several different perceptual systems. Perceiving a fire involves isolating nonchange from a myriad of chemical and ecological changes and this occurs across the different perceptual systems.

As Dr. James J. Gibson writes in Chapter 6 of his book, 'The Ecological Approach to Visual Perception', "A fire with flames, considered as an ecological event, instead of an abstract chemical event, consists of complex motions and deformations, fluctuating luminous surfaces, reddening and blackening of the opaque surfaces, billowing smoke and finally, a disappearance of the solid surfaces." This nonchange can be picked up by animal and human visual systems. A fire is also specified to the skin, the ears and the nose in addition to the eyes. Regardless of which perceptual system is used to pick up the presence of fire, it means warmth, comfort, a means of cooking food, or danger, depending on the situation. A fire is specified to the ears by characteristic rumble and puff sounds along with snap, crackle and pop sounds. In English it is called fire, in French, feu, in German, feuer, in Spanish, fuego, in Portuguese, fogo, and in Russian, pozhar, but it means the same thing to everybody no matter what the language. In French, the term for a large fire is incendie. There are similar sounding words in English such as incinerate and incendiary. Notice the fricative "f" sound, the plosive "p" sound and the sibilant "s" sound in the words for fire in different languages designed to mimic the puffs, pops and hisses in the sounds of fire. It is likely that somebody at the Kellogg Company decided to apply the "snap, crackle and pop" expression to describe the sound of Rice Crispies in a bowl of milk because of pleasant associations with listening to the sounds of wood burning in a fireplace.

To the skin, fire is specified by a gradient of heat which is inversely proportional to the distance between the fire and the skin. Notice the similarity between hot and hiss. The smaller the distance, the greater the perception of heat. There is also a gradient of pain which is inversely proportional to the distance between the skin and the fire. The closer the skin is to the fire, the greater the perception of pain. Beyond a limit of comfort, fire will burn the skin. Notice the plosive sound in "burn". A person can perceive the existence of flames by touch because flames cause the perception of intense heat at great distances from the source of the flames. Notice the fricative sound in "flame".

It is not hard to understand how fire is specified to the nose through the smell of smoke and the smell of burning substances such as wood, fabric or rubber. Even the smell of smoke and burning involves isolating nonchange from change. As we breathe the air in and out there is a flow of air molecules in and out of the nose and yet despite and perhaps because of this changing flow of air molecules, we are able to detect the constancy in the molecules which specifies burning.

The fact that we can perceive fire through the eyes, ears, skin and nose makes the point that there is equivalent information across different perceptual systems. Some might argue that this point is rather obvious and somewhat trite. However, the point applies in more complicated situations, as well.

Some have argued quite strenuously that blind people are at a great disadvantage because they do not see people's faces. They have suggested that blind people are less able to perceive people's emotions and motives because they are not aware of people's facial expressions. This line of argument has been used to keep blind people from entering several professions. It has been argued that because a blind person cannot perceive facial expressions directly, he or she will be less effective in teaching, counseling, the practice of law, as a juror or witness, as a parent and in almost every other human endeavor which involves social interaction. While this line of argument may seem appealing on the surface, it is pure nonsense when you consider how absolutely devastated our society would be if it were suddenly required to function without telephones, radios and written information. Although some important business is conducted in person, much important business is conducted on the telephone or by written correspondence. The rise in the popularity of talk radio in the last twenty years is a striking example of the fact that faceless communication has become extremely important in our society. For better or for worse, we have adapted to the telephone and we use it to full advantage.

Think of the many advice call-in programs on the radio today. The most recent spiritual and psychological advisor to have become extremely popular in the United States and Canada is Dr. Laura Schlessinger. Because of her expertise and training, Dr. Laura can usually figure out the dynamics of the social situations described to her by her callers within a matter of minutes, sometimes even seconds. She never sees her callers, yet she can pick up their emotional states by what she hears over the telephone. She is using information about people's emotional states available in the auditory signal and she can do it to the great envy of some of her professional competitors who work in social obscurity face to face with their comparatively small clientele. Thus, there is equivalent information across the perceptual systems. This is just one of the many marvels of the world and the animals who live in it.

Speaking of marvels of the world, some people have agonized over the fact that I will never see the faces of my children. They assume that because I cannot see their faces, I am not able to experience the full extent of their beauty and preciousness. How can they presume to know what I feel? How can they stand in judgment just because they can see? I try to explain that I am not fixated on the children's faces. As I touch my children through the normal course of parent-child interactions, I find beauty in many parts of their body, not just the face. The texture of their skin and hair is pleasant and beautiful to the touch. The shape of their head, arms and legs distinguishes them from any other children. The shape of their hands and feet and the intricacies in the actions of the joints in the fingers and toes are a tribute to our creator. They are so perfectly put together and I am overwhelmed with gratitude at the lives my wife and I have been able to produce. At this time, our marriage has been blessed with two children; Joanne, 6 and Jeffrey, 3. We are expecting a third child any day now.

I now want to return to a point I made earlier, which is that invariants in structure are perceived despite and because of dynamic stimulation to the perceiver. This fact has bedeviled conventional sensory and perceptual psychologists for years. This is because most of them only study vision, and only vertebrate vision. They ignore the complexities of the vision of insects and mollusks which relies on compound eyes.In compound eyes, no chambers are present, there is no lens and there is no retina, so no image can be formed on the retina to be sent to the brain. These psychologists regard the eye as a camera which sends pictures to the brain, and they compare the retina to a film in a camera. Their theories of vision ignore the fact that, in many animals, vision occurs without a retina. Comprehensive theories of vision must take this biological fact into account.

Pursuing the camera analogy, the retina receives images from the lens. Nerve fibers from the retina conduct the image to the brain. The nerve fibers may sharpen the image through neural coding, but these fibers, nonetheless, are generally considered to be communication cables between the retina and the brain. The brain is supposed to make sense of these pictures so that the mind can see a coherent congruent world in a sea of changing stimulation. But how is this to be accomplished?

To answer this basic question, the traditional psychologists have taken refuge from the complexity of a world swarming with dynamism by studying static displays. By experimental design, they often deliberately prevent their subjects from moving their eyes. Subjects are forced to keep their head immobile. How can we learn anything about normal perception in abnormal situations like these?

If perception is considered to be a passive process, the static approach makes sense. You project an image to the static eye, the eye sends it to the brain, and the brain spontaneously displays a perception to the mind through the miracle of physiology and neural networks. After 130 years of psychology, many perceptual psychologists haven't left Alice in Wonderland, despite the fancy laboratories and the big grants.

How are the principles associated with this static approach to perception going to tell us anything about normal vision or other perceptual systems such as touch and hearing which rely heavily on dynamic stimulation? Perception through the skin, joints and muscle tendons relies almost exclusively on dynamic stimulation. There is no way that principles derived from the study of static vision can ever apply to haptic perception of layout. Since most psychologists still study static vision and generalize their findings to other perceptual systems, which they consider minor in importance, how can the principles derived from conventional perceptual studies have any application to the way blind people perceive and function in the world? The answer is that they can't and yet the way we function in the world is laden with fruitful avenues of research, if only the research psychologists would bother to look.

I believe that research in haptic pictures for blind people affords ground-breaking theoretical possibilities as well as practical applications for psychology. This type of research allows us to study the pickup of invariants over a wide range of textures and representational systems. Just think of the many techniques available for producing tactile displays and all the resulting textures. The textures must become background and the invariants of structure across textures must be isolated as foreground. In addition, this research allows us to study the pickup of invariants which are constant in arrays of information differing in energy characteristics. For example, for a picture to be seen, an array of structured reflected light is necessary. For a picture to be available to touch, a tangible structure affording significant deformations to the skin and joints must be available. For picture perception to occur, invariants of structure must be isolated from the change in energy flow, regardless of the energy characteristics.

Also, this research allows us to study the pickup of invariants which are not affected by differences in receptor characteristics, differences in structures along different afferent and efferent nerves, and differences in cortical afferent and efferent areas associated with specific afferent and efferent nerves. For example, seeing a picture and touching a picture involve different receptor characteristics, different structures along different afferent and efferent nerves, and different cortical afferent and efferent areas associated with specific afferent and efferent nerves. For picture perception to occur, it is the process of isolating invariants of structure in the changes necessary to obtain stimulation which is key, not the particular pathways or brain centers involved.

Finally, this research allows us to study the pickup of invariants within a constantly changing flow of stimulation. In order to perceive an extended array by touch, the observer must continuously change the points of observation under the fingers. Thus, the pressure changes under the skin are constant. The changes in the joint angles in the fingers, wrists, elbows, and shoulders are also constant. Yet, from all of this changing stimulation, perception occurs. Isn't this remarkable? We, as blind people, have an enormous amount to teach science and the public. As members of the National Federation of the Blind, we are in a good position to present the scientific and lay public with an understanding of the world, as we know it, which is often beyond their ken. Let's go ahead and do it!