Submitted to Psycoloquy
FORMATION OF KNOWLEDGE AND FUNCTIONS OF SENSES
Department of Behavioral Sciences, University of Oulu, Finland
From the ancient times the senses have thought to have the role of channels through which knowledge arrives from the environment into the organism. This conception was so strong and untenable that in earlier attempts to treat organism and environment as one system just here the system had to be divided into two subsystems. According to the theory of organism-environment system the formation of knowledge is not based on any transfer process from the environment into the organism, because there are no two systems between which this transfer could occur. It is argued in the present review on the basis of experimental evidence and trheoretical considerations that the senses do not transmit information from the environment into the organism, but they make the direct connection between the organism and environment possible. With the help of senses and motor apparatus new parts of environment may be joined to the structure of the organism-environment system in a constantly changing environment. In this connection process an essential significance has the efferent influence on receptor activity. Such conclusions have far reaching influences as well on the interpretation of results of sensory physiology as on philosphical considerations on the process of knowledge formation.
Key-words: Sensory physiology - Receptors - Knowledge - Efferent influences -
Senses - Motor systems - Epistemology
During the present century several researchers have stressed the mutual dependence of organism and environment. Koffka (1935), for example, describes an organism as a system which includes both the body of the organism and its behavioural environment.The basic problem in understanding the characteristics of such system has been the question of formation of knowledge. From the ancient times the senses have thought to have the role of channels through which knowledge arrives from the environment into the organism. The conception of senses as windows of knowledge was so strong and tenable that in earlier attempts to treat organism and environment as one system just here the system had to be divided into two subsystems. The arguments of sensory physiologists were self-evident: The eye responds to light and transmits from the environment a picture, let the philosophers speculate anything else! Light stimulus is outside and perception inside!
Although during the history of philosophy and psychology there has always been some dispute on whether the human knowledge is based directly on the functioning of senses or whether it is in some sense constructed by thinking (empirism contra rationalism) there has been no question about the role of senses as a transmitter of at least some kind of raw data or simple sensations from the environment.
The role of movement in perception
According to the theory of organism-environment system the formation of knowledge is not based on any transfer process from the environment into the organism, because there are no two systems between which this transfer could occur. Knowledge is the form of existence of the system and new knowledge is created when the structure of the system is changing. The increase of knowledge would mean widening of the system and its reorganisation which makes new kinds of action and new results possible. From this would follow that knowledge is not as such based on any direct action of the senses.
Such conclusion may seem to be simply contrary to the facts. However, there are some earlier considerations which go to the same direction, namely those ideas in which the role of movement has been stressed in the perceptual activity. Already
Alexander Bain (1855) proposed that sensory and motor action constitute together conscious perception. He stressed the role of eye movements and thought that they determine to a large extent what we see. If the eyes move in a circle we see a circle and the perception of straight line is based on linear movement of the eyes. He maintained that the content of perception was directly related to the character of the motor activity.
Also the founder of experimental psychology, Wilhelm Wundt, saw the importance of motor activity when trying to explain visual illusions, for example. Horizontal-vertical illusion was in his opinion a typical example: Here we have an illusory lengthening of the vertical line, because the eyes must move upwards along the line and oppose gravity and thus the energy needed for the eye movement is higher than with the horizontal movement of the eyes. Wundt (1897) writes.
"The phenomena of seeing teach us that the idea of distance between two points depends on the motor energy of the eye used when the eye moves this distance (…)The motor energy becomes a component of the idea by combining with the sensation which we may perceive." (Wundt, 1897, p. 133).
Wundt regarded thus sensation and motor energy as separate components of an idea. This would mean that movements have besides the sensory stimulation an essential significance for the perception. Perception would thus not be simple copying of the environmental stimuli.
Associated with these early ideas also recently several researchers have developed "motor" theories of perception (see e.g. Coren, 1986), according to which perception is always a result of co-operation between the sensory organs and muscles. However, these theories usually preserve the traditional conception of the role of senses as transmitters of environmental information and the movements are thought only to modify this process. It were the experimental findings during the last ten years which forced to see this whole situation and the role of movement from a quite new point of view.
The dynamic character of action of nervous system and senses
The traditional conception of senses as transmitters of knowledge has been during the last decades formulated by the help of information theory (see e.g. Lindsay and Norman, 1972). According to this theory, developed originally for the description of automata, formation of knowledge is based on information transmission carried out by a signals in which the information is stored by the help of a code. When applied to the description of the action of senses this means that the environmental stimuli are transformed in the receptors into nervous activity according to a well-defined rule, the neural code which may be later used by the central nervous system in the process of decoding, reading the information from the neural signal.
There have been several candidates for the neural codes: Firing frequency in the neurone, intervals between the discharges, patterns of intervals, number of fibres or cells activated, location of the neurones etc. (see e.g. Somjen, 1972). Let the code be anything, the information processing approach presupposes that there must be a decoder, group of cells, some brain area, or homunculus which may read the information from the signals. Such decoding process is possible only if this decoder knows the code used in the modification of the signal in the periphery, and that this code stays as constant or does not change suddenly without previous announcement. Basically, the decoding process is possible only if the relations between the cells in the periphery and in the central nervous system stay constant under different action situations.
However, the experimental findings during the last decade have questioned just this basic assumption.
Many neurophysiological studies have recently shown that neural responses do not simply follow the given stimuli, but have often a dynamic character, showing no simple dependence on the stimulus parameters. For example, if the same stimulus is repeated or presented under different conditions the responses may considerably vary. This is true as well of specific cells in the central nervous system as of receptor cells in the periphery. Furthermore, Alexandrov and Alexandrov (1982) showed that the neurones in the visual cortex of the rabbit were activated in relation to the behavioural phases of the rabbit independent, whether the rabbit got visual information from the environment or not. The results indicated that the neurones in the visual cortex are related rather to the behaviour of the rabbit than directly to any specific visual stimuli.
Up to the last years it has been a self-evident fact that the peripheral nervous system acts as a kind of passive transducer coding the environmental stimuli for the use in the central nervous system (see e.g. Näätänen, 1990). However, in research on almost all senses there have recently appeared results which indicate that also the activity of the receptor cells may be dependent on the state and behavioural acts of the subject (see Alexandrov and Järvilehto, 1993).
Receptor cells have not connections to the central nervous system only through afferent fibres, but there are also efferent fibres from the central nervous system which may influence the activity of the sensory neurones. During the last years there are results showing that such connections may be shown at least for audition, vision, sense of balance and skin senses (Alexandrov and Järvilehto, 1993; Liberman et al., 1990; Biondi and Grandori, 1976; Highstein, 1991; Mikkelsen, 1992).
It was earlier difficult to study efferent influences on receptor organs, because such functional research is possible only with awake and behaving animals. However, already much earlier such connections were suggested to exist: Mead (1934) and
Goldstein (1939) proposed such possibility and Livingston (1959) was speculating that central control of receptors would make possible the active character of the sensory processes.
Two experiments: Efferent influences in touch and vision
Recent experimental results show that Livingston (1959) was right in his speculation: There are indeed efferent influences on sensory organs which seem to be dependent on the behavioural situation and goals of action of the experimental subject (animal/man). In our research we got such results when investigating responses of cutaneous peripheral neural units in experimental situations with varying tasks of the subject (Astrand et al. 1986).
In the first situation the subject was attending to tactile pulses of varying intensity, applied to the receptive field of a mechanoreceptive unit, and reported numerically the intensity of the touch sensations elicited. In the other situation the identical pulses were applied to the receptive field of the same unit, but the subject's task was to count deviant tones in a rapidly presented series of standard tones. Thus, this task had nothing to do with the presented tactile stimuli. In both situations peripheral responses of the single mechanoreceptive units were recorded by microelectodes from the radial nerve at the wrist level (for the recording technique, see Järvilehto, 1976 ).
The results showed that the thresholds and response characteristics of the recorded mechanoreceptive units changed with the subject's task. When the subject was attending to the touch stimuli the thresholds of the units were lower, more impulses were elicited with identical stimuli, and the latencies of the responses were shorter than during the counting task. From the point of view of the "coding" this would mean that the nervous system could not identify the identical stimuli from one situation to another. Therefore, the central nervous system would not receive unequivocal information from identical events in the environment during the two tasks.
However, such results could also be interpreted as showing only that the dynamic changes in the receptors are not related to the tactile stimuli as such, but would rather indicate a general sensitisation of receptors during attending certain kind of stimuli. It could be furthermore assumed that this state is somehow indicated to the central decoder which would the correspondingly correct the incoming signals. But, even with such an interpretation we should admit that unequivocal neural coding in the peripheral nervous system is in question, and that the peripheral neural system is not an automatic or mechanical transducer of the parameters of environmental stimuli.
However, in our research with freely moving rabbits (Alexandrov et al., 1986) we obtained results which indicate that the interpretation of attention effect is not correct. The results showed that the dynamic changes at the receptor level are not simply due to attention (whatever this may mean) or to the use of certain receptor field which would be sensitised in a certain task. Such changes are rather related to the whole behavioural situation.
In our experiments we had a freely moving rabbit which was acquiring food in a cage by pressing a pedal. In contrast to the study of Alexandrov and Alexandrov (1982), we now recorded unit activity directly from the optic nerve before its entering into the lateral geniculate body. When the rabbit was performing the food-acquisition task we could observe activations of the units in the optic nerve which had a constant relation to certain phases of the rabbit's behaviour. The units were activated, for example, always when the rabbit was approaching the pedal or when it was moving to the automatic feeder. Apparently, such activations could be interpreted as responses of the optic nerve units to the visual stimulation by the pedal or the feeder.
Before starting the recordings we had taught the rabbit to perform the task also when its eyes were covered with nontransparent cups preventins the use of any visual information. When during the experimental session and having constant activations of a certain unit to the pedal, for example, we closed the eyes of the rabbit so that no visual stimulus could influence the retina, we found that the recorded unit continued to show activations in relation to the pedal. Thus, such activation could not be related to any direct visual effects from the environment, but for many units the activation seemed to be independent of visual stimulation. Consequently, such activations could not be due to the effects of stimuli, but it had to be mediated over the efferent influences upon retina. On the basis of their latencies to direct visual stimulation we could also show that the unit discharges were not from efferent fibres, but reflected activations of the ganglion cells.
Such results question the attention hypothesis, because when the eyes of the rabbit are closed there is nothing to be attended in the visual modality. Thus, there should be neither any reason to modulate the peripheral activity or sensitize the receptors. The results should rather be interpreted as showing that at all levels of the nervous system unequivocal coding of environmental information is difficult, if not impossible. But this leads then to a quite new way of thinking about the formation of knowledge and the functions of receptors.
The present conception of neural coding and of constant responses of neurons to specific stimuli seems to be based only on the fact that the experimental situations have mostly been constant. In the usual experiments with restricted or even anesthetized animals, the experimental subjects and their receptors have had no possibilities for alternative ways of functioning. Therefore, stimulus-response functions have had a very regular character. If we standardize the behavior of the experimental subject with our experimental method it is clear that the results will show that only this behavior will appear in the experiment and therefore there is no variation in the neural responses if these responses are different with different behaviors. Unfortunately, the results of most neurophysiological experiments are therefore in this way predetermined already by the experimental method.
However, in the freely moving rabbit we may record from any part of its nervous system responses to many kinds of stimuli. If we give to the experimental subject larger variation of behavioural possibilities we may notice that the responses of the neurones are not in a constant relation to the stimulus parameters defined by the experimenter, but they are rather constant in relation to the different behaviours. According to the theory of organism-environment system such results may be well understood, because the activations of the neurones are only one part of the system organising for the result of action, and the stimuli are just parts of the same organism-environment system.
When a stimulus precedes in time an activation of the neurone we have the impression that the stimulus was its cause. However, in reality we prevent with our basic assumptions and with our experimental method anything else to occur, because we are not even interested in the neural events which do not follow our pre-set causal assumptions. If such responses occur, they are interpreted only as noise or artefacts. Constant stimulus-response relations are a self-evident fact if we limit the behavioural possibilities of the experimental subject so that the expected response is the only action possibility of the subject after the presentation of the stimulus.
Receptors as organs creating the connection between the organism and environment
The results of our experiments lead to the conclusion that there is no simple coding of environmental stimulus information by the receptors. This conclusion has far-reaching consequences. First of all, we must conclude that the information theory is not a useful theory in the description of the functioning of the senses. Second, we must conclude that the knowledge about environmental features and events is not simply based on the assumed transduction in the sensory systems.
But if the receptors are not coding environmental information and transmitting it to the central nervous system, how is then knowledge formed and why the organisms at all have receptors? The idea of transfer of knowledge from the environment into the organism is a cogent hypothesis, because it is based on our every-day experience and on the common sense explanation of causal factors in behaviour. If it is not true, are there any other possibilities for the formation of knowledge or should we turn to some sort of parapsychological explanations, like telepathy? Efferent influences on the receptors seem to destroy all possibilities for unequivocal coding of environmental information. Why such influences had developed during evolution?
If during the evolution the receptors developed to organs responsible for exact coding of environmental stimuli it is difficult to conceive why their action should be distorted from the central nervous system by the efferent influences. Of course, we could suppose, as indicated by the attention hypothesis, that the influences on receptors are controlled in the way that a model of influences is stored in the central nervous system when such influence is exerted in the periphery and this model would then be used in the correction of the incoming information.
But even then we have the question, how the central nervous system would "know" how much the receptors should be influenced? And if the knowledge comes through receptors how anything about the behavioural situation could be known before reception of the information from the receptors? And if this situation would already be known then it were no more necessary to modify the action of receptors. It seems that there is something basically wrong in the hypothesis of information processing as a basis of perception.
Thought experiment: Knowledge formation without senses
But could we even imagine that knowledge formation were possible without the help of receptors? Let's have a thought experiment:
Let us assume an imaginary organism which would have no receptors, but only motor organs. Such organism is, of course, impossible, because a receptor is simply a cell which is connected both to the organism and to the environment. As no organism may develop without environment it necessarily has such cells and could not live without such cells. But let us imagine such an organism only for the purposes of our thought experiment.
Could such an organism have knowledge from its environment, from the structures outside of its surface boundary, or would it be closed into its inner life only? Now, we must understand the concept of knowledge broadly, as a possibility to act in the environment appropriately. Could such an organism learn something about the environment to which it would have no direct access by senses?
Let us put our organism into an environment which consists of a cube with smooth walls. The cube is filled with a homogenous energy field (like water) and the organism is able to swim in the field by using two pairs of fins which move the organism in two dimensions: forwards-backwards or right-left. The pairs of fins are connected by a sensitive and dynamic set of interneurons which join the pairs of fins so that only one pair may be used at once. The muscles of the fins and the interneurons feed from some mysterious inner energy which the organism may supply from the energy field in the form of induction when its body is moving in relation to the field. If the movement of the organism stops the amount of inner energy for one pair of fins goes down and finally ends for the pair of fins which were moving the organism. The other fins have, however, still their own energy storage which they may use when the other fins are no more working, and therefore the movement of the organism is restored to some other direction. These fins then work so long as the movement continues and simultaneously the energy storage of the other fins is restored. If the movement of the organism stops completely it cannot restore the inner any energy and it dies.
Now the organism is moving to one direction inside of the cube by moving one pair of fins. This movement inhibits through interneurons the movements of the other pair. During the movement the organism may induce more inner energy from the homogenous energy field and thus it would move indefinitely if the walls would not exist. When it hits the wall preventing its movement the original pair of fins is still moving, until their energy storage is depleted. Then they stop and the inhibition to the other pair disappears and these start to move giving the organism movement to some other direction. This movement continues again so long the organism hits another wall, stops and the other fins start again to move.
Let us now further suppose that the connections of the interneurons between the pairs of fins are such that they may be dynamically changed. The continuous movement of the organism within the cube to different directions starts therefore to change these connections so that the use of energy by the fins and the induction of energy from the energy field becomes optimal. Therefore, the organism starts to turn already before it hits the wall, and develops continuous movement even with the existence of the walls.
Thus, it seems that the organism learns to know the structure of its environment in the sense that it may anticipate the walls and the instant of hitting them. The walls and the organism start to form one system the result of which is the continuous movement of the organism. The walls of the cube are elements of this system in the sense that their existence explains partly the action of the organism (turning). Essential in the functioning of such system is the number of interneurons and their dynamics and the constancy of the environment. In a randomly changing environment constant connections between the interneuron could not be formed.
Probably it would not be too difficult to build a computer simulation demonstrating the actions of this kind of organism. As a matter of fact this kind of connectivistic models showing learning only on the basis of changing connections have been demonstrated. In any case the result of the thought experiment so far seems to show that an organism may be connected to its environment in a reasonable functional way even in the absence of any receptors; even in absence of senses it may learn to know its environment. For what do we need then receptors?
The thought experiment is impossible therefore that there are no organisms without some kind of receptors. Even the idea of induction of energy from the energy field means assumption of some sort of general receptor. However, all organisms have cells which may use environmental energy (like photoreceptors) or whose function may be distorted by energy gradients (like mechanoreceptors).
The significance of receptors may be seen when the conditions of our thought experiment are changed such that we add one hole (a receptor) to the surface of the organism through which it may directly use certain kinds of energy foci (concentrated
spots) in the field. The environment of the organism is thus no more homogenous, but consists of energy gradients. Here the walls do no more exist. The receptor hole has a certain size making possible the direct use of only certain spots. Let us further suppose that the main energy for the movement must come from such spots, the induction from the energy field is no more a sufficient energy source. So the organism must every now and then hit such energy spots with the receptor to have enough energy for its life process. Let us further assume that the spots stay in certain places and are restored at once when they are used; so far the environment is constant. We may also assume that there are now many pairs of fins making the movements of the organism possible to any direction. However, also these fins have reciprocal innervation so that movement to one direction inhibits the fins working to the opposite direction.
Now the organism is moving in the heterogeneous environment. If it does not hit any energy spots it dies. Eventually one of the organisms (we may also assume that there are now many of them) encounters such spot giving it energy to move further to this direction. Slowly the energy for this direction is depleted and some other fins start working turning the organism to some other direction: Again one spot is found and then later direction of movement changed again. If there are dynamic interneurons enough connecting the fins the organism starts to move from one energy spot to an other optimising its energy consumption similarly as the organism within four walls. Such organism would then live forever. The life process of the organism is, however, very sensitive to any change in the structure of the environment.
Now, we go the last part of our thought experiment and assume a heterogeneous environment which is continuously changing. The place and size of the energy spot is continuously changing. Furthermore, we add efferent fibres to the receptors which may regulate the size and the quality of the receptor hole. It may now use different kinds of energy spots of varying size. What happens now?
First of all, most organisms with fixed receptors disappear and the new organisms with efferent control of receptors start to show behaviour which differs from the behaviour of the earlier organisms, in principle. When the organism does not get energy supply with one size or quality of the receptor, it changes the receptor hole so that it may fitted also to the energy spots of other sizes and qualities. Thus, the organism starts to search, to investigate its environment. The movement is no more randomly moving it to a fixed energy spot, but the organism may locate spots of different sizes and qualities and it may also search other spots if the original ones disappear. Through this fitting process the organism starts to be a functional whole with its environment to which it may join in many qualitatively different places. The organism starts to "perceive" its environment.
Conclusions from the thought experiment
Now, we may better see, first, why receptors exist even if they are not transmitters of information, and, second, why efferent influences are important for all receptors. The results of our thought experiment point out, furthermore, that knowledge formation is possible also on the basis of movement only even in the absence of receptors, but receptors and especially efferent influences give much more efficient ways for the learning of the structure of the environment. It is, however, necessary to consider shortly what kind of knowledge was created in our thought experiment.
The most thinking mistakes associated with "knowing" are connected to the idea that only that is "knowledge" which may be reported, told to another person or to oneself. As language is limited to the description of indicators of common results such way of thinking neglects all such knowledge which is not shared with other people.
According to the theory of organism-environment system knowledge is the form of existence of the system; every living organism must necessarily know something so far it can act in its environment. It is just the organisation of the system, making actions possible, what we may call knowledge in a broad sense. Therefore, we should not think that the organism in our experiment knows something about its environment in the usual sense of the word; that it would know to exist or that it would know to be in a space of certain form. This sort of knowledge presupposes already existence of consciousness, the possibility to separate in the knowing the own body and the environment. The organism knows the cube or parts of its environment only in the sense that it may join to the structure of environment in its actions to obtain results.
Our thought experiment stresses the significance of senses: even a small direct connection to the environment giving the possibility of energy flow into the organism gives it new action possibilities and new means for structuring its environment. However, it is not enough to have receptors, because essential is that the receptors and motor organs form one unitary system making the use of energy possible. The possibility to modify purposefully the functioning of the receptors, the existence of efferent connections, gives again qualitatively new action possibilities making the search and active exploration of the environment possible.
In conclusion, the senses do not help in transmission of information from the environment into the organism, but they make the direct connection between the organism and environment possible, they join the both into an organism- environment system. With the help of senses and motor apparatus new parts of environment may be joined to the structure of the organism-environment system in a constantly changing environment. In this process of connection an essential significance has the efferent influence on receptor activity.
We could also say the senses represent channels through which the environment may flow through the organism, making the connection between the environment and motor organs possible. With these channels working together with motor organs, the organism may create its own action environment on the basis of the possibilities offered by the environment and in relation to its own behavioural situation.
The theoretical significance of the efferent control of sense organs
The earlier researchers presenting theories about the motor theories of perception were right so far as they saw the significance of movement and sense action as the basis of perception. From the point of view of the theory of organism-environment system these theories were, however, incomplete in the sense that they were still based on the idea of information transmission from the environment: the movement was seen only as a component modifying the sensation coming through senses. This may be well seen in the conceptions of Munsterberg (1914), for example, who to some extent was very close to the theory of organism-environment system.
According to the theory of organism-environment system the knowledge about the structure of the environment does not move into the organism through the senses, but is created when new parts of environment join the structure of the organism-environment system. Perception is activity of the whole organism-environment system, its reorganisation, in which both actions of senses and motor organs join together and catch new parts of environment into the system. This process of attachment may be partly seen as efferent influences on receptors. The properties of receptors are continuously modified, and such receptor patterns are created which fit complex energy configurations of the environment and make possible new results of action.
It is just the sensitivity change of the receptor for different types of energy which makes possible the widening of the action environment (or its narrowing). If the sensitivity of the receptor increases there is the corresponding increase of the action environment and if it decreases this leads to disappearance of such parts of environment which earlier belonged to the system. Mead (1934) pointed this beautifully out already in 1930ees probably without knowing anything about the possibility of efferent influences:
"We have seen that the individual organism determines in some sense its own environment by its sensitivity. The only environment to which the organism can react is one that its sensitivity reveals. The sort of environment that can exist for the organism, then, is one that the organism in some sense determines. If in the development of the form there is an increase in the diversity of sensitivity there will be an increase in the responses of the organism to its environment, that is the organism will have a correspondingly larger environment.(…) In this sense it selects and picks out what constitutes its environment. It selects that to which it responds and makes use of it for its own purposes, purposes involved in its life-processes. It utilises the earth on which it treads and through which it burrows, and the trees that it climbs; but only when it is sensitive to them." (Mead, 1934, 245).
Consequently, the senses do not act as "windows of knowledge", they could be rather compared to tools of hypothesis testing. Every organism assumes something about its environment; i.e. it has a structure which makes possible its fit with certain parts of the environment. It is as if every organism would have a theory about the structure of the environment, expectations about what kind of action is possible and what kind of parts of the environment may momentarily join its organisation in the achievement of results of action. The senses are just the tools by which such hypotheses are tested, and the corresponding parts of the environment joined to the organism-environment system. All perceptual activity has, first of all, a theoretical character and leads to the creation of the specific action environment based on the possibilities offered by the heterogeneous character of the environment. It is just this action environment, behavioural environment (Koffka, 1935), optimal environment (Goldstein, 1939), or experienced environment (v. Uexkull and Kriszat, 1932) that every organism has to create itself. The active process of creation is made possible by the senses and the associated efferent systems (motor and efferent influences on receptors).
The finding of the efferent influences on receptors is probably one of the most significant neurophysiological result of the last decades from the theoretical point of view, because this finding should change the whole way of thinking about the basic principles of neural action. This finding means that the neurones do not process environmental information and the information processing generally is not the basic function of the human brain, as generally assumed (cf. also Edelman,1987). This finding gives also possibility to see the relations between the organism and environment in a new light. It was just this experimental finding which made it possible to understand how the organism and environment could join to form functionally a single system.
The conception of formation of knowledge based on the theory of organism-environment system joins the empiristic and rationalistic conceptions about the formation of knowledge. Knowledge is created empirically, through the experience, in the sense that formation of knowledge presupposes reorganisation of the organism-environment system and joining of new elements into the system. Knowledge is not, however, based on the functioning of the senses, but on the structure of the organism-environment system and on its modifications in the process of change and widening of the system according to the new results of action (cf. Popper, 1962). Therefore we may as well say that knowledge is formed rationally. Knowledge means the form of existence of the organism-environment system, it is created in the action of the system, and it is therefore specific for each single organism. On the other hand, it is also common so far it may be shared in the social system by consciousness.
The separation of ontology and epistemology is based on separation of man and environment. If the environment may exist with all its properties also without a human being it is quite intelligible to ask separately the questions on the existence of man and matter and on knowing of the world. If man is born into a ready environment it is, of course, completely logical to ask how he may get knowledge from the surrounding environment and what the ultimate parts of this environment really are and how we may be sure that we may have correct knowledge about these properties. All such problems disappear if we see that man and environment belong to the same system. Then the question "What exists?" is identical with the question "What can we know?".
Alexandrov, Yu.I., & Alexandrov, I.O. (1982) Specificity of visual and motor cortex neurons activity in behaviour. Acta neurobiologiae experimentalis, 42, 457-468.
Alexandrov, Yu.I., Grinchenko, Yu.V., Shvyrkov, B., Järvilehto, T. & Soininen, K. (1986) System-specific activity of optic tract fibres in open and closed eye behaviour. The Soviet J. Psychol., 7, 299-308.
Alexandrov, Yu.I. & Järvilehto, T. (1993) Activity Versus Reactivity in Psychology and Neuropsychology. Ecological Psychology, 5, 85-103.
Astrand, K., Hämäläinen, H., Alexandrov, Yu.I. & Järvilehto, T. (1986) Response characteristics of peripheral mechanoreceptive units in man: relation to the sensation magnitude and to the subject's task. Electroenceph. and Clin. Neurophys., 64, 438-446.
Bain, A. (1855) The senses and the intellect. London: Longmans, Green.
Biondi, E. & Grandori, F. (1976) Do efferent fibres to hair cells intervene in acoustic stimulus peripheral coding? Int. J. Bio-Medical Computing, 7, 205-211.
Coren, S. (1986) An efferent component in the visual perception of direction and extent. Psychol. Rev. 93, 391-410.
Edelman, G.M. (1987) Neural Darwinism. The theory of neuronal group selection. New York: Basic Books.
Goldstein, K. (1939) The Organism. A holistic approach to biology. New York: Amer. Book Comp.
Highstein, S.M. (1991) The central nervous system efferent control of the organs of balance and equilibrium. Neurosci. Res., 12, 13-30.
Järvilehto, T.: Neural basis of cutaneous sensations analysed by microelectrode recordings from human peripheral nerves - a review. Scand. J. Psychol., 1977, 18, 348-359.
Koffka, K. (1935) Principles of Gestalt Psychology. London: Bradford.
Liberman, M.C., Dodds, L.W. & Pierce, S. (1990) Afferent and efferent innervation of the cat cochlea: quantitative analysis with light and electron microscopy. J. Comp. Neurol., 301, 443-460.
Lindsay, P.H. & Norman, D.A. (1972) Human information processing. New York: Academic.
Livingston, R.B. (1978) Central control of receptors and sensory transmission systems. In handbook of physiology, Section 1: Neurophysiology, 741-760. Washington: American Physiol. Society.
Mead, G.H. (1934) Mind, self, and society. Chigago: Chigago Univ. Press.
Mikkelsen, J.D. (1992) J.D. Visualization of efferent retinal projections by immunohistochemical identification of cholera toxin subunit B. Brain Res. Bull., 28, 619-623.
Muensterberg, H. (1914) Psychology, General and Applied. New York: Appleton.
Näätänen, R. (1990) The role of attention in auditory information processing as revealed by event-related potentials and other brain measures of cognitive function. Behav. Brain. Sci., 13, 201-288.
Popper, K.R. (1962) Conjectures and refutations: The growth of scientific knowledge. New York: Basic Books.
Somjen, G. (1972) Sensory coding in the mammalian nervous system. New York: Meredith.
Uexküll, J. v., & Kriszat, G. (1932) Streifzuge durch die Umwelten von Tieren und Menchen. Frankfurt am Main: Fischer. Reprinted in J. Schiller
(Ed) Instinctive Behavior. New York: International Univ. Press, 1957.
Wundt, W. (1897) Outlines of psychology. Leipzig, East Germany: Engelmann.