I do not disagree with most of Smagt's (1999) points; and Virsu & Nanni too (1998) acknowledge the need for a revision of the theory of sensing towards a more dynamic and complex notion. However, they offer only additions to the traditional linear model (feedback, modulation by memory, context, interpretations and acts) that leave the basic core of linear information processing intact. It is unlikely that any organism dependent on such complicated processing to act could survive in the world. A much simpler model is at issue: the organism joins its environment at those places which offer the possibility of behavioral results. This means that the senses do not act as analyzers of complicated physical forms of energy but are more like filters allowing what is useful for behavioral results to be used.
2. Smagt also indicates his basic agreement about the significance of efferent influences in sensing, but continues (Abstract): "but there can be other explanations for why this is so." I do not doubt this, and would be interested in reading these other explanations. Smagt comes to the conclusion that my argument concerning the role of efferent influences is erroneous, and hardly novel. I have some difficulties in understanding his conclusion, because I do not see any rigorous statements supporting it. As to the novelty, efferent influences on receptors have been experimentally demonstrated during recent decades, but I think one can honestly say there is not yet a well-formulated theoretical account of the findings. In the target article (Jarvilehto 1998a) I tried to provide such an account.
3. One must again emphasise a misunderstanding: I do not argue for the significance of efferent influences as such, but for their necessity in the organism-environment theory. They present a problem for the traditional theory of perception, as pointed out by Virsu & Vanni (1998), but in the organism-environment theory their existence is predicted, because in a certain kind of environment the survival of the organism presupposes the possibility of modifying the properties of the receptors (Jarvilehto 1999, para. 3). Thus, my own conclusion could likewise be: "when perception and motion are fully united, this observation becomes self-evident" (Smagt 1999, para. 2).
4. Virsu & Vanni agree with the target article in recognizing the importance of revising the theory of perception from a simple linear information transmission model towards a more dynamic notion. In fact, their commentary is a good illustration of this necessity, because one can see there many of the basic problems inherent in the traditional psychophysiological explanations of perception. These commentators arbitrarily mix all kinds of concepts: physiological, cybernetic, psychological and even social. They see the importance of feedback pathways as well as the critical role of movements, and they stress the significance of memory, context, and interpretations in creating percepts. However, they do not offer any conceptual basis for sorting out these different factors. They insist on the analysis of both the whole and the parts of a system, but they do not give any clue what the whole and the parts could be when perception is studied, or what really belongs to the system of perception.
5. Virsu & Vanni's eclectic approach can be seen in their use of neurophysiological and psychological concepts: attention, motivation, and vigilance have effects on the "input organization of the sensory system." I think these commentators would have difficulty in giving a rigorous definition of these psychological concepts, to which they ascribe quite an important explanatory role in the physiology of the receptors.
6. According to organism-environment theory it is essential that such psychological factors as attention or motivation are not on the "outside," whence they would exert their effect upon the physiological processes in the receptors or at subsequent levels of the nervous system;t they are characteristics of the whole organism-environment system. A theory of perception should include such concepts, but not as mysterious factors influencing "perceptual inputs," but as integral aspects of the system studied. My theory starts with the proposition that mental activity is activity of the whole organism-environment system (Jarvilehto 1998b). Hence attention, motivation, or emotions, for example, are not factors outside the system, but different aspects of its organization or functioning.
7. One can agree with Virsu & Vanni that parts of the system may be analyzed by isolating them from the whole system. It is not a trivial question, however, how such a partitioning is accomplished and what kind of explanations are put forward on the basis of the results. In sensory physiology, the usual mistake is that a part is isolated, but then treated as if it were the whole system. An isolated eye certainly does not see any pictures, but it is typical for retinal processes to be treated as if a picture were created on the retina and as if visual perception could be explained on the basis of this retinal picture alone.
8. The receptor is a part of the system of perception, but it is not the receptor (nor any brain area!) that perceives or gets information from the environment. A receptor is a cell that is "interested" in its metabolism and must coordinate its actions with other cells of the body; otherwise it dies. A receptor does not need information, but nutrition. The receptors are connected to the environment, not in order to perceive something, but because this connection is necessary for their existence. If the receptor acts properly it will get its metabolites from the environment or from other cells of the body (see Jarvilehto 1998c).
9. Traditionally, knowledge formation has been described as a result of some sort of processing of environmental information or data. Information has an exact mathematical meaning only in formal information theory, in which it is defined by the probability of occurrence of a certain event. This definition presupposes knowing the number of possible alternatives in order to determine the probability. The concept of information cannot be applied to receptor systems in this way, however, because we have no means of estimating the number of possible events that may influence a receptor. Hence in sensory physiology the concept of information is used in a more figurative sense, implying that there is a certain order or certain physical properties in the environment, that can be transmitted to the organism by the receptors.
10. Such a concept of information presupposes two things: (1) that the information/order exists in the environment in the given form even without any organisms and (2) that the information/order may be moved from one place to another, or at least "copied" as some sort of representation. These assumptions are in turn based on more general ideas such as that there is a world "out there" which will be revealed by our perceptual apparatus, and that the properties of matter exist objectively independent of any observer.
11. This way of thinking is natural if the human being is regarded as the center of the universe and if the whole world is constructed for his purposes and for his perceptual apparatus. I would be more humble, however, thinking of a human being is a part of nature as much as an ant or a spider, and that all such beings have their own ways of dividing the world into significant parts from the point of view of their behavior and survival.
12. When an organism makes contact with certain parts of the world, only some aspects of reality are revealed to it. These aspects are not a construction of the organism behind which a "Ding an sich" is veiled; it is a real part of environment as it can be used by the organism in question. Properties are not located in some absolute way in "things"; they are relations, and hence they can only be defined only as parts of the organism-environment system. This means that properties cannot be "transmitted"; they must be created in the process of action. The senses do not act as analyzers of complicated physical forms of energy; they are more like filters allowing what is useful for behavioral results to be used in action.
I would like to thank Ms. Suzy McAnsh for the helpful reading of my reply.
Jarvilehto T (1998a) Efferent influences on receptors in knowledge formation. PSYCOLOQUY 9(41) ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/ psyc.98.9.41.efference-knowledge.1.jarvilehto http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?9.41
Jarvilehto T (1998b) The theory of the organism-environment system: I. Description of the theory. Integrative Physiological and Behavioral Science, 33, 317-330.
Jarvilehto T (1998c) The theory of the organism-environment system:
Jarvilehto T (1999) Afferent and efferent processes as a functional whole in knowledge formation. PSYCOLOQUY 10(003). ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1999.volume.10/ psyc.99.10.003.efference-knowledge.11.jarvilehto http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?10.003
Smagt van der P (1999) There is no Motion Without Sensing. PSYCOLOQUY 10(005). ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1999.volume.10/ psyc.99.10.005.efference-knowledge.12.smagt http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?10.005
Virsu V and Vanni S (1998) Efference does not foil perception. PSYCOLOQUY 9(84). ftp://ftp.princeton.edu/pub/harnad/Psycoloquy/1998.volume.9/ psyc.98.9.84.efference-knowledge.10.virsu http://www.cogsci.soton.ac.uk/cgi/psyc/newpsy?9.84