International Encyclopedia of Systems and Cybernetics

1) An effective adaptive internal response to a stimulus.

This is merely one way to view perception. The subject is and probably will remain widely discussed and controverted. The following quotes only introduce some characteristic, more or less systemic views.

R.L. ACKOFF and F.E. EMERY add to the definition that the stimulus should "… produce a change in at least one structural property of the respondent" (1972, p.66).

Perception implies of course an observer, whose phenomenological and epistemological status is quite difficult to determine (see von FOERSTER's comments on the observer and "Observing systems").

J.J. GIBSON for ex., states: "Perceiving is a psychosomatic act, not of the mind or of the body, but of a living observer… It is a keeping in touch with the world, an experiencing of things rather than having an experience. It involves awareness-of instead of just awareness" (1986, p.239-40).

For K. SAYRE: "Perception occurs within a cascade of information channels originating at the surface of the perceptual object and terminating in the cortex of the perceiving organism…

"This characterization is general enough to hold true independently competing views about the nature of the intermediate stages. It is true for someone (like ARISTOTLE) who holds that structure present in external objects are conveyed directly to the sensorium of the perceiving subject, as well as for someone (like LOCKE) who holds that there are intermediate objects (such as sense-data) of which alone the subject is directly aware. It is true for someone (like BERKELEY) who treats perceptual awareness as a passive response to external influences, as well as for someone (like KANT) who emphasizes the participation of the mind itself in the formation of the structures of which we are aware" (1976, p.153).

Of course, such an omnibus explanation does not explain much about "the nature of the intermediate stages".

From another angle, D. Mac KAY writes: "It is not denied that in observer-language we can distinguish two stages. Of all the objects in the field of vision, for example, only a few are normally perceived at anyone time – those that have "caught the attention" as we say. Stimuli corresponding to the presence of the others are received; but they evoke no "matching response" in the organism" (1956, p.105)… "at least none structured to correspond to the individual objects. These objects are not perceived" (Ibid, p.61).

This corresponds obvioulsy to BRENTANO's perceptive intentionality. Also, as expressed by von FOERSTER: "The keys to perception are not only the sense organs, but moreover in their interaction with the motor system" (1992, p.76).

2) "The adaptive updating of the state of orientation" (of the system) (D. Mac KAY, 1969, p.98).

According to Mac KAY: "A solitary organism keeps its orienting system up to date in response to physical signs of the state of the environment, received by its sense organs" (Ibid).

An integrated system also perceives – at least up to some point – what happens inside itself.