A perception is a philosophical term which roughly means an individual's observation/perception of something external to one's self; more specifically, the resultant of perceiving. It is the representation of an external event that affected the senses and which - by perceptual processing - caused the activation of a certain category in the mind, i.e., the percept. The term percept is typically used in contrast to the terms distal stimulus (the external object) and proximal stimulus (the physical stimulation pattern on the senses, e.g., the pattern of light wavelength projected on the retina off the distal stimulus).
This term is exceedingly important in the understanding and discussion of human perceptual processes and is functionally critical to the discussion of optical art and visual illusions. Particular examples of the criticality of the term include optical illusions dependent upon the process of 'ambiguity' wherein one image can create two entirely separate and distinct percepts. This is commented upon by Ludwig Wittgenstein in his Philosophical Investigations (1953), and Rudolf Arnheim in Art and Visual Perception (1954). It is also a term used in Rudolf Steiner's theory of knowledge, which treats the relation of percept and concept.
Percept is also a term used by Bergson and Deleuze to define perception gone independent from their authors. According to Deleuze, science uses percepts, while art works with affects and philosophy creates concepts.
The term percept is also gaining use in the information technology industry in how to price data transfer. For example, rather than charging an individual, who is remotely retrieving data from say a weather sensor or a GPS device, by the size of the data, a company would charge that individual by the percept. Here a percept would constitute a statistical data point, as a GPS location. Pricing per percept would mean that a customer or individual using that GPS device would actually be charged per unit of true economic value to him/her, a GPS location datapoint, rather than on the size of that datapoint in bits/bytes/kilobytes etc.
A SENSE-DATUM in turn is defined as:
In the first definition, the word "back-formation" means that the longer word "perception" was simply shortened to form "percept". A distinction between the two words is not obvious. The first non-obsolete definition of perception (i.e. #2 in the quote below) is:
Alfred North Whitehead and Bertrand Russell decline the use of the word "percept" in their lengthy discussion of "Truth and Falsehood" in Principia Mathematica (1913, 1927). But observe, in the following, the subtle distinction between a "judgment of a relation" by a "percipient" (a relation of four terms) versus "the observation-as-relation" in relation to the percipient (a relation of two terms). They write:
They allow for error of judgment (i.e. What I thought I saw (I judged to be) was a bird but when it alighted I saw it was really a bat), but in fact the percept is an unassailable truth -- a sense datum in the definition above -- an unassailable private object of sensation. A falsehood, then, must come from of the failure of the second sort of relation (the percipient's perception of her percept), i.e. that the relation "a-in-the-relation-R-to-b" and "the percipient" does not hold. Thus, although I can assert, truly, that I saw a "bird" (my private sense-datum, my unassailable percept), in fact (as determined by further percept and perception) the flying shape "a-in-the-relation-R-to-b" was a bat.