February 1977
Preliminary Tabulation of Processes that have been
Supposed to Mediate Perception (Subject to Revision)
J. J. Gibson, Cornell University
The World Wide Web distribution of James Gibson’s “Purple Perils” is for scholarly use with the understanding that Gibson did not intend them for publication. References to these essays must cite them explicitly as unpublished manuscripts. Copies may be circulated if this statement is included on each copy.
There is some agreement that perception must involve processes like the selective filtering of the millions of inputs from all the sensory surfaces, and the correcting of sensory inputs so as to achieve “constancy” of perception, but little agreement about other processes. The variety put forward is astonishing. Here is a rough classification.
I. Mental and Cognitive Processes. Perception involves:
1. the operations of the mind upon the deliverances of the senses, that is, on the data.
2. the understanding of the sensory inputs in terms of the “mental set” of the perceiver.
3. the operation on the sensory input of prior assumptions (presuppositions) about that which is to be perceived.
4. the apprehending of the sensations in terms of the a priori “categories of understanding” of the perceiver (Kant).
5. the cognitive “reworking” of the sensory input.
6. the cognitive “processing” of the sensory input.
II. Processes Related to Past Experiences. Perception involves:
1. the arousal of past experience by the sensory input (formerly the “summoning” of memories, now the “retrieval” of stored information.).
2. the bringing to bear of past experience on the sensory input (the application of memories to sensations).
3. the accrual of a context of memory images to a sensory core. This is Titchener’s theory, the supplementing of sensory inputs by memory images and feelings aroused by association with the sensations.
4. the fusing of a sensation with a memory image (e.g., Perky exp’t).
5. the assimilation process. This can be assimilation of a new sensory image with an old general image (composite image), or assimilation to a concept, or to a schema, or to an idea, or to a type.
6. the categorizing of each sensory input, matching it to its category, putting it in its class, assigning it to its type, etc. In Koffka’s theory, adding it to the proper trace-column. Note that the prior establishment of categories or types is taken for granted.
7. the enhancing of the distinctiveness of sensory inputs by associating a different response to each (acquired distinctiveness of cues).
8. the integrating (combining, fusing, assimilating, etc.) of each new sensory image of the world with a “stored representation” of the world.
III. Processes Emphasizing Interpretation. Perception involves:
1. unconscious inferences about the external causes of the sensations (Helmholtz). The causes must be deduced since they cannot be detected, as Johannes Muller showed.
2. the quasi-rational process of estimating the properties of distal objects on the basis of the proximal cues, i.e., the sensory inputs. This is Brunswik’s formula, a sophisticated modern modification of Helmholtz.
3. the “interpreting” of the “signals” transmitted by the senses. This is the commonest popularization of Helmholtz’s theory. Many other terms are in use, cues, clues, signs, messages, and indicators, but they all assume that the nerves transmit in something like a code.
IV. Processes of Gestalt Organization. Perception involves:
1. The organizing of simultaneous sensory inputs to yield a figure (grouping, or self-distribution).
2. The integrating of successive inputs to yield a simple event (Wertheimer) or a complex event.
3. The transforming of the sensory input (although it was never wholly clear into just what it was supposed to be transformed).
V. Processes based on Responses. Perception involves:
1. Conditioned response-tendencies to the sensory inputs.
2. Partial responses, implicit responses, or motor attitudes to the inputs.
3. Covert problem-solving in response to the inputs.