Hello all,
Please excuse the cross-post, but I feel that this useful other perspective
might shed light of a different wavelength on some recent discussions
cheers,
ppl
----- Original Message -----
From: "Peter Meijer" <Peter.B.L.Meijer@philips.com>
To: <seeingwithsound@topica.com>
Sent: 12 November 2000 10:31
Subject: [The vOICe] About James Gibson
Hi All,
Peter Lennox referred to the psychologist James Gibson. For those
who are not familiar with Gibson's ideas but interested in learning
about them, I've appended some material copied from two web pages.
The first part is a very brief introduction to Gibson, followed by
the second part, which is an article written by Gibson himself, titled
"The Comparison of Mediated Perception with Direct Perception".
Please note that this is for your information, indiscriminate of
whether I endorse Gibson's ideas or not, or to what extent. It just
happens to be the case that Gibson is referred to by many psychologists,
so it might be useful for us to know something about the perceptions
of psychologists on how human perception works and develops.
Best wishes,
Peter Meijer
Seeing with Sound - The vOICe
http://www.seeingwithsound.com/winvoice.htm
Information Pickup Theory (J. Gibson).
Overview:
The theory of information pickup suggests that perception depends entirely
upon information in the "stimulus array" rather than sensations that are
influenced by cognition. Gibson proposes that the environment consists of
affordances (such terrain, water, vegetation, etc.) which provide the clues
necessary for perception. Furthermore, the ambient array includes invariants
such as shadows, texture, color, convergence, symmetry and layout that
determine what is perceived. According to Gibson, perception is a direct
consequence of the properties of the environment and does not involve any
form of sensory processing.
Information pickup theory stresses that perception requires an active
organism.
The act of perception depends upon an interaction between the organism and
the environment. All perceptions are made in reference to body position and
functions (proprioception). Awareness of the environment derives from how it
reacts to our movements.
Information pickup theory opposes most traditional theories of cognition
that
assume past experience plays a dominant role in perceiving. It is based upon
Gestalt theories that emphasize the significance of stimulus organization
and
relationships.
Scope/Application:
Information pickup theory is intended as a general theory of perception,
although it has been developed most completely for the visual system. Gibson
(1979) discusses the implications of the theory for still and motion picture
research. Neisser (1976) presents a theory of cognition that is strongly
influenced by Gibson.
Example:
Much of Gibson's ideas about perception were developed and applied in the
context of aviation training during WWII. The critical concept is that
pilots
orient themselves according to characteristics of the ground surface rather
than
through vestibular/kinesthetic senses. In other words, it is the invariants
of
terrain and sky that determine perception while flying, not sensory
processing
per se. Therefore, training sequences and materials for pilots should always
include this kind of information.
Principles:
1. To facilitate perception, realistic environmental settings should be used
in
instructional materials.
2. Since perception is an active process, the individual should have an
unconstrained learning environment.
3. Instruction should emphasize the stimulus characteristics that provide
perceptual cues.
References:
Gibson, J.J. (1966). The Senses Considered as Perceptual Systems. Boston:
Houghton Mifflin.
Gibson, J.J. (1977). The theory of affordances. In R. Shaw & J. Bransford
(eds.), Perceiving, Acting and Knowing. Hillsdale, NJ: Erlbaum.
Gibson, J.J. (1979). The Ecological Approach to Visual Perception. Boston:
Houghton Mifflin.
Neisser, U. (1976). Cognition and Reality. San Francisco: W.H. Freeman.
Source URL: http://www.gwu.edu/~tip/gibson.html
===
March 1965.
The Comparison of Mediated Perception with Direct Perception.
By 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.
Children are said to learn from images and pictures as well as from
words, but this is a thoroughly muddled question in education. In order
to clarify it we need a theory of the relation between the perception of
things and the mediated perception of things. Mediated or indirect
perception is of three common types (1) that which depends on the
understanding of images and pictures, (2) that which depends on the
understanding of speech, and (3) that which depends on the
understanding of writing. All these can be described as perception or
knowledge at second hand(Gibson 1954). Images, pictures, vocal
speech and written language will be called here mediators. They are
media of communication among persons. Only men communicate by
these means although, of course, animals and men can also communicate
by other means like cries, gestures, attitudes and grimaces, that is, by
reactions that we loosely call "expressive".
Mediators, it should be noted, are not stimuli as ambient light, impinging
sound, and mechanical energy are stimuli, but sources of stimulation as
the objects, events, and other animals of the environment are themselves
sources of stimulation. The common mediators use light and sound or,
rarely, touch. It is assumed (1) that the main function of stimulation is
to carry information, and (2) that information does not necessarily depend
on the kind of energy that conveys it.
The hypothesis is that direct or first-hand perception is that which comes
from environmental sources and that indirect or second-hand knowledge
is that which comes from mediators. It is further assumed that the
uniquely human media of information-transmissions are of two types,
iconic and symbolic. Iconic mediators have been described (e.g.,
Morris 1946) as "similar" to what they stand for; symbolic mediators are
not. But this is not very satisfactory. I have tried to define models and
pictures, the iconic mediators, as being specific to what they stand for by
proportion or by projection whereas vocal speech and written
language, the symbolic mediators, are specific to what they stand for by
convention (Gibson 1954). The symbolic object is informative because
of the establishment of a social code; the iconic object is informative by
non-social laws of stimulus information. A license-plate corresponds to
an automobile by virtue of conventional rules but its shadow corresponds
to it by optical rules. It is here assumed that perspective geometry
derives its validity from laws of space-filling light-rays and that ideal
pictorial perspective is therefore not a convention of Renaissance
painters but a discovery (Gibson 1960,1961).
The iconic and the symbolic kinds of mediation admittedly must be
thought of as pure cases, not as mutually exclusive types, since many
images and pictures show the influence of convention, are
semi-symbolic, and many forms of writing show the influence of iconic
mediation, notably graphs. The two cases are hard to separate in visual
art (Grombrich, 1960). Even spoken words may in part represent the
sounds of what they stand for. Mixtures of the purely iconic and the
purely symbolic relation can be accounted for by the assumption that
some qualities of things and events can best be communicated by
stimulus representation, by displaying, while other qualities of the world
can only be conveyed by symbolic media, such as verbal propositions.
Elements of both may be found in the mediator. Both art and language
are also, to be sure, mixed with elements of primitive expressive
communication but this is a different question. The matter is full of
difficulties, but the above assumptions at least have the virtue of being
explicit.
Development of Mediated Perception.
Consider the order of development of some perceptual mediators in
human evolution as compared with the order in which the child learns to
use them. Primitive man had to invent them; the child does not. The
conventionalizing of vocal sounds may be supposed to have begun with
the emergence of the human species, perhaps a million years ago.
Proto-man could make and hear a variety of sounds because they were
already highly vocal animals. The making of sculptures and pictures
began, it is now fairly certain, some twenty or thirty thousand years ago
in the caves of the Ice Age. This invention depended on visually guided
manual skills, on making tools, fire, torches, and on shaping of materials.
Finally the invention of writing, the second-order conventionalizing of the
picture-making skill so as to make the vocal symbols themselves visible
and permanent, came only about five thousand years ago.
The child begins to develop the understanding and the production of
speech at about the same time, at the age of one year, and does so
spontaneously in a family group. Just when he begins to comprehend the
iconic mediators is not clear. He is given models in the form of toys and
dolls and pictures in the form of drawings and photographs (Hochberg
1962) but not much is known about what he perceives, although there is
a great deal of speculation (and muddled theorizing) about the
perception of forms vs. the perception of solids. More experimental
evidence is needed, taking off from the hypothesis of visual stimulus
information instead of the classical dogma of flat visual sensations. What
evidence there is suggest that the equivalence of the optical information
from an object and from a picture of it is detected early, and there is also
some indication that the equivalence of small-scale models and full-scale
replicas is effective. Apart from this there are no experiments on what
the young child comprehends from moving picture displays or
perspective transformations, despite the prevalence of television in the
home. Nor is there evidence about working models. What the child
learns from unregulated gamut of iconic things presented to him is not
known, although it must be important.
It is certain that the young child does not learn to produce iconic
mediators, even the simplest pictures or models, until well after he can
comprehend them. The necessary manipulative skill seems to lag behind
the perceptual skill. However he is usually given much practice in the
fundamental graphic act of trace-making or scribbling, that is, making
(and controlling) visible marks on a surface. But the perceptual value of
this practice has not been studied. Similarly he is often given
opportunities for plastic manipulation so as to develop his "creative"
capacities but experimenters have not ventured into this field. Iconic
information and iconic communication are mixed up in our culture with
the concept of play as distinguished from work. Scribbling, however, is
not simply play; it provides an opportunity for educating visual
perception in a special way.
Finally, the child learns to read around age five or six and to write
somewhat later. He has to detect the equivalence of alphabetic
combinations (utterances) before he can do this. Sometimes it is easy;
sometimes hard. The difficulty may depend on how well he has
previously learned to discriminate the variables of graphic displays
the dimensions of variations among surface-tracings.
It is likely that the order of similarity of these mediators to natural
information is first and experience, or knowledge by direct acquaintance
is given by the first. This hypothesis should be tested. If so, images could
usefully be given the child at an even younger age than is now customary.
Experiments on Mediated Perception.
It is proposed to explore some of the questions that have been raised to
see what experiments are feasible.
1. Comparison of full - size replicas and scale models. To what
extent does a minified optic array, preserving ratios, carry the same
information as an ordinary array for the young child? A systematic study
of miniature animals, persons, objects, places, etc., should be made to
determine the degree of equivalence of stimulus information.
2. Comparison of solid object, photograph, and line-drawing.
Evidence on the perceptions of primates and infants is being obtained
and should first be surveyed. Further experiments on the equivalence of
pictures, with controlled variation, to what they portray can then be
carried out.
3. Comparison of still pictures and motion pictures. There is reason
to believe that perspective transformations convey information better that
forms. This should be tested with young children. The perception of
"animate" motions should also be studied, with a view to systematic
experiments. One way to do this is to take a "still" (or series of stills)
from a motion picture shot and determine how much more information a child
gets, if any, from the latter than he does the former.
4. Analysis of the "fundamental graphic act" (tracing, scribbling)
in young children. What is the nature of this special visual feedback
and what is learned from seeing a permanent trace being made? At what
age do children begin to see Michotte's "tracage" effect (1964)? A
separate note has been written on possible experiments to answer these
questions.
5. Tests of the hypothesis that environmental information may cut
across perceptual systems (cross-modal information). The present
approach is based on the idea that stimulation, although necessary, is less
relevant for perception than information. The equivalence of information
across different media of communication is fairly well accepted. But the
equivalence of information across stimulus energies is a new idea that
needs verification. It can be tested in various ways, for example by
determining the extent to which children can equate the visual
appearance of an unfamiliar texture with the tactual feel of it.
Cross-modal equivalence can also be tested with solid shapes previously
unknown to the child.
References:
Gibson, J. J. A Theory of Pictorial Perception. Audio Vis.
Communication Rev. 1954, 1, 3-23.
Gibson, J. J. Pictures, Perspectives, and Perception. Daedalus, 1960
(winter issue) 216-227.
Gibson, J. J. Ecological Optics. Vision Research, 1961,1, 253-262.
Gombrich, E. H. Art and Illusion. N.Y. Pantheon, 1960.
Hochberg, J. The Psychophysics of Pictorial Perception. Aud. Vis.
Communication Rev. 1962, 10, 22-54.
Morris, C. Signs, Language, and Behavior, N.Y., 1946.
Source URL: http://lor.trincoll.edu/~psyc/perils/folder3/mediated.html
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