Subject: Re: Gibson From: Al Bregman <BREGMAN(at)HEBB.PSYCH.MCGILL.CA> Date: Sat, 3 Mar 2001 17:29:01 -0500Mikael Fernstr=F6m wrote: "October 1969: he [Gibson] provides an elegant definition of affordances and direct perception - "Information .... does not consist of signals to be interpreted, nor data that must be supplemented from a store house of knowledge. I am suggesting that nothing less than the hypothesis that meanings are not subjective contributions but objective facts. I prefer to call the meanings of things their affordances, that is, what they afford the observer. The meanings of things in this sense are perceptible properties of things...." This is not a definition. If it were, there would be nothing to disagree with. It would only tell you how Gibson wished to use words. Gibson, in this excerpt, calls it a hypothesis, not a definition; so one can disagree with it. E-mail peril: -------------- I have trouble with the idea that "information" or "meaning" is in things. Let me focus my discussion on "information", although an analogous argument could be made for meaning. Using the word "information" to refer to any physical fact or relation in the world broadens the idea of information too much. The thing that is in the world, is "pattern", not "information". Pattern only becomes information when it is used in a communication system to send a message from a sender to a receiver. Furthermore, it is important to recognize that the kinds of pattern that count as information will depend on the properties of the receiver. If you send Morse code to a TV receiver, the signal isn't information, but noise. I agree that there is a pattern of flow in the light that reaches the eyes as we walk forward. However, until the brain makes sense of this pattern, it is not "about" the world. It is merely "caused by" the world. These ideas "about" and "caused by" are not synonymous. Everything is caused by something, but if everything is information, the word loses its unique meaning. Another example: Suppose there were a device that took a pixelized photo, A, and mapped each point in it onto an output photo, B. If the mapping were: Y (i,j) =3D X (i,j) then the output photo would be a copy of the input. Suppose, instead, that we used a random, but fixed, function to do the mapping such that, for example, Y (1,1) =3D X (14, 201) Y(1,2) =3D X (3113, 21) ... etc., these fixed rules applying to every case in which the mapping is done. This could be done for every frame of a movie, mapping an A movie onto a B movie (no pun intended). In Gibson's terms, this new B movie would have the same "information" about the environment as the A movie did, but just encoded in a different way. All the affordances would be there. Yet I don't think that the human brain could make use of these affordances. (Incidentally, a self-organizing "connectionist" neural net -- containing a set of simple elements that have no properties except strength of connection with other elements, with random initial weights -- would have no preference for movie A over movie B). All regularities in A also exist in B. The reason that A is better for a human perceiver is that the human brain is *built* to use movie A, and not movie B, as input. Movie B is not "information" for a human brain, although it bears a one-to-one correspondence with the environment, and is caused by it. The only thing that is in movie B is "pattern", not information, since it sends no "message" to the brain. To be "information", the "pattern" must tell the brain (the receiver of the "message") about something. The existence of "information" is a property of the whole system, not the patterns taken alone. Since the properties of the brain (or *any* receiver) figure in the definition of "information", then information can't exist, by itself, in the environment. However, "pattern" can. Al ----- Original Message ----- From: <Mikael.Fernstrom(at)UL.IE> To: <AUDITORY(at)LISTS.MCGILL.CA> Sent: 27-Feb-01 12:19 PM Subject: Re: Get lost, Mr. Cochlea! > Regarding "ignore/discard", I'd like to point in the direction of J.J. > Gibson's Purple Perils (http://lor.trincoll.edu/~psyc/perils/): > > June 1960: he recognizes the minimum principle of perception (perception is > "economical", only picks up, or processes, what's necessary), which implies > that graceful degradation of sound works. > > October 1969: he provides an elegant definition of affordances and direct > perception - "Information .... does not consist of signals to be > interpreted, nor data that must be supplemented from a store house of > knowledge. I am suggesting that nothing less than the hypothesis that > meanings are not subjective contributions but objective facts. I prefer to > call the meanings of things their affordances, that is, what they afford the > observer. The meanings of things in this sense are perceptible properties of > things...." > > > --------------------------------------------------------------- ----- > Mikael Fernstr=F6m, M.Sc. > Interaction Design Centre & ULIM University of Limerick Interactive Media, > Computer Science Building, CS232, University of Limerick, Ireland > Phone: +353-61-202606, Mobile: +353-86-8188079 Fax: +353-61-202734 > Email: mikael.fernstrom(at)ul.ie <mailto:mikael.fernstrom(at)ul.ie> Web: > www.idc.ul.ie <http://www.idc.ul.ie> > www.softday.ie <http://www.softday.ie> >