[Martin Taylor 2010.11.15.23.06[
[From Bill Powers
(2010.11.14.1600 MDT)]
Martin Taylor 2010.11.14.10.50 --
An open door affords access to a
room.
BP: How does it do that?
By being perceived as affording that possibility, by someone who
might at some point want to enter the room.
MMT: A well frozen
lake affords
the opportunity to go skating.
BP: How does it do that?
By being perceived by someone as affording that opportunity.
Understand that I'm trying to discuss this on a
technical, denotative level of discourse. You say that a door can
do
something, a lake can do something, something called
“affording.”
What I don't understand is why you have this notion in your head (as
does Kent and Kenny) that there is something active about
“affording”, while I don’t and never have had that notion. Have you
ever heard someone say “I afford you this gift” or even “I afford
you this way to do X”. I don’t think so – at least I never have.
One uses the word only when the grammatical subject is a
pragmatically passive object or pattern (like “open”) that can be
used. It would be interesting to know whether this is a difference
between US and UK or Canadian language. It seems extraordinarily
strange to me that you think of affording as “doing something”. But
you do say you think of it that way, so there’s a problem with the
word.
I'm going to quote here from a message I wrote off-line to another
CSGnet reader who couldn’t find “affordance” in a dictionary and
wanted an explanation (I have slightly edited the message for form,
not for content).
--------quote-------
>Can you help me understand word affordance in relation to for
ex. “stabilization of environmental variable”.
Affordance is a word invented by J.J.Gibson, I suppose in the
1950’s. I’m not surprised you couldn’t find it in your dictionaries.
It isn’t in my big Oxford English Dictionary, though it should be. I
thought it was a good word to use to refer to a situation or
structure that “affords” a possibility for action.
You may be able to find the word "afford". It has a lot of different
meanings, but the meaning from which I derive “affordance” is based
on the meaning that you can get from understanding “The open door
affords entrance to the room” and “the bridge affords a way of
crossing the river”. The fact that the door is open allows you to
enter the room. The fact that the bridge is there allows you to
cross the river.
Gibson used the term "affordance" in the sense that a particular
sensory pattern “affords” a particular perception; to Gibson the
perception is the “affordance” of that pattern. The problem for Bill
and Kent is that the implication of Gibson’s usage is that a
particular sensory pattern allows only one possible perception. I
don’t know whether they are right, but it’s not true when you use
“affordance” as a noun meaning “something that allows one to perform
a particular action”. The fact that the bridge affords a way of
crossing the river doesn’t mean that this is the only thing it
allows: “Sur le Pont d’Avignon, l’on y danser” (or something like
that – my French is very rusty, and the bridge at Avignon doesn’t
actually afford you a way of crossing the river because it is
broken).
You ask about the relation of "affordance" to "stabilization of
environmental variable". If an environmental affordance permits a
way of doing something, PCT says that a “way of doing something” is
behaviour that is control of a perceptual variable. Control means
stabilization (even though what is stabilized may be a rate of
change or an acceleration). The affordance allows a particular way
of acting to control that perceptual variable. So an affordance
forms at least part of an environmental feedback pathway that could
be used in controlling a perceptual variable. Controlling a
perceptual variable usually implies that some environmental variable
is also stabilized, so you could say that an affordance is a means
that could be used to stabilize an environmental variable.
There's another sense in which "affordance" is related to
stabilization of environmental variables, and that is the inverse of
the sense I just described. Suppose you are trying to control some
perceptual variable, but are unable to do so. You reorganize until
you find an affordance that allows you to act to control that
variable. If the environment is stable, the resulting organization
will probably stick around, but if the environment is not stable,
quite probably the next time you try that action in controlling that
variable, it won’t work, and you will have to reorganize some more.
So, if someone else is stabilizing something you use as an
affordance, you can rely on your actions continuing to work.
What Kent showed is that if a lot of people are stabilizing a number
of variables, those variables will probably be more stable than they
would be if only one person was stabilizing them. This implies that
what I call “network stabilized” variables can become part of
various environmental feedback pathways that continue to work, even
if one or more of the people who were controlling them stop their
control behaviour. The further implication is that the control loops
that use these network stabilized affordances can become parts of
more elaborate control structures within an individual. To put it in
everyday language, if you behave in a way appropriate to your
culture, you are likely to get along pretty well.
So can you explain to me what's the difference if I say that with
collective control process we “stabilize” some environmental
variable (bridge, road, swimming-pool) as Kent said or what does
it mean that with collective control we “make” an affordance
(bridge, road) ?
Both are correct, I think. Which way you look at it depends on your
point of view. If you are wanting to cross the river, you are making
the affordance. If you are wanting to construct something, you are
stabilizing your perceptions of your environment.
Did I
understood right the meanning of affordance as “something that
people can control in environment” ? Maybe something like
posibility for perceptual control ? Or does both have some other
meanning ?
I rely on the idea "it's all perception". There may or may not be
real structures in the environment corresponding to any particular
perception. If I’m in the desert and want a drink, I may see a lake
in front of me. That’s a real perception, but it may not correspond
to a lake from which I could get water. It might be a mirage. It’s a
perceived affordance for controlling the perception of thirst, but
when you come to use that perceived affordance, it doesn’t work.
Basically, that’s how one tests the reality of one’s perceptions.
An affordance is a perception, controllable like any other. If I
want to see a way of crossing a stream without getting wet, and do
not see any way of doing so, I have an error in a controlled
perception. I don’t perceive an affordance when I have a reference
to perceive one. Now I see a strong plank lying by the stream bank
and lay it across the stream, and when it has been placed, I do
perceive an affordance for crossing the stream. I have effectively
removed the error in the perception, by controlling the perception
of the affordance. I had a reference value “affordance exists” and a
perceived state “does not exist”, which I have changed by my
actions.
So yes, "affordance" implies "possibility for perceptual control",
and it is a “perception that people can control by acting in the
environment.”
---------end quote---------
Back to commenting on BP.
Of course I understand the informal colloquial
intent in this way of speaking, and that the customary meaning of
a
transitive verb is not really what you intend, but that’s of no
use in a
scientific discussion. In a scientific discussion, I want the
words to
refer to reliable, agreed-upon, unambiguous, literal meanings.
Yes, as do I. I think I have explained "affordance" in a reliable,
could-be-agreed-upon, unambiguous way.
But I do not accept that there exist words with "literal meanings".
Instead, I agree with what you said, both about “affordances” and
about “meanings”: “BP: I don’t think that objects “have” affordances
any more than
words “have” meanings.” No, objects don’t have affordances. People
perceive affordances. Words don’t have meanings (as this thread
shows most clearly). People perceive meanings in the words (both
when writing them and when reading them).
If you
want to say in a technical discussion that a lake can afford
something,
you should be prepared to discuss the mechanisms by which it can
do that,
and what determines the things it can afford.
Sure. If a person perceives that the frozen lake affords something,
and tries to control some perception using that affordance, either
the feedback path will influence the controlled perception
appropriately or it won’t. If it won’t, the perceived affordance may
well have been illusory. The ice may not have been thick enough to
skate on. What determines the things the frozen lake can afford is
the set of all perceptions that any person might control using the
frozen lake. I would hate to try to enumerate that set!
If your intent is not to
have a technical discussion that’s to be taken seriously, you
should say
so. It’s OK with me but I like to know the context in which I
speak.
I hope your intent is not to dismiss as not to be taken seriously my
efforts in that direction. I need to use the concept of “affordance”
in technical discussion, especially (now) in the context of Kent’s
work. Your comments are unhelpful in this.
In science, I think we are supposed to take words
literally, and if there
isn’t a word with the literal meaning we want, we make one up, and
then
have to explain it to everyone.
I have tried to do that with "affordance". Although I didn't
actually make it up, it is not in my biggest dictionary and has no
everyday meaning, which is more than I can say for most of the words
used technically in PCT in senses related to but different from
their everyday meanings. I have followed your instructions above,
but you refuse my explanations and definition of “affordance”. Where
does that leave us?
The word you're looking for in place of
affordance is property.
"Property" would have to be redefined if it were to be used in the
restricted sense of affordance. It is true that all properties are
perceptions, as are all affordances. It may be true that there
exists some perceptual variable for the control of which any
perceived property could become an affordance. But until a
perception is specified for which the environmental feedback path
could use the value of that property, the property is not an
affordance.
The properties of an environmental
feedback function determine how acting through it will affect
other
variables.
This is true. Those properties determine the set of perceptions for
whose control they could become affordances.
MMT: But the word
is commonly
used in similar situations. Why not use it in a closely
related technical
sense within PCT, just as “perception” is used in a technical
sense in PCT rather more different from its sense in everyday
speech?
BP: We've had this argument over and over for years. Why be fussy
about
what is meant by “control?” Why be fussy about whether
“disturbance” refers to the cause or the effect?
Interesting. You take my side and yet you seem to be trying to argue
against me. I am being fussy about what is meant by “affordance”,
and I take the technical use of the everyday word “perception” to
illustrate the need sometimes to use a familiar word in a precise,
technical sense. What is to argue about in respect of the (not
everyday) word “affordance”, except that you don’t want to use
“affordance” in a technical sense because you have some personal
connotation for its root word “afford”. Why be fussy, indeed!
Because I must be fussy if I want to argue technically.
Why be fussy
about words at all? My answer has always been “For clarity of
communication; to eliminate ambiguity; to reason consistently.”
Yes. Accept it.
I don't really care
what word
you use as a substitute for “feature of the environment that
could
form part of an environmental feedback path for some
perception”,
but I don’t want to keep using that long phrase whenever I
talk about the
possibilities the environment affords for control. If you come
up with a
word I think easier to remember, that has better connotations
for you,
I’ll try to use it. Until then, I’ll stick with talking about
the
controllable perception of “environmental
affordance”.
BP: Fine. The word I want to use is "property."
Fine, but if you want to use the word "property" to refer only to
what I have been calling “affordance”, we would then have to be
fussy about using “property”, and say that when we perceive
something to be “red” we would not necessarily be talking about
perceiving a “property” of the object. And you would have to explain
to everyone who uses it in its current sense why you were now using
“property” in this specialized sense. I think that would cause more
confusion than introducing to PCT a word that is not even in the big
Oxford Dictionary (compact edition).
I'd be quite happy to have a different neologism, if it really pains
you so badly to use the obvious word in its defined technical sense.
How about “viamode”, “transperty”, “possiway”, (if I knew Greek I
might think of better suggestions, but I don’t). The only thing I
insist on is that I don’t want to keep using a complex line of text
to refer to the simple concept that I like to call “affordance”.
Martin
