Transcript Skinner's Molecular Interpretations

B. F. Skinner's
Molecular Interpretations
Jack Michael, WMU
TxABA
Houston
Saturday, 3/5/05
Molecular is usually contrasted with molar.
Molecular interpretation: Behavior is due to consequences over
a brief period following each response (and any long term
effects are due to the accumulation of the immediate effects).
Molar interpretation: Behavior is due directly to
consequences over the long term.
This distinction is currently introduced in learning textbooks (e.g.
Catania, 1998) in terms of
a. the reinforcement for avoidance responding w/o a warning S,
b. why response frequency "matches" rfmt frequency--the
matching law.
These issues arose around 1960-61.
The Skinner interpretations that I present today occurred before
the molecular-molar contrast became explicit (Are Theories of
Learning Necessary, 1950; Science and Human Behavior, 1953).
Still Skinner was much concerned with the events immediately
following reinforcement. Here is the statement in Schedules of
Reinforcement (Ferster & Skinner, 1957, page 3)
Under a given schedule of rfmt, it can be shown that at the
moment of reinforcement a given set of stimuli [including those
resulting from the recent behavior of the organism] will usually
prevail. . .
Reinforcement occurs in the presence of such stimuli, and the
future behavior of the organism is in part controlled by them or
by similar stimuli according to a well-established principle of
operant discrimination.
pecking
key
Pigeon Operant Chamber
key lights
aperture light
food aperture
key lights
grain hopper down
Rfmt unavailable: aperture light
off, grain hopper down where
grain cannot be accessed.
food aperture
pecking
key
Pigeon Operant Chamber
key lights
aperture light
food aperture
key lights
grain hopper up
food aperture
Rfmt available: aperture light on,
grain hopper up. After 3 sec, light
goes off and hopper goes back
down.
pecking
key
Pigeon Operant Chamber
key lights
aperture light
food aperture
key lights
grain hopper
food aperture
Rfmt unavailable: aperture
light off, grain hopper down
where grain cannot be
accessed.
total responses
Fixed interval
Fixed interval scallop: Low
10 min rfmt
rate immediately after reinforcement, then increasing up to the
time the next rfmt is due, then
low after rfmt, and so on.
reinforcement
Why the low rate after rfmt?
time 10' 20' 30'
Because the bird knows that it will not get any grain for
pecking after reinforcement? Cognitive explanation.
Skinner's explanation in terms of stimulus control:
Because the stimulus conditions immediately after rfmt-food dust on the beak, residual effects of rapid head
movements, etc.--have become an S∆ (S delta) for
pecking because responses have never been reinforced in
the presence of those stimulus conditions. *
Spontaneous Recovery: What is it?
30 min extinction sessions
Day 1
end of extinction session 1
responses
Response rate at
the start of
extinction session 2
is greater than at
the end of ext.
session 1.
start of
And greater at the
extinction
session 2
start of extinction
session 3 than at
start of
end of extinction
extinction
session 2.
session 3
And so on.
Day 2
end of extinction session 2
Day 3
0
minutes
30
Spontaneous Recovery (cont'd.)
Why does it happen?
30 min extinction sessions
Day 1
responses
Some theories (Pavlov, Hull,
others) contended that
responding without reinforcement generates a form of
inhibition* (an hypothesized
neurochemical substance, or a
hypothetical entity of some sort),
but with the passage of time this
entity dissipates. *
Day 2
Day 3
0
minutes
30
Skinner offers another explanation based on operant stimulus
control. (Skinner, 1950, p. 85)
*For a thorough treatment of spontaneous recovery and its relation to the
concept of inhibition see Catania, 1998.
Stimulus Change Decrement: After an operant function-altering
operation (reinforcement, extinction, punishment, recovery from
punishment, and others), the changed function is seen at its
maximum value when the stimulus conditions are exactly the
same as during the function-altering operation.
Any change from those conditions results in a decrement in the
changed function.
When the changed function is an increase in responding due to
reinforcement, then a stimulus change results in less behavior than
if the stimuli were the same as during reinforcement.
When the changed function is a decrease due to
extinction or punishment, then a stimulus change
results in more behavior than if the stimuli were the
same as during extinction or punishment.
Demonstration of stimulus change
decrement with respect to extinction
responses
• Nine pigeons were given a
1800
history of variable ratio (VR)
reinforcement for pecking a
yellow triangle.
VR
• In the session at right the
rfmt
triangle is yellow for the first
30 minutes with more than
1100 rsps per bird*.
• When extinction starts key
color is changed to red.
extinction
• After 15 minutes the color was
0 time in minutes 60
changed back to yellow.
*Group data: Curve is based on the responses for all 9 birds.
Spontaneous recovery analogy: A hypothetical
experiment that is more like the actual
spontaneous recovery situation
VI 30" Rfmt
responses
• Phase 1: Pigeon is
placed in the
experimental chamber
with red ceiling light
flashing,
• but the light fades to
off in 2 minutes.
• Key pecking gets VI
30 sec rfmt in
presence and absence
of the flashing red
light.
300
flashing light
on but fading
to off in 2 min
flashing
light off
0
bright
off
0
time in minutes 10
intensity of
flashing red light
time in minutes 10
Spontaneous recovery analogy (cont'd.)
• Phase 2: Ext. session, with
flashing red light on at the
beginning of the session
but fades rapidly to off in 2
min, as during
reinforcement sessions.
• There is thus only 2 min
extinction in flashing light
before it goes off,
• then about 8 min ext. with
light off.
• Then after 10 minutes
flashing light is turned on.
• Responding recovers as in
Skinner's procedure.
ext inction session
red light on again
0 t ime in minut es 1 0
high
off
int ensit y of red flashing light
Spontaneous recovery analogy (cont'd.)
• At the beginning of reinforceext inction session
spont aneous recovery
ment sessions there are residual
stimulus effects from being
removed from the home cage,
transported to the experimental
removed f rom chamber,
put back in t he next day
chamber, etc.
0 t ime in minut es 1 0
• These rapidly fade to off just like high
the flashing red light in the
off
int ensit y of st imuli from handling
hypothetical experiment.
• During an extinction session there is only a small extinction
history in the presence of the residuals of handling stimuli.
• There is much more extinction in the absence of these stimuli.
• Thus more behavior occurs when they are again present at the
beginning of the next ext. session than were occurring at the
end of the previous ext. session in their absence.
Spontaneous Recovery (still cont'd.)
Somewhat controversial. Some studies (e.g. Welker &
McAuley, 1978) support Skinner's interpretation but some (e.g.
Thomas & Sherman, 1986) do not.
But the analysis illustrates Skinner's broad interpretation of the
stimulus, and his concern for environment-behavior details.
How About "Late" Spontaneous Recovery?
Pigeons were given 1-hour reinforcement sessions, then very
brief extinction sessions, until no responding occurred in the
brief sessions. Then when a session lasted the usual duration,
responding occurred in the later part of the session. Extinction
had occurred in the presence of the stimuli of having just been
placed in the chamber, but there had been no extinction in the
presence of stimuli consisting of having been in the chamber
for a while. (Kendall,1965).
Objections
In the introduction to About Behaviorism (1974,
pp.4-5) Skinner lists 20 common objections to
behaviorism or to the science of behavior, all of
which he asserts, and later argues, are wrong.
Objections 10 and 11 pertain to the move from
the animal laboratory to human behavior.
These are cited when we refer to the
animal research literature as a basis for
solving a problem in human behavior.
10. It works with animals but not with people,
therefore its picture of human behavior is
confined to those features which humans
share with animals.
11. Its achievements under laboratory control
cannot be duplicated in daily life.
"The Analysis of Complex Cases" (Ch. 14, SHB)
A popular way to resist a behavioral approach is to cite
a common event that contradicts a behavioral principle
(with, I think, the hope that the whole behavioral thing
will go away).
Such examples often depend on failure to recognize the
multiple control of behavior. One type of multiple
control consists in an independent variable having
more than one effect on behavior.
For example a single occurrence of an aversive stimulus
may
Elicit unconditioned respondent behavior (painful S
elicits heart rate changes, GSR, pupillary dilation, etc.)
Respondently condition the organism so that a
neutral S will have effects similar to those of the
aversive S (make the neutral S into a CS for
autonomic, and perceptual Rs).
Evoke any behavior that has in the past terminated
similar aversive stimuli (function as an MO/EO).
Decrease the future frequency of any behavior
that immediately precedes the occurrence of the
aversive S (function as a punisher).
The Principle of Satiation
With some forms of reinforcement, the strength of the
motivating/establishing operation is decreased as a
function of consumption or contact with the reinforcer,
and behavior evoked by that MO/EO becomes less
frequent.
Food ingestion results in a decrease in food-reinforced
behavior.
The critic says "But here is an example--giving a small
child a piece of candy--where satiation doesn't work--so
the principle must be invalid, (and perhaps we can
forget about all this behavioral stuff!)."
Giving a Child a Piece of Candy
A person gives a small piece of candy to a child who is
playing happily by himself (the person has given candy
before).
Much objectionable behavior emerges--asking for
more candy, crying if it is not provided, perhaps a
temper tantrum.
We appear to have increased the relevant establishing
operation, although our definition of satiation implies
that we should have decreased it.
But the sight & taste of candy is a stimulus condition
with another effect besides satiation.
It also functions as an SD (discriminative stimulus)
for further asking. More than one piece of candy has
usually been available at a time.
Now assume that repeated candy-seeking is
unsuccessful, a situation which evokes emotional
behavior.
Discriminative (SD), satiating, and emotional
effects can be separated by never giving more than
one piece of candy at a time.
Then one piece will not be an SD for further asking,
and the emotional behavior will have extinguished
(or never been reinforced in the first place).
It should then be possible to demonstrate a small
decrease in the evocative strength of the
establishing operation.
Social Behavior (Ch. 19 of SHB)
Many social scientists believe that human social
behavior requires its own special science.
From his behavioral perspective, Skinner argues that no
social phenomena emerge that cannot be understood in
terms of the way one person's behavior is affected by the
behavior of another person, and vice versa.
As a conditioned eliciting stimulus (CS), an operant
discriminative SD, a conditioned reinforcer (Sr), a
conditioned punisher (Sp), and as a conditioned
establishing operation (CEO).
The relations may be based on very complex
contingency histories, but the contingencies don't differ
in principle from those of the nonsocial environment.
To counteract this view, social behavior is often
described which seems beyond the scope of behavior
analysis, for example, catching someone's eye.
The surprising power of an apparently trivial event is
the common experience of catching someone's eye
(in a flirtation, under amusing circumstances, at a
moment of common guilt, and so on--Skinner's e.gs.
The change in behavior which follows may be
considerable. This has led to the belief that some
nonphysical 'understanding' passes between persons.
But the rfmt history offers an alternative explanation.
This is a stimulus that is very important because of the
contingencies in which it is involved.
Catching Someone's Eye (cont'd.)
• Our behavior may be very different in the presence or
absence of a particular person.
• When we simply see such a person in a crowd, our available
repertoire immediately changes.
• If in addition, we catch his eye, we fall under the control of
of an even more restrictive stimulus--he is not only present,
he is watching us.
• When we catch his eye, we also know that he knows that we
are looking at him. A much narrower repertoire of behavior
is under the control of this specific stimulus: if we behave in
a way which he censures, it will be not only in opposition to
his wishes, but brazen.
• It may also be important that "we know that he knows that
we know that he is looking at us" and so on.
• But there is nothing other than the current environment and
the organism's histories regarding similar environments.
A few more examples of Skinner's
concern for details
Operant conditioning as a possible self-control
technique? Science and Human Behavior, 237-238
The remarkable properties of language that are related
to its indirect reinforcement. Verbal Behavior, 204-206
Conditioned perceptual responses. Science and
Human Behavior, 266-275
Discrete and continuous repertoires. Science
and Human Behavior, 116-119
Review
Spontaneous recovery was analyzed in terms of stimuli
related to handling.
Giving a child a single piece of candy as a criticism
of the principle of satiation, analyzed in terms of
multiple control.
Catching someone's eye as an example of a social
stimulus of surprising power, analyzed in terms of
reinforcement contingencies.
All exemplify Skinner's interpretation of behavior in
terms of the details of environment-behavior relations.
Thanks for your attention.
References
Catania, A. C. (1998). Learning, fourth edition.New Jersey: Prentice Hall.
Ferster, C. B., & Skinner, B. F. (1957)Schedules of reinforcement. New York:
Appleton-Century-Crofts.
Kendall, S. F. (1965). Spontaneous recovery after extinction with periodic
time-outs. Psychonomic Science, 2, 117-118.
Skinner, B. F. (1950). Are theories of learning necessary? Psychological
Review, 57, 193-216. (Page references are to Cumulative record, Definitive
Edition, 1999.)
Skinner, B. F. (1953). Science and human behavior. New York: Macmillan.
Skinner, B. F. (1957). Verbal behavior. New York: Appleton-Century-Crofts.
Skinner, B. F. (1974). About Behaviorism. New York: Knopf.
Thomas, D. R., & Sherman, L. (1986). An assessment of the role of handling
cues in "spontaneous recovery" after extinction. Journal of the
Experimental Analysis of Behavior, 46, 305-314.
Welker, R. L., & McAuley, K. (1978). Reduction in resistance to extinction
and spontaneous recovery as a function of changes in transportational and
contextual stimuli. Animal Learning and Behavior, 6, 451-457.
[Sidman,Herrnstein, Herrnstein and Hineman, Hineman, Dinsmoor ]
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