Chapter 4 Basic processes of learning
Pavlov discovered by accident
the phenomenon of classical
conditioning, a part of the
learning system of organisms.
In summary classical
conditioning goes as followed:
An certain stimuli (food) initiates
a response (saliva). If the certain
stimuli is preceded by another
stimuli (bell) multiple times
(paired), after a while the
preceded stimuli alone (bell) will
enlist the response (saliva)
If the initial neutral stimulus becomes a conditioned stimulus, it
does not mean that this is carved in stone for eternity. If the
conditioned stimulus is not paired with unconditioned stimulus
multiple times in a row the conditioned response of the
organism goes extinct. “The conditioned stimulus becomes
neutral again” Neurons promote the inhibition of the
conditioned response. However it seems that sometimes
spontaneous recovery takes place in time. And the
conditioned stimuli can be quicker relearned that at baseline.
Black square Grey square Grey square
3
Food
In classical conditioning
Saliva
generalization can occur. Black square
This means that the
conditioned response
1
occurs not just for the
original conditioned
stimulus but also for stimuli
2
Black square
that look like the Saliva
Saliva
conditioned stimulus. An
example: 1 -> 2 -> 3
However, with discrimination training the organism can learn to make
distinctions between the similar conditioned stimuli, and therefore only react to
e:g the black square and not to the grey square. This is a great way to map the
sensory ability of a organism, in the example the researchers found out the
shades of black to grey a dog can distinguish. Humans generalize conditioned
stimuli as well, humans do it even with the ‘meaning’ behind words.
,According to the S-R
theory, supported by early
behaviorists, a link between
the conditioned stimulus
and response is learned.
According to the S-S
theory, an association
between the conditioned
and unconditioned
stimulus is learned
Expectation theory helps make sense of the observation that conditioned responses often differ
from unconditioned responses. According to expectancy theory conditioned responses don’t
occur because they were previously elicited by unconditioned stimuli but because they are the
responses to the expectation of the unconditional stimuli. “Conditioned stimuli consist of the
expectancy behavioral responses of the unconditioned stimulus.”
bell -> expectation of food -> tail wagging, food begging, salivation,
Successful conditioning
The conditioned stimulus The conditioned stimulus Conditioning is ineffective
must precede the must signal heightened when the animal already has
unconditioned stimulus. (A) probability of occurrence of a good predictor (blocking
the unconditioned stimulus. effect) (D)
(C)
, In general, conditioned stimuli trigger responses that Evaluative conditioning refers to
help prepare the individual for a biologically significant changes in the strength of liking or
event. Studies show that conditioned organisms have disliking of a stimulus as a result
a higher reproduction rate. E.g: mobilizing sperm- of being paired with another
release mechanism in quail, results in increased positive or negative stimulus.
number of sperm cells during copulation
The effect of the drug can’t be conditioned, however usually with drugs after intake the
body produces a compensatory counter-effect in order to regulate, or try to. This
counter-effect is can become a conditional response. When a certain drug is taken
regularly the body starts this counter-effect already after receiving the conditional stimulus
e.g: vision of the pill one is going to intake. This is partly why people build up a tolerance,
because the body gets more effective/start the counter effect sooner.
For an addict the chances of overdose in a different environment becomes higher because
the body is less effective in producing a counter-effect, the tolerance is lower
Addicts in a rehabilitation center can experience less cues and therefore less withdrawal
symptoms because they are in a different environment. There is a chance that when they
return home they get exposed to the cues from their natural environment which results in
a relapse. E.g: When someone comes home and opens their front door that for the first
time that can elicit a crave for a beer because a while ago every time the individual came
home from a long day, opened his front door and got a beer right afterwards. The opening
of the front door became the conditional stimulus.
Thorndike and B.F Skinner were the first behaviorists that researched the phenomenon of operant
conditioning.
An operant response is an action that produces an effect. Operant conditioning can be defined
as a learning process by which the effect, or consequence, of a response influences the future rate
of production of that response. “Operant responses that produce favorable effects increase the
rate, operant responses that produce unfavorable effects decrease in rate” - Law of effect
Thorndike’s puzzle
, To let an organism learn a relatively difficult
task, it is necessary to train the it to do the
task in the first place. This is called shaping.
Due to small incremental steps that each get
reinforced, an organism eventually learns to
complete the full task.
If the operant response is not positively or
negatively reinforced it will eventually go
extinct.
Lever presses Skinner’s box
Schedules
Partial Continuous
A reinforcer occurs after every nth response, where n is some
Fixed-ratio schedule whole number greater than 1. For example, in a fixed-ratio 5
schedule every fifth response is reinforced.
A fixed-ratio schedule except that the number of responses
Variable-ratio schedule required before reinforcement varies unpredictably around some
average.
A fixed period of time must elapse between one reinforced
Fixed-interval schedule response and the next. Any response occurring before that time
elapses is not reinforced.
A fixed-interval schedule except that the period that must
Variable-interval schedule elapse before a response will be reinforced varies
unpredictably around some average.
Behavior that is been
reinforced in one of
these two schedules
results in a lower
number of operant
responses but is very
difficult to extinguish
Just as in classical
conditioning organisms Reinforcement vs Punishment
generalize, it is in operant In the overjustification effect, previously reinforced behavior
conditioning as well the declines because the reward presumably provides an unneeded
case. This is solvable by extra justification for engaging in the behavior. In other words,
discriminative training people will stop engaging in certain behavior if they don’t get
whereby the researcher anymore rewards from it. E.g: positive reinforcing generosity in
provides a discriminative child makes child less generous later in life.
stimulus and let the other
stimuli go extinct.
