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Lecture 19

PSYC 101 Lecture Notes - Lecture 19: B. F. Skinner, Classical Conditioning, Tuning Fork


Department
Psychology
Course Code
PSYC 101
Professor
Luke Clark
Lecture
19

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Learning 2: Operant Conditioning
BF Skinner (1904-1990)
The “Skinner box"
Founded operant conditioning based upon reinforcement
the food reinforcement strengthens that response
reinforcement is behaviour that is strengthened
punishment is decreasing the response
increases the likelihood of
behaviour
decreases the likelihood
of behaviour
stimulus is presented positive reinforcement positive punishment
stimulus is removed negative reinforcement negative punishment
positive reinforcement: mom give you a hug for doing the washing uo
positive punishment: electric fences deter cattle/prisoners from escaping
negative reinforcement: remove unpleasant drug withdrawal eects by taking more drug
negative punishment: remove child’s favourite toy for a period of time
reinforcement works better on children because you are not trying to tell them what to do
punishment as a means of discipline
Why don’t phobias extinguish?
the phobic person avoids the CS
dog in distance —> anxiety —> AVOID run away —> anxiety subsides
Mowrer’s 2 factor model of phobias (1947)
phobia is established by (pavlovian) classical conditioning
phobia is maintained by operant conditioning via negative reinforcement
shaping: method of successive approximations
you can shape behaviours through training
this is done through through the method mentioned above
establishing a more complex response
superstitious conditioning: we attribute reward to wrong response
we can learn and condition to completely random and attribute them wrongly
hockey player has elaborate rituals of doing something before the match —
superstitious ritual “luck"
they continue to retain those behaviours when they experienced the luck
before
gambling behaviour
most phobias seem to be set up through an aversive counter with a dog that works
through Pavlovian conditioning — scary encounter
how does that turn into a phobia?
that fear should slowly extinguish, but in phobics that extinction hasn’t occurred
the key thing that turns into phobia: is avoidance
conditioned response: anxiety and avoidance
lets escape
if the person does this, that takes away that anxiety
avoidance turns it into a phobia
Delay reinforcement
Same principle applies to classical conditioning
if you increase the delay tuning fork, a few minutes later the plate appears
delay is an important factor
conditioned taste aversion
if you try a new food then feel sick
we can learn from a single trial that we will never touch that food again in our lives
tried guacamole for the first time — leave and feel sick but because of the alcohol
you will never touch the guacamole: conditioned to the taste of the guac
conditioned to the wrong thing
Schedules of reinforcement
two factors to consider:
interval and ration
fixed and variable
fixed interval: e.g. 10s delay before next prize available
there is a reward every minute — doesn’t matter how many times you press of
peck, but you’ll receive one prize every minute
variable interval: radio promos
you don’t know when the prize is gonna be available
fixed ratio: 1 prize every 10 presses
you have to press 10 times in order to get the prize
not defined based on a unit of time, but number of behaviours u have to make
variable ratio: slot machines
you don’t know how many presses you’ve got to make
slot machine - gambling
reinforcement is the jack pot win — you might be lucky, or you may not spin thirty
times
the steepness of the response
two eects:
two ration schedules have much steeper lines, compared to the two interval
you make more responses on ratio schedules than interval schedules
the orange one: scalloping
after the reward is delivered, you get a period of dead time.
the animal just sits there, and as the delay starts to draw close, the
animal presses the lever again
you are inspected on an hourly basis
brain mechanisms of reinforcement
Olds and Milner (1945): intra-cranial self stimulation of medial forebrain bundle (same eect
in Ventral Striatum/Nucleus Accumbens)
the animal has a stimulating electrode in a particular region in its brain
its only gonna get an electro current when he presses the lever
it triggers action potentials in its brain
if you have the electrode implanted in the medial forebrain the rats will do that
constantly
they will press that lever instead of eating food when they’re hungry — does
not satiate (don’t get full of it - until point of exhaustion)
they thought that they put that they had put it in the hypothalamus but they
put it through the bundle of dopamine axons
electrode which project through the hypothalamus to the nucleus
acumen’s
Dopamine and Addiction
Measuring dopamine in the synapse, in the Nucleus Accumbent (part of the basal ganglia)
if you give it amphetamine you get an increase of basal release by 100%
they hit the system way more aectively
Dopamine and Classical Conditioning
Dopamine neurons (in the midbrain) signal unexpected rewards and CSs that predict
reward
Once the pairing has been learned, the neutron only fires to the CS, not the reward
dopamine involved in prediction/information more than reward per se
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