Chapter 8 Flashcards
What is an example of controlling stimulus?
A discriminative stimulus.
What is a discriminative stimulus?
A discriminative stimulus sets the occasion for reinforcement of an operant. I.e it signals whether reinforcement is likely following operant behaviour.
What are 2 types of discriminative stimulus?
S(+) which signals an increased probability of reinforcement following operant in S(+) presence & S(-) signals extinction ie. that there is a low probability of operant being reinforced.
How do we test if stimulus is discriminatory?
Using differential reinforcement & discrimination. This involves reinforcing operant in the presence of one stimulus and not the other to form S(+) and S(-). Once this is done we test behaviour during extinction- i.e. there is no reinforcement present and see if there is discrimination between responses to S(+) and S(-). S(-) will go into extinction whereas (+) should be more resistant to extinction.
What is stimulus control?
Change in behaviour that occurs when either S(+) or S(-) is present. In the presence of S(+) behaviour should increase because it signals the increased probability or reinforcement following operant. S(-) signals that the likelyhood of being reinforced for operant behaviour, in its presence, is unlikely I.e it signals extinction.
What is a response chain (successive approximation)?
Shaping behaviour through successive approximation. Method of shapingoperant behaviorby reinforcing responses similar to the desired behavior. Initially, responses roughly approximating the desired behavior are reinforced. Later, only responses closely approximating the desired behavior are reinforced. The process gradually leads to the desired behavior. Thus, a rat should be able to press a lever for a blue light and peck a key for red I.e of successful then the organism should be able to discriminate.
Note: that the controlling stimulus has both a discriminative and reinforcement function (reinforcing during shaping).
What is a real life example of reaction chain application?
Infants use of social referencing when presented with an ambiguous object. An infant will shift their gaze from the object to their mother to read her facial expression. The mother’s reaction acts as a discriminative stimulus to whether or not grabbing behaviour will be reinforced. i.e. happy= reinforced & angry=punishment.
what is he reaction chain formula look like for social referencing?
SD1 - R1 - SD2- R2 - S (p or r) SD= discriminatory stimulus R= response SR=reinforcement. SP= punishment
Responses to happy and sad are equal before conditioning but after infants show an increased response to happy face compared to angry. Social referencing refers to infants tendency to generalise this technique to all faces in order to navigate their social world. (+) = reinforcement & (-) punishment.
What is a multiple schedule experiment?
Two different basic reinforcement schedules with their own discriminative stimuli are presented on at a time. They are differentially reinforced before 1 gets placed on extinction. This results in a phenomenon called behavioural contrast. Where changes to one schedule contigency reinforces behaviour in the other contingency.
Why are variable interval schedules used for multiple schedule experiments?
Variable Interval schedules are used to remove the confound where time itself could become a discriminative stimulus. This way the rat can not simply wait for reinforcement he needs to respond as well.
How do multiple schedules work?
still use differentiation. I.e change from S(+) VI 30s to extinction S(-). at the beginning RR for S(+) and S(-) are the same but RR for S(-) rapidly decreases across trials. till extinction. Then we have complete control over peck rate, red= high RR & green- no pecking.
How do we measure the control stimulus on multiple schedule experiments?
Using the “Discrimination Index”.
It compares the RR of S(+) with the sum RR of both S(+) & S(-) phases.
I(D)= S(+)/ (S(+) + S(-))
I(D)=0.5 when S +/- are the same i.e no discrimination
I(D)=1 when all responses are to S(+) i.e discrimination is complete
What did Pierrel, Sherman, Blue, and Hegge (1970) study show?
In general, acquisition speed and discrimination accuracy increase the as the difference between S(+) and S(-) increases.
what is superstitious behaviour?
During extinction trial where rat inadvertantly associates a peack to green as a cause for the light to turn red
What can remove superstitious behaviour?
Differential reinforcement of other behaviour contingency. Simply, any responses to S(-) following extinction delay the onset of S(+), e.g. 1 peck to green key delays red light 2secs, per peck.
