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Chapter 10 – Aversive Control: Avoidance and Punishment Outline –Active Avoidance vs. Passive Avoidance Negative Reinforcement vs. Positive Punishment.

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Presentation on theme: "Chapter 10 – Aversive Control: Avoidance and Punishment Outline –Active Avoidance vs. Passive Avoidance Negative Reinforcement vs. Positive Punishment."— Presentation transcript:

1 Chapter 10 – Aversive Control: Avoidance and Punishment Outline –Active Avoidance vs. Passive Avoidance Negative Reinforcement vs. Positive Punishment –Avoidance Origins of the Study of Avoidance Discriminated Avoidance (Signaled Avoidance) Mowrer’s Two-Factor Theory of Avoidance Experimental Analysis of Avoidance Behavior –Acquired Drive Experiements –Extinction of Avoidance –Nondiscriminated (Free-Operant) Avoidance –Punishment What is Punishing? Is Punishment Effective? Rules of Punishment

2 Avoidance procedures increase the occurrence of instrumental behavior –Active avoidance Negative Reinforcement (Escape or Avoidance) –Learn to make a response to avoid a negative outcome Punishment procedures suppress instrumental responding –Passive avoidance Positive Punishment –Learn to withhold responding to avoid a negative outcome.

3 Origins of the study of avoidance –Vladimir Becherev (1913) Participants were asked to put their finger on a metal plate. –tone (CS) was followed by a shock (US) through the metal plate –Participants quickly learned to pick up their finger (CR) when they heard the tone (CS). This was considered to be a standard example of classical conditioning. –But it was different Removing finger cancelled the US –avoidance

4 Brogden, Lipman, and Culler (1938) –Directly compared classical conditioning to avoidance learning Guinea pigs in a running wheel. –CS- tone –US – shock The shock stimulated the guinea pigs to run (UR) Gp1Gp2 ClassicalAvoidance US always followedUS followed the tone the toneunless the Guinea’s ran The Avoidance group ran much more than the classically conditioned animals.

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7 Discriminated Avoidance procedure (signaled avoidance procedure) –There is a warning stimulus (CS) –What happens after the CS depends upon what the animal does. –Escape Trial Don’t respond fast enough –US is presented until response is made –Successful Avoidance Trial Respond quickly enough –CS is turned off and there is no US on that trial.

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9 During early training most trials are escape trials eventually the animals learn to make the avoidance response, and then avoidance behaviors take over. These experiments have often been performed in shuttle boxes.

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11 Shuttle avoidance –Two-way move back and forth. –One-way always start each trial on one side –move to the other.

12 Mowrer’s two factor theory of Avoidance. –The problem for avoidance tasks is that once animals are performing well, the outcome (shock) doesn’t occur anymore Looks like extinction So what motivates responding? Pavlovian (emotional conditioning) –Signaled CS – US Instrumental –After fear is conditioned the second thing that is learned is the instrumental response (jump barrier). What motivates responding? –Negative RF –escape from conditioned fear.

13 Experimental Analysis of Avoidance Behavior Acquired drive experiments –In the typical avoidance procedure the classical conditioning, and instrumental conditioning, occur simultaneously. –But if two-factor theory is correct it should be possible to train these two kinds of learning separately. 1) condition fear to a CS with a pure classical conditioning procedure. –CS (tone) --> US (shock) –CR (fear) 2) the animals are periodically presented with the CS, but an instrumental response can prevent it. –No shocks are delivered in phase 2.

14 Brown and Jacobs (1949). Classical conditioning Confined rats in one side of a shuttle box – the shuttle opening was blocked. –Light/tone (CS) --> shock (US). 22 trials. Instrumental conditioning The shuttle box opening was opened. CS came on, and remained on until the rats went to the other side – escape. –The animal was removed until the next trial. Over time the shock conditioned animals learned to cross over to the other side sooner after the initiation of the CS. Do we need a control group?

15 Extinction of Avoidance? –Solomon, Kamin, and Wynne (1953) One dog avoided shock for 650 straight trials after escaping a few. –Is it possible to extinguish? Flooding or Response Prevention –Participant is prevented from making the instrumental response during CS The US is omitted (extinction) –Block off door to shuttle box CS alone Has clinical implications –Help people extinguish pathological avoidance Learn to avoid anxiety producing situations.

16 Nondiscriminated (Free-Operant) Avoidance –Executive Monkey Press key every 15 seconds to avoid shock. –S-S interval – time between shocks if you don’t respond –R-S interval – period of safety created if you do respond »Don’t have to be the same. »S-S 8s »R-S 15s. –you will receive a shock every 8s unless you respond. –If you do respond you buy yourself 15s in the absence of shock.

17 Chimps have been trained with several schedules to keep track of to avoid shock (Koestler & Barker, 1965). –respond every 5-s on a button to avoid shock (Free operant avoidance) –any key that lit up with a light (Sd) had to be pressed within one second or they would be shocked (Signaled Avoidance). –a separate unlit key had depressed within one second of a second Sd ( a tone; Signaled Avoidance) –The Chimps were able to keep track of all of this at once motivated by fear?

18 So Fear motivates responding? –Kamin, Brimer, and Black ran an experiment that showed that this may not be the case. –Conditioned Suppression Phase 1 –Rats trained to barpress for food Phase 2 –Then put into a shuttle box where a tone Sd set the occasion to jump the barrier to avoid shock –There were four groups (they differ in amount of training) group 1 = avoid shock by jumping barrier on 1 trial group2 = avoid shock by jumping barrier on 3 consecutive trials group 3 = avoid shock by jumping barrier on 9 consecutive trials group 4 = avoid shock by jumping barrier on 27 consecutive trials Test –returned to the operant chamber continued to barpress for food. The tone was sounded

19 Rats that had reached the 1, 3, or 9 consecutive trial criterion, showed considerable suppression when the tone sounded. –Fear tone. surprisingly the rats that had had 27 consecutive trials of avoidance did not suppress responding. –It seems that increasing experience with the situation lessens the fear. –especially because the animals have learned they have control over the situation. Think of an air traffic controller. –are they motivated by negative reinforcement? –are they afraid all of the time? –are they only afraid when they think they have made a mistake? Nevertheless Two- Factor theory is the theory of avoidance against which all others are compared.

20 Punishment –As we have already discussed. Punishment is some manipulation that causes a decrease in responding As a society we tend to be very interested in punishment –Crime –Children Is Punishment effective? Skinner initially argued that Punishment was not very effective –Possibly came to this conclusion because he was using weak punishers Electronic slap of the paw –It has been shown that punishment can be effective if the correct conditions are met Domjan’s example –Ticket for speeding –Child sticks fork in electric socket.

21 Experimental Analysis of Punishment –Punishment involves decreasing a behavior in order to measure it you must initially have a baseline of that behavior –In real life or therapeutic situations punishment is used to decrease some maladaptive behavior Self injurious behavior Drug taking –In the lab, we typically first train the animals to perform a behavior Then introduce punishment to see if it suppresses responding This can make things complicated –Is responding more influenced by reward or punishment? »It depends »Skinner’s paw slap

22 Characteristics of the Aversive Stimulus and its Method of Introduction Types of Stimuli –Remember one form of punishment (positive punishment) involves presentation of an aversive stimulus Shock Loud noise slap Squirt of lemon juice in the mouth

23 negative punishment involves taking away something the organism wants –Loss of positive RF –Time out Removal of personal freedoms –Can’t get typical RF

24 When is Punishment most effective? –Let’s go through what could be considered the “Rules for Effective Punishment” –This list is backed up by empirical findings from the animal literature Think about how we often don’t follow these rules in real life though 1) punishment must be delivered soon after a response to be most effective –“Catch them in the act” Delayed punishment is far less effective –Can work well with your dog or cat. Kids? Criminals?

25 2) Punishment must be strong as possible to be effective –Mild shock causes only moderate suppression of behavior The effect of mild shock dissipates with repeated application –Habituation –Intense, longer lasting shocks are far more effective Kids? Criminals?

26 3) Punishment must be delivered consistently to be effective. –Punishment works best if it is applied every time –How does this compare to the effects of partial reinforcement? Kids? Criminals?

27 4) Punishment should be as strong as possible initially –It is not very effective to start off weak and then increase with repeated infractions. Kids? Criminals?

28 5) Response-Contingent versus Response-Independent Aversive Stimulation –Random punishment can suppress responding. Especially if intense –Learned helplessness –Typically, however, random punishment is not as effective as contingent punishment With random punishment in a rat you might see some initial decline in responding –but as the animal becomes used to it responding tends to increase

29 6) noncontingent punishment decreases the effectiveness of contingent punishment –If animals are shocked at random initially they take longer to associate shock with a specific stimulus, or response. Phase 1: Random shocks Phase 2: Lever press = shock –US preexposure effect Kids? Criminals?

30 7) Punishment is more effective if animal if offered an alternative response to the punished response –Herman and Azrin (1964) Human smokers Two levers Phase1 (Training) –Lever 1: cigarette VI schedule –Lever 2: cigarette VI schedule Phase 2 (Test) –Condition 1 Lever 1: loud noise; cigarette VI schedule Lever 2: cigarette VI Schedule –Condition 2 Lever 1: loud noise; cigarette VI schedule Findings? –How much pressing of lever 1? Condition 1? Condition 2?

31 The findings from Herman and Azrin (1964) may seem obvious, but the implications are important If you want to discourage a particular behavior, you can punish it. –But it would be more effective to punish that behavior while providing the organism alternative reinforcing/reinforced behaviors »Punish playing too much x-box, but supply lots of new books/magazines? »Punish self-injurious behavior, but supply other activities (painting, music, social interaction). –Providing alternative behavioral opportunities can make even mild punishment much more effective.

32 8) Punishment can come under stimulus control –Discriminative punishment Responding is punished in the presence of an S+ –Light indicates lever pressing will result in shock –Otherwise responding is RF »Animals quickly learn not to respond to the lever when a light is on. Kids? –Parent present or not –Classroom effects Teacher present Substitute/weak teacher Criminals? –Police car  speeding


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