Presentation on theme: "Psychology Summer School 2005 Peter Ward"— Presentation transcript:
1Psychology Summer School 2005 Peter Ward LearningPsychology Summer School 2005Peter Ward
2Reference: Gleitman: Chapter on learning Any other basic psychology textbook should cover much of the material
3Overview of Lecture Why is learning important? Classical conditioning Instrumental conditioningCognitive views on learning
4Why Learning? Humans are born with a number of ‘built-in programs’ Muscle reflexesThe Universal GrammarBut much of what humans do and think is a result of learning.The things that make individuals, societies and nations different are almost all due to learning.Obviously a complex process, so psychologists have tried to understand it from the most basic level upwards
5Learning and MemoryThe simplest form of learning: Habituation
11Habituation The point being… Leaning involves REMEMBERING Strong link to another crucial area of psychologyMoving on…
12Classical Conditioning Part 2Classical Conditioning
13Classical Conditioning First type of learning studied in depthFocused on learning associations between events.Russian physiologist, Ivan Pavlov ( ), worked on digestive reflexes in dogsRealised he could study learned reflexes as well as innate onesDiscovered he could actually train, or condition reflexes (hence the name)
14How did he do it?Pavlov and his amazing drooling dogs.
15How did he do it?The man himselfA dogSome Russians
16How did he do it?Dogs in the lab salivated when you put meat powder in their mouths.But they would also salivate whenThey saw the meatThey saw the dishThey saw the person who brought itThey heard the person’s footsteps
17Classical Conditioning Method Food = salivatingFood + Bell = salivating…do it enough times…Bell = salivating
18Classical Conditioning Theory Different types of response, different types of stimulusThe innate bit:Unconditioned stimulus = meatUnconditioned response = salivatingThe learned bitConditioned stimulus = bellConditioned response = salivating (to bell alone)
22Classical Conditioning Same pattern of learning found inCrabsAntsAnt eatersCatsPEOPLE Fundamental type of learning!
23The important parts of Classical Conditioning 1. Acquisition of Conditioned responsesCS (bell) and UCS (meat) must be paired several times. The CS must be presented just before the UCS for the association to be strongest.These pairings are called reinforced trials, because they reinforce the connection. Trials with only the CS are called unreinforced trials.
24The important parts of Classical Conditioning Measuring the strength of the conditioned response:Response amplitude, or strengthE.g. amount of salivaProbability of response (when CS is presented alone)Response latency (how long a gap is there between the CS and the CR?
25The important parts of Classical Conditioning The learning Curve:
26The important parts of Classical Conditioning Second order conditioningBell => salivating.Fair enough, but…Black square + bell => salivating…Black square => salivating
27The important parts of Classical Conditioning Extinction‘Undoing’ the connectionsImportant so an animal doesn’t get locked into behaviours that aren’t useful.
28The important parts of Classical Conditioning GeneralisationIn the real world, two stimuli are rarely the sameE.g. voices at different intonationsfootsteps at a different paceThe more different the stimulus from the original CS, the weaker the response
29The important parts of Classical Conditioning DiscriminationTo avoid ‘over-generalisation’It may take many trials for an animal to tell the difference between e.g. a black square and a grey square, but if only the black square is reinforced, it will eventually tell them apart perfectly.
30Extensions of classical conditioning HungerEmotionsHow we feel about certain peopleDaddy + Disney world => happinessHopefully … daddy => happinessPhobias and their treatmentDrugs e.g. insulin needlesDrug addictionSight of needle => body’s compensatory response => toleranceDanger of overdose if compensatory reaction is not elicited by a relevant CS such as location.CS, (such as needle) but without the US (the drug) means the compensatory response just carries on. This causes cravings.
31Important point:In classical conditioning, psychologists thought that an animal learns to respond in a reflexive manner to some new stimulus.There was no thinking involvedThe animal was basically like a machineIt matched its old response to a new stimulus for no good reason.Learning is a bit ‘stupid’
32Classical Conditioning Quiz What is the simplest form of learning called?Give an example of something humans don’t have to learnWho accidentally discovered classical conditioning?In the experiments, was the bell the conditioned stimulus or the unconditioned stimulus?To get the best effect, should the bell come before or after the meat?What is it called when an association ‘wears off’?What is it called when an animal cal tell the difference between two different bells?Why can taking drugs in an unusual place be dangerous?
33AnswersHabituationThe rules of speaking their own language, jumping at a loud noise etc.Ivan Pavlov, Russian PhysiologistThe conditioned stimulusBeforeExtinctionDiscriminationThe body doesn’t get the conditioned stimulus (the location) to prepare for the drugs
34Instrumental Conditioning Part 3Instrumental Conditioning
35What is it?When a seal does a trick and gets a fish, it learns an instrumental response – the trick is instrumental to getting the fish…
36What is it? Different from classical conditioning NOT an improvement or replacement of classical conditioning.This time the reinforcement (e.g. food) depends on making the right response. Pavlov’s dogs could not influence when they were fed by making a particular response.The response the animal makes has to be deliberately selected – Pavlov’s dogs had no choice whether or not they salivated.
37Instrumental Conditioning Thorndike and the Law of Effect (1898)Studied animals’ behaviour to see if they showed signs of ‘human’ thinking and reasoning
39Thorndike’s catsThe wrong responses led to failure, and the right response led to success. The wrong ones had to be ‘stamped out’, the right ones had to be ‘stamped in’The cats did learn to make the right response, but it was a slow process. No evidence of thinking!
40The law of effectIf a response is followed by a reward, it will be strengthened.If a response is not followed by a reward, or is followed by punishment, it will be weakened.The strength of a response is adjusted according to the response’s consequences
41Skinner and Operant Conditioning B.F. Skinner ( )Insisted Instrumental conditioning was different from classical conditioning as an animal’s response is basically voluntaryHe called instrumental responses operants because they operate on the environment.Developed better puzzle boxes
42The main features of Instrumental Conditioning ReinforcementIn classical conditioning, reinforcement strengthens a response.In Instrumental conditioning, this is done by presenting some stimulus AFTER the correct response has been madeTwo ways of doing this…
431(a) Presentation of ‘Appetitive’ Stimulus Correct response => Nice juicy fish
441(b) Removal of aversive stimulus Shock + correct response = no more shockEvil PsychologistGigantic rat
45ReinforcementAs in CC, the more reinforcements, the more likely the response will be to occurAs in CC, the response will suffer extinction if it is not reinforced.
462. Generalisation and Discrimination The responses might be voluntary, but outside stimuli can affect it, e.g. discrimination.Pigeon pooRed light vs. Green light
47Generalisation and Discrimination The responses might be voluntary, but outside stimuli can affect it, e.g. discrimination.The difference is, in instrumental conditioning, the stimulus tells the animal what to do, not just what’s going to happen.
48Generalisation and Discrimination Generalisation is just the same: if the stimulus is quite similar to the training stimulus, the animal is quite likely to make the same responseLess likelyto respondTraining stimulusQuite likely to respond
493. Shaping The way to train animals… Kung fu hamster ? Water-skiing squirrel
50How? The method of successive approximations Little bit at a time Takes a looooonnnnngggggg timeRequires perfect timingSomeone trained a pig to turn on a radio, eat breakfast at a kitchen table, put dirty clothes in a wash basket, hoover the floor, select a certain type of pig food from lots of alternatives
51AndDogs playing the pianoPigeons playing ping pong…Etc. etc. etc…
524. Reinforcers Many different types (food, money, less pain etc.) Not just things that meet immediate needs.
53Reinforcers It seems a reinforcer is anything that motivates behaviour Reinforcers will motivate behaviour differently depending on what other rewards are available.If a kid gets no pocket money, £5 is a good reinforcerIf they get £30 pocket money, suddenly £5 is not so interesting.
54ReinforcersSome behaviours have their own reinforcers ‘built-in’ (intrinsic motivation)ArtSportSex
555. Schedules of Reinforcement In the lab and in real life, reinforcement is usually partialReinforcement usually comes in patterns or after a delay.The rules for reinforcing are known as schedules of reinforcement
565(a). Ratio Schedules Fixed ratio: Variable ratio: E.g. 10 responses for each rewardVariable ratio:Roughly 10 responses for a reward.The uncertainty produces a high response rateThis is how gambling machines make money
575(b). Interval Schedules Reinforcement only comes at a fixed time since the last one.Responses slow down after a reward, and then start to pick up near the end of the 5 minute period. So you can train an animal to respond every 5 mins.Example: you only check for mail in the morning, because that’s when the effort is rewarded.
586. Punishment The opposite of reward Timing is crucial Escape and avoidanceThe point is toweaken responses.
59In the real world Table manners Prisons Token economies Mental health treatments
60Instrumental Conditioning Why do we use the term ‘instrumental’?Why do we use the term ‘operant’Are instrumental responses voluntary or reflexive?Does the reinforcer come before or after the response?Can an instrumental response become extinct?What is the correct term for the way you train animals?How do we define a reinforcer?Give an example of intrinsic motivationWhat reinforcement schedule do gambling machines use?
61Answers The response is instrumental to getting some reward The response is a way of operating on the environmentVoluntaryAfterYesShaping, or Successive ApproximationsAnything that motivates behaviourDrinkingVariable ratio
63Cognitive learning ‘Cognitive’ = information processing Psychology today, in this university, is cognitive psychology.More concerned with what goes on in the mind than simple reflex actions.Earlier psychologists treated people almost like machines – they believed you couldn’t study mental processes because you couldn’t see them.
64Cognitive learningLearning cannot just be a change in behaviour – it involves new KNOWLEDGEThe proof ?Carry a rat round a maze and it will learn the layout of the mazeWithout doing anything!
65Cognitive views of classical conditioning. The conditioned stimulus (bell) doesn’t become a substitute for the unconditioned stimulus (meat). Often the CR and the UR can be different, as in the drug example.The dog learns that the bell means the food is on it’s way, so it responds appropriately.It learns the relationship between the two stimuli.
66Cognitive views of classical conditioning. It learns the relationship between the two stimuli.Ah, I see…Ah, I see…
67Why does conditioning work? Pavlov thought it was just because the the bell and the meat occurred close to each other.But we now understand in terms of signals: the dog hears the bell and knows it signals approaching food.Presenting the stimuli the other way around is poor at producing the response, and having them at the same time is pretty useless…
68Why does conditioning work? Think about road signsSigns have to come before the thing they warn us about. It’s no good having them at the same time, or after the thing itself!
69Why does conditioning work? The important thing is that the bell predicts the food, not just that they happen closely together in time.Storm clouds – we look at them and predict storms. We don’t immediately dive for cover.Storm clouds are not a substitute for an actual storm; they serve as a signal
70The role of surpriseThe CS – US pairing has to be NEW, it has to make an animal sit up and pay attention.If the dog was already expecting the food, it would ignore the bell because it doesn’t tell it anything new.Animals tend not to make new connections when the old ones are good enoughTemperature example
71Cognitive view of Instrumental Conditioning An animal doesn’t just learn to perform a response – it learns the relationship between a response and it’s outcomeThis is called an act-outcome representationAh, I see…**Deep thoughts**
72Latent learningRats know their way around a maze, but only bother demonstrating this when it gets them some food!So what they have learned is knowledge, not just behaviour
73Cognitive view of Instrumental Conditioning Animals can learn which action leads to which reward.Press lever => foodPull chain => sweet water…Poison the water…No more chain pullingPoints to quite complex knowledge
74Cognitive view of Instrumental Conditioning Animals (and humans) know when there is a relationship between two events and when there isn’tAnd they seem to prefer it when there is one!
75Cognitive view of Instrumental Conditioning Learned helplessnessWhen we fail to learn the relationshipHow to make a dog depressed
76Link to depression in humans People may be in situations when they really were helplessLosing jobLosing a court caseSomeone dyingIllnessThey end up learning that there is no relationship between what they do, and the things that happen to them
77SummaryIn the cognitive view, animals and people actually gain knowledge when they learn.They don’t just learn new reflex actions, or new complex behaviours. They don’t just act like machines.Learning about relationships is highly useful, but can also be damaging, as in the case of depression.Psychologists only work with dogs, pigeons and rats because they’re too scared to work with tigers