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Psychology Summer School 2005 Peter Ward

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1 Psychology Summer School 2005 Peter Ward
Learning Psychology Summer School 2005 Peter Ward

2 Reference: Gleitman: Chapter on learning
Any other basic psychology textbook should cover much of the material

3 Overview of Lecture Why is learning important? Classical conditioning
Instrumental conditioning Cognitive views on learning

4 Why Learning? Humans are born with a number of ‘built-in programs’
Muscle reflexes The Universal Grammar But 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

5 Learning and Memory The simplest form of learning: Habituation

6 Habituation (loud noise)

7 Habituation Goodness me! What a surprise!

8 Habituation That’s still quite surprising…

9 Habituation Okay, I’m less surprised now

10 Habituation Boring.

11 Habituation The point being… Leaning involves REMEMBERING
Strong link to another crucial area of psychology Moving on…

12 Classical Conditioning
Part 2 Classical Conditioning

13 Classical Conditioning
First type of learning studied in depth Focused on learning associations between events. Russian physiologist, Ivan Pavlov ( ), worked on digestive reflexes in dogs Realised he could study learned reflexes as well as innate ones Discovered he could actually train, or condition reflexes (hence the name)

14 How did he do it? Pavlov and his amazing drooling dogs.

15 How did he do it? The man himself A dog Some Russians

16 How did he do it? Dogs in the lab salivated when you put meat powder in their mouths. But they would also salivate when They saw the meat They saw the dish They saw the person who brought it They heard the person’s footsteps

17 Classical Conditioning Method
Food = salivating Food + Bell = salivating …do it enough times… Bell = salivating

18 Classical Conditioning Theory
Different types of response, different types of stimulus The innate bit: Unconditioned stimulus = meat Unconditioned response = salivating The learned bit Conditioned stimulus = bell Conditioned response = salivating (to bell alone)

19 In pictures:

20 In pictures:

21 In pictures:

22 Classical Conditioning
Same pattern of learning found in Crabs Ants Ant eaters Cats PEOPLE  Fundamental type of learning!

23 The important parts of Classical Conditioning
1. Acquisition of Conditioned responses CS (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.

24 The important parts of Classical Conditioning
Measuring the strength of the conditioned response: Response amplitude, or strength E.g. amount of saliva Probability of response (when CS is presented alone) Response latency (how long a gap is there between the CS and the CR?

25 The important parts of Classical Conditioning
The learning Curve:

26 The important parts of Classical Conditioning
Second order conditioning Bell => salivating. Fair enough, but… Black square + bell => salivating Black square => salivating

27 The important parts of Classical Conditioning
Extinction ‘Undoing’ the connections Important so an animal doesn’t get locked into behaviours that aren’t useful.

28 The important parts of Classical Conditioning
Generalisation In the real world, two stimuli are rarely the same E.g. voices at different intonations footsteps at a different pace The more different the stimulus from the original CS, the weaker the response

29 The important parts of Classical Conditioning
Discrimination To 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.

30 Extensions of classical conditioning
Hunger Emotions How we feel about certain people Daddy + Disney world => happiness Hopefully … daddy => happiness Phobias and their treatment Drugs e.g. insulin needles Drug addiction Sight of needle => body’s compensatory response => tolerance Danger 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.

31 Important point: In classical conditioning, psychologists thought that an animal learns to respond in a reflexive manner to some new stimulus. There was no thinking involved The animal was basically like a machine It matched its old response to a new stimulus for no good reason. Learning is a bit ‘stupid’

32 Classical Conditioning Quiz
What is the simplest form of learning called? Give an example of something humans don’t have to learn Who 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?

33 Answers Habituation The rules of speaking their own language, jumping at a loud noise etc. Ivan Pavlov, Russian Physiologist The conditioned stimulus Before Extinction Discrimination The body doesn’t get the conditioned stimulus (the location) to prepare for the drugs

34 Instrumental Conditioning
Part 3 Instrumental Conditioning

35 What 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…

36 What 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.

37 Instrumental Conditioning
Thorndike and the Law of Effect (1898) Studied animals’ behaviour to see if they showed signs of ‘human’ thinking and reasoning

38 Thorndike’s not-so-clever cats

39 Thorndike’s cats The 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!

40 The law of effect If 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

41 Skinner and Operant Conditioning
B.F. Skinner ( ) Insisted Instrumental conditioning was different from classical conditioning as an animal’s response is basically voluntary He called instrumental responses operants because they operate on the environment. Developed better puzzle boxes

42 The main features of Instrumental Conditioning
Reinforcement In classical conditioning, reinforcement strengthens a response. In Instrumental conditioning, this is done by presenting some stimulus AFTER the correct response has been made Two ways of doing this…

43 1(a) Presentation of ‘Appetitive’ Stimulus
Correct response => Nice juicy fish

44 1(b) Removal of aversive stimulus
Shock + correct response = no more shock Evil Psychologist Gigantic rat

45 Reinforcement As in CC, the more reinforcements, the more likely the response will be to occur As in CC, the response will suffer extinction if it is not reinforced.

46 2. Generalisation and Discrimination
The responses might be voluntary, but outside stimuli can affect it, e.g. discrimination. Pigeon poo Red light vs. Green light

47 Generalisation 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.

48 Generalisation 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 response Less likely to respond Training stimulus Quite likely to respond

49 3. Shaping The way to train animals… Kung fu hamster ?
Water-skiing squirrel

50 How? The method of successive approximations Little bit at a time
Takes a looooonnnnngggggg time Requires perfect timing Someone 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

51 And Dogs playing the piano Pigeons playing ping pong… Etc. etc. etc…

52 4. Reinforcers Many different types (food, money, less pain etc.)
Not just things that meet immediate needs.

53 Reinforcers 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 reinforcer If they get £30 pocket money, suddenly £5 is not so interesting.

54 Reinforcers Some behaviours have their own reinforcers ‘built-in’ (intrinsic motivation) Art Sport Sex

55 5. Schedules of Reinforcement
In the lab and in real life, reinforcement is usually partial Reinforcement usually comes in patterns or after a delay. The rules for reinforcing are known as schedules of reinforcement

56 5(a). Ratio Schedules Fixed ratio: Variable ratio:
E.g. 10 responses for each reward Variable ratio: Roughly 10 responses for a reward. The uncertainty produces a high response rate This is how gambling machines make money

57 5(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.

58 6. Punishment The opposite of reward Timing is crucial
Escape and avoidance The point is to weaken responses.

59 In the real world Table manners Prisons Token economies
Mental health treatments

60 Instrumental 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 motivation What reinforcement schedule do gambling machines use?

61 Answers The response is instrumental to getting some reward
The response is a way of operating on the environment Voluntary After Yes Shaping, or Successive Approximations Anything that motivates behaviour Drinking Variable ratio

62 Part 4 Cognitive Learning

63 Cognitive 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.

64 Cognitive learning Learning cannot just be a change in behaviour – it involves new KNOWLEDGE The proof ? Carry a rat round a maze and it will learn the layout of the maze Without doing anything!

65 Cognitive 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.

66 Cognitive views of classical conditioning.
It learns the relationship between the two stimuli. Ah, I see… Ah, I see…

67 Why 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…

68 Why does conditioning work?
Think about road signs Signs 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!

69 Why 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

70 The role of surprise The 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 enough Temperature example

71 Cognitive view of Instrumental Conditioning
An animal doesn’t just learn to perform a response – it learns the relationship between a response and it’s outcome This is called an act-outcome representation Ah, I see… **Deep thoughts**

72 Latent learning Rats 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

73 Cognitive view of Instrumental Conditioning
Animals can learn which action leads to which reward. Press lever => food Pull chain => sweet water Poison the water… No more chain pulling Points to quite complex knowledge

74 Cognitive view of Instrumental Conditioning
Animals (and humans) know when there is a relationship between two events and when there isn’t And they seem to prefer it when there is one!

75 Cognitive view of Instrumental Conditioning
Learned helplessness When we fail to learn the relationship How to make a dog depressed

76 Link to depression in humans
People may be in situations when they really were helpless Losing job Losing a court case Someone dying Illness They end up learning that there is no relationship between what they do, and the things that happen to them

77 Summary In 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

78 The End. Thanks for listening!

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