Cognitive Functions of the Mind

Transcription

1 Chapter 6 Learning

2 Cognitive Functions of the Mind Mediate adaptive behaviours Interactions between person and world Form internal representations of the world Perception, memory Reflect on this knowledge (transform in imagination) Reasoning, problem-solving, decision, choice Use knowledge to guide behaviour Action Communicate knowledge to others Language Major function of the mind is to engage in these cognitive functions and mediate adaptive behaviour to mediate interactions between individual and the world.

3 Traditional View of Learning Associationists Mind forms associations between: Stimulus events in environment correlates and consequences Responses organism s action correlates and consequences

4 Some Associations are Innate Reflexes Involve individual muscles (patella reflex, eye blink) Taxes Involve entire body (innate S-R patterns) Positive (move towards), Negative (move away) Instincts Shaped by evolution to help organism adapt to a particular environment Very discriminating Can be VERY complex patterns of behaviour

5 Tinbergen (1947)

6 Limitations of Innate Responses Work fine as long as environment doesn t change, but can become maladaptive... Need to have mechanism for individual species to modify responses to stimulation... And THAT is what happens by virture of learning.

7 Learning Defined Relatively permanent change in current or potential behaviour occurring as a result of experience. Not drugs Not injury Not maturation All organisms with nervous system have some capacity to learn. Permits individual organisms ability to acquire new behaviours under new circumstances adding to the repertoire already present as a result of evolution

8 Classical Conditioning Ivan Pavlov (early 1900 s) Physiologist who did Nobel prize winning research on digestion, discovered (partly by accident) that neutral stimuli had the capacity to elicit reflexive responses.

9 Classical Conditioning Terms Unconditioned Stimulus (UCS) reliably evokes a reflex response on part of organism. Unconditioned Response (UCR) is the reflex response reliably evoked by UCS. Conditioned Stimulus (CS) a previously neutral stimulus that, once paired with UCS, has acquired the capacity to elicit the same response as UCS. Conditioned Response (CR) a learned response to a CS. (This happens after many pairings [i.e. TRIALS] of CS with UCS).

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12 Processes of Classical Conditioning Acquisition process by which a CS acquires the power to evoke a CR. Reinforcement of CS by UCS Response gains strength (measured in terms of magnitude and probability) as trials continue. Extinction process by which the CS loses power to evoke CR by withdrawal of reinforcement. No reinforcement CR loses strength Spontaneous Recovery (itself subject to extinction) Rest after extinction Retest CS alone (will see some degree of CR) Re-Acquisition - relearn faster CS reinforced by UCS Shows CR is not lost rather inhibited or suppressed Generalization CS 0 vs. CS 1..CS n (baby Albert) Discrimination response to two CS for a time but eventually organism is able to discriminate as one CS is reinforced while the other is not.

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14 XX 6.7

15 XX 6.10 Higher-Order Conditioning is another of the Processes of Classical Conditioning.

16 Classical Conditioning: More Terminology Stimulus contiguity = occurring together in time and space 3 types of Classical Conditioning Simultaneous conditioning: CS and UCS begin and end together Short-delayed conditioning: CS begins just before the UCS, end together Trace conditioning: CS begins and ends before UCS is presented

17 Too Extreme but... Pavlov felt ALL forms of learning are basically variants on Classical Conditioning. Now we know that s too extreme be we do understand that to a very large extent, the laws of Classical Conditioning are laws of emotional life. By virtue of processes like Classical Conditioning, we acquire our fears, aversions, joys, preferences, etc. Some of these are innate but most we have learned to respond to as a result of a process very similar to Classical Conditioning.

18 Classical Conditioning in Everyday Life... Conditioned Fears Conditioned Emotional Responses Conditioning and Physiological Responses Conditioning in Advertising Conditioning and drug effects

19 Thorndike s Puzzle Box F 6.11 Conclusion learning motivated by reward

20 Instrumental Learning ~ Thorndike s Laws of Learning (1913) Law of Readiness learning is motivated by an organism s internal state (which activates a whole sequence of behaviours. Law of Effect Responses that lead to reward, are strengthened while those not leading to reward are weakened. Law of Exercise Connections between stimuli and responses are strengthened by practice (repetition) and weakened by disuse.

21 Operant Conditioning B.F. Skinner (1953) principle of reinforcement

22 Operant Conditioning B.F. Skinner ( ) "All we need to know in order to describe and explain behaviour is this: actions followed by good outcomes are likely to recur, and actions followed by bad outcomes are less likely to recur." (Skinner, 1953)

23 Instrumental Learning/ Operant Conditioning General Principles:. Organisms acquire adaptive behaviour through the experience of success or failure. Organisms OPERATE on their environment and their behaviour changes their environment. (Skinner,1953) Behaviour is INSTRUMENTAL to obtaining a desired outcome. (Thorndike,1913) Whereas in Classical Conditioning we see animals forming associations between CS and UCS, in Operant Conditioning, the associations are between behaviour(s) and outcome(s).

24 Operant Conditioning Skinner (1938) revised: the Law of Effect Used operant conditioning chamber Two changes: Specifically defined reinforcement as strengthening the connection between response and a consequence: R Sr Also defined increase as a change in probability of occurrence of a response (more definable) When a response is followed by a REINFORCER, that response increases in probability. When a response is followed by a PUNISHER that response decreases in probability

25 Operant Conditioning Operant Conditioning type of learning in which behaviour is strengthened if followed by reinforcement or diminished if followed by punishment. Type of learning in which the future probability of a behaviour is affected by its consequences. Law of Effect Thorndike s principle that behaviours followed by favorable consequences become more likely, and behaviours followed by unfavorable consequences become less likely.

26 Skinner box: Pigeon pecks or rat presses bar to receive reinforcers

27 Operant Chamber Skinner Box chamber with a bar or key that an animal manipulates to obtain a food or water reinforcer contains devices to record responses

28 Basic Processes in Operant Conditioning Acquisition the initial stage of learning operant responses Shaping a gradual process consisting of reinforcement of closer and closer approximations of a desired response (KEY in pet tricks) Extinction gradual weakening and disappearance of a response (no longer reinforced). Stimulus Control Generalization Discrimination

29 Operant Conditioning B.F. Skinner (1953) principle of reinforcement Operant chamber Skinner Box F 6.13a Emission of response (because Operant Responses tend to be voluntary, they are said to be emitted rather than elicited ). Reinforcement contingencies antecedents, behaviours, and consequences (ABC) Cumulative recorder F 6.13b

30 Figure 6.13 Skinner box and cumulative recorder

31 Operant Conditioning Reinforcer any event that strengthens the behaviour it follows. Reinforcement Contingencies Circumstances or rules that determines whether response leads to reinforcer. Shaping operant conditioning procedure in which reinforcers guide behaviour toward closer and closer approximations of a desired goal.

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33 Operant Conditioning

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35 Reinforcement: Consequences that Strengthen Responses Delayed Reinforcement (immediate produces fastest conditioning) Longer delay, slower conditioning Primary Reinforcers - events that are inherently reinforcing because they satisfy biological needs (food, water, warmth, sex, and maybe affection expressed through hugging and close bodily contact). Satisfy biological needs Secondary Reinforcers - events that acquire reinforcing qualities by being associated with primary reinforcers. (money, good grades, attention, flattery, praise, and applause). Conditioned reinforcement

36 Schedules of Reinforcement Continuous Reinforcement reinforcing the desired response each time it occurs Partial (Intermittent) Reinforcement reinforcing a response only part of the time results in slower acquisition greater resistance to extinction

37 Schedules of Reinforcement Fixed Ratio (FR) reinforces a response only after a specified number of responses faster you respond the more rewards you get different ratios very high rate of responding like piecework pay Variable Ratio (VR) reinforces a response after an unpredictable number of responses average ratios like gambling, fishing very hard to extinguish because of unpredictability

38 Schedules of Reinforcement Fixed Interval (FI) reinforces a response only after a specified time has elapsed response occurs more frequently as the anticipated time for reward draws near Variable Interval (VI) reinforces a response at unpredictable time intervals produces slow steady responding like pop quiz

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40 Schedules of Reinforcement Number of responses 1000 Fixed Ratio Variable Ratio Rapid responding near time for reinforcement Fixed Interval Variable Interval Steady responding Time (minutes) 80

41 Partial Reinforcement Schedules Fixed Ratio: every n th response is reinforced Fixed interval: the first response after x amount of time is reinforced Variable ratio: an average of every n th response is reinforced (hardest to extinguish) Variable interval: the first response after an average of x amount of time is reinforced Big Bang

42 Reinforcers vs. Punishers Positive vs. Negative Reinforcer = rate of response INCREASES Punisher = rate of response DECREASES Positive: something is ADDED to environment Negative: something is TAKEN AWAY from environment NOTE that both reinforcement AND punishment can be in positive and negative forms.

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45 Punishment A consequence that decreases an organism s tendency to make a particular response. aversive event that decreases the behaviour that it follows. powerful controller of unwanted behaviour

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47 Punishment How to make it more effective while reducing its side effects: Apply swiftly (if delay too great, ineffective). Use punishment just severe enough to be effective. Make it consistent (if you want to eliminate a response, punish the response every time). Explain the punishment (reason for punishment should be made very clear. Punishment combined with reasoning if more effective than either alone). Use noncorporal punishment, such as withdrawal of privileges.

48 Escape/Avoidance Learning Soloman & Wynne, 1953 Two kinds of association Lights shock (C.C) Vaulting barrier shock goes away (O.C.) Response during shock ESCAPE Response prior to shock AVOIDANCE Two-Factor Theory (Mower, 1947) 1 st condition fear to light 2 nd reinforce escape/avoidance by association of light to shock

49 Significance of Operant Conditioning Voluntary behaviours come under control of environmental events. behaviour outcome Ubiquitous all vertebrates and many non-vertebrates can show this type of learning. Thorndike/Skinner felt ALL learning was a variant on Operant Conditioning. This view is also too extreme but it s very clear that the laws of Operant Conditioning appear to account for much of the acquisition and display of a great deal of adaptive (and not so adaptive) behaviours. Habits Incentives (all behaviours that organisms learn to do under the condition of incentives).

50 Operant vs Classical Conditioning

51 Table 6.1 Comparison of Basic Processes in Classical and Operant Conditioning

52 Assumptions of S-R Theory Association by contiguity Co-occurrence in space and time Arbitrariness Any stimuli any response Empty Organism Understand animal s behaviour solely in terms of S-R input and responding output. Black Box connects S s and R s (why? how? Don t care). Passive Organism (hidden assumption and metaphor of conditioning) Animals aren t trying to figure anything out.

53 Assumptions of S-R Theory No sense of expectations or free will on the part of the organism. Things happening to the organism. Now know that these assumptions are all wrong But we need to talk about them because they DOMINATED the psychology of learning for half a century! Still see residues in some psychology theories today.

54 Changes in Our Understanding of Conditioning Biological Constraints on Conditioning Breland and Breland (1961) misbehavior of organisms Instinctive Drift Conditioned Taste Aversion Garcia & Koelling (1966) Figure 6.22 Preparedness and Phobias Cognitive Influences on Conditioning Signal relations Response-outcome relations Latent learning F 6.23 Evolutionary Perspectives on learning

55 Experiments that Challenged Garcia and Koelling (1966) research on conditioned taste aversion. see p.239; Figure 6-23 Rats Compound CS Bright light Loud noise Sweet water US 1) Foot shock (immediate) 2) X-Ray (delayed nausia) Later given choice of water source 1) Bright & Noisy 2) Sweet Shocked rats preferred sweet source X-Rayed rats preferred bright and noisy Seligman and Haager (1972) taste aversion Sauce bérnaise see p.238; Figure 6-22 Association between sight and sound shock Association between taste nausia

56 Experiments that Challenged These landmark experiments showed that associations are NOT arbitrary. Avoidance learning capitalizes on species-specific repertoire of defensive reactions built in by evolution. Learning seems to be governed by what s now known as PREPAREDNESS PRINCIPLE (Seligman,1970) By virtue of its evolutionary history, every species is predisposed to form certain kinds of associations. Prepared (predisposed to acquire) Unprepared (not predisposed to acquire) Contraprepared (not possible to acquire) Organism CANNOT be treated as if it is empty. Have to know about the internal biological structures to know what it can and can t learn how brain has been shaped by evolution. RATS vs. BIRDS

57 Cognition and Learning Latent learning (Tolman, 1932) Learning that occurs but is not apparent until there is some reason to demonstrate it Cognitive map (Tolman,1932) A mental representation of the layout of one s environment. For example, after exploring a maze, rats act as if they have learned a cognitive map of it. Overjustification effect The effect of promising a reward for doing what one already likes to do. The person may now see the reward, rather than the intrinsic interest, as the motivation for performing the task.

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59 Cognition and Learning Intrinsic Motivation desire to perform a behavior for its own sake and to be effective Extrinsic Motivation desire to perform a behavior due to promised rewards or threats of punishments

60 Other Cognitive Processes in Learning Learned Helplessness (Seligman, 1967) Occurs when an organism believes that behaviors are not related to consequences When people s past experience leads them to believe that nothing they can do will change their lives, they tend to stop trying. Insight (Kohler, 1947) The sudden grasp of new relationships that are necessary to solve a problem and that were not learned in the past. Kohler s studies of chimpanzee problem-solving

61 Observational Learning: Basic Processes Albert Bandura (1977, 1986) Observational learning Vicarious conditioning Bandura, Ross, & Ross (1963) featured study p key processes attention retention reproduction motivation acquisition vs. performance

62 Bandura, Ross, & Ross (1963) featured study - p Figure 6.25

63 Observational Learning and the Media Violence Controversy Studies demonstrate that exposure to TV and movie violence increases the likelihood of physical aggression, verbal aggression, aggressive thoughts, and aggressive emotions The association between media violence and aggression is nearly as great as the correlation between smoking and cancer F 6.26 third variable problem

64 Figure Comparison of the relationship between media violence and aggression to other correlations.