slide 1 chapter 5 learning and behaviour. slide 2 the big picture this chapter focuses on the manner...

Chapter 5

Learning and Behaviour

The Big Picture

This chapter focuses on the manner in which we learn tobehave in certain ways given certain environmental conditions

The emphasis will be primarily on stimulus-responsemappings, and how they are formed

There will be very little discussion of cognitive statesor processes … which contrasts quite strongly with themethods that are more popular today

Chapter 5 - Learning and Behaviour

The Starting Place - UCSs & UCRs

We come equipped with many stimulus response mappingsthat simply reflect our machinery in action … for examples:

> When we put food in our mouths, digestive processes are initiated> If a projectile is coming at our face we close our eyes, duck our heads, raise our hands, and sometimes hold our breath

These associations are the produce of evolution (or creation)and the components of them are labeled as unconditionedstimuli (UCS) and unconditioned responses (UCR)

> Food (UCS) -> Digestive Process (UCR)


Habituation - Weakening the SR Mapping

The occurrence of some novel stimulus in the environment(UCS) tends to lead to a startle response (UCR).

However, if the stimulus occurs repeatedly without anypositive of negative consequence, the startle response stopsoccurring.

This is a process called habituation … as examples of it consider:

(1) Those weird house noises you no longer hear(2) Airplanes at my old place

Basically, if the UCR proves itself unnecessary in thepresence of some UCS … the UCR may occur less and less


Classical Conditioning - The Extensionof SR Mappings to New Stimuli

In 1904, a Russian scientist named Ivan Pavlovstumbled across an interesting phenomenon whilestudying how the canine digestive system worked.

This phenomenon has come to be called classicalconditioning, and it explains how new stimuli can cometo be associated with certain behavioural responses.

Pavlov’s is now known as one of the most influentialfigures in psychology, and his experiments helped tostart the wave of behaviourism that ruled psychologyfor many years.


Pavlov’s Experiment - Baseline

At the beginning of the experiment, if a bell was rungnear the dog it did not salivate.


Pavlov’s Experiment - Baseline

However, if food (UCS) was presented to the dog, itwould salivate (UCR)

UCS

UCR


Pavlov’s Experiment - Conditioning

Over a number of trials, the bell the CS or conditioned stimulus is rung just before the food is delivered

UCS

UCR

CS


Pavlov’s Experiment - Testing

After a number of conditioning trials, if the CS is presented alone, it will typically lead to a conditioned response … which is similar in form, if not degree, tothe unconditioned stimulus

CRCS


Classical Conditioning Overview

In order for classical conditioning to be effective, theUCS must reliably follow the CS.

If this association is not strong throughout the conditioningphase, the learning will be weak.

If the association between the CS and UCS is terminatedafter conditioning … the CR will eventually not occurin response to the CS - a process called extinction.

However, an extinct CS-CR mapping can become activeagain quickly if the CS/UCS association again becomesstrong again - a process called spontaneous recovery.


Operant Conditioning

The term “operant” refers to the notion that humans learnfrom operating on their environment. We behave, thennote the consequences and use them to modulate futurebehaviour.

The famous cat torturer Edward Thorndike was one of thefirst to study operant conditioning. Early on, his researchfocused on “learning by trial and accidental success”

Through this, he formed the Law of Effect which states thata behaviour that is followed by a positive consequence willtend to be repeated --- note similarity to evolution theory.


Behavior Analysis & B. F. Skinner

Skinner strongly championed the experimental studyof the Law of Effect, and he made strong claims to itsapplication to human behaviour -- Walden Two

He invented a number of devises for studying operantconditioning … the most famous being the operantchamber or “Skinner Box”

This device allows the experimenter to control a numberof environmental stimuli, and allows him to deliver bothrewards (most typical) or punishment.


Basic Skinner Box

Lights

Speaker

Lever

Food Hopper (reward)

Floor the can beelectrified (punishment)


Measuring Behaviour

Behaviour is often measured in terms of rate of responding(i.e., number of responses within some period of time)

Skinner came up with a response recorder apparatus thatallowed him to record each response over time. This deviceis called a cumulative recorder because it keeps track of thetotal number of responses over time.

Thus, the effects of variables on the response rate could bemeasured allowing one to see if certain variables strengthen(i.e. increase) the response of interest, or weaken (i.e., decrease) the response of interest.


Graph from a Cumulative Recorder

0

10

20

30

40

50

60

70

1 2 3 4 5 6 7 8 9 10 11 12

Reward eachresponseReward each 2ndresponse

Time (Minutes)

Num

ber

of R

espo

nses


Notion of a Three-Term Contingency

Skinner described any behavioural event in terms ofthree parts:

(1) The preceding event, which usual involves the presentation of a discriminative stimulus

(2) The behavioural response to the discriminative stimulus

(3) The following event, which represents the consequence of our behaviour

e.g., training killer whales at Sea World


Ways of Altering Behaviour

Positive Reinforcement - A given behaviour tends to increase in frequency if it is followed by an appetitive(desirable) stimulus.

Negative Reinforcement - A given behaviour also tends toincrease in frequency if it is reliably followed by the termination of an aversive (undesirable) stimulus.

Punishment - A given behaviour tends to decrease in frequency if it is reliably followed by an aversive stimulus

Response Cost - A given behaviour tends to decrease infrequency if it is reliably followed by the termination of anaversive stimulus

Extinction - The reduction of a behaviour if it is not reinforced


Shaping Behaviours

Shaping - Teaching an organism to learn a new behaviourthrough successive approximation.

In the case of a Dolphin learning a new trick, this involvesfirst rewarding behaviours that are very generally consistentwith the trick … then altering the criterion for reward,making it more and more specific to the trick

What about a prof learning Karate, or someone learning anew language?


Intermittent Reinforcement

Refers to situations in which not every occurrence of a response is reinforced. This leads to an issue termed schedule of reinforcement

Fixed-ratio: An animal can be rewarded after makingsome set number of responses - leads to behaviour bursts

Variable-ratio: Same as above except it is delivered onaverage every so many behaviours - leads to rapid and constant responding (slot machines)

Fixed Interval: Reinforcers can be deliver after a set periodof time has passed - leads to responding just before

Variable Interval: Same as above except random - leads toslow, steady responding


Resistance to Extinction

A behavior that has been learned on an intermittentreinforcement schedule is much more resistant toextinction that one that had been rewarded moreconsistently

The higher the ratio of the reinforcement, the higherthe resistance

What does all this suggest about gambling?


Generalization and Discrimination

In classical conditioning, generalization refers to the extent to which a stimulus similar to the CS can elicit the CR.

In operant conditioning, generalization refers to the extentto which a stimulus similar to the discriminative stimuluselicits a response.

Animals can learn to both generalize, and simultaneously,to discriminate. In a sense, they learn to categorize stimuliinto those that should be responded to, and those that arenot worth the effort.

> Pigeon learning human concept> Why are weddings so stressful!


The Importance of Secondary Reinforcers

Most operant conditioning experiments use primaryreinforcers during learning (e.g. food, pain).

However, much of our learning in the real world ismore affected by secondary reinforcers (e.g., money, smiles,“pats on the back”, compliments).

These secondary reinforcers gained their importance viagood old classical conditioning … being predictive of UCSsthat are associated with primary reinforcers (UCRs).

Without secondary reinforcers we would be focused only onshort-term responding, and would not learn very complexsets of behaviours … sociopaths?


Conditioning Complex Behaviours

Our society contains many means to shape behaviourvia aversive reinforcers (e.g., fines, jails).

Punishment is an effective means of changing behaviourand it often leads to fairly immediate results … whichreinforces the punisher of course.

Society cannot always control the positive reinforcers present in some situation, but it can control the negative.


Current Research with Humans

Rules & Reinforcers

Human behaviour is often an interaction betweenreinforcers and rules.

Rules are descriptions (often inaccurate) of behaviours thatwill rewarded or punished in various ways

Often people will obey the rules (instructions) originally,but then modify their behaviour in accordance with thereinforcers.

> text book example> rolling stop example


Current Research with Humans

Drug Use and Abuse

Behavioural Psychopharmocology is the study of how drugsinfluence behaviour.

In this area, Skinner’s 3 term contingency translates into:(1) drugs, (2) their effects on behaviour, and(3) their reinforcing effects

As it turns out, most psychoactive drugs act as strong reinforcers in both humans and animals

Most preferred drugs correlate with those most abusedby humans - Monkey coke-heads


An Few Final Thoughts

Note once again the lack of attention to “thought” inall of this

In response to attempts at artificial intelligence, Skinnerresponded, “The important question is not whether machinescan be made to think, it is whether humans think”

Consider this in light of the “Conditioning to Kill” situationand its possible links to post-traumatic stress disorder.

Think also of the quote from “How the Mind Works”


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