Lecture4:Nature of learning-Dr.Naif

Use with Atkinson & Hilgard’s Introduction to Psychology 15th editionNolen-Hoeksema, Fredrickson, Loftus, Wagenaar ISBN 9781844807284 © 2009 Cengage Learning

Chapter 7

Learning and Conditioning


Learning & Conditioning

• Learning– Learning is defined as a relatively permanent change

in behavior that occurs due to experience– Two basic kinds of learning

• Non-associative – involves learning about a single stimulus & includes habituation and sensitisation

• Associative – more complex as it involves learning about relationships among events, and includes classical conditioning and instrumental conditioning


Classical Conditioning

• Classical conditioning– Learning process in which previously neutral stimulus

becomes associated with another stimulus through repeated pairing with that stimulus

• Pavlov’s experiments– Pavlov’s research involved measuring dogs’ salivation

in response to food and found that the dogs began to salivate when they saw food dish



• Unconditioned stimulus (US) – food

• Unconditioned response (UR) – salivation

• Neutral stimulus (NS) – unrelated event, e.g. light on

• During conditioning, pair presentation of food with light

• After number pairings, dog will salivate when light on

• Conditioned stimulus (CS) – light

• Conditioned response (CR) – salivation



• ...Pavlov’s experiments– Drug tolerance

• Refers to the decreased effect of a drug when taken repeatedly

• Regular intake of drug will trigger compensatory response of the body, e.g. caffeine raises blood pressure so compensatory response lowers it. If caffeine then taken under unusual circumstances, e.g. by injection, compensatory response, which has been learned through classical conditioning, does not kick in and blood pressure raised

– Acquisition – early stage of process where repeated pairings of CS & US take place – the learning curve



• ...Pavlov’s experiments– Extinction – CR gradually diminishes if US omitted– Spontaneous recovery – if participant allowed to rest

and then presents only CS again, CR reappears– Stimulus generalisation – adaptive ability to react to

new stimulus which is similar to familiar one by generalising response

– Stimulus discrimination – adaptive ability to react to differences if negative association with aspect of stimulus



• ...Pavlov’s experiments– Second-order conditioning – possible to condition

participant to produce CR to novel stimulus by pairing novel stimulus to CS repeatedly even though novel stimulus never paired with US

– Conditioning and fear – CS leads to CR because it predicts occurrence of certain US – also true for emotional reactions. If particular CS reliably predicts pain, then absence of CS predicts pain not coming



• Cognitive factors– Pavlov & others believed conditioning occur if CS &

US were temporally contiguous (occurred close together in time)

– Some argued that a critical factor behind classical conditioning is what is known – classical conditioning provides new knowledge of relationship between two stimuli

– Research has shown a predictive relationship between CS & US more important than temporal contiguity or frequency of pairings



• Biological constraints– To some extent animals are “pre-programmed” to

learn particular things in particular ways• Learned taste aversion – bad experience with certain food

puts a person off that particular food but this conditioning does not entirely comply with classical conditioning – taste aversions common after just one bad experience (no repeated pairings), & CS-US interval usually very long (number of hours rather than immediate)


Instrumental Conditioning

• Instrumental conditioning– Involves learning the relationship between responses

and their outcomes– Thorndike carried out experiments where animals

engaged in trial-and-error learning where behavior strengthened if immediately followed by reward (law of effect)



• Skinner’s experiments– Skinner’s experiments involved putting a hungry

animal in box which is bare except for a bar with food dish under. Animal’s initial rate of pressing bar through exploration = baseline level

– Acquisition & extinction – after the baseline is established, each time the bar is pressed food is released which results in frequent pressing of the bar. If food stops being released then similar extinction of response, as in classical conditioning.





• ...Skinner’s experiments– Shaping

• If desired behavior is novel there is a need to condition it by reinforcing only variations in behavior which deviate in the desired direction

– Conditioned reinforcers • Conditioned reinforcer – almost any stimulus consistently paired

with a primary reinforcer (which satisfies basic drives)

– Generalization and discrimination • Organisms generalize learning - can be curbed by discrimination

training which is effective where discrimination stimulus clearly identifies cases for response or response suppression



• ...Skinner’s experiments– Schedules of reinforcement

• Ratio schedules – reinforcement depends on the number of responses an organism makes: fixed ratio schedule (FR) – number of responses needed fixed at particular value whereas for variable ratio schedule (VR) – value for responses needed varies unpredictably

• Interval schedules – reinforcement is available only after certain time interval elapsed (& animal makes a response): fixed interval schedule (FI) – organism reinforced for first response after time interval elapsed since last reinforcement whereas for variable interval schedule (FR) – interval duration varies unpredictably



• ...Skinner’s experiments– Aversive conditioning

• Receiving a negative event immediately after an undesired response results in response weakening or being suppressed

– Escape and avoidance behavior • Punishment training can be used to learn new responses –

escape learning is where a response terminates aversive event & avoidance learning is where a response is learned to prevent an aversive event



• Cognitive factors– In an instrumental conditioning situation, temporal

contiguity is again an important factor for it occur– Another key factor is control – instrumental response

is conditioned only when an organism interprets reinforcement as being controlled by its response

– Contingency – in classical conditioning, a behavior is contingent on a particular stimulus; in instrumental conditioning, a behavior is contingent on a particular response



• Biological constraints– As with classical conditioning, biology imposes

constraints on what may be learned through instrumental conditioning – organisms find it easier and faster to learn response if the behavior required makes sense on an ethological level


Learning and Cognition

• Observational learning– Humans often learn without behavior being reinforced

immediately through imitation & observational learning – copying behavior of others you deem successful

– Bandura• Models inform us about consequences of behavior – so

reinforcement is “vicarious”• Studied observational learning of aggressive behavior in

children – found a learner needs to pay attention to a model’s behavior, remember & be able to reproduce behavior & be motivated to do so


Learning and Cognition

• Prior beliefs– With learning relationships between stimuli that are

not perfectly predictive, people often invoke prior beliefs which constrain learning

• Non-existent but plausible relationships detected by participants referred to as spurious associations


Learning and the Brain

• Neural plasticity– Ability of neural system to change through experience

• Change in the synapse is the neural basis of learning and the effect of this change is to make synapse more (or less) efficient

• Habituation and sensitization– Types of non-associative learning– Habituation – a behavioral response decreases over

successive presentations of a stimulus– Sensitisation – a behavioral response increases during

presentations of an intense stimulus



• Classical conditioning– Eye-blink conditioning – conditioning an eye to blink

at just a sound, is associated with changes in synaptic transmission in the cerebellum, known as long-term depression (which leads to decrease in synaptic transmissions)



• ... Classical Conditioning– Fear conditioning



• Cellular basis of learning– What causes the changes in synaptic transmissions?

Possibilities include:• Learning results in increase/decrease in a neurotransmitter

secreted because of an increase/decrease in the number of axon terminals that secrete a neurotransmitter

• There may be no change in a neurotransmitter but change in number of postsynaptic receptors

• Synapse could change in size, or entirely new synapses could be established


Learning and Motivation

• Arousal– Physiologically – arousal refers to the level of alertness

of an organism– Psychologically – arousal refers to the tension that can

accompany different levels of arousal, ranging from calmness to anxiety

– Hebb proposed that organisms are motivated to maintain levels of arousal appropriate to the behavior it is engaged in



• From incentives to goals– Early theorists focused on incentives (behavior

motivated by expected reward) but not all behavior could be motivated in this way – our ability to anticipate long-term consequences of current behavior is an example of goal-oriented behavior

• Intrinsic motivation and learning– In a cognitive approach to the study of motivation,

emphasis is placed upon an individual’s understanding and interpretation of their own actions



• ...Intrinsic motivation and learning– People intrinsically motivated are motivated by

internal feelings, whereas those extrinsically motivated are motivated by anticipated external rewards

– Intrinsically motivated individuals more persistent at a task, their memory of complex concepts is better and they handle complex material in more creative ways

– External rewards can harm intrinsic motivation

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Lecture4:Nature of learning-Dr.Naif