operant conditioning

Operant conditioning

Behaviour shaped by the learner’s history of experience rewards and punishments for their actions

According to Skinner - our behaviours are shaped by our history of experiencing rewards and punishments as consequences

Reinforcement

A behaviour is reinforced (strengthen) whenever a desirable outcome is the consequence.

Behaviours that are reinforced are more likely to be repeated.

Reinforcer

Any consequence of a behaviour that makes that behaviour more likely to recur in future.

Reinforcers can be either positive (+) or negative (-)

Positive reinforcer for positive reinforcement

Something pleasant that is added to increase behaviour

Eg food, lollies, treats, etc

Negative reinforcer for Negative reinforcement

Something unpleasant that is removed to increase behaviour

Eg. Electric shocks

Positive reinforcement

Learn to reproduce a behaviour if the consequence is receiving something pleasant

Rat press lever: receiving a rewarding consequence

Negative reinforcement

Learn to reproduce a behaviour if the consequence is that something unpleasant will stop

Rat press lever: to terminate an unpleasant stimulus as a consequence, such as the electric shock

Continuous reinforcement

Rarely occurs in natural environments, leads to rapid extinction once the reinforcer is withheld

Partial reinforcement

Leads to more persistent learning because the learner becomes accustomed to reinforcement occurring on some occasions and not others.

Extinction of reinforcement

Extinction of an operantly conditioned behaviour occurs when reinforcement is withheld.

Not immediate - sometimes there is a brief increase in responding referred to as an extinction burst followed by a decrease in trained behaviour.

Shaping of complex behaviours

Reinforces successive approximations to the desired behaviour (reinforcing small steps)

Start by reinforcing a high frequency component of the desired response

Then drop this reinforcement - behaviour becomes more variable again

Await a response that is still closer to the desired response - then reintroduce the reinforcer

Keep cycling through as close and closer approximations to the desired behaviour are achieved

Enables the moulding of a response that is not normally part of an animal’s repertoire

Punishment

A behaviour is punished (weakened) whenever the learner experiences an undesirable consequence for that behaviour

Behaviours that are followed by punishment are less likely to be repeated

Punisher

Is any consequence of behaviour that makes that behaviour less likely to recur in future, can also be either positive (+) or negative (-)

Positive punisher for positive punishment

An inherently unpleasant stimulus (UCS) that weakens behaviour when added as consequence of the behaviour

Eg shocked, spanked

Negative punisher for negative punishment

A pleasant stimulus that weakens behaviour when removed as a consequence of the behaviour

Eg phone taken away

Positive punishment

An animal will stop producing a behaviour if the consequence is the presentation of an unpleasant stimulus

Eg shocked

Negative punishment

An animal will stop producing behaviour if the consequence is that something desirable (UCS) is taken away

Antecedent stimuli

‘Cue’ that signals the availability of a reinforcer.

Antecedent-reinforcer relationship is based on a classically conditioned CS-UCS association

Classically conditioned associations become cues for operant behaviours

Eg. The sight of my mobile-phone is associated with the rewarding consequences of scrolling through social media: the phone becomes a cue (antecedent) for the voluntary behaviour of scrolling social media and its attendant rewards

Antecedent stimuli drive habitual behaviours:

The sight of my favourite cafe is associated with the rewarding consequences of my morning coffee

The cafe is an antecedent for the behaviour of buying a coffee

The sign for the pokies is an antecedent for gambling behaviour. It is associated with the rewards of winning

“ABC” model of operant conditioning

Antecedent → Behaviour → Consequence

Discriminant stimuli

An antecedent becomes a discriminative stimulus when it signals which of two or more behaviours will be rewarded in a particular context.

Eg. Swearing is punished in some contexts but is associated with rewarding outcomes in others - the context allows us to discriminate between situations associated with rewards or punishments for a particular behaviour

In Skinner box, a green light may signal food availability whereas a red light may signal impending foot-shock

Receiving the food or avoiding the foot-shock may then be contingent on pressing a lever OR moving to the opposite side of the cage, respectively

NOTE: the discriminant stimulus-reward/punisher relationship is based on a classically conditioned CS-UCS association (related to the process of stimulus discrimination in CC)

Other examples:

Animal training involves learning discriminant signals for different behaviours

• different hand signals and/or verbal command signals which behaviour to produce for a reward

• Skinner taught pigeons to turn circles counter-clockwise to receive a reward in one box, and clockwise to receive a reward in another box

  • the pigeons learned that each box provided a distinct discriminant stimulus for each behaviour

Studying operant conditioning: The Skinner Box

Skinner could control the animal’s experience of reinforcement and punishment.

Reward: pellet dispenser releases food

Punishment: electric grid shocks mouse

Example: the mouse might receive a food pellet each time it presses the lever (positive reinforcement). Or it might be consequence of lever pressing to terminate an unpleasant consequence (negatively reinforcement)

When is punishment effective? The three Cs

Contingency, Contiguity and Consistency

Contingency

The relationship between the behaviour and the punisher must be clear

Contiguity

The punisher must follow the behaviour swiftly

Consistency

The punisher needs to occur for every occurrence of the behaviour

Drawbacks of punishment

Positive punishment rarely works for long-term behaviour change - tends to only suppress behaviour

Does not teach a more desirable outcome

Produces negative feelings in the learner, which do not promote new learning

Harsh punishment may teach the learner to use such behaviour towards other (social learning)

If the threat of punishment is removed, the behaviour returns. Why?

Alternative to punishment

Stop reinforcing the problem behaviour (extinction)

Reinforce an alternative behaviour that is both constructive and incompatible with the undesirable behaviour

Reinforce the non-occurrence of the undesirable behaviour