Week 2: Classical Conditioning Notes

Basic Concepts of Classical Conditioning (CC)

• Elicited Behavior: Behavior doesn't happen randomly; there's always a cause.

• Behavior often follows a predictable sequence, allowing anticipation and preparation.

• Classical Conditioning (CC): Learning an association between two stimuli or events.

• Learning the relationship between stimuli enables preparation for stimulus 2 based on stimulus 1.

What is Conditioning?

• Conditioning = learning or training.

• Classical = a specific method of conditioning.

• Focus on learning that:

  • Has lasting effects on behavior.

  • Is established through mental associations.

• Association: A link between mental representations (e.g., doctor-nurse).

• Associations form through repeated pairing, forming the basis of classical conditioning.

Classical Conditioning History

• Pavlov's dogs and their "psychic secretions" are a classic example.

Classical Conditioning Paradigm

• Before Conditioning:

  • Unconditioned Stimulus (US) --> Unconditioned Response (UR) (e.g., Food --> Salivation).

  • Neutral Stimulus --> No response (e.g., Bell --> No salivation).

• During Conditioning:

  • Neutral Stimulus + Unconditioned Stimulus --> Unconditioned Response (e.g., Bell + Food --> Salivation).

• After Conditioning:

  • Conditioned Stimulus (CS) --> Conditioned Response (CR) (e.g., Bell --> Salivation).

Key Terms

• Unconditioned Stimulus (US): Naturally provokes a response (e.g., Food, Sex, Shock).

• Unconditioned Response (UR): Naturally elicited by the US (e.g., Salivation, Arousal, Startle).

• Conditioned Stimulus (CS): Initially neutral; paired with the US (e.g., Bell).

• Conditioned Response (CR): Learned response to the CS (e.g., Salivation to the bell).

Acquisition (Excitatory Conditioning)

• Acquisition: CS is followed by an outcome.

• Excitatory Associations: CS predicts the occurrence of an outcome.

• Excitatory CS: A CS that predicts the US.

Excitatory Conditioning Procedures

• Timing and Stimulus Duration:

  • Inter-stimulus interval (ISI).

  • Inter-trial interval (ITI).

• Order of Stimulus Presentations:

  • CS --> US

• Types of Excitatory Conditioning Paradigms:

  • Delay.

  • Trace.

  • Long-delay.

  • Simultaneous.

  • Backward.

Delay Conditioning

• Rapid and strong conditioning.

Trace Conditioning

• The rate and strength of conditioning decrease as the trace interval increases.

Long-Delay Conditioning

• Early inhibition, later excitation.

Simultaneous Conditioning

• No direct demonstration of conditioning or learning.

Backward Conditioning

• Evidence of both excitatory and inhibitory learning.

• Organisms learn the temporal relationship between the CS and US.

• Distinction between knowing and performing.

Measuring CRs

• Quantifying Behavior:

  • Magnitude: Amount of response (e.g., amount drank, amount of conditioned emotional responding (CER)).

  • Probability: Likelihood of response (e.g., blinking in human conditioning studies).

  • Latency: Time to respond (RT - Reaction Time).

• These measures are not always convergent.

Extinction (Inhibitory Conditioning)

• Extinction: Stop reinforcing a previously excitatory CS.

• Inhibitory Associations: CS predicts the absence of the outcome.

• Slower to learn.

• Eventually, the subject stops producing a CR to the CS.

Inhibitory Conditioning Procedures

• Knowing when to expect the absence of negative events maximizes potential rewards.

• Knowing when to expect the absence of positive events minimizes wasted time and energy.

• Predictable aversive events are preferable to unpredictable ones.

• Inhibition is dependent on an expectation of an event occurrence.

Conditioned Stimuli in Context

• Conditioned Stimulus (CS) in Excitatory Conditioning: Conditioned Excitor (CE).

• Conditioned Stimulus (CS) in Inhibitory Conditioning: Conditioned Inhibitor (CI).

Types of Inhibitory Conditioning Paradigms

• Pavlovian Conditioned Inhibition (CI).

• Differential CI.

• Explicitly Unpaired CI.

• Inhibition of Delay.

• Backward CI.

Pavlovian CI

• CE US, CE Cl

Differential CI

• CE US, Cl

Explicitly Unpaired CI

• US Cl, Cl US

Inhibition of Delay

• US

Backward CI

• Cl

Measuring CI

• Bi-directional response systems:

  • CI = change in the negative direction.

  • CE = change in the positive direction.

  • Neutral = no change or 0.

• Other response systems require indirect measures because inhibition depends on the presence of excitation.

Conventional Tests

• Negative Summation Test

• Retardation Test

Why Two Tests?

• Summation test results alone might be explained by the organism paying too much attention to the CI, at the expense of attention to the CE.

• Retardation test results alone might be explained by the organism paying too little attention to the CI.

• But, both tests' results cannot be explained by either attentional explanation.

Control Procedures

• Assess whether and how much responding to the CS is due to the CS-US pairings.

• Pseudo-conditioning: General increase in responding to a previously ineffective stimulus due to exposure to the US.

• Differs in only one way.

• May need multiple controls.

Basic Control Procedures

• Random control procedure (Rescorla, 1967) - not so good due to occasional CS-US pairings.

• Explicitly unpaired control.

• Counterbalancing.

Counterbalancing

• Equate stimulus identities across CSs.

• Controls for confounding properties of the stimulus properties.

Experimental Conditioning Paradigms

• Aversive conditioning.

• Appetitive conditioning.

• Eyeblink conditioning.

• Sign and goal tracking.

• Conditioned taste aversion/preference.

• Evaluative conditioning.

Fear/Aversive Conditioning

• Uses a frightening or startling US (e.g., electric shock or loud noise).

• CSs can be tones, lights, odours, contexts, and pictures.

• Acts on the defensive action pattern.

• Measure conditioned emotional response (CER).

• Assess CER by measuring fear-potentiated startle / augmented startle response.

• Learning is indicated by decreases in behaviour in presence of CS.

• Conditioned suppression/freezing:

  • Lick suppression.

  • Lever suppression.

• Conditioned Suppression Formula:

  • SR = \frac{CS}{CS + preCS} = \frac{a}{a + b}

Appetitive Conditioning

• Outcome (US) associated with the CS is rewarding (e.g., food or sex).

• CSs can be a range of stimuli.

• Learning is indicated by increases in behaviour in the presence of CS.

Eyeblink Conditioning

• Eyeblink reflex is an early component of the startle response.

• Used to study learning in infants.

• Shows the importance of pairing events for learning.

• Shows separation of learning and performance.

• The rate of learning eyeblink conditioning is used to differentiate normal ageing and Alzheimer’s disease (AD).

• Presumably due to changes in the cerebellum and disruptions of the hippocampal cholinergic system.

Sign Tracking / Autoshaping

• Organisms approach and contact stimuli that signal the availability of the US.

• CS must be a discrete and localized visual signal.

• This is Pavlovian conditioning – no act is required for food to be presented.

Goal Tracking

• Organism orients towards the location of US delivery.

• Differentiate autoshaping and goal tracking by physically separating the sign and goal (long-box procedure).

• Adding delay (i.e., trace) between presentation of sign and US increases goal tracking behavior.

• Individual differences in sign tracking and relation to impulsivity and drug abuse.

Conditioned Taste Aversion/Preference

• Sensory aspects of food serve as CSs for the feelings we get after eating, which are USs.

• Seeing or smelling food influences how much food we will eat.

• Robust:

  • One-trial learning.

  • Long-delay learning, evolutionarily adaptive.

  • Duration.

  • Resistant to extinction.

  • Occurs even though the individual knows the food was not the cause of illness.

• Clinical applications: chemotherapy induced anorexia.