SR

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.