Study Notes for PSYC 351: Chapter 5 - Stimulus Relations in Pavlovian Conditioning
PSYC 351 - Fundamentals of Learning
Chapter 5: Stimulus Relations in Pavlovian Conditioning
Outline
Excitatory Conditioning
Inhibitory Conditioning
Blocking Effect
Conditioning in the Absence of the US
Stimulus Relations in PC
Pavlovian conditioning (PC) is a type of associate learning
Two stimuli become associated (e.g., CS-US connection)
In order for two stimuli to become linked, they must be related to each other in some way (thus, the CS and US must be related)
Excitatory Conditioning
Explicitly means that the prediction you’re making is that the CS predicts the presence of the US — Pavlov’s bell predicts the presence of food.
Excitatory conditioning does not necessarily involve ‘excited’ behaviour
If CR is a reduction in behaviour (e.g., freezing), it is still considered excitatory conditioning
Excitatory conditioning can occur with a US that is either appetitive or aversive
Conditioning Procedures
Temporal relation is the most prominent relationship between the CS and US
When in time the two stimuli occur in relation to each other
Temporal alterations can have drastic effects on the conditioned response
Types of Excitatory Conditioning
First-Order Conditioning
a) Short-delayed conditioning (ISI < 1 min)
CS is encountered first, then the US is presented while the CS is still present
b) Long-delayed conditioning (ISI > 5 min)
CS is encountered first for a long time, then the US is presented while the CS is still present
c) Trace conditioning
CS is encountered first, and then separately the US afterwards
d) Simultaneous conditioning
CS and US are presented simultaneously, and end at the same time
e) Backward conditioning
US is encountered first, then the CS is presented while the US is still present
If US is so intense, you’re using anything to predict it in the future
—
Similar results with all types of conditioning (except backwards which can be variable)
neuroscientisits are interested in trace - you gotta linkem togwther yourself, whereas others you experience them together
timing matters
blcks of time with trials in them
Measuring Conditioned Response
Test Trial: presentation of the CS without the US
Inhibitory Pavlovian Conditioning
In order to predict absence of stimulus, you first gotta be able to predict its presence
CS+ (means you’ve learned to predict presence of US) → US, then add CS- (means you’ve learned to predict the absence of US)
Example — school is predictive of bullying, except when the teacher is there
Inhibitory conditioning doesn’t say anything about the nature of the US
excitatory vs. inhibitory - predicting presence or absence of US
appetitive vs. aversive - nature of US (good or bad)
How to Measure
Bidirectional Response Systems
Compound Stimulus (or Summation) Test
Cole, Barnet, & Miller (1997): Standard procedure for CI
Lick suppression in rats — Conditioned Emotional Response
Phase 1
Light → Shock (A+)
Light + Sound → No Shock (AX-)
Sound → Shock (B+)
Phase 2
Measure how long it takes to accumulate 5 seconds of uninterrupted drinking (as they are water deprived)
Retardation of Acquisition Test
Cole, Barnet, & Miller (1997)
Rate of acquisition of excitatory conditioning should be lower for CI
The Role of CS-US Contingency
Contingency measures how well the CS reliably predicts the occurrence of the US
Thinking to oneself “What is the probability that the US will occur after the CS has been presented?”
Thinking to oneself “What is the probability that the US won’t occur without the presence of the CS?”
When the US never occurs without the CS…
… it is known as a perfect positive contingency
e.g., fire (US) always occurs in the presence of smoke (CS)
When the US never occurs with the CS
… it is known as a perfect negative contingency
If the US occurs equally as often with and without the CS
… It is known to have zero contingency
This is characteristic of the random control procedure
Blocking Effect
That the US needed to be surprising or unexpected for conditioning to occur was the first problem recognized in a phenomenon referred to as ‘blocking’
Blocking effect: The interference with conditioning of a novel stimulus because of the presence of a previously conditioned stimulus
Control Group:
Trained to ton + light CS preceding shock US
Afterwards, both tone and light produced modest CRs (freezing)
Pre-trained Group:
Pre-trained with light CS preceding shock US
Then same tone + light CS training as in the control group
Afterwards, light produced large CR and tone produced none
Kamin’s Blocking Study
Temporal contiguity is not enough (it helps, but it isn’t sufficient on its own)
What matters is US surprisingness for pavlovian conditioning to occur
Learning Without a ‘US’
Higher-order conditioning
First-order conditioning
Pairing of a CS and US together → predictability
In the diagram, the dog leash → dog’s wagging tail
EX: McDonald’s toy → happiness
Second-order conditioning
Predicting the predictor
In the diagram, getting dressed predicts dog leash, so winter clothes → dog’s wagging tail
EX: McDonald’s happy meal box has toy, so Happy meal box → happiness
Sensory pre-conditioning
If NS1 is paired with NS2, NS2 may elicit a CR when NS1 becomes a CS
If two stimuli become linked together (for whatever reason, like peanut butter and jelly), and then one takes on meaningful predictiveness (via pavlovian conditioning), the second can take on that meaning too (e.g., if past sauce is bad you might develop taste aversion to noodles too)
Theoretical implications:
S-S associations may occur in the absence of an UR
Evidence for latent learning
Stimulus Relations in Pavlovian Conditioning (PC)
Definition of Pavlovian Conditioning (PC): A form of associative learning where two stimuli become associated with each other.
CS-US Connection: Refers to the relationship between the conditioned stimulus (CS) and the unconditioned stimulus (US).
Requirements: The CS and US must have a relationship for conditioning to occur.
Excitatory Pavlovian Conditioning
Process: It involves learning the relationship between the CS and the presentation of a US.
The CS activates a neural and behavioral representation of the US without the actual presentation of the US.
Conditioned Response (CR): This response is related to the presence of the US.
Important Notes on Excitatory Conditioning
Not Necessarily 'Excited' Behavior:
Example: If the conditioned response is a reduction in behavior (like freezing), it is still considered excitatory conditioning.
Can occur with either appetitive (pleasant) or aversive (unpleasant) USs.
Conditioning Procedures
Temporal Relation: Indicates the most prominent relationship between the CS and the US based on the timing of their occurrences.
Temporal alterations can drastically affect the conditioned response.
First Order Conditioning Methods
Short-Delayed Conditioning: Interstimulus interval (ISI) less than 1 minute.
Long-Delayed Conditioning: ISI greater than 5 minutes.
Trace Conditioning: Involves a delay between the CS and US.
Simultaneous Conditioning: Both CS and US are presented at the same time.
Backward Conditioning: US is presented before the CS.
Variations of Excitatory Conditioning
Types:
Short delay conditioning
Long delay conditioning
Trace conditioning
Simultaneous conditioning
Backward conditioning
Behavioral Outcomes:
Generally similar results in all types, except for backward conditioning, which may yield variable results.
Different brain regions may be involved in each type, e.g., prefrontal cortex (PFC) in trace conditioning.
Timing Matters
Terminology:
Conditioning Trial: A single presentation of the CS and US pair.
Training Session: Multiple conditioning trials.
Intertrial Interval (ITI): The time between consecutive trials.
Interstimulus Interval (ISI): The time between the CS and US during a single trial.
Measuring Conditioned Responses
Test Trial: Involves presenting the CS without the US.
Measurement Aspects:
Magnitude: Size, vigor, or length of CR. Example: Amount of saliva or duration of freezing behavior.
Probability: Percentage of trials where CR is exhibited. Example: In eye-blink conditioning.
Latency: Time taken for CR to occur after CS presentation. Example: Port-entry response time.
Inhibitory Pavlovian Conditioning
Process: A CS predicts the absence of a US, requiring an expectancy of the US within an excitatory context.
Example:
CS+ indicates the presence of the US, while CS- indicates its absence.
Behavioral Impact:
US is more likely to appear when not paired with the CS.
CS- inhibits behaviors elicited by the US.
Types of Conditioning:
Aversive Conditioning Example:
EC: CS+ linked to shock leads to freezing (US).
IC: CS- linked to no shock inhibits fear responses.
Appetitive Conditioning Example:
EC: CS+ leads to food and subsequent salivation.
IC: CS- signals absence of food, leading to frustration.
Conditioning Procedures for Inhibitory Conditioning
Standard CI Procedure (Pavlov):
Type A (A+ Trials): Presenting CS+ with the US.
Type B (AB Trials): Presenting CS- alongside CS+ in absence of the US.
Negative CS-US Correlation:
Environmental context dictates the excitatory conditions for inhibition.
CS- decreases the probability of US occurrence.
Measuring Inhibitory Conditioning Responses
Bidirectional Response Systems:
Certain behaviors can exhibit two opposing responses, e.g., approach versus withdrawal.
Challenges arise due to baseline behaviors (like blink) or lack of oppositional behavior (e.g., freezing).
Compound-Stimulus (or Summation) Test:
Conducted by Cole, Barnet, & Miller (1997) to measure conditioned emotional responses via lick suppression in rats.
Assessed by the time taken to achieve 5 seconds of uninterrupted drinking.
Retardation of Acquisition Test:
Investigates the slower acquisition of excitatory conditioning when preceded by an inhibiting stimulus.
The Role of CS-US Contingency
Defines how reliably the CS predicts the occurrence of the US.
Calculative aspects include:
Probability of US occurrence after CS presentation.
Probability of US occurring without CS presence.
Perfect Positive Contingency: The US always occurs with CS. Example: Fire (US) occurs in presence of smoke (CS).
Perfect Negative Contingency: The US never occurs with CS.
Zero Contingency: US occurs equally with and without CS.
Blocking Effect
Definition: The blocking effect refers to interference in the conditioning of a novel stimulus due to the presence of a previously conditioned stimulus.
Illustration Through Experiments:
Control Group: Trained with tone + light paired prior to shock (US), yielding modest CRs in both.
Pre-Trained Group: Trained with light (CS) before shock; later tone + light training showed strong CS (light) and no conditioning for tone.
Analogy for Understanding:
Relates to the redundancy of information: When new information (stock analyst Bob) is encountered after familiar information (stock analyst Anne), it becomes less impactful.
Blocking in Pain Fear Learning
Phases:
Phase 1 involves learning about CS1 (associated with painful bite) blocking learning about CS2.
Phase 2 involves learning about CS2 only due to increased magnitude of the US.
Kamin’s Blocking Study
Experimental Design:
Phase 1 presents A (tone) + B (light) leading to the US.
Phase 2 tests A (tone) with the US while checking the response to B (light). Shows no CR for B.
Core Conclusions:
Temporal contiguity (CS-US pairing) is insufficient for Pavlovian conditioning.
For learning to occur, the US must be surprising.
Learning Without a ‘US’
Higher-order Conditioning:
Links a first-order conditioning CS1 to a second-order CS2, creating a CR without direct US involvement.
Sensory Pre-conditioning:
Entails pairing two neutral stimuli (NS1, NS2) before any US interaction.
Results in NS2 potentially eliciting a CR when NS1 becomes a CS.
More effective when NSs occur together and with reduced prior experience to prevent latent inhibition.
Summary of Key Concepts
Initial Reflexes in Pavlovian Conditioning:
Unconditioned stimulus (US) elicits an unconditioned response (UR).
A neutral stimulus presented before the reflex creates a conditioned response (CR).
Types of Conditioning:
Appetitive (like in Pavlov's dog) and aversive forms (like in eyeblink conditioning).
Progression of Learning:
The CR is formed gradually through repeated pairings of the CS with the US.
Notably, CR and UR may differ in nature, sometimes even displaying compensatory responses.
Complexities in Pavlovian Conditioning:
Occasion setting represents hierarchies in conditioning.
Conditioning is sensitive to timing; delayed conditioning is most effective.
Increasing the trace interval reduces the likelihood of CS-US learning.
CS-US contingency is critical, influencing learning outcomes.
The blocking effect illustrates how the CS conveys informative value about the US.
Signal Relations:
Excitatory connections indicate presence (CS+) and inhibitory connections signal absence (CS-).
In summation tests, CS+ can increase responses, while subsequent CS- can decrease them.
The retardation-of-acquisition test indicates the challenges of converting a CS- to a CS+ status.
Next Steps
Upcoming Content: Chapter 6 - Focus on Pavlovian Conditioning Mechanisms & Theories.
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