Classical Conditioning Lecture Notes PDF

8/09/2024 Classical Conditioning PSYU2236/PSYX2236 Biopsychology & Learning Lecturer: Dr Patrick Nalepka (he/him) 1  8/09/2024 Outline 1. Introduction to Classical Conditioning Th...

8/09/2024 Classical Conditioning PSYU2236/PSYX2236 Biopsychology & Learning Lecturer: Dr Patrick Nalepka (he/him) 1  8/09/2024 Outline 1. Introduction to Classical Conditioning The key elements of Classical Conditioning 2. Variations and Limitations in Conditioning Example of Conditioned Response without an Unrelated Stimulus – Conditioned Stimulus Pairing When learning fails to happen 3. Timing, Extinction and Inhibition E ect of varying the temporal relationship between unconditioned and conditioned stimuli Reduction or elimination of behaviours Inhibiting learning 2  8/09/2024 1. Introduction to Classical Conditioning 1. What is Classical Conditioning? How does it di er from non-associative learning? 2. Key elements of classical conditioning Neutral Stimulus (NS) Unconditioned Stimulus (US) Unconditioned Response (UR) Conditioned Stimulus (CS) Conditioned Response (CR) 3. Examples of classical conditioning 4. Types of Unconditioned Stimuli (US) Appetitive Aversive 5. Accounts of classical conditioning Stimulus Substitution Hypothesis Preparatory Response Theory Compensatory Response Model 6. Stimulus generalisation and discrimination processes 3  8/09/2024 Associative Learning INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Learning to associate one stimulus with another 4 4  8/09/2024 What is Classical Conditioning? INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Classical Conditioning: The procedure of repeatedly pairing an initially neutral stimulus (NS) and an Unconditioned Stimulus (US) – a stimulus that reliably elicits a (Unconditioned) Response (UR) After conditioning the neutral stimulus, it becomes established as a Conditioned Stimulus (CS) with the capacity to elicit a (Conditioned) Response (CR) that usually resembles the Unconditioned Response (UR) 5 5  8/09/2024 What is Classical Conditioning? INTRODUCTION TO CLASSICAL CONDITIONING LECTURE The difference between classical and operant conditioning 6 - Peggy Andover - YouTube 6  8/09/2024 Key element of Classical Conditioning INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Key elements of classical conditioning ― Neutral Stimulus (NS) ― Unconditioned Stimulus (US) ― Unconditioned Response (UR) ― Conditioned Stimulus (CS) ― Conditioned Response (CR) Make sure you are comfortable with this terminology! 7 7  8/09/2024 Classical Conditioning Terminology INTRODUCTION TO CLASSICAL CONDITIONING LECTURE In the beginning… Then the NS is paired with US… And voilà an association forms! CS  CR 8 8  8/09/2024 Examples of Classical Conditioning INTRODUCTION TO CLASSICAL CONDITIONING LECTURE e.g. Separation anxiety in dogs Jingle of keys Oh No – she’s leaving me Classical conditioning imbues the previously neutral sound of jingling keys with the capacity to elicit separation anxiety 9 9  8/09/2024 Classical Conditioning of Separation Anxiety INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Happy dog jingle Owner goes to work Sad/anxious dog ♬ ♪ ♫ Neutral Unconditioned Unconditioned Stimulus Stimulus Response CR of anxiety CS Several trips to ♬ ♪ work later… ♫ 10 10  8/09/2024 Classical Conditioning Overview INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Acquisition Extinction Spontaneous Recovery 11 11  8/09/2024 Acquisition of Learning INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Learning follows a negatively accelerating curve You can only respond so much 12 12  8/09/2024 Types of Unconditioned Stimuli (US) INTRODUCTION TO CLASSICAL CONDITIONING LECTURE The US used in classical conditioning studies are typically of two types: 1. Appetitive US automatically elicits approach responses, such as eating, drinking, caressing, etc. These responses give satisfaction and pleasure. 2. Aversive US such as noise, bitter taste, electric shock, painful injections, etc. are painful, harmful, and elicit avoidance and escape responses. Appetitive classical conditioning is slower and requires greater number of acquisition trials, but aversive classical conditioning is established in one, two or three trials depending on the intensity of the aversive US. 13 13  8/09/2024 What form does the Conditioned Response (CR) take? INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Stimulus Substitution Theory That bell is looking very tasty Pavlov thought that the CS became a substitute for the US Innate US-UR reflex pathway ― CS substitutes for the US in evoking the same response ― CR and UR produced by same neural region ― Food  salivation ― CS  salivation If so, the CR should always be the same as the UR! 14 14  8/09/2024 Evidence FOR stimulus substitution hypothesis INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Jenkins and Moore (1973) study: Sign tracking (aka Autoshaping) in pigeons ― One group had CS (light)  US (grain)  Pigeons tried to “eat” the lit key (open beak & closed eyes) when they pecked Photographs showing pigeons pecking keys when receiving water reward (left) or food (right). ― Another group had CS (light)  US (water) Pecks to the water-related key included drinking  Pigeons tried to “drink” the lit key (closed beak & like movements such as licking. Pecks to the open eyes) when they pecked food-related key were made with the beak slightly open, as if to seize a piece of grain. CR is sometimes directed at the CS Jenkins, H. M. & Moore, B. R. (1973). The form of the auto-shaped response with food or water reinforcers, Journal of the Experimental Analysis of Behavior, 20, 163–181. doi: 10.1901/jeab.1973.20-163 This shows that the nature of the US determines the form of the CR 15 15  8/09/2024 Sign-tracking and individual differences INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Some animals are sign-trackers and some are goal trackers Sign trackers direct their behaviour at the CS (i.e., the sign) (e.g., light) even at the expense of the US (reward/goal). Goal trackers’ behaviour is directed to the US. 16 16  8/09/2024 Sign-tracking and individual differences INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Both sign and goal trackers are learning that the CS predicts the food outcome, but only sign trackers ascribe incentive to the cue (CS). Rats who display sign tracking towards a CS predictive of food are more likely to develop compulsive cocaine self-administration (Tunstall & Kearns, 2015). 17 17  8/09/2024 Sign tracking and addiction in humans INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Research from animals on sign tracking is frequently applied to looking at whether people who over eat or who are susceptible to addiction are overly sensitive to cues associated with food, alcohol, or drugs! Conditioned stimuli that signal reward can become motivational magnets that capture attention, even when individuals are motived to ignore them. Sign-tracking offers an account of how impulsive and involuntary behaviour begins and is triggered by cues. It offers a theory of how addiction gets started, while, at the same time, explaining why the erosion of self-control induced by sign-tracking goes largely unnoticed. Tomie, A. (1995). CAM: An animal learning model of excessive and compulsive implement-assisted drug-taking in humans, Clinical Psychology Review, 15, 145-167. (CAM= Cue and Manipilandum) 18 18  8/09/2024 Evidence AGAINST stimulus substitution hypothesis Any study in which the elicited CR is different from the UR ― This is often the case with aversive US  e.g., when a tone is paired with shock, rats will jump to the US (shock), but the CR is typically freezing  Freezing is a preparatory defense response 19 19  8/09/2024 Alternative Accounts: Preparatory Response Theory INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Kimble’s (1961, 1967) theory proposed that the CR is a response that serves to prepare the organism for the upcoming US Better warm-up my jaws and get the e.g., following acquisition of CRs in eye-blink saliva flowing…food is on its way conditioning, the CR eye-blink may actually prepare the person for the upcoming air-puff such that the eye would be partially closed when the air-puff occurs Kimble, G.A. (1961). Hilgard and Marquis’ conditioning and Learning (2nd ed.) New York, NY: Appleton Century Crofts. Kimble, G. A. (1967). The definition of learning and some useful distinctions. In G.A. Kimble (ed) Foundations of conditioning and learning. 20 New York, NY: Appleton-Century-Crofts. 20  8/09/2024 Alternative Accounts: Compensatory Response Theory INTRODUCTION TO CLASSICAL CONDITIONING LECTURE The compensatory-response model is one version of preparatory-response theory Better get that saliva flowing to off-set In this model of classical conditioning, my dry mouth when eating the compensatory after-effects to a US are what come to be elicited by the CS Based on the opponent-process theory of emotion / motivation Central goal is to maintain a state of homeostasis 21 21  8/09/2024 Generalisation, transfer, and discrimination INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Stimulus Generalisation: A tendency to respond to stimuli that are similar, but not identical to, a conditioned stimulus ― Transfer of Training: Being able to apply knowledge gained in one situation to that of a similar one. Stimulus Discrimination: The learned ability to respond differently to similar stimuli – to pick the ‘real deal’ from the look-alikes! 22 Image generated using ChatGPT 4o 22  8/09/2024 Classical Conditioning & Generalisation INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Pavlov found that conditioning resulted in salivation not only to the CS presented during training, but also to other stimuli that were similar to it In one experiment, he conditioned salivation to a tone of 1000 Hz… ― after conditioning the dogs also salivated to 1100 Hz and 1200 Hz, among other ― the greatest salivation occurred to the tones most similar to the training stimulus. 23 23  8/09/2024 Discrimination INTRODUCTION TO CLASSICAL CONDITIONING LECTURE No, but why not? 24 24  8/09/2024 Discrimination INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Pug is discriminating between different sounds Telephone ringing is not a good predictor of owner leaving house Picking up her bag might cause some concern as it’s a better predictor of leaving. 25 25  8/09/2024 Brief Summary: Introduction to Classical Conditioning INTRODUCTION TO CLASSICAL CONDITIONING LECTURE Classical conditioning is a type of associative learning – it involves the formation of a relationship between two stimuli Key elements of classical conditioning are: ― Neutral stimulus (NS), Unconditioned stimulus (US), (UR)unconditioned response, (CS) conditioned stimulus, and (CR) conditioned response Unconditioned stimuli can be appetitive (positive) or aversive (negative) There are a number of accounts of classical conditioning ― Stimulus Substitution Hypothesis ― Preparatory Response Theory ― Compensatory Response Model Generalisation (transfer of training) and discrimination of the CS occurs 26 26  8/09/2024 Break Break Time 27  8/09/2024 2. Variations and Limitations in Conditioning 1. Variations on basic classical conditioning The case of a CR without a US! Higher order conditioning Sensory pre-conditioning 2. Limitations in conditioning: When learning fails Overshadowing Blocking Latent inhibition 28  8/09/2024 Variations on basic classical conditioning What?!? A CR without a CS-US pairing! Higher-Order Conditioning Also known as second-order conditioning Sensory Pre-Conditioning 29  8/09/2024 Higher Order Conditioning Higher-order or second-order conditioning refers to conditioned responses that involve neutral stimuli (i.e., stimuli that are not directly threatening or rewarding). The conditioned response is established because of a pairing of a neutral stimulus (NS) with a conditioned stimulus (CS) 30  8/09/2024 An example of Second-order Conditioning Phase 1: Phase 2: Test: Second-order conditioning! 31 31  8/09/2024 Example of second-order conditioning A conditioned fear of highways after a person travels down one following an accident with a truck. Fear of trucks is a first order-conditioned response since the vehicle was directly harmful Fear of highways is a second-order conditioned response since the highway (a formerly neutral cue) was not the cause of the trauma 32  8/09/2024 Limitations of Higher-Order Conditioning The CR to CS2 is weaker than to CS1 ~ 50% as strong. Higher-order conditioning is difficult to accomplish because conditioned inhibition also arises More pairings result in inhibition 33  8/09/2024 Sensory Preconditioning In second-order conditioning, one CS is capable of becoming associated with another CS … What if this pairing occurs before they acquire associative strength by pairing one of them with a US? 1. 2. 3. Or ? 34  8/09/2024 Sensory Preconditioning Stages Preconditioning Train light (CS2) metronome (CS1) Conditioning Train metronome (CS1) food (US) Test light (CS2) CR? OR 35  8/09/2024 Sensory pre-conditioning Conditioning Yes! A conditioned response (CR) to an untrained stimulus can even occur when the association between the conditioned stimulus (CS1) and the second neutral stimulus (NS2) is established BEFORE the first-order conditioned response is learned….. …this is called sensory pre-conditioning…. 36  8/09/2024 Sensory pre-conditioning Conditioning Phase 1: Phase 2: Test: Sensory pre-conditioning! 37 37  8/09/2024 Sensory Preconditioning & Second-Order-Conditioning Phase 1 Phase Test 2 Sensory Pre- Conditioning S2 S1 S1 US S2 Second-Order- Conditioning S1 US S2 S1 S2 Irrespective of the order of the training phases– both CSs can produce the CR 38  8/09/2024 Real world example sensory preconditioning Sensory preconditioning can happen a lot in our everyday lives. When two stimuli are associated with each other, if one becomes a CS, the other will become a CS too For example…. 39  8/09/2024 E.g. Neighbour has a large dog: Sensory Preconditioning Example CLASSICAL CONDITIONING (PART 2) LECTURE Neighbour (NS1)  dog (NS2) One day the dog bites you Dog(CS1)  bite (US) You become afraid (CR) of the dog (CS1) and develop a dislike of your neighbour (CS2)! 40  8/09/2024 Sensory Preconditioning To get the strongest CR: Timing is important – first CS must precede second CS Needs to be a contingency (one predicts the other) Can only do a few CS-CS pairings to prevent learned irrelevance i.e. metronome  light – if there is no consequence, then the association is irrelevant 41  8/09/2024 2. Variations and Limitations in Conditioning 1. Variations on basic classical conditioning The case of a CR without a US! Higher order conditioning Sensory pre-conditioning 2. Limitations in conditioning: When learning fails Overshadowing Blocking Latent inhibition 42  8/09/2024 Simultaneous Limitations of Classical Conditioning: presentation Overshadowing Conditioning with a Compound Simultaneous presentation CS i.e. simultaneously present Test elements of compound CS: Salient element “Bright Light” OVERSHADOWS Less salient “Metronome” element. 43  8/09/2024 Overshadowing can be used to prevent the forming of maladaptive associations Training phase: [Regular Food+ Novel Flavour](NS) : Chemo(US)sick(UR) [Regular Food+ Novel Flavour](CS)sick(CR) Test Phase: Novel flavour(CS)Sick(CR) but… Regular food(NS)no response e.g., to prevent conditioned taste aversions during chemotherapy and/or reduce anticipatory nausea 44 OFFICE | FACULTY | DEPARTMENT 44  8/09/2024 Limitations of Classical Conditioning: Overshadowing Harnessing classical conditioning during chemotherapy to minimise taste aversions: A salient/strong flavoured food is eaten with each chemotherapy session. An association is formed with this taste and chemotherapy induced nausea. This food (stimulus) overshadows the forming of taste aversions with the other flavours/food that the individual eats so their enjoyment of their favourite foods is not destroyed by an association with chemotherapy-induced nausea! 45  8/09/2024 Limitations of Classical Conditioning: Blocking Conditioning fails to develop if the individual does not register that any new (predictive) information is present… If an existing, learned association appears to provide all the information needed to predict the occurrence of the US, this existing association will serve to block the learner from developing a new association… 46  8/09/2024 Limitations of Classical Conditioning: Blocking Phase 1: Train Light CS Phase 2: Train Light CS in compound with Simultaneous presentation neutral (but equally salient) Metronome CS Phase 3: Test elements of compound individually: Pre-trained Light Blocks conditioning to Metronome From the learner’s perspective, there is no new info about when US will appear, so no need to learn anything! 47  8/09/2024 Limitations of Classical Conditioning: Latent Inhibition Metronome NO Salivation Several presentations of the metronome Neutral Stimulus – NS This new pairing is Metronome Food Salivation inconsistent with prior experience  NS US UR Metronome NO Familiar stimuli are more Salivation difficult to condition as CSs than are novel NS stimuli! Lubow, R. E. (1973). Latent inhibition. Psychological Bulletin, 79, 398–407. 48  8/09/2024 Real world example of latent inhibition Training phase 1: Fire alarm falsely goes over a couple of times a week Training phase 2: Fire alarm (NS) is paired with emergency/fire (US)  Fear (UR) Test Phase: Fire Alarm (CS)  ??? We learn that redundant stimuli in the environment are not important and should be ignored! OFFICE | FACULTY | DEPARTMENT 49 49  8/09/2024 Variations and Limitations in Conditioning Summary Conditioning of a NS, that is, the development of a CR, can occur without an US ― Higher order conditioning or secondary conditioning  The new NS is associated with a CS and can produce the same CR. ― Sensory pre-conditioning  If a NS is associated with another NS, which then becomes a CS, the first NS also becomes a CS and can produce the same response. Limitations in conditioning ― Overshadowing  After training, the less salient stimulus in a compound NS will fail to become a CS and will not produce the CR. ― Blocking  If a NS is conditioned to become a CS prior to being presented as a compound stimulus, it will serve to block the conditioning of the NS it is presented with. ― Latent inhibition  If a NS is presented without the US prior to the CSUS conditioning training, conditioning is impaired. 50 50  8/09/2024 Break Break Time 51  8/09/2024 3. Timing, Extinction and Inhibition What factors determine whether and how much classical conditioning occurs? 1. Impact of the temporal relationship between CS and US Short-Delay Simultaneous Trace Backward 2. How can we reduce or eliminate a behaviour? Extinction Spontaneous recovery Rapid Reacquisition Disinhibition 3. Inhibition phenomena Latent inhibition Conditioned inhibition External inhibition Inhibition of delay Disinhibition 52  8/09/2024 Determinants of Classical Conditioning 1. Intensity of Unconditioned Stimuli (US) 2. Excitatory Vs. Inhibitory Conditioned Stimuli 3. Time Relationships between Stimuli Simultaneous conditioning Delayed conditioning Aka forward conditioning Trace conditioning Backward Conditioning 4. Acquisition Extinction  spontaneous recovery 53  8/09/2024 Intensity of Stimuli Stimulus intensity influences the course of both appetitive and aversive classical conditioning More intense Conditioned Stimuli (CS) are more effective in accelerating the acquisition of a CR i.e. fewer trials needed  CR More intense Unconditioned Stimuli (US) are especially powerful Extremely intense aversive US can produce PTSD! 54  8/09/2024 Excitatory Vs. Inhibitory Stimuli To make our environment more predictable we search for relationships between stimuli. Some stimuli are predictive of the occurrence (+) of a stimulus and some are predictive of its absence (-). Both stimuli are just as important to learn about! 55  8/09/2024 Excitatory Conditioned Stimuli When the CS predicts the occurrence of the US, it becomes an excitatory conditioned stimulus (CS+). CS has a positive relationship with the US - CS acquires an ability to “excite” the organism - The CS activates behavioural and neural responses related to the US in the absence of the actual presentation of the US 56  8/09/2024 Inhibitory Conditioned Stimuli When the CS predict the absence of the US, it will become a conditioned inhibitory stimulus ( CS-) CS has a negative relationship with the US 57  8/09/2024 Why predict the absence of something? We function best in a predictable environment In bad environments (abusive) we need to know when we’re safe – so anxiety levels can drop. In good environments we need to know to seek alternatives Trackwork on train line so select alternative response – bus CS- Sign is an inhibitory stimulus it inhibits us from sitting on a bench for hours! 58  8/09/2024 Temporal Relationships between pairings a) Simultaneous conditioning: CS and US are presented and terminated together. b) Delayed conditioning: CS is presented alone for a while, then the US is presented and the CS & US typically terminate together. This is most effective way! c) Trace conditioning: CS begins and ends before US is presented. d) Backward conditioning: CS is presented after US is terminated. 59  8/09/2024 Temporal Relationships between pairings Most easily established Ease of conditioning depends on the length of the trace Very little conditioning established No conditioning i.e. CS can’t predict US 60  8/09/2024 Temporal Relationships: How do they compare? Simultaneous conditioning (CS and US presented at same time) Much weaker conditioning May be product of distraction of US If CS not before US, how can it serve as a signal? Trace conditioning (CS and US separated by longer time interval in which neither stimulus is present) “Memory trace”- requires memory As CS-US interval increase, so does the decline in level of conditioning 61  8/09/2024 Temporal Relationships between pairings Delayed conditioning is the most e ective (fastest) way of producing a strong conditioned response! But the optimal delay between the onset of CS and the onset of US is very short Typically ~0.5 – 1.0 sec. As the interval increases, CR usually weakens. When this gap is more than several seconds, no learning is achieved. (taste aversions are an exception!) Why do you think (short) delayed conditioning is most effective? 62  8/09/2024 Temporal Relationships Between CS and US What happens when there is a long delay? Onset of CS precedes US by at least several seconds CS continues until US presented Like Trace, CS-US interval impacts conditioning, but not as severe Pavlov’s dogs - 10 second Tone (CS) – Food (US) delay - 1st salivated as soon a tone presented - Over time, dogs began to estimate delay. Salivary response only occurs after 8-9 seconds. - Compound stimulus: Onset of Tone + delay 63  8/09/2024 Temporal Relationships Between CS and US Backward conditioning (CS presented after US) Level of conditioning markedly lower Order is important Predictiveness principle: The onset of CS signals a time in which the US will be absent 64  8/09/2024 Reducing, Eliminating, or Inhibiting a Behaviour Sometimes we need to decelerate a behaviour Some behaviours are bad for us or bad for society Punishment – subject of a later lecture Extinction Inhibition 65  8/09/2024 Extinction Extinction is a method for eliminating a conditioned response Extinction paradigm: Repeatedly present the conditioned stimulus (CS) alone (without the US) With repeated exposure to the CS, it stops being a predictor of the US and the CR decreases and eventually stops Systematic Desensitisation/Exposure therapy uses an extinction-like paradigm Represents gradual way to expose CS Highly e ective treatment for phobias and PTSD 66  8/09/2024 Virtual reality technology is sometimes used in exposure therapy 67  8/09/2024 Virtual reality technology is sometimes used in exposure therapy 68  8/09/2024 Acquisition, Extinction, and Spontaneous Recovery 69  8/09/2024 Acquisition, Extinction, and Spontaneous Recovery Extinction: Repetition of CS without US reduces CR. Spontaneous Recovery: After extinction, if there is a delay, the CS will often produce a weak CR. 70  8/09/2024 Extinction Occurs gradually After extinction, there is no CR. But CS-US association is not erased! Three phenomena illustrate this point: 1. Spontaneous recovery 2. Disinhibition 3. Rapid Reacquisition 71  8/09/2024 Relearning/Reacquisition E ect Extinguish CR Recondition with CS-US pairing Fewer trials required Rapid reacquisition! 72  8/09/2024 Acquisition, Extinction, and Spontaneous Recovery Spontaneous Acquisition Extinction Recovery Reacquisition Strength of CR CS&US CS alone CS alone CS&US Trials/Time 73  8/09/2024 Rate of Extinction: Total Duration Matters Most The number of trials does not determine rate of extinction The total duration of exposure to the CS determines how fast the CR is extinguished The impact of the duration, rather than the number of times an individual is exposed to the CS, is an important consideration for exposure therapy! Shipley, R.H. (1974). Extinction of conditioned fear in rats as a function of several parameters of CS exposure. Journal of Comparative and Physiological Psychology, 87(4), 699-707. 74  8/09/2024 Inhibition Phenomena Latent inhibition Pre-exposure to the CS (without the US) inhibits later learning (discussed earlier in this lecture) External inhibition – presence of a novel cue during conditioning inhibits the CR Conditioned Inhibition – a CS that predicts the absence of the US Inhibition of Delay – the CR is withheld until an appropriate time Disinhibition – removal of inhibition by the presentation of a novel stimulus 75  8/09/2024 Inhibition Phenomena Latent inhibition Pre-exposure to the CS (without the US) inhibits learning later (discussed in the previous lecture) External inhibition – presence of a novel cue during conditioning inhibits the CR Conditioned Inhibition – a CS that predicts the absence of the US Inhibition of Delay – the CR is withheld until an appropriate time Disinhibition – removal of inhibition by the presentation of a novel stimulus 76  8/09/2024 Pavlov’s “eureka” moment The dog is brought in….. Pavlov decided to demonstrate his discovery of conditioned responses to the other members of his academy…. 77  8/09/2024 Pavlov’s “eureka” moment ….but nothing happens The dog is on the bench in the lecture theatre looking at Pavlov, the metronome tick-tocks – but no drooling Why not? Pavlov had discovered external inhibition! 78  8/09/2024 Pavlov’s “eureka” moment The context has changed! The presence of the audience (a novel stimulus) inhibited the dog’s conditioned response (CR) of salivating And so Pavlov makes yet another serendipitous discovery … the phenomenon of inhibition of a CR 79  8/09/2024 Inhibition Phenomena Latent inhibition Pre-exposure to the CS (without the US) inhibits learning later (discussed in the previous lecture) External inhibition – presence of a novel cue during conditioning inhibits the CR Conditioned Inhibition – a CS predicts the absence of the US Inhibition of Delay – the CR is withheld until an appropriate time Disinhibition – removal of inhibition by the presentation of a novel stimulus 80  8/09/2024 Conditioned inhibition Conditioning in which a neutral stimulus is associated with the presentation of a US is known as excitatory conditioning. The result is that the CS (now called an excitatory CS or CS+) acquires the capacity to regularly elicit a CR. Conditioning in which the neutral stimulus is associated with the absence or removal of a US is known as inhibitory conditioning. The result is that the CS (now called an inhibitory CS, conditioned inhibitor or CS-) comes to inhibit the occurrence of a CR. 81  8/09/2024 Conditioned inhibition Conditioned inhibition has an important prerequisite: for the absence of a US to be a significant event, the US has to occur periodically in the situation There are many signals for the absence of events in our daily lives: Signs such as ‘Closed’, ‘Out of Order’ and ‘No Entry’ are of this type. However, these signs provide meaningful information and influence what we do only if they indicate the absence of something we otherwise expect to see. 82  8/09/2024 Conditioned inhibition General rule: inhibitory conditioning and inhibitory control of behaviour occur only if there is an excitatory context for the US in question Pavlov recognised this and provided such a context in his standard inhibitory training procedure: 1. Stimulus A is a metronome 2. Stimulus B is a light 3. Food is the US 4. Dogs as subjects 83  8/09/2024 Conditioned inhibition Definition: A CS signals the absence of an otherwise expected US. Standard Method: Conditioned Inhibition Procedure A+  US follows CS CSA Excitatory conditioning AB-  No US after compound CS CSA + CSB Inhibitory conditioning Why do you think that CSB is presented with CSA in stage 2? 84  8/09/2024 Pavlov’s procedure for conditioned inhibition Trial Type A On some trials (Type A), the CS+ (metronome) is paired with the US (food). Time On other trials (Type B), the CS+ (metronome) is presented with the CS- Trial Type B (light) and the US (food) is omitted. The procedure is effective in conditioning inhibitory properties to the Time CS- (light) 85  8/09/2024 What is learned in Conditioned Inhibition? There are two ways to interpret the inhibition results: 1. The light has become a conditioned inhibitor (i.e., its presence causes a reduction in the size of the CR) 2. The animal has learned nothing about the light on its own, and only about the compound CS as a unit To examine whether the light has developed inhibitory properties itself, other tests were developed... Homework: please read about summation and retardation tests 86  8/09/2024 Inhibition Phenomena Latent inhibition Pre-exposure to the CS (without the US) inhibits learning later (discussed in the previous lecture) External inhibition – presence of a novel cue during conditioning inhibits the CR Conditioned Inhibition – a CS that predicts the absence of the US Inhibition of Delay – the CR is withheld (inhibited) until an appropriate time Disinhibition – removal of inhibition by the presentation of a novel stimulus 87  8/09/2024 Inhibition of Delay ― Pavlov’s dogs  10 second Tone (CS) – Food (US) delay  At first, they salivated as soon a tone presented  Over time, dogs began to estimate delay. Salivary response only occurs after 8-9 seconds.  Compound stimulus: Onset of Tone + delay i.e., delay becomes part of the CS First Few Trials Later Trials CS CS US US UR CR UR CS = metronome US = food UR = salivation Time CR = salivation 88  8/09/2024 Inhibition Phenomena CLASSICAL CONDITIONING (PART 3) LECTURE Latent inhibition Pre-exposure to the CS (without the US) inhibits learning later (discussed in the previous lecture) External inhibition – presence of a novel cue during conditioning inhibits the CR Conditioned Inhibition – a CS that predicts the absence of the US Inhibition of Delay – the CR is withheld until an appropriate time Disinhibition – removal of inhibition by the presentation of a novel stimulus 89  8/09/2024 Disinhibition Disinhibition is the removal of inhibition the CR increases in strength Disinhibition can occur during extinction Presentation of a novel stimulus interrupts extinction E.g., disinhibition of the inhibition of delay occurred with a novel stimulus. - Kimmel (1965) CR was withheld for 4.0 secs, but only for 2.3 secs with a novel stimulus (i.e., when a novel tone was presented). 90  8/09/2024 Summary Numerous factors determine whether and how much conditioning is demonstrated E.g., stimulus intensity, the nature of the stimulus (excitatory/inhibitory), the presentation context (e.g., acquisition stage, during extinction etc.), and the temporal relationship between the CS and the US. Different temporal relationships between CS and US lead to differences in the size and nature of conditioning E.g., Short-Delay, Simultaneous, Trace, Backward Learning is not unlearned during extinction Spontaneous recovery, rapid reacquisition, and disinhibition demonstrate the enduring and complex nature of learning Inhibition phenomena are varied and insightful and demonstrate: the importance of context and novelty on conditioning that predicting the absence or delay of something is just as important as learning/predicting the presence of something 91  8/09/2024 Next Time Reminder that the next two weeks is a break from lecture! The Peer-Review Activity is due by the end of the first week of break (11:55pm Sunday, 22nd September) The next lecture topic is “Classical Conditioning – Continued!” Reading: The Mazur chapter titled “Theories and Research on Classical Conditioning” Make use of our PSYUX2236-2024-S2 Team for unit discussions, ask questions, or help answer questions from your peers! Have a good day! 92