Classical Conditioning Notes by Dr. Ilija Gallego The Simplest Type of Learning: Pavlovian or Respondent Conditioning Classical conditioning is based on Stimulus > Response A stimulus in anything you can pick up on using your senses The response is what you do as a result of coming into contact with a stimulus Responses in Classical Conditioning The responses in classical conditioning are all internal, involuntary, automatic, reflex type responses. This is true of the unconditioned response (UR) and the conditioned response (CR) Learning by Association In classical conditioning the learner learns by association. An association is involuntarily made between 2 stimuli. The association occurs because we pair a stimulus that always leads to an involuntary response (an unconditioned stimulus - US), with a stimulus that leads to no particular response (a neutral stimulus - NS) EXAMPLES OF UNCONDITIONED REFLEXES US Onion juice Food Touching hot object Extreme heat Extreme cold Increase in light Puff of air aimed at eye Loss Pain UR Tear up Salivate Pull away Sweat Shiver Pupils contract Blink Sadness Fear and avoidance
Formula for Classical Conditioning 1. Before Conditioning (Learning) A neutral stimulus (NS) (one that elicits no response) is chosen. An unconditioned stimulus (US) is chosen. This is a stimulus that always leads to an internal, involuntary, automatic, reflex type response. The US elicits an unconditioned response (UR) (an internal, involuntary, automatic, reflex type response). This is the unconditioned (unlearned) response. 2. During Conditioning The neutral stimulus is paired with the US. The US stimulus elicits an UR. The UR is an internal, involuntary, automatic and INBORN response. The pairing of the stimuli is usually done repeatedly. 3. After Conditioning The neutral stimulus is presented alone. If it elicits a response, then it is no longer neutral. We now call it a conditioned stimulus (CS). The response elicited is internal, involuntary, automatic and reflex like, but it is not inborn it is LEARNED. We call this the conditioned (learned) response. Analysis to Pavlov s Work Before Conditioning Bell (Neutral Stimulus) > No response Food (US) > Salivation to Food (UR) During Conditioning Bell (NS) is Paired with the Food (US) > Salivation to Food (UR)
After Conditioning Extinction Bell > Salivation to the Bell (CR) The bell is no longer a NS, but has become a CS Pairings of the CS and US lead to conditioning whereas presentation of the CS only leads to loss of the conditioned response Extinction refers to loss of CR due to the CS presented without the US Extinction is useful in clinical situations Extinction of a phobia can be treated by exposure to the CS only Spontaneous Recovery Sometimes after extinction the CR returns. This shows us that the response is gone but not forgotten. The learner does not think, Oh, there is the CS, I ll make a CR now. There is no thinking involved in classical conditioning. Instead the CR is made involuntarily. Conditioning of Emotional Responses John Watson documented that conditioning of emotional responses in the Little Albert study NS/CS: a white rat US: a loud banging sound UR: fear/startle response Eventually Albert exhibited a learned fear (CR) to the white rat (NS became the US) Other instances of classical learning Positive: conditioning of attraction in advertising Brand name (CS) + model (US) => positive reaction to product
Generalization Negative: aversion Flavor (CS) + illness (US) => flavor aversion This is when the learner makes a CR to a stimulus that is not the CS, but is similar to it. Examples Discrimination Pavlov s dogs salivate to a tone that is similar to the bell, but is not the original bell A person becomes afraid of all dogs (or some dogs) after being bitten by one dog. Little Albert became afraid of white furry things The learner distinguishes between the CS and other similar stimuli. S/he responds (makes a CR) only to the CS. Examples Pavlov s dogs are taught to salivate to ding but not to dong. A person becomes afraid of only the dog that bit him/her. 4 FACTORS INFLUENCING CLASSICAL CONDITIONING 1. Number of pairings (learning trials) between the US and the CS More trials leads to stronger CR 2. Intensity of the US Higher intensity leads to stronger CR and faster learning of CR 3. Consistency of the CS and US pairings Higher consistency leads to more consistent and stronger CR 4. Temporal relationship (timing) between the CS and the US
4 Subtypes of Classical Conditioning Based on the temporal relationship between the CS and the US Delayed Conditioning Trace Conditioning Simultaneous Conditioning Backwards Conditioning 1. Delayed Conditioning Bell (CS) is rung BEFORE AND DURING the time that the food (US) is given Bell (CS) comes BEFORE the food (US) Presentation of bell (CS) OVERLAPS with the presentation of the food (US) 2. Trace Conditioning Bell (CS) is rung BEFORE BUT NOT DURING the time that the food (US) is given Bell (CS) comes BEFORE the food (US) Presentation of bell (CS) DOES NOT OVERLAP with the presentation of the food (US) 3. Simultaneous Conditioning Bell (CS) is rung only DURING the time that the food (US) is given Bell (CS) comes with, but NOT BEFORE the food (US) Presentation of bell (CS) OVERLAPS with the presentation of the food (US) 4. Backwards Conditioning Bell (CS) is rung AFTER the food (US) is given Bell (CS) DOES NOT COME BEFORE the food (US) Presentation of bell (CS) DOES NOT OVERLAP with the presentation of the food (US)
Determining the Effectiveness of the Subtypes 1. Does the subtype allow for the learner to passively ANTICIPATE what they are focused on (the US or food)? The CS must come before the US 2. Does the subtype maximize the likelihood that the learner will make a passive ASSOCIATION between the CS (bell) and the US (food)? The CS and US must overlap in time Evaluating the Effectiveness of the Subtypes Delayed: anticipation & association Most effective Trace: anticipation, but not association Somewhat effective Simultaneous: association, but not anticipation Not very effective Backwards: neither anticipation, nor association Barely effective or completely ineffective Exceptions to the Rules: One Trial Learning Some CRs can be learned after only one pairing between the NS and the US Example: Learning to fear a dog or all dogs from having been bitten once Nonetheless, more pairings does lead to stronger learning. How afraid of dogs would you be if you were repeatedly bitten? Taste Aversion Learning to dislike a food or taste often happens in only one trial. Typically it happens in a trace conditioning pattern, but the time between having a certain food or taste and becoming ill can be as long as 12 hours, and we might still develop the taste aversion.
Summary of Classical Conditioning Learning occurs through pairing 2 stimuli Responses, both inborn (UR) and learned (CR) are involuntary, automatic, internal. No thinking is involved. Learner is passive Learner is focused on the US Responses learned include only simple responses such as reflexes, likes and dislikes, fears and emotional responses