Learning: What does it mean to learn? • Learning is the single largest area of Psychology second only to clinical psychology
I. Classical Conditioning – learning through association • Philosophical roots: English Empiricists • John Locke – Primary and Secondary Qualities • David Hume – Reflection , Cause and Effect
Ideas • Anything that stimulates the CNS
1. Pavlov and the conditioned reflex • The procedure is what distinguishes classical conditioning from other modes of learning
Classical Conditioning in America was Stated by Watson and Rayner (1920) • Albert was set on a rug, held by Rayner and presented with a fuzzy rabbit. • Watson slammed two sticks together behind Albert as he reached for the animal. • After several trials Albert began to cry when the rabbit was presented
Habituation • Works at the neuron level to organismic level. • Habituation decreases the responses over time both for magnitude and frequency per unit time. • The most basic level of learning. Requires no reinforcement.
Habituation (cont.) • Habituation allows the organism to ignore irrelevant stimuli. • Dishabituation is the stopping of habituation to an attended stimuli
Condition Stimulus (CS) • A neutral stimulus, can be sound, light or internal craving.
Uncondition Stimulus (UCS) • The natural stimulus that drives the CNS to elicit the reflex. • In the vernacular of instrumental learning this hookup of the UCS-UCR is known as the reinforcement.
Uncondition response (UCR) • The basic reflex that is become controlled by procedure.
Reinforcement vs Reward • One reinforces a response! • One rewards the animal!
Condition Response (CR) • The response when driven by the Condition Stimulus
2. Major phenomena of classical • Two types of “effective” procedures that lead the animal to predict up coming events.
Critical Measures: ½ mm movement is a response, Latency to onset of movement, Latency to peak of response.
3 Characteristics of Delay Conditioning • The CS starts before the UCS
There is a time period between when the CS in On and the start of the UCS – known as the Inter-Stimulus-Interval (ISI).
The association • The explicit pairing of the CS with the UCS • (in eye-blink, if tone and then air-puff) sets up the contingency that leads the animal to predict what is to come. • This analysis of expectation was put forth by Rescorla.
3 Characteristics of Trace Conditioning • The CS starts before the UCS
The time period between the CS turns “Off” and the UCS comes “On” is the trace interval (the inter – stimulus – interval).
The animal must remember to delay its response, and respond only at the end of the trace interval.
Backward Conditioning (cont) • UCS comes “ON” before the CS. • UCS goes “OFF” with “ON- set” of CS • Ineffective for producing a conditioned response.
Formal Classical Conditioning is a Three Stage Process • Habituation – Paired Training - Extinction
Pavlov’s study • Condition stimulus, CS, was the sound of a metronome (will become the condition reinforcer)
The Uncondition Stimulus (UCS) was meat powder (the reinforcer).
Trial - By - Trial Presentation • Trials are presented singularly and continues until some criterion is met or a fixed number of trials completed.
Paired trials • When both the CS and the UCS are presented in a fixed order and time frame • (an explicitly paired trial).
CS Alone Trials • Periodically only the CS is presented • Known as CS alone trials. • Measure the effectiveness of the CS to drive the behavior
Statistics • Mean and SD change in the timing or magnitude of the paired trials. • Mean and SD of the CS alone trials
Results • In the beginning trials the CS does not elicit the CR
Across trials there is a change in the ability of the CS to drive the CR. The change increase as the trials progress. • The CR looks like the UCR, but micro analysis of the two behaviors will show clear difference
Results of Explicit Pairing CS-UCS • By the end of the trials, both for paired and CS alone trials, the CS is able to elicit the CR. • Magnitude increases, time shortens or frequency changes for the behavior
How does one know that one has stimulus control? • Use Extinction trials.
Present the trials in the manner of Habituation (but is not habituation) • Repeated presentation of the CS alone will drive the changes that were learned during CS presentation to zero.
EXTINCTION • Note at the beginning of day 2, the first response is larger than last response on day one. Called spontaneous recovery.
Generalization vs discrimination • Generalization is the tendency to respond to like stimuli the same way. • If a rabbit is trained on a 1200Hz tones, to a critiereon, his percent correct for a 800, or a 1600Hz tone will be less than the 1000Hz tones • See next slide
Discrimination training • The correct stimulus is explicitly paired with a given reinforcement (see Mauk and Ruiz slides 65- 71 below). • Or two different responses are paired with two explicitly different stimuli.
Eyeblink Studies • First done by Ernest Hilgard in humans, dogs and monkeys 1928 – 1936).