Paradigm
-Experimental Pattern
-Conceptual framework through which a scientist views the research in his field
Four Basic Experimental Paradigms
- Habituation and Sensitization
- Classical Conditioning
- Instrumental Conditioning
- Operant Conditioning
Habituation
-the decrease of an innate reaction to a stimulus due to repetition
-the unconditioned response decreases
-i.e. you hear the tone constantly and it eventually decreases in conditioning
-more effective with the repetition of a weak stimulus than a strong one
-shows stimulus generalization and spontaneous recovery
Dishabituation
-unconditioned stimulus is repeatedly presented, resulting in habituation of the unconditioned response
-Pavlov’s description – disinhibition: a recovery of the response, due to presentation of a strong stimulus like a loud noise
-a temporary increase in the strength of the response which leaves the underlying habituation intact
Extinction
-A learned response to a conditioned stimulus grows weaker because the conditioned stimulus is presented without the unconditioned stimulus
–Elimination of the UCS and presentation of the CS alone results in extinction
Spontaneous Recovery
-if time is allowed to pass following extinction and the CS is again presented alone, the CR will show spontaneous recovery
Sensitization:
-The opposite of habituation
-The unconditioned response increases in responsiveness
-does not have long lasting effects
-more effective with the repetition of a strong stimulus
-A higher form of learning than habituation
Example of Habituation and Sensitization
Habituation: Your neighbor’s radio is playing at a low level and you get accustomed to it and it slowly doesn’t bother you
Sensitization: Your neighbor’s radio is playing very loudly and you become more and more distracted
Pseudoconditioning
-a result that is mistaken for conditioning
Classical Conditioning
-Pavlov and Twitmeyer
-Also known as: Pavlovian conditioning and respondent conditioning
-Process by which a neutral stimulus PCS) comes to be associated with another stimulus PUCS) that elicits a response PUCR) -CS + UCS = UCR
Unconditioned Stimulus PUCS)
-biologically potent stimulus that evokes an unlearned or reflexive reaction -i.e. food
Conditioned Stimulus PCS)
-biologically weak stimulus, initially neutral
-the CS may evoke an orienting response but not the strong response evoked by the US
Unconditioned Response PUCR)
-the unlearned response triggered by the US
-powerful and reflexive -i.e. salivation to food
Conditioned Response PCR)
-Elicited by the CS and represents the learned behavior
Temporal Arrangements of CS and UCS
Simultaneous: when the CS and UCS happen at the same time
Delay: the CS stays on until the UCS is presented Pa delay of .5-1.0 second is most effective)
Trace: the CS goes on and off some time before the UCS is presented
Backward: the UCS precedes the CS Pdifficult to achieve)
Temporal: there is no CS; the UCS is just repeated continuously
Higher-Order Conditioning
-Established in 2 stages
-Refers to a situation in which a stimulus that was previously neutral Pe.g., a light) is paired with a conditioned stimulus Pe.g., a tone that has been conditioning with food to produce salivating) to produce the same conditioned response as the conditioned stimulus.
- CS1 Plight) + UCS Pfood) = salivation
- CS2 Pbuzzer) + CS1 Plight) + no UCS
Compound Stimulus Conditioning
-a compound stimulus, composed of CS1 and CS2 is paired with the UCS
-configuring: when the animal only responds to the compound as a whole and not individual parts
Blocking
-prior conditioning of one component of the compound stimulus apparently prevents or blocks the conditioning of the other component
-i.e. if CS1 was presented in the first trial and CS2 is presented in the second trial, CS1 will have more of an effect to elicit the conditioned response PCR) whereas CS2 will not.
Instrumental Conditioning
-Edward Thorndike
-The behavior learned is instrumental in obtaining some desired outcome or reward Preinforcement)
-Trial-by-trial learning
-Ex: Puzzle Box Experiment
Thorndike’s Puzzle Box Experiment
-a hungry cat is placed in a puzzle box
-food is placed outside of the box
-the cat must press a lever to escape and get the food
–Escape Latency: the amount of time it took for the correct response to occur
-Over time the cat’s latency became shorter and shorter Pas in, it took less time for the cat to press the lever to go and get the food)
-The reinforcers: the food and the confines of the box
Difference Between Instrumental Conditioning and Classical Conditioning
–Instrumental: the reinforcer Psuch as food) is only presented when an animal first makes an appropriate response
-Classical: the reinforcer Punconditioned stimulus) does not depend on whether or not the animal first responds
Complex Maze
-start box: where the animal is placed in initially
-goal box: which contains the award
-pathway: links the start and the goal boxes
-experimenter measures the number of errors and the speed of the animal
T-Maze
-shaped like a T; has a start box at its base and a single choice point branching off toward two goal boxes
-places one reward, like sugar water, in one goal box and plain water in another goal box -used to study preferences and discrimination learning
The Straight-Alley Maze
-start box and goal box with runway in between
-measures response latency Ptime) and speed
-can also be used to study discrimination learning Pgo – no go discrimination: a tone is sounded when the animal is in the start box – high tone = food, low tone = empty)
Shuttle Box
-Studies the effects of aversive stimuli such as electric shock
-2 compartments separated by a barrier in which the animal must jump over
–Escape learning: the response that will terminate the aversive stimulus with no warning Pi.e. jumping over the barrier)
-Avoidance learning: the animal predicts that the aversive stimulus is there, usually because of a warning signal – by responding, the animal can avoid contact with the aversive stimulus
Reinforcement
-a manipulation that, if it follows a particular response, increases the tendency of that response to occur again
Positive Reinforcer
-the presentation of a stimulus
Negative Reinforcer
-the removal or termination of a stimulus
-ex: escape learning Panimal is shocked and will escape the room because of the negative reinforcer)
Primary Reinforcers
-stimuli that are reinforcing because of the animal’s genetic makeup rather than experience
Primary Positive Reinforcers
–appetitive stimuli that a deprived animal will approach, such as food, or water
Primary Negative Reinforcers
–aversive stimuli that an animal will learn to avoid Psuch as a shock)
Punishment
-following a response with the presentation of an aversive stimulus
-i.e. aversive stimulus response
Reinforcement Parameters Amount of Reward:
-the larger the reward, the greater the speed -the larger the reward, the shorter the latency Delay of Reward:
-the time between performance of the response and administration of reinforcement
Grice’s Rat Study on Black-White Discrimination
-the shorter the delay, the more quickly the animals learned
-the animals with a 10 second delay of reward showed no evidence of improvement over the 50% rate even after several hundred trials
Classical and Instrumental Conditioning Both Use:
-extinction
-spontaneous recovery
Continuous Reinforcement
-Rewarding an animal on every trial P100 percent)
Partial Reinforcement
-Rewarding the animal on some fraction of the trials
Partial Reinforcement Effect PPRE)
-partial reinforcement groups extinguish more slowly than those of a group receiving continuous reinforcement
-Ex: Bower’s Straight-Alley Runway Experiment: the running of a rat group that had been receiving 100% reinforcement extinguished more rapidly than those that had received 50% reinforcement or less. Therefore, partial reinforcement = less extinction
Operant Conditioning
-B. F. Skinner
-i.e. Skinner Box
-animal can make a response at any time
Skinner Box
-consists of a chamber, a floor, a food dispensing machine, and a manipulandum Pa lever)
-secondary stimuli Pdiscriminative stimuli): a tone or light
-behavior is recorded by a cumulative recorder and cumulative curve Pif animal responds at a fast rate = curve is steep, at a slow rate = curve is gradual)
Free Operant
-a response like pressing a lever, which the subject can repeat as often as desired
Two Areas of Investigation in Operant Conditioning
-schedules of reinforcement
-investigation of control of behavior by discriminative stimuli
Reinforcement Schedule
-a rule relating to the presentation of reward to the behavior of the animal
-continuous reinforcement: animal receives an award every time the correct response is made
-intermittent schedules: not all responses are reinforced
-ratio schedules: there is a predetermined ratio of responses to reinforcements Pthe more responses per unit time, the more reinforcements are received)
–fixed-ratio schedule: every nth response is reinforced Pif n=5 then the animal must make 5 responses to get an reward)
-variable-ratio schedule: the animal must make a certain number of responses to obtain the reward but n varies from one reward to the next Pif n=5 the first time, then n might equal another number the next time) [ex: game of chance]
–interval schedules: regardless of behavior, a certain period of time must follow a reward before another reward can be obtained Pstrictly limited time)
-fixed-interval schedules: responses are rewarded no more often than once every t seconds Pon a
60-second schedule, the animal can receive at the most one reinforcer every 60 seconds)
[scallop: following each reward, there is a pause and then a gradual increase in response rate] -variable-interval schedules: a certain time interval must elapse after each reward before another reward can be obtained, but the length of time varies
Extinction is fastest for: -continuous reinforcement
Extinction is slowest for:
-variable-ratio and variable-interval schedules
DRL Schedules Pdifferential reinforcement of a low rate of responding)
-reinforcement can only occur when an animal responds at a slow rate
Response Differentiation
-deliberate manipulation of characteristics of an animal’s response, such as its force
Stimulus Control
-if a stimulus is present whenever responding leads to reinforcement and is absent when it does not, the animal learns to respond only when the stimulus is present
Discriminative Stimuli PS D and S Δ)
S D
-the stimulus that signals availability of reward
-response rates are higher the more the test stimulus resembles the SD
S Δ -the stimulus that signals non-availability of reward
Peak Shift
-there is a shift in the peak of the generalization gradient
-the behavioral response bias arising from discrimination learning in which animals display a directional, but limited, preference for unusual stimuli or avoidance of unusual stimuli
Fading
-does not produce a peak shift
-an initial prompting to perform an action is gradually withdrawn until the need for it fades away -produces errorless discrimination learning
Animal Psychophysics
-the investigation of the sensory capabilities of animals
Summary: A Comparison of Paradigms
UCS: a stimulus reflexively eliciting an innate response
Habituation: a decrease in the strength of the UCR
Sensitization: an increase in the strength of the UCR Classical Conditioning: CS + UCS
Instrumental Conditioning: animal makes a response and is rewarded, either by positive or negative reinforcers
Operant Conditioning: the animal makes a response which is then reinforced; the response is freely available and there are no trials, which increases the rate or frequency with which the response is made
Habituation and Sensitization Compared with Conditioning
-Both display stimulus generalization and fading
-Habituation is like extinction of a conditioned response, decreases in response strength with repetition but also shows spontaneous recovery over time
-Dishabituation, produced by an intense extraneous stimulus, is like disinhibition in classical conditioning
Classical Conditioning vs. Instrumental and Operant Conditioning
-The UCS in Classical Conditioning plays a role similar to the reward in instrumental conditioning
-In classical conditioning, the reinforcer is presented just after the CS Pcontingent on the stimulus)
-In instrumental conditioning, the reinforcer is presented just after the response Pcontingent on the response)
-Instrumental conditioning will only occur if the response that is to be conditioned does not easily habituate
OR Porienting response):
-when an animal hears or feels something and he orients himself in a particular way, i.e. perks his ears or looks up
Autoshaping:
-a light is turned on shortly before the pigeons are given food
-the pigeons naturally peck Punconditioned response) at the food Punconditioned stimulus)
-through learning, the pigeons come to peck Pconditioned response) at the light source Pconditioned stimulus) that predicts food
Secondary Reinforcement: A Mixed Paradigm
-reinforcing power is acquired through learning
-secondary reinforcement refers to a situation in which a stimulus reinforces a behavior after it has been associated with a primary reinforcer
-Can be positive or negative
-Secondary Negative reinforcer: pairing a neutral stimulus with a primary negative reinforcer, such as a shock
-Money is one example of secondary reinforcement. Money can be used to reinforce behaviors because it can be used to acquire primary reinforcers such as food, clothing, shelter and other such things.
-Animal trainers sometimes use clickers as a type of secondary reinforcement. After pairing the sound of a clicker with praise or treats, the sound of the clicker alone can eventually work as a reinforcer.
Saltzman’s Secondary Reinforcement Experiment
- rats are fed in the goal box
- rats are given 15 trials of running a maze, with the choice between 2 paths
- the rats were not fed in the maze, but they learned to pick the correct path that was associated with where they were fed originally
*the secondary reinforcers lose their power if they are not occasionally paired with primary reinforcers
Fear Conditioning
-the paradigm for demonstrating secondary negative reinforcement is often referred to as fear conditioning
-ex: the animal becomes afraid of a certain place because it was originally shocked there
Watson’s Little Albert Experiment:
-the baby performed an instrumental response Pcrawling away) to escape the white rat, which became a secondary reinforcer by being paired with the loud noise -example of secondary reinforcement fear conditioning