Chapter 6: Learning

Conditioning

• Can lead to some very unique behaviors– Phobias…

• Classical Conditioning: a type of learning where a stimulus acquires the ability to give a response that was originally caused by another stimulus– In English- …

Classical Conditioning

• Ivan Pavlov: prominent Russian physiologist in the early 1900’s, who did Nobel prize winning research on digestion, – discovered (partly by accident) that dogs

will salivate in response to the sound of a tone.

– In doing so, he discovered classical, Pavlovian, conditioning.

Classical Conditioning

• Terminology – Unconditioned Stimulus (UCS): a stimulus that

elicits an unconditioned response without previous conditioning…Pavlov’s meat powder.

– Conditioned Stimulus (CS): a previously neutral stimulus that has acquired the capacity to elicit a conditioned response...the sound of a tone

– Unconditioned Response (UCR): an unlearned reaction to a UCS that occurs without previous conditioning…salivating

– Conditioned Response (CR): a learned reaction to a conditioned stimulus…salivating to the tone

Figure 6.1 Classical conditioning apparatus

Figure 6.2 The sequence of events in classical conditioning

Classical Conditioning

• Conditioned responses:– Conditioned fears: bridges, dentist, storms– Pleasant Emotions: love (gum), that is why

barely clothed women sit on truck hoods– Physiological Responses:

immunosuppressant drugs and weird tasting liquid in animals, allergic reactions, drug tolerance, withdrawal symptoms, sexual arousal, fetishes

Figure 6.3 Classical conditioning of a fear response

Classical Conditioning: More Terminology

• Trial = pairing of UCS and CS… (How many times have the tone and the meat powder been paired?) Some behaviors are learned after only one trial or pairing, while others take many trials.

• Acquisition = initial stage in learning, acquiring the response

• Stimulus contiguity = Conditioning has been shown to depend on stimulus contiguity; that is, the occurring of stimuli together in time and space

Classical Conditioning: More Terminology

• 3 types of Classical Conditioning– Simultaneous conditioning: CS and UCS

begin and end together– Short-delayed conditioning: CS begins

just before the UCS, end together, • appears to most promote acquisition of a

classically conditioned response. ideally the delay should be very brief, about ½ a second.

– Trace conditioning: CS begins and ends before UCS is presented

Processes in Classical Conditioning

• Extinction: occurs when the CS and UCS are no longer paired and the response to the CS is weakened– We know that the response is still there, just not

active, because of spontaneous recovery• Spontaneous Recovery: an extinguished response

reappears after a period of non-pairing.• Stimulus Generalization: occurs when conditioning

generalizes to additional stimuli that are similar to the CS; – for example, Watson and Rayner’s study with

Little Albert, who was conditioned to fear a white rat but later came to be afraid of many white, furry objects.

Figure 6.7 Acquisition, extinction, and spontaneous recovery

Processes in Classical Conditioning

• Discrimination: the opposite of generalization; that is, the response is to a specific stimulus– similar stimuli don’t work

• Higher-order conditioning: occurs when a CS functions as if it were a UCS to establish new conditioning…– condition to respond to a tone with saliva,

pair the tone with a light.

Figure 6.10 Higher-order conditioning

Operant Conditioningor Instrumental Learning

• Operant Conditioning– Learning in which responses come to be

controlled by their consequences• Classical conditioning regulates

involuntary responses, operant cond. voluntary responses (not absolute)

–Some argue they are 2 different aspects of a single learning process

Operant Conditioningor Instrumental Learning

• Edward L. Thorndike (1913) – Thorndike’s law of effect stated that if a response in the presence of a stimulus leads to satisfying effects, the association between the stimulus and the response is strengthened.

• This law became the cornerstone of Skinner’s theory.

Operant Conditioningor Instrumental Learning

• B.F. Skinner (1953) – principle of reinforcement: – organisms tend to repeat those responses

that are followed by favorable consequences, or reinforcement.

• Operant chamber or “Skinner box”: small enclosure in which an animal can make a specific response that is recorded, while the consequences of the response are systematically controlled

Operant Conditioningor Instrumental Learning

– Emission of response: Because operant responses tend to be voluntary, they are said to be emitted rather than elicited.

– Reinforcement contingencies: the circumstances, or rules, that determine whether responses lead to the presentation of reinforcers.

– Cumulative recorder: creates a graphic record of responding and reinforcement in a Skinner box as a function of time

Figure 6.12 Reinforcement in operant conditioning

Figure 6.13 Skinner box and cumulative recorder

Figure 6.14 A graphic portrayal of operant responding

Basic Processes in Operant Conditioning

• Acquisition: initial stage of learning• Shaping: gradual process which consists of

the reinforcement of closer and closer approximations of a desired response…key in pet tricks

• Extinction: the gradual weakening and disappearance of a response tendency, because the response is no longer followed by a reinforcer…stop giving food when the rat presses the lever…results in a brief surge of responding followed by a gradual decline until it approaches zero

Basic Processes in Operant Conditioning

• Stimuli that precede a response can exert considerable influence over operant behavior, basically becoming “signals” that a reinforcer is coming

• Discriminative stimuli are cues that influence operant behavior by indicating the probable consequences of a response

• Stimulus Control– Generalization: occurs when a new stimulus is

responded to as if it were the original – Discrimination: occurs when an organism

responds to one stimulus, but not another one similar to it

Table 6.1 Comparison of Basic Processes in Classical and Operant Conditioning

Reinforcement:Consequences that Strengthen Responses

• Primary Reinforcers– events that are inherently reinforcing because they

satisfy biological needs• Primary reinforcers in humans include food,

water, warmth, sex, and maybe affection expressed through hugging and close bodily contact.

• Secondary Reinforcers– events that acquire reinforcing qualities by being

associated with primary reinforcers.• Secondary reinforcers in humans include things

like money, good grades, attention, flattery, praise, and applause

Schedules of Reinforcement

• Continuous reinforcement: when every instance of a designated response is reinforced (faster acquisition, faster extinction).

• Intermittent reinforcement occurs when a designated response is reinforced only some of the time (greater resistance to extinction).

Schedules of Reinforcement

• Intermittent (partial) reinforcement– Ratio schedules: require the organism to

make the designated response a certain number of times to gain each reinforcer• Fixed: entails giving a reinforcer after a

fixed number of non-reinforced responses

• Variable: entails giving a reinforcer after a variable number of non-reinforced responses

Schedules of Reinforcement

– Interval schedules: require a time period to pass between the presentation of reinforcers• Fixed: reinforcing the first response that

occurs after a fixed time interval has elapsed

• Variable: entails giving the reinforcer for the first response after a variable time interval has elapsed

Figure 6.17 Schedules of reinforcement and patterns of response

Schedules of Reinforcement

Number of Times Amount of Time

Know Fixed-Ratio Fixed Interval

Don’t Know Variable-Ratio Variable-Interval

Schedules of Reinforcement

• Now Ask:– 1) What is the reward?– 2.  Do I know or not know WHEN I will get

the reward (note:  not if...when!  This will help with the confusion). 

– 3.  By me repeating a behavior will that bring my reward FASTER (not will it bring it - you always assume you will get the reward).  (If you answer yes it is under the number of times, if no it is amount of time)

Consequences:Reinforcement and Punishment

• Responses can be strengthened either by presenting positive reinforcers or by removing negative reinforcers :– Positive reinforcement = response followed by

rewarding stimulus– Negative reinforcement = response followed by

removal of an aversive stimulus, regulates escape and avoidance learning

• Escape learning: an organism learns to perform a behavior that decreases or ends aversive stimulation (turning on the air conditioner).

• Avoidance learning: an organism learns to prevent or avoid some aversive stimulation (turn on the a/c before it gets too hot).

Consequences:Reinforcement and Punishment

• Decreasing a response:– Punishment: occurs when an event following a

response weakens the tendency to make that response

• Punishment is much more than disciplinary procedures…wear a new outfit and friends laugh…punishing.

• Punishment may involve presentation of an aversive stimulus (spanking) or removal of a rewarding stimulus (taking away TV).

– Problems with punishment: can trigger strong emotional responses (anxiety, anger, resentment, hostility); physical punishment can lead to an increase in aggressive behavior

Figure 6.18 Positive reinforcement versus negative reinforcement

Figure 6.19 Escape and avoidance learning

Figure 6.20 Comparison of negative reinforcement and punishment

Changes in Our Understandingof Conditioning

• Biological Constraints on Conditioning– Instinctive Drift: occurs when an animal’s innate

response tendencies interfere with conditioning, • (the raccoon who would rather rub the coins

together than obtain the reinforcer).– Conditioned Taste Aversion: can be readily

acquired, after only one trial and when the stimuli are not contiguous

• becoming ill occurs hours after eating a food• suggesting that there is a biological mechanism

at work.

Figure 6.22 Conditioned taste aversion

Changes in Our Understandingof Conditioning

• Preparedness and Phobias– Martin Seligman has outlined the fact that

some phobias are more easily conditioned than others,

– Preparedness: we are biologically prepared to learn to fear objects or events that have inherent danger.• Spiders, snakes, bad tasting foods

Changes in Our Understandingof Conditioning

• Cognitive Influences on Conditioning– Signal relations: (Rescorla) illustrates that the

predictive value of a CS is an influential factor governing classical conditioning.

• Rats and shocking (100% vs 50%)

Changes in Our Understandingof Conditioning

– Response-outcome relations: when a response is followed by a desired outcome, it is more easily strengthened if it seems that it caused the outcome (predicts)…

• you study for an exam and listen to Frank Sinatra…you make an A. What is strengthened, studying or listening to Frank Sinatra?

• We try to figure out what behaviors lead to what in order to minimize aversive situations and maximize pleasant ones

Changes in Our Understandingof Conditioning

• Evolutionary Perspectives on learning– assumes that an organism’s biological

heritage places certain constraints on the learning process

– some theorists see as merely specialized mechanisms designed to solve particular types of adaptive problems for particular species

Latent Learning

• Learning not apparent from behavior when it first occurs– Learning can take place when no

reinforcement is given– The Rats in Tolman’s study formed a

cognitive map (spatial layout)

Observational Learning: Basic Processes

• Albert Bandura (1977, 1986) outlined the theory of observational learning– Observational learning : vicarious

conditioning occurs by an organism watching another organism (a model) be conditioned• Observational learning can occur for

both classical and operant conditioning–Vicarious conditioning: being

conditioned indirectly by virtue of observing another’s conditioning

Observational Learning: Basic Processes

• In order for observational learning to take place, 4 key processes are at work

• 4 key processes– Attention: the organism must pay attention

to the model– Retention: retain the information observed– Reproduction: be able to reproduce the

behavior– Motivation: observed response is unlikely

to be reproduced unless the organism is motivated to do so

Observational Learning: Basic Processes

• acquisition vs. performance– Bandura distinguishes between acquisition (having

the response in your repertoire) – performance (actually engaging in the behavior)

• Bandura asserts that reinforcement usually influences already acquired responses, more than the acquisition of new responses.

Figure 6.25 Observational learning

Featured Study

• Bobo Doll (Bandura)– 80 Children (average age 4)– Watched 3 different film clips (rewarded

aggressive behavior, punished aggressive behavior, non-aggressive behavior) or no clip

– Put in a room with toys and psyc. Observed play behaviors

• Children who watched rewarded agg. behavior clip were much more violent, children who did not watch a clip were least aggressive