Chapter 6 Learning and Behavior

Learning n A more or less permanent change in behavior that results from experience

Behavior n The ways in which animals act or respond in an environment –influenced by both biological and learned components

Richard Dawkins: Memes n A cultural invention that is passed on from one generation to the next n Marvin Harris (1974) –“Our primary mode of biological adaptation is cultural not anatomical”

Ivan Pavlov n Learning is an associative process –Pavlov studied a learned association between a neutral stimulus and a reflexive response

Classical Conditioning n US - Unconditioned Stimulus –stimulus that evokes the behavioral response of interest (Meat powder) n UR - Unconditioned Response –the reflexive response to the presentation of the US (Salivation) n NS - Neutral Stimulus –a stimulus that does not result in an unconditioned response (Bell)

Classical Conditioning NS (Bell) No UR (No Salivation) Before Conditioning produces

Classical Conditioning Before Conditioning NS (Bell) No UR (No Salivation) produces US (Meat) UR (Salivation) produces

Classical Conditioning NS (Bell) + US (Meat) UR (Salivation) During Conditioning produces + Trial 1

Classical Conditioning NS (Bell) + US (Meat) UR (Salivation) During Conditioning produces + Trial 2

Classical Conditioning NS (Bell) + US (Meat) UR (Salivation) During Conditioning produces + Trial 3

Classical Conditioning NS (Bell) + US (Meat) UR (Salivation) During Conditioning produces + Trial 4

Classical Conditioning CS (Bell)CR (Salivation) After Conditioning produces

Classical Conditioning n CS - Conditioned Stimulus (Bell) –what used to be called the neutral stimulus. Initially it evoked no response, but, after conditioning, it now evokes a response n CR - Conditioned Response (Salivation) –similar (but often not identical to) the unconditioned response but is evoked by the conditioned stimulus

Habituation and Sensitization n Can animals learn without association? n Habituation –Decreased responsiveness to repeated stimulation n Sensitization –Increased responsiveness following a single stimulus presentation

Extinction n A reduction in the conditioned response when the conditioned stimulus is presented without the unconditioned stimulus –e.g. presenting the bell repeatedly without the meat will eventually eliminate the salivation

Spontaneous Recovery n The reappearance of the conditioned responses following a delay in the extinction process

CR: Drops of Saliva Trials Acquisition Bell+Meat Extinction Bell Only Spontaneous Recovery Bell Only 24 Hour Delay

Higher Order Conditioning n First Order Conditioning: –Associating Bell + Meat Powder eventually leads to salivation to Bell alone (Bell = CS 1 ) n Higher Order Conditioning –Associate CS 1 with a new CS (e.g. Light) –Associating Bell + Light eventually leads to salivation to Light alone (Light = CS 2 )

Higher Order Conditioning CS 1 (Bell) + NS (Light) CR (Salivation) During Conditioning produces +

Higher Order Conditioning CS 2 (Light)CR (Salivation) After Conditioning produces Important: The Light is never directly associated with meat

Basic Rules of Conditioning n The more association trials, the better the conditioning n CS and US must be closely linked in time n Physically intense stimuli are conditioned more easily n Some things are more easily conditioned than others

Stimulus Generalization and Discrimination n Stimulus Generalization –Animals will show a Conditioned Response to stimuli similar to the original CS

Stimulus Generalization and Discrimination n Discrimination –If you repeatedly associate one CS with the US and do not associate the second, the CR will discriminate the two CS+CS-

Figure 6.4

Real-Life Examples of Classical Conditioning n Conditioning Emotional Responses –Baby Albert (Watson and Rayner, 1920) Conditioned fear to a white rat by associating a loud noise with the rat –CS = rat –US = loud noise –UR = startle to loud noise –CR = startle to rat

Real-Life Examples of Classical Conditioning n Learning the meaning of words –Word is associated with the sensory impression e.g. “apple” and view of an apple –“Second-signal system”

Real-Life Examples of Classical Conditioning n Conditioned Taste Aversion –a taste (CS) associated with a toxin (US) leads to nausea (UR) –later, the taste alone evokes nausea (CR)

Real-Life Examples of Classical Conditioning n Drug Tolerance –drug users become increasingly less responsive to the effects of the drug –tolerance is specific to specific environments (e.g. bedroom) –familiar environment becomes associated with a compensatory response taking drug in unfamiliar environment leads to lack of tolerance

Instrumental Learning n Pavlov –Classical conditioning of reflexes n Can learning occur with nonreflexive behavior? –Instrumental Response: a voluntary response that acts on the environment in a meaningful way

Instrumental Learning n The modification of instrumental responses using reinforcers and punishers

E.L. Thorndike’s Puzzle Box n Cat placed in a box that can be opened from inside by pushing on latch n Initially, cat shows random behaviors –scratching –sniffing n Eventually cat will hit latch –hitting latch leads to pleasant consequence - escape increases likelihood action will occur again

Thorndike’s Law of Effect n Responses followed by “satisfiers” tend to be repeated n Those followed by “annoyers” are not repeated –useful behaviors are stamped in

Operants n B.F. Skinner: –An operant is an instrumental response that operates on the environment n Positive Reinforcer –Any stimulus that increases the likelihood of an operant response n Skinner developed a general model of learning called “operant conditioning”

The Operant Chamber

Shaping Behavior n Reinforce responses that approximate the target behavior

Secondary Reinforcement n Neutral stimuli can acquire reinforcing properties through the process of higher-order conditioning –e.g. the reinforcing effect of language (“good boy”)

Schedules of Reinforcement n Rate at which reinforcer is delivered influences nature of response n Continuous reinforcer –each response is reinforced n Partial Reinforcement –reinforcer is not delivered for each response

Partial Reinforcement n Fixed Ratio (FR) Schedule –reinforcer is delivered only after a fixed number of responses have been made e.g. FR-10 schedule: reinforcer delivered after every 10th lever press

Partial Reinforcement n Variable Ratio (VR) Schedule –the number of responses before a reinforcer is delivered varies

Partial Reinforcement n Fixed Interval (FI) Schedule –the first response following a specified time interval is reinforced e.g. FI-10 schedule: only responses made after 10 seconds are reinforced

Partial Reinforcement n Variable Interval (VI) Schedule –the first response following a varying time interval is reinforced

Partial Reinforcement affects Response Rate

Partial Reinforcement Effect n If you train an animal using partial reinforcement, it is more resistant to extinction than one that received continuous reinforcement n Extinction –a reduction in the rate of response when a reinforcer is withheld

Differential Reinforcement n Differential Reinforcement of a High Rate of Response (DRH) –reinforce bursts of responses n Differential Reinforcement of a Low Rate of Response (DRL) –reinforce pauses between responses

Behavioral Control n Skinner: –The likelihood of any behavior depends on reinforcement and punishment contingencies n Environmental Determinism –environmental stimuli exert total control over behavior

Stimulus Control n The Discriminative Stimulus (S d ) –a signal that indicates when a response will be reinforced e.g. reinforcing lever pressing only when light is on n Negative Discriminative Stimulus (S  ) –A signal that indicates that a response will not be followed by reinforcement

Stimulus Control n Responding only in the presence of S d and not in the presence of S 

Punishment n Another potential consequence of behavior –An aversive stimulus that decrease the rate of responding n When is punishment most effective? –It must be relatively intense –It must follow the response relative quickly –It must be applied consistently

Negative Reinforcement n Any stimulus whose withdrawal increases the probability of a behavior –e.g. pushing a lever to turn off a shock n Avoidance Learning –when an instrumental response prevents and aversive stimulus e.g. pushing a lever before the onset of shock

Persistence of Avoidance Learning n Negatively reinforced responses show slower extinction than positively reinforced responses –avoidance learning - gaining both positive reinforcement and avoiding punishment

Observational Learning n Not all learning occurs through direct reinforcement n We can learn by watching others and through imitation

Limitations to Pavlov’s and Skinner’s Theories of Learning n Instinctive Drift –Animals will often show instinctive behaviors even if they are not being reinforced e.g. raccoons “washing” coins

Limitations to Pavlov’s and Skinner’s Theories of Learning n Cognitive Maps –Animals can create a mental representation of a maze even if they haven’t been reinforced to solve the maze

Limitations to Pavlov’s and Skinner’s Theories of Learning n Latent learning –when animals that have not been reinforced are reinforced, they show faster than expected learning

Limitations to Pavlov’s and Skinner’s Theories of Learning n Preparedness –some associations are learned more easily than others e.g. associating taste with nausea is easier than associating noise with nausea

Conceptual Learning n Do associations or reinforcement explain all types of learning? n Learning to learn: –some animals can learn strategies –win-stay, lose-shift: continue response if reinforced, switch response if not reinforece

Behavioral Complexity and Environmental Complexity n The more complex the behavior, the more complex the environment required