Published on November 16, 2007
Behavioral Learning (1): Behavioral Learning (1) “...any technology of control will be bought, adapted, and monopolized by the powerful for their own not always benevolent purposes.” Why Study Behavioral Learning?: Why Study Behavioral Learning? Train a pet Clinical significance Control your friends (?) Habituation: Habituation The simplest of all behavioral learning forms A decline in the tendency to respond to familiar stimuli The faster we habituate the faster we recover and the slower we habituate the slower we recover Why habituate? Darwin would say...It narrows the range of stimuli that elicit escape reactions, thus freeing resources to focus on new stimuli that might be dangerous Habituation to Conditioning: Habituation to Conditioning In habituation, one learns a familiar event but doesn’t learn to associate it with anything Association is the basis for Conditioning Ivan Pavlov (1849-1936) is credited with the advancement of conditioning The Conditioned Reflex: The Conditioned Reflex Repeated bell-food pairings led to salivation when the bell was presented alone Pavlov described this phenomena in terms of unconditioned and conditioned reflexes Unconditioned stimuli (US) is normally associated with an unconditioned response (UR) A conditioned stimulus (CS) is paired with a (US) Giving a number of presentations the (CS) will be perceived as a (US) and lead to a conditioned response (CR) Extinction: Extinction The (CS) will gradually disappear of repeatedly presented without being enforced Reconditioning can occur with fewer reinforcement trials Thus, the learning wasn’t completely gone but rather masked Generalization: Generalization Will a response be given only if the stimulus is identical? A dog conditioned to a tone of 1000 Hz will give a response when the tone is 900 or 1100 Hz However, there is a generalization decrement such that a weaker (CR) will be elicited if not the original (CS) Discrimination: Discrimination Even if a stimulus is similar we may not want to generalize our behavior to it (may be dangerous) Thus, we need to discriminate A dog is conditioned to a black square. The dog will also salivate to a gray square (generalization). After withholding reinforcement to the gray square the dog will gradually discriminate and only respond to the black square Blocking: Blocking When a stimulus is redundant (information that an organism already has) it will not become connected to the CS Group I - (stage 1) noise-shock, (stage 2) noise+light-shock, (test) light alone, (result) no conditioned fear Group II - (stage 1) no stimulus, (stage 2) noise+light-shock, (test) light alone, (result) conditioned fear Once they’ve discovered a stimulus that signals the US they no longer connect other stimuli to the US Proactive Interference? Bases for Prejudice The Drug Effect: The Drug Effect Opiates (morphine or heroin) have effects such as euphoria, relief from pain, and relaxation (UR) The needle becomes the CS The sight of the needle produces depression, restlessness, and increased sensitivity to pain thus increasing the likelihood of an overdose The CR is actually the opposite of the UR Given a different environment the Drug Effect is weaker Classical to Instrumental Conditioning: Classical to Instrumental Conditioning Instrumental conditioning is also called operant conditioning Differences: Instrumental - reinforcement (reward) depends upon the proper response. The response must also be selected from a sometimes large set of alternatives Classical - the US is presented regardless of behavior Instrumental Conditioning: Instrumental Conditioning Edward Thorndike (1874-1949) is credited with Instrumental (Operant) Conditioning The idea was developed by observing hungry cats in a Puzzle Box Through random movements the cat would hit the trigger to open the door Give enough trials and the cat would trigger the door right away Law of Effect: Law of Effect According to Thorndike, some responses get strengthened and other weakened as learning proceeds The response determines whether the tendency to perform is strengthened or weakened If followed by a reward it will be strengthened; if followed by a the absence of reward (or punishment) it will be weakened No intellectual process required Skinner’s Distinction: Skinner’s Distinction In Classical, the animal’s behavior is elicited by the CS (from the outside) In Instrumental, reactions are voluntary (emitted from within) Tendencies for reactions are strengthened or weakened Measured response rate with the Skinner box Skinner’s Terminology: Skinner’s Terminology Appetitive Stimulus = Positive Reinforcement Aversive Stimulus = Negative Reinforcement Shaping: Shaping Method of Successive Approximations Start by reinforcing a general behavior Change the reward placement so there needs to be a more specific behavior Change the reward placement so there needs to be another more specific behavior Your dog puts the paper on the table Partial Reinforcement (Schedules): Partial Reinforcement (Schedules) Fixed-Ratio Schedule - produce a specified number of responses for every reward Variable-Ratio Schedule - reinforcement comes after a certain number of responses, but that number varies irregularly Fixed-Interval Schedule - Reinforced after a certain interval (i.e. every 2 min) Variable-Interval Schedule - Interval varies irregularly around some average period (i.e. 4 min) Question: Question What kind of reinforcement is better? Partial or Continuous Both receive the same number of trials but no the same number of reinforcements Partial seems to be better, but which schedule? Ratio engender greater resistance to extinction if they are variable Aversive Conditioning: Aversive Conditioning What is the reward in aversive reinforcement? It is not absence of the aversive condition that is the reward, but rather the absence of the aversive condition when it is expected Behavioral Learning (2): Behavioral Learning (2) Cognitive Interpretations Question: Question What are test animals actually learning? Simple associations or causal links? Behaviorists - learning is in terms of associations, either between events, or action and consequences. Learning can only be achieved by doing, thus performance is indispensable Cognitive psychologists - learning is in terms of causal links Cognitive View - Classical Conditioning: Cognitive View - Classical Conditioning Hilgard (1938) - Two lights (left & right), when one light became brighter there as an airpuff delivered to one eye causing a blink. Conditioning occurred. When subjects were told that no airpuff would result given a right light the conditioning in that right eye was immediately extinguished Instruction works; thus, subjects need to be aware of the stimulus-response relationships Support for Cognitive View (2): Support for Cognitive View (2) Gleitman (1963) Rats were ferried from one end of a large room to another in transparent trolley cars Latter tests showed that they had learned something about the general features of the room even thought they had not performed any relevant responses Relation Between CR and UR: Relation Between CR and UR Are the two the same? Pavlov believed that they are the same However, his own data show that they look the same but under are not identical There was a greater amount of salivation measured under UR conditions compared to CR conditions Thus, the CS serves as a preparatory signal but does not become a substitute for it (cognitive link) Cognitive View - Instrumental Conditioning: Cognitive View - Instrumental Conditioning Evidence for Act-Outcome Associations Rats were run in an enclosed maze that had a black end-box on one side and a white end-box on the other side, both had food Later, rats were placed into each box w/out running the maze. In the black box they found food and in the white box they were shocked When put back in the maze they ran to the black box The rats combined two experiences; this doesn’t fit into the instrumental learning framework Clinical Considerations: Clinical Considerations Maladaptive Learning & Application of the Conditioning Theories Learned Helplessness: Learned Helplessness How do people reach the state of helplessness and depression? Experiment - Two groups of dogs who received electric shocks. Dogs were linked such that Group 1 could turn off the shock by pushing a panel. Group 2 had no power but rather received the same shocks as Group 1 (same fate). Given a new situation Group 1 dogs learned to push the button quickly. Group 2 dogs ended up becoming passive. They lay down and took whatever shocks were delivered Group 2 dogs had learned helplessness Learning Fear: Learning Fear While fear and phobias may be generated by conditioning in some cases, there seems to be more at work Fear of the Dentist may be conditioned but fear of snakes and spiders may be cause by a cognitive association Someone tells you a story of a tick that ate someone’s brain will make you fear ticks Overcoming fear and depression are difficult Treatment Methods: Treatment Methods Desensitization - brief approaches Modeling - Therapist approaches object then subject Flooding - Rapid prolonged approach to the stimulus Operant Shaping - Rewarded for a steady approach to object Treating Panic Attacks: Treating Panic Attacks Behavior modification has been helpful in treating panic attacks The problem is a feedback loop between the initial chance symptom and the patient’s fearful interpretation of it Teaching relaxation and breathing exercises alleviate the physical symptoms Treating Self-Injurious Behavior: Treating Self-Injurious Behavior Maladaptive behavior is often associated with anxiety (caused by need for attention, feeling of vulnerability, confronting difficulty...) Replace self-injurious behavior with relaxation Relaxation drugs are often used (nitrous oxide or anesthetic) Thus, relaxation becomes associated with anxiety When Conditioning Fails: When Conditioning Fails Token economies have been experimented with for a number of years Rewards for good behavior are tokens which can be exchanged for things Often subjects will not perform unless directly rewarded. Thus, behavior is conditional In real life rewards are not always given for being good Question: Question Why don’t we use conditioning more often in humans? Why does conditioning often fail in human subjects?