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Transcript of Chp 6
Learning is a relatively enduring change in behaviour that is due to experience.
Learning is crucial for survival. We need to learn which types of foods are dangerous, when it is safe to sleep, and which sounds indicate potential danger.
Learning is central to our lives, too. We learn basic abilities such as walking and speaking and complex ones, such as flying a plane. Learning also shapes many aspects of daily live, from food preferences to social rules.
Psychologists tried to understand the complexities of how people and animals learn.
Since 1890’s many theories about learning were constructed.
Many of these theories and studies on learning came from Behaviourists.
Behaviourists, believing in the major role of environment on our behaviours, became very influential on the psychological thinking for a significant period of time.
Of course, their ideas and theories were criticized by other psychologists and new learning theories were proposed after.
According to behaviourism, the essence of learning is in understanding how events are related to each other.
Associations between the events are critical. The process of associating events is known as conditioning.
Behaviourists studied two types of conditioning: classical and operant.
Classical conditioning occurs when we learn that two types of events go
Operant conditioning occurs when we learn that certain behaviour leads to a
Classical conditioning was first described by a Russian physiologist, Ivan Pavlov around 1900.
Pavlov was studying digestive system. He was working on the salivary reflex, the production of saliva when the food is presented.
Pavlov created an apparatus to collect saliva from dogs. He was collecting saliva by means of a surgically implanted tube.
One day he realized that after a while dogs were salivating well before the meat was presented.
Indeed, the dogs were salivating the moment that a lab technician walked into the room, or whenever they heard the sound of the door.
Pavlov noticed that unlike inborn reflexes, salivation at the sound of a door is not automatic and therefore must have been acquired through experiences.
To test this idea and clarify what was happening, he paired the presentation of the meat with various stimuli.
In one study, he presented a tone with the meat for number of times.
After being paired with the meat number of times, dog associated the two (tone and meat) and the dog responded the tone by producing saliva.
This type of learning is called as classical conditioning, when a neutral object elicits a reflexive response after being paired/associated with a stimulus that already produces that response.
Classical conditioning affects our life.
Many phobias and fears, emotional and even physiological responses are resulting from classical conditioning.
How does it really work?
How are new responses formed? Acquisition
An association should be formed between two events, UCS and CS.
The important factor in this formation is the contiguity. These two stimuli should occur together in time and space.
Not all paired stimuli leads to classical conditioning. Novel, unusual or intense stimuli have more potential to become conditioned.
How long does conditioning persist in the absence of UCS? Extinction
What if Pavlov's dog produced saliva after hearing the tone, but food stopped appearing?
Eventually the animal will stop producing saliva after hearing the tone.
This gradual weakening and disappearance of the conditioned response is called as extinction.
Many factors affect how long it takes to extinguish a conditioned response. Generally, conditioned response extinguishes quickly, if the strength of the condition bond is weak.
Does extinction breaks the associative bond between CS and UCS? Spontaneous Recovery
What happens if we give the tone again, after conditioned response is extinguished.
Pavlov, after extinguishing the dog’s salivation, gave the dog some time to rest in his cage and then brought it back to the experimental room again. He gave the tone alone to see what happens.
The dog produced saliva again, but the amount was less, or the response was weak. This reappearance of an extinguished conditioned response is called as spontaneous recovery.
Does responding occur after a stimulus similar to CS? Stimulus Generalization/Discrimination
In Pavlov’s experiment, the dog was responding to the tone which was 1,200 Hertz (Hz). What happens if the dog is given another tone, which is 800 Hz?
After the conditioned learning occurs, tones similar to the original tone will also produce conditioned response. This is called as generalization. The dog will salivate to other sounds but the likelihood and amount of generalization to a new stimulus depend on the similarity between the new and original stimulus.
If the food only comes after the original tone, then Pavlov’s dog will also learn to discriminate among the stimuli. However, if the new stimulus is similar to the original conditioned stimulus, the discrimination will be relatively difficult to learn.
Can another stimulus paired with the CS and elicit CR?
Pavlov also tested the association between a stimulus and Conditioned Stimulus and its effect on the dog.
After the tone is established as a CS, the tone is paired with a new stimulus; let’s say a red light, for 15 trials. With the tone, red light was also presented 15 times. What happens if we just give the red light to the dog? Do you think the dog will produce salivation?
Yes, even though the red light has never been paired with the meat, the dog will produce saliva because the red light has been paired with the tone. This is called higher-order conditioning.
Here, the tone (the first conditioned stimulus) functions as if it were an unconditioned stimulus.
If a phobia or fear is resulting from classical conditioning, can we be also conditioned not to be afraid?
Behavioural therapists developed a treatment based on this idea and it is called as “systematic desensitization”.
They expose patients to what causes them the fear but they relax them( by using relaxation techniques, drugs, virtual reality programs) at the same time, so they replace the aversive classical conditioned fear with something more positive.
Classical conditioning is a relatively passive process in which subject associate events that happen around them.
Many of our actions are instrumental; they are done for a purpose.
We learn to behave in certain ways in order to be rewarded; and we avoid behaving in certain ways in order not to be punished. This is called operant conditioning.
The first person studying operant conditioning was Edward Thorndike.
He was studying whether animals showed signs of intelligence.
For his research, Thorndike built a small cage with a trapdoor, known as puzzle box, to see if the cats could figure out how to escape.
He stated that cat’s escape behaviour cannot be explained thinking but by a learning principle called as law of effect. Any behaviour that leads to a satisfying state is more likely to occur again.
Thorndike’s idea was developed by Skinner after 30 years.
Skinner was a dedicated behaviourist who thinks unobservable things have no place in science, he did not like the term satisfaction in Thorndike’s law of effect and replaced it with “reinforcement”.
Skinner believed that behaviour occurs because it has been reinforced. He interpreted whole life in terms of reinforcement. He believed that we actually have no control or free will in our lives and we are shaped by reinforcers.
Skinner worked with rats and pigeons.
Since behaviourists believed that there is no higher mental processing, understanding learning in animals would explain learning in humans.
He developed a box, known as, Skinner box and attached mechanical recording devices.
How are new responses learned? Acquisition and Shaping
Skinner was trying to teach animals to do certain tasks, such as pressing the lever or pecking a disk.
The idea was to reinforce the animal (by giving food) every time it presses the lever.
Pressing a lever was not a natural response or behaviour for a rat.
To solve that problem, Skinner developed a procedure, called as shaping. Instead of waiting for the animal to respond in a specific way, behaviours that are similar to desired behaviours (approximations) were reinforced.
As well as being used in training animals, shaping has also been used by parents, educators and professionals to teach certain skills to children, students or adults.
While primary reinforcers that is necessary for survival, such as food and water, were mostly used for animals. Secondary reinforcers that are established through classical conditioning, such as money, attention, and praise are also very important in reinforcing our behaviours.
Does responding occur in the presence of a particular stimulus?
In operant conditioning, stimulus discrimination is the tendency for a response to happen only when a particular stimulus is present.
Ex: If you trained your dog to bring the remote for TV, but you reward him only when he does it during the day. Here, time of the day becomes a discriminative stimulus for the dog.
If your dog still brings you the remote during the night whenever a bright light was on at night, thinking you would probably pat him, this is called stimulus generalization.
In operant conditioning, stimulus generalization is the tendency to respond to a new stimulus as if it is the original discriminative stimulus.
How long does responding persist? Extinction
In operant conditioning, extinction occurs when the response is no longer followed by a reinforcer.
Response tendency gradually become weaker and disappears.
If you are working hard and hard, hoping for promotion at the end of the year and never get those promotions, you will decrease your efforts and stop working hard.
However, your boss will want you to work hard still, so they will try some techniques to make the extinction harder.
Which factors do affect extinction?Quantity and Timing of Reinforcement
Different schedules of reinforcement affect extinction.
-Continuous reinforcement vs. partial reinforcement:
The behaviour can be reinforced each time it occurs, which is referred as continuous reinforcement. This kind of reinforcement is seldom the case in real life and actually, it is not very effective in making the extinction harder.
Most of the time behaviour is reinforced intermittently, which is referred to as partial reinforcement. Compared to continuous reinforcement, partial reinforcement makes a response more resistant to extinction.
-Ratio vs. interval reinforcement schedules:
You can reinforce after a certain number of response. If you reinforce every third or tenth response, this is a fixed-ratio schedule. If you reinforce after a variable number of response, this is a variable-ratio schedule. In this case, the third and the tenth, and fifth response is reinforced.
Reinforcement can also be based on a specific unit of time. If the behaviour is reinforced after a fixed amount of time, it is called as fixed-interval schedule. You will be reinforcing the behaviour after every hour, for example. If the response is reinforced after a variable time interval, it is called as variable-interval schedule.
Variable schedules in general yield steadier responding and greater resistance to extinction.
How is behaviour controlled? Reinforcement or Punishment
There are consequences that either increase (reinforcement) or decrease (punishment) our tendency to make a particular response. There are different ways to reinforce or punish a response/behaviour.
Positive reinforcement is administration of pleasant stimulus. Rat is given food after pressing the lever. Your profs will give high marks after your good performance.
Negative reinforcement is removing an unpleasant stimulus. When the rats were given electric shock in Skinner’s box, they learn to press lever (strengthening a response). This leads to removal of the electric shock (unpleasant stimulus).
-Negative reinforcement leads to escape learning and might lead to avoidance behaviour. We learn to
prevent that aversive stimulus by learning to avoid. Avoidance learning also explains why phobias are
so resistant to extinction. By avoiding the feared object/situation, you negatively reinforce yourself by
relieving your conditioned fear. That’s why phobias are resistant to extinct because every time you
avoid them you reinforce yourself.
In positive punishment, an aversive stimulus follows response.
Negative punishment decreases the likelihood of a behaviour by removal of a pleasurable stimulus. When driving privileges of young people are revoked for speeding, this is negative punishment and the person is less likely to speed again. On the other hand, if you get a ticket for speeding, this is positive punishment.
Even though they had been dominant thought in psychology for long period, there have been other studies and theories showing that not every behaviour can be explained by law of effect. These studies also challenged the main positions of the behaviourists.
No higher mental processes
No Innate knowledge & Laws of learning are
valid across all domains and species
Behaviourists thought if animals such as rats or warms can be conditioned, then it means conditioning cannot depend on higher mental processes.
First challenge: Tolman's study. In his experiments rats had to learn how to run through complex mazes to get food. He believed that rats developed cognitive maps of the maze and these cognitive maps helped them learn the maze quickly when they were given the food as a reinforcer. He argued that reinforcement has more impact on performance than on learning.
Other studies also showed that insight learning occurs in animals. A solution suddenly emerges after a period of contemplating on the problem. Reinforcement does not account for this kind of learning, even though it predicts whether the behaviour will be repeated or not.
Cognitive studies showed that we actively think about the causal relationship between the events. For ex: If you wear the same shoes, study at the same place and listen to the same songs when you were studying for the exam. You would know that it is studying hard that brought you a good mark.
Contrary to what Behaviourists thought, animals just like humans were found to have innate capabilities. There are built-in mental systems.
Behaviourists also argued that there are no animal-specific constraints for learning. You can teach any behaviour to any animal. However, conditioning is not possible if it interferes with innate adaptive behaviours. Pigeons cannot be trained to peck at keys to avoid electric shock. However, they can learn to avoid shock by flapping their wings because it is their natural means of escape. This effect is called as instinctive drift; and it shows us that laws of learning are not valid across all species.
Laws of learning are also not valid across all domains. Some response and stimulus associations are created easily, while some are impossible. The association between taste and nausea are formed very easily (Garcia effect-conditioned taste aversion).
We also acquire certain fears more readily than others because of our preparedness to be conditioned in certain way. We develop phobias to snake, spider, dark, and heights easily, while we hardly develop a phobia towards a stove even though we touched it couple of times and burned our fingers.
For many behaviours, we learn not by doing but by observing the actions of others. For example, animals learn that food is safe by watching what their parents eat. Similarly, children imitate their parents’ behaviour and learn many things through this way, such as how to tie their shoes.
As many skills and actions, fear was also shown to be learned through observation. This kind of learning is called as observational learning.
Imitating others’ behaviours is called as modeling. We are more likely to imitate the actions of models that are attractive, have high status, and are somewhat similar to ourselves. Modeling occurs implicitly without our awareness.
Albert Bandura was the most well-known psychologists who worked on observational learning and modeling.
In his famous Bobo doll experiment, preschool children were shown adults playing with an inflated doll called Bobo, either quietly or aggressively. Children who saw that adult was playing aggressively were more likely to be aggressive toward the doll compared to control group.
In another version of the study, children watched adults were rewarded or punished for playing aggressively with Bobo doll, or they watched adults were given neither punishment nor reward (control group). Children who saw that adult was rewarded were more likely to be aggressive, while children who saw that adult was punished were less likely to play with the doll aggressively compared to control group.
If they were offered a reward for imitating the adult’s behaviour, all groups behaved aggressively. All children learned the behaviour (acquisition), but only those who saw the model was being rewarded actually performed the behaviour (performance).
Biological basis of learning
Recently, it was discovered that a specific type of neurons in the frontal and parietal lobe can account for observational learning. These neurons are called as mirror neurons. These neurons become activated when we observe someone acting. Actually, these neurons would be the same neurons that would be activated if we performed the behaviour ourselves.
Biology of Reward:
Although behaviourists avoided any reference to internal mental states, biological studies provided new insights about neural mechanisms in our learning. During their studies with animals, scientists discovered that there are pleasure centres in the brain. Most psychologists think that these pleasure centres might be activated by natural (primary) reinforcers such as food, water and sex.
Studies also showed that these pleasure centres and natural reward (eating food, drinking water) use same neurotransmitter system, release of dopamine. Release of dopamine was found to be crucial for positive reinforcement and setting the value of reinforcer. As you eat food when you are hungry, more dopamine is released and you experience pleasure. Secondary reinforcers such as paycheck, getting a good grade or sight of a loved one were also found to stimulate a release of dopamine.
If your dog brings the remote only during the day, this is called stimulus discrimination.