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45.7B: Conditioned Behavior - Biology

45.7B: Conditioned Behavior - Biology



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In classical conditioning, a behavior is paired with an unrelated stimulus; in operant conditioning, behaviors are modified by consequences.

Learning Objectives

  • Distinguish between classical and operant conditioning techniques

Key Points

  • In classical conditioning, a response called the conditioned response is associated with a stimulus that it had previously not been associated with, the conditioned stimulus; the response to the original, unconditioned stimulus is called the unconditioned response.
  • Classical conditioning is a major tenet of behaviorism, a branch of psychological philosophy that proposes that all actions, thoughts, and emotions of living things are behaviors that can be treated by behavior modification and changes in the environment.
  • In operant conditioning, the conditioned behavior is gradually modified by its consequences as the animal responds to the stimulus.
  • Operant conditioning relies on the use of reinforcement (i.e. a reward) and/or punishment to modify a conditioned behavior; in this way, the animal is conditioned to associate a type of behavior with the punishment or reward.

Key Terms

  • classical conditioning: the use of a neutral stimulus, originally paired with one that invokes a response, to generate a conditioned response
  • operant conditioning: a technique of behavior modification through positive and negative reinforcement and positive and negative punishment

Conditioned Behavior

Conditioned behaviors are types of associative learning where a stimulus becomes associated with a consequence. Two types of conditioning techniques include classical and operant conditioning.

Classical Conditioning

In classical conditioning, a response called the conditioned response is associated with a stimulus that it had previously not been associated with, the conditioned stimulus. The response to the original, unconditioned stimulus is called the unconditioned response. The most cited example of classical conditioning is Ivan Pavlov’s experiments with dogs. In Pavlov’s experiments, the unconditioned response was the salivation of dogs in response to the unconditioned stimulus of seeing or smelling their food. The conditioning stimulus that researchers associated with the unconditioned response was the ringing of a bell. During conditioning, every time the animal was given food, the bell was rung. This was repeated during several trials. After some time, the dog learned to associate the ringing of the bell with food and to respond by salivating. After the conditioning period was finished, the dog would respond by salivating when the bell was rung, even when the unconditioned stimulus (the food) was absent. Thus, the ringing of the bell became the conditioned stimulus and the salivation became the conditioned response. Although it is thought by some scientists that the unconditioned and conditioned responses are identical, Pavlov discovered that the saliva in the conditioned dogs had characteristic differences when compared to the unconditioned dog.

Some believe that this type of conditioning requires multiple exposures to the paired stimulus and response, but it is now known that this is not necessary in all cases; some conditioning can be learned in a single pairing experiment. Classical conditioning is a major tenet of behaviorism, a branch of psychological philosophy that proposes that all actions, thoughts, and emotions of living things are behaviors that can be treated by behavior modification and changes in the environment.

Operant Conditioning

In operant conditioning, the conditioned behavior is gradually modified by its consequences as the animal responds to the stimulus. A major proponent of such conditioning was psychologist B.F. Skinner, the inventor of the Skinner box. Skinner put rats in his boxes that contained a lever that would dispense food to the rat when depressed. While initially the rat would push the lever a few times by accident, it eventually associated pushing the lever with getting the food. This type of learning is an example of operant conditioning. Operant learning is the basis of most animal training: the conditioned behavior is continually modified by positive or negative reinforcement (such as being given a reward or having a negative stimulus removed) or by positive or negative punishment (such as being given a punishment or having a pleasing stimulus removed). In this way, the animal is conditioned to associate a type of behavior with the punishment or reward. Over time, the animal can be induced to perform behaviors that they would not have done in the wild, such as the “tricks” dolphins perform at marine amusement park shows.


45.7B: Conditioned Behavior - Biology

Much of animal learning is captured by the conditioning paradigm. In its simplest form (probably what actually happens under field conditions) an association is formed between an action and a reward. Associative learning allows birds to efficiently find bugs under rocks and bees to find nectar in specific flowers. This simple type of learning allows animals to behave efficiently, seeking resources where they have been found before, or collecting them in ways that have worked previously.

Learned associations can be built using normal stimulus-response patterns. A normal stimulus, such as the odor of food, elicits salivation in dogs. These are termed the unconditioned stimulus (US) and unconditioned response (UCR). When Pavlov rang the bell at the same time he presented food (a US), the bell became what we can a conditioned stimulus (CS). Though the bell is irrelevant to normal feeding in a dog, the dog associates the bell with the food (the US with the CS) and eventually responds by salivating when the bell is run (CS) even if no food is present.

Taking this one step further, many animals are able to build an association with a reward between seemingly irrelevant actions and stimuli, if the stimulus is given at the time the reward is received. You can teach your dog to "shake" hands when you present your hand, based on the dogs expectation of receiving a food reward after shaking. Once the association between your hand signal and the dogs' extension of its paw is built, then you can stop giving the food reward. Such behavior is built on positive reinforcement--association of the desired action with the receipt of a reward.

Not all animals can learn something as irrelevant to their biology as shaking hands. Ease of conditioned learning is often dictated by the importance of the stimulus and response to the animal species' evolutionary history and ecological conditions.

You might think that negative reinforcement would be effective in the same way as positive reinforcement. Indeed, many animals can be taught boundaries based on painful experiences, such as electric fences or shock collars. Most training using negative reinforcement, though, is less effective than positive reinforcement. This is because when being trained using positive reinforcement, an animal is encouraged to associate an act with the reward because the trainer is planning, in advance, to elicit the desired response. Going back to the example of dog shaking hands, it is likely that you would start the training by showing the dog the food. This would get her interest, and helps to build the association between the desired behavior and subsequent reward.

Negative reinforcement, on the other hand, generally comes after an act which the trainer cannot predict. If your dog urinates on the floor, and you then hit the dog, will it associate the punishment with the bad behavior? Likely not, because it was unaware that punishment was likely before it urinated--and even if the association is made, how does the dog know what alternative behavior will receive a positive reward? Urinary retention is a more common result that learning to go outside to urinate. Moving the urinating dog to an appropriate location, combined with positive reinforcement, is much more likely to achieve the desired result. Understanding this critical difference between positive and negative reinforcement in training is an important step in learning how to train domestic animals.

In studies of conditioning, negative reinforcement can be used in "extinction", or inhibition experiments, to determine if a previously learned association can be masked by later experience.

Operant conditioning is an extension of classical conditioning, in which the animal learns to operate an environmental feature to receive a reward. We most commonly think of rats and pigeons pressing levers in boxes (the "Skinner box") in operant conditioning the hand-shaking dog has probably been operantly conditioned, as well.

Much insight animal learning and memory has been gained from the study of conditioning. Ethologists and behavioral ecologists often dismiss laboratory tests of conditioning as being so far removed from the animal's biology as to be irrelevant to "natural" biology. Observations of animals in the field, though, suggest that the trial-and-error learning which often is used to gain experience with the environment is, in fact, one and the same as conditioning.

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copyright ©2001 Michael D. Breed, all rights reserved


Classical Conditioning Theory

Classical conditioning theory began with Ivan Pavlov in the early 20 th century, when he looked into the response of the digestive system in the presence (sight and odor) of food. Pavlov’s research animals – dogs – would automatically salivate whenever food was offered. By sounding a whistle every time the dogs were fed, they were eventually conditioned by a usually ineffective stimulus to salivate without any food being present. The whistle alone caused a physiological effect that was previously an automatic response to the stimulus of food.

Classical conditioning theory is composed of three phases – before, during, and after.

Before Conditioning

Before an animal or a human is conditioned to respond to a usually ineffective (neutral) stimulus, physiological or psychological responses only occur in the presence of certain, naturally occurring stimuli. These are known as unconditioned stimuli or UCS. When we think of conditional circumstances, we think of some kind of control or restriction. You can go to the party on the condition that you tidy your room first, for example. When we think of unconditioned circumstances – unconditional love, for example – there are no restrictions. So an unconditioned response is not controlled, it is an involuntary act. More specifically, no learning is required. The definition of classical conditioning is to do with external control – you react on the condition that you have learned to associate an unusual sensory stimulus with a natural one.

An example of an unconditioned response is a newborn baby using the muscles of its mouth to carry out a sucking motion. It is a reflex that occurs when an unconditioned stimulus or UCS is placed in the newborn’s mouth – a nipple or the teat of a bottle offers nutrient-rich milk. It is not the mode of delivery that is the unconditioned stimulus during the very first feeds, but the milk. The unconditioned response to this stimulus is the sucking reflex. It is easy to see how unconditioned responses are often survival mechanisms. If the newborn does not know how to suck, it cannot eat and it will die.

Eventually, the infant will learn to associate the form of the nipple or teat in its mouth with the sucking reflex. It has then become a conditioned response, because the baby has learned that these provide a source of milk. A further step will be the baby associating the sight of a bottle or breast – any breast, even at a distance or on television – with food. A conditioned stimulus is a stimulus associated with the natural unconditioned stimulus. If a bell would be rung every time a newborn baby had a feed, that baby would eventually begin to suck at the air if only a bell rings – the same type of learned behavior as the conditioned salivation response of Pavlov’s dogs.

During Conditioning

The second phase of classical conditioning is the during phase. This is when a neutral stimulus (noise, touch, smell, taste) is added every time there is an unconditioned stimulus. This is the conditioned stimulus (CS) – the subject must learn to respond to it as the stimulus will not cause the unconditioned response on its own. Pavlov introduced a bell between one to two seconds before he fed his dogs. It is very important that the conditioned stimulus is given very shortly before or during the unconditioned stimulus. The dogs needed time to learn to associate the bell with food – this is the during conditioning phase.

However, the during conditioning phase of classical conditioning does not have to take a long time. Sometimes, an unconditioned stimulus is so strong it will immediately be associated with a conditioned one. Many of our learned fear responses are based upon short-term during conditioning phases. Another term for the during conditioning phase is the acquisition phase, where a conditioned stimulus is introduced and the association between it and the unconditioned stimulus is strengthened.

After Conditioning

After conditioning is self-explanatory. Classical conditioning has occurred and there is now a conditioned response to a conditioned stimulus. The conditioned response is the same type of response as the unconditioned response, but the conditioned and unconditioned stimuli are not the same. The subject has developed a new learned response to a stimulus that in normal circumstances would not cause this effect. The unconditioned stimulus no longer needs needs the unconditioned stimulus to create an effect that mimics the natural, involuntary response. Natural responses are the result of the parasympathetic and sympathetic nervous system and with classical conditioning, stimuli that would not activate either system in normal circumstances can eventually produce them.

So if you are asked the question, “What is classical conditioning”, you should now be able to answer it. A very short answer would be the association of an neutral stimulus with the natural cause of an involuntary physiological response, and that this association becomes so strong the neutral stimulus is all that is needed to create the effect.

How long this lasts depends on how long the brain associates the CS with the UCS. When the bell is no longer rung one to two seconds before food, Pavlov’s dogs will eventually stop salivating in response to that sound. This is called classical conditioning extinction, where extinction refers to the conditioned response.

However, memory is complex and spontaneous recovery of a conditioned response is possible after classical conditioning extinction occurs. This is usually very short-term. In the absence of the pairing of an unconditional and conditional response, the subject will ‘learn’ that there is no need for a response. The association between conditioned and unconditioned stimulus is rarely completely lost. If, after a long period of time, the during conditioning phase is repeated, it will take much less time to develop the same conditioned response.

Sometimes the conditional stimuli will become generalized. If someone said “Oliver Twist” one to two seconds before they burn your left hand with a match at every opportunity you will become conditioned to pull your left hand away when you hear those words. But other memory pathways may cause you to include more generalized conditional stimuli. You may suddenly jerk your left hand if someone says “Dickens”, for example. This is called stimulus generalization.

The opposite effect is stimulus discrimination. Only extremely specific stimuli will cause the conditional response. Perhaps “Oliver Twist” must be said a certain way or at a certain tempo or rhythm for you to pull your left hand out of danger. Or perhaps only small spiders with hairy legs will cause a fear response, while those with long, thin legs have no effect on anxiety levels at all.


Biology and Neurophysiology of the Conditioned Reflex and its Role in Adaptive Behavior

International Series of Monographs in Cerebrovisceral and Behavioral Physiology and Conditioned Reflexes, Volume 3: Biology and Neurophysiology of the Conditioned Reflex and its Role in Adaptive Behavior focuses on the biological roots, characteristics, and nature of conditioned reflex and its function in adaptive behavior. The monograph first discusses the biological roots of the conditioned reflex. Concerns include sequential order of external influences and living protoplasm anticipatory processes of protoplasm and the conditioned reflex adaptive features of the conditioned reflex and inborn signalization in higher animals. The book then takes a look at the nature of the unconditioned reflex, including biological nature of reinforcement value of the temporal relationships of conditioned and unconditioned reflexes and fixation of sequential order without the factor of reinforcement. The text describes systemogenesis as an evolutionary basis for the development of unconditioned reflexes concepts concerning the nature of the coupling process and hypothesis of the convergent coupling of the conditioned reflex. The book also examines functional system as a basis of the physiological architecture of behavioral acts. The monograph is a dependable source of data for readers interested in conditioned reflex and its function in adaptive behavior.

International Series of Monographs in Cerebrovisceral and Behavioral Physiology and Conditioned Reflexes, Volume 3: Biology and Neurophysiology of the Conditioned Reflex and its Role in Adaptive Behavior focuses on the biological roots, characteristics, and nature of conditioned reflex and its function in adaptive behavior. The monograph first discusses the biological roots of the conditioned reflex. Concerns include sequential order of external influences and living protoplasm anticipatory processes of protoplasm and the conditioned reflex adaptive features of the conditioned reflex and inborn signalization in higher animals. The book then takes a look at the nature of the unconditioned reflex, including biological nature of reinforcement value of the temporal relationships of conditioned and unconditioned reflexes and fixation of sequential order without the factor of reinforcement. The text describes systemogenesis as an evolutionary basis for the development of unconditioned reflexes concepts concerning the nature of the coupling process and hypothesis of the convergent coupling of the conditioned reflex. The book also examines functional system as a basis of the physiological architecture of behavioral acts. The monograph is a dependable source of data for readers interested in conditioned reflex and its function in adaptive behavior.


What can animal models tell us about depressive disorders?

2.6.2.1 Increased reactivity to aversive stimuli

Emotional reactivity to aversive stimuli is considered to involve the amygdala, and enhanced amygdala reactivity to aversive emotional stimuli, such as negative emotional faces, is a prominent feature of depression. Processing of negative emotional information and fear learning by the amygdala are frequently studied in rats using fear-conditioning paradigms. In fear-conditioning procedures, the animal first receives a series of trials in which a mild footshock is delivered in association with a tone stimulus. After conditioning, the test phase consists of delivering the tone stimulus, but not the footshock. The typical response of fear-conditioned rats upon hearing the tone stimulus during the test phase is “freezing,” that is, remaining completely motionless for a variable period of time. The emotional reactivity to fear-conditioned stimuli can be assessed by considering the duration of time the animal spends motionless. Thus, enhanced freezing behavior in response to a fear-conditioned stimulus can be considered a measure of increased emotional reactivity to negative stimuli. In the rat, repeated restraint stress (a chronic stress procedure) increases the duration of conditioned freezing, as well as increasing neuronal activity in the basolateral amygdala ( Zhang and Rosenkranz, 2013 ).


Conditioned responses in courtship behavior of normal and mutant Drosophila

Male courtship behaviour in Drosophila melanogaster is modified by prior sexual experience. Whereas naive males nearly always court virgin females persistently, males previously paired with unreceptive fertilized females subsequently court virgin females in an abbreviated manner, if at all. The probability of diminished male courtship is directly related to the duration of the prior 𠇌onditioning” period with a fertilized female. Naive males court fertilized females less vigorously than they court virgins this depression of male behavior occurs even if the male is blind or if the fertilized female cannot actively reject his courtship. These results suggest that fertilized females are a source of both courtship-provoking and courtship-inhibiting olfactory cues and that the central association of these cues in males is sufficient to bring about the retention of modified courtship behavior. Mutant 𠇊mnesiac” males, selected as memory-deficient in a learning test unrelated to courtship [Quinn, W. G., Sziber, P. P. & Booker, R. (1979) Nature (London) 277, 212-214], are trainable by exposure to fertilized females, but the experience-dependent behavior𠅍iminished courtship performance—wanes abnormally rapidly—i.e., less than 1 hour, compared to 2-3 hr for wild-type flies.


Foraging

Foraging is the act of searching for and exploiting food resources. Feeding behaviors that maximize energy gain and minimize energy expenditure are called optimal foraging behaviors, and these are favored by natural section. The painted stork, for example, uses its long beak to search the bottom of a freshwater marshland for crabs and other food ([link]).



Conditioning

Conditioning in behavioral psychology is a theory that the reaction ("response") to an object or event ("stimulus") by a person or animal can be modified by 'learning', or conditioning. The most well-known form of this is Classical Conditioning (see below), and Skinner built on it to produce Operant Conditioning.

Conditioning
Pavlov's Discovery of Conditioning

This mode of learning was demonstrated by the experiments of Ivan Pavlov, who decided to research conditioning after discovering during separate gastric tests that his dog subjects began to salivate not only when meat powder was presented to them, but more significantly, when the person feeding them came into proximity with them. The dogs had been inadvertently trained through classical conditioning to associate the person feeding them with the food itself, and reacted in a similar way (salivation) to the feeders. This is known as a stimulus-response (SR), when salivation becomes a responsive action to the stimulus of the person feeding the dogs:

At the start of the experiments:

  • The Unconditioned/Neutral Stimulus (US/NS) is the person arriving to feed the dogs before the salivation as a result of their presence had began.
  • The Unconditioned Response (UR) was for the dogs not to salivate.

By the end of the experiments, when the unconditioned stimulus and responses had been conditioned:

  • The Conditioned Stimulus (CS) becomes the person arriving to feed the dogs, which stimulates the Conditioned Response:
  • The Conditioned Response (CR) becomes salivation (normally a reflex action to aid digestion when feeding is going to begin) at the sight of the person.

On disovering this associative learning on the part of the dogs, Pavlov decided to carry out further research specific to conditioning.

Classical Conditioning

Russian physiologist Ivan Pavlov (1849-1936) became eponymous with his dog conditioning experiments.

The most famous experiment by the physiologist related to conditioning followed this research. Commonly referred to as "Pavlov's Dogs", the experiment aimed to condition the dogs to associate the opening of a doorwith feeding time. By selecting a bell as the Unconditioned Stimulus instead of the person arriving to feed the dogs, as in his previous tests, Pavlov was providing a stimulus to which feeding was unrelated.

At feeding time, the door was opened and food was then provided. Initially, salivation was not secreted with the opening of the door, but over time, the stimulus became conditioned, and when the door was opened but food was not provided, salivation still occured, suggesting that the door opening had become a Conditioned Stimulus.

Instrumental Learning

An extension of Classical Conditioning was devised by Edward Thorndike (1874-1949), who placed cats in a puzzle box. The incentive of a fish as food was placed outside of the box, giving the cats a reason to try to escape from the box. Initially, they had trouble escaping, and only gained freedom by knocking the latch of the box. Over time, they learnt that the undoing of the latch would enable their escape, and so the time spend being trapped in the puzzle box decreased as their knowledge of how to leave it increased.

Thorndike termed this conditioning the "Law of Effect" in 1911: a positive outcome to a situation resulted in the stamping in of a particular behavior (in the case of the puzzle box, the opening of the latch was stamped in). Conversely, if an outcome is undesirable - had the cats been punished as a result of leaving the box - the action leaving to it would be stamped out - become less frequent.

Operant Conditioning and Reinforcement

In 1938, B.F. Skinner carried out an experiment with caged rats in an "operant conditioning chamber" - Skinner's Box - who learnt through Operant Conditioning that if they pressed on a lever, food would be released for them. Under Operant Conditioning, reinforcement plays a key role:

Reinforcement Type:

Description:

Tendency to Behave in a Particular Manner:

Positive Reinforcement

A stimulus is introduced which incentivises a particular behavior. e.g. the reward of a pellet of food in Skinner's Box.

Negative Reinforcement

A desirable incentive is introduced to not behave in a particular way.

Positive Punishment

An undesirable punishment (e.g. electric shock) is introduced when the subject behaves in a particular way, discouraging such behavior.

Negative Reinforcement

Removing the desirable stimulus (e.g. food) to prevent a particular behavior.

The key difference between operant conditioning and classical conditioning is that the former creates association based on the result of a subject's behavior and the outcome that it generates as a secondary effect, whereas classical conditioning more primitively concentrates on the behavior itself.

Examples of Conditioning

A dog receiving positive attention after fetching a stick back to its owner, learns to associate bringing the object back with favorable attention - positive reinforcement.

A rat in a cage with an electrified floor learns that by pressing a lever, the electrical shock will stop - negative reinforcement.

A cat being shouted at for scratching furniture is discouraged to repeat this - positive punishment.

A child not being allowed to watch television after misbehaving associates bad behavior with an absence of rewards - negative punishment.


Imprinting

If newly-hatched geese are exposed to a moving object of reasonable size and emitting reasonable sounds, they will begin to follow it just as they would normally follow their mother.

This is called imprinting.

The time of exposure is quite critical. A few days after hatching, imprinting no longer occurs. Prior to this time, though, the results can be quite remarkable. A gosling imprinted to a moving box or clucking person will try to follow this object for the rest of its life. In fact, when the gosling reaches sexual maturity, it will make the imprinted object &mdash rather than a member of its own species &mdash the goal of its sexual drive.

Much of our knowledge of imprinting was learned from the research of Konrad Lorenz, shown here with some of his imprinted goslings. Lorenz shared a Nobel Prize in 1973 for his discoveries. (Photo by Tom McAvoy courtesy of LIFE Magazine, ©1955, Time, Inc.)

Male mice become imprinted with the odor of littermates during the first three weeks of life. When they reach sexual maturity, they avoid mating with close relatives. The odor is controlled by the major histocompatibility complex (MHC).


A Word From Verywell

In reality, people do not respond exactly like Pavlov's dogs. There are, however, numerous real-world applications for classical conditioning. For example, many dog trainers use classical conditioning techniques to help people train their pets.

These techniques are also useful for helping people cope with phobias or anxiety problems. Therapists might, for example, repeatedly pair something that provokes anxiety with relaxation techniques in order to create an association.

Teachers are able to apply classical conditioning in the class by creating a positive classroom environment to help students overcome anxiety or fear. Pairing an anxiety-provoking situation, such as performing in front of a group, with pleasant surroundings helps the student learn new associations. Instead of feeling anxious and tense in these situations, the child will learn to stay relaxed and calm.