History and Development of Psychology

BEHAVIOURISM

Ivan Pavlov (1849 – 1936)

Since the 19th century the development of psychology has been influenced by many individuals. One of the earliest was Ivan Pavlov (1849 – 1936)

The Russian psychologist Ivan Pavlov is remembered primarily for his development of the concept of conditioned reflex. In a well-known experiment he trained a hungry dog to salivate at the sound of a bell. The bell had previously become associated by the dog with the sight of food. Pavlov's work laid a foundation for the scientific analysis of human behaviour.

The work that made Pavlov a household name in psychology actually began as a study in digestion. He was looking at the digestive process in dogs, especially the interaction between salivation and the action of the stomach. He realized they were closely linked by reflexes in the autonomic nervous system (the part of nervous system that regulates involuntary action, as of the intestines, heart, and glands); therefore, the unconditioned response is a natural response. Without salivation, the stomach didn't get the message to start digesting. Pavlov wanted to see if external stimuli could affect this process, so he rang a bell at the same time he gave the experimental dogs food. Pavlov wondered if the closely linked reflexes that he had observed could be influenced by external factors. Classical conditioning is also known as learning by association because we learn to associate two stimuli together.

Theory

A three step process will bring about conditioning. The three steps are 1) Before conditioning, 2) Conditioning, 3) After conditioning.

 

For example:

 

Step one) before conditioning,

 

Food (UCS) = Salivation (UCR)

 

Bell (NS) = No salivation

 

In the first stage you can see that food is an unconditioned stimulus. In other words you do not need to be conditioned to react to food…this is a natural process…you have not conditioned…therefore this is an unconditioned stimulus.

 

The bell is a neutral stimulus…it is simply an object that will not cause you to salivate.

 

Pavlov wanted to see if he could condition the dogs to salivate at the sound of the bell. In other words he wanted to see if he could condition the behaviour of the dogs. If he could do this then it might be possible to use his techniques for the purposes of teaching.

 

 

Step 2) conditioning

 

Bell + Food = Salivation

 

Pavlov rang a bell just before he fed the dogs. He repeated this process over and over. Eventually the dogs came to associate the bell with the food. The dogs would now salivate when they heard the bell…the food did not need to be present…the dogs had been conditioned by a process of Stimulus – Response.

 

Step 3) after conditioning

 

Bell (CS) = Salivation (CR)

 

The Bell, which had previously been a neutral object, has now been associated with food. Pavlov has conditioned the dogs to expect food when they hear the bell. He has conditioned the neutral stimulus…the bell is now the conditioned stimulus.

 

STUDENT EXERCISE:

 

Suppose that a follower of Pavlov had observed that:

A human subject jerked his foot in response to an electric shock to the sole.

Flashing a blue light caused no movement in the foot.

After pairing the blue light with an electric shock, the light acting on its own elicited a jerk of the foot.

 

In this example, what is: a) the unconditioned stimulus; b) the unconditioned response; c) the neutral stimulus; d) the conditioned stimulus; and e) the conditioned response? (SOURCE: Roth, 1990).

 

 

imagePavlov concluded that he was able to pair a neutral stimulus with an excitatory one and have the neutral stimulus eventually elicit the response that was associated with the original, unlearned reflex.

 

In Classical Conditioning terminology, an unconditioned stimulus (US) is an event that causes a response to occur, which is referred to as the unconditioned response (UR). And, in Pavlov's study with dogs, the food is the US, and the salivation that results is the UR.

 

 

Pavlov took a step further and added an element known as the non-excitatory, conditioned stimulus (CS), which is paired with the US.

Pavlov used a bell as the CS which he rang first, then fed the dogs. He repeated this process every time the dogs were fed. This repeated pairing would eventually establish the dog's conditioned response (CR) of salivating to the sound of the bell. After repeating this procedure several times, Pavlov was able to remove the US (food) and by only ringing the bell the dogs would salivate (CR). Since the bell alone now produced the unconditioned response (salivation), the association had been established (Conditioned).

Pavlov continued to present the CS with any pairing with the US until the CR no longer occurred. That is to say, he rang the bell but did not present any food. This elimination of the CR is known as extinction. Pavlov continued working on the conditioned response. He replaced the bell with other stimuli for use as the CS.

He conditioned the dogs using a buzzer, the flash of a light, a touch on the dog's harness, and the use of different pitches of a whistle, which the dogs had to differentiate between to determine which pitch resulted in access to food. Pavlov termed this higher order conditioning.

So, we have seen that after a while, the dogs would begin to salivate when the bell sounded, even if no food were present. Similarly, the dogs would salivate at the sight of the lab assistants who brought the food. Previously the dogs only salivated when they saw and ate their food.

In 1903 Pavlov published his results calling this a "conditioned reflex," different from an innate reflex, such as yanking a hand back from a flame, in that it had to be learned. He summarized his discoveries in his remarkable book, Conditioned Reflexes.

Pavlov called this learning process (in which the dog's nervous system comes to associate the sound of the bell with the food, for example) "conditioning." He also found that the conditioned reflex will be repressed if the stimulus proves "wrong" too often. If the bell sounds repeatedly and no food appears, eventually the dog stops salivating at the sound. He called this extinction.

Pavlov believed that conditioned reflexes could explain the behaviour of psychotic people. For example, he suggested, those who withdrew from the world may associate all stimulus with possible injury or threat. As his work progressed, Pavlov established the basis for conditioned reflexes and the field of classical conditioning.

According to Pavlov’s theory of classical conditioning, even when we are learning something as complex as mathematics we are merely conditioning our reflexes into ‘chains’ of action and reaction. Eventually these reflex chains will form into complete and complicated sequences of behaviour. Classical conditioning has been successful in treating simple behaviour disorders such as phobias.

An illustrated review of Pavlov's experiments is available on the Discovery Web Site. Figure 10.9 from Ryckman (2004) (below) shows an illustrated depiction of the 3 stage process involved in Pavlov’s classical conditioning.

 

 

 

 

 

 

Edward L. Thorndike (1874 – 1949)

The history and development of psychology continued with the work of E. L. Thorndike (1874 -1949). Thorndike proposed that the most important cause of learning concerns the consequences which that behaviour has for us. For instance, if you obtain something which pleases you - after you have behaved in a certain way - then you link that behaviour with the pleasant outcome. Such an association will cause you to repeat the behaviour for as long as it keeps reproducing pleasurable outcomes. If behaviour leads to something nice happening to then you are likely to repeat that behaviour. Thorndike called this the law of effect (Davis and Houghton, 1991).

Edward. L. Thorndike used what he called a ‘puzzle box’ to illustrate the law of effect. His puzzle box was a simple box which had a grill covering one half of the front and a door with an accessible latch covering the other half of the front. The other three sides and the roof and the floor were solid. The only means of ‘escape’ was to manipulate the latch. A contingency (when something is contingent it is dependant on something else happening – so contingency means dependency) was arranged between the animal’s behaviour and a consequence (in this case escape from the box). So, escape was contingent on a response.

A hungry cat was put into a puzzle box. In order to get out of the box, it was necessary for the cat to manipulate a latch that held the door in place. At first, when placed in the box, the cat would struggle and meow. After a while, apparently by accident, the cat would manipulate the latch and gain its freedom and access to food. The cat would be returned to the box for the next trial. Thorndike recorded the time elapsing between placing the cat in the box and its escape. Over a series of such trials the cat got steadily quicker at escaping. Thorndike used these recordings as an indication of learning. The assumption was that the shorter the time to escape, the stronger the learning.

Thorndike produced a learning curve to show the pattern of escape. It’s like a graph – down the ‘y’ axis is the escape time – along the ‘x’ axis is the number of trials. The curve showed that on the first trial the cat too longer than on the subsequent trial and so on. This produced a curve that started high on the ‘y’ axis and ended low on the ‘x’ axis.

How did Thorndike explain the result of the puzzle box experiment? Did the cat show sudden insight into the problem? Thorndike dismissed this as an explanation on the grounds that, if insight were involved, the form of the learning curve would display a sudden fall in the escape time. However, in Thorndike’s experiment the escape time decreased gradually over a number of trials, thus supporting the idea of gradual learning.

Thorndike arrived at the conclusion that learning involves the gradual formation of an association between the stimulus and the response that was instrumental in the escape – a stimulus-response (S-R) association.

In Thorndike’s experiment, learning was defined in terms of learning of forming associations between stimulus and response, in a rather similar way to the account given earlier for classical conditioning. However, the technique used to produce the association was fundamentally different. In classical conditioning, two stimuli (food and a bell) were presented to the animal. The animal’s own behaviour is not a factor in the sequence of events. By contrast, in Thorndike’s experiment, the animal’s own behaviour is instrumental in the sequence of events; that is, the manipulation of the paw causes the door to open and escape is possible. For this reason, the type of conditioning studied by Thorndike is called instrumental conditioning, in contrast to classical conditioning. (SOURCE: Roth, (1990)

Pavlov and Thorndike’s ideas played a large role in the ideas behind the Behaviourist school of psychology, introduced by John Watson around 1913.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

John Watson (1878 – 1958)

John Watson was formulating ideas that would become a whole branch of psychology: Behaviourism. He studied the biology, physiology, and behaviour of animals, inspired by the recent work of Ivan Pavlov. He began to apply the features of Pavlov’s work to the behaviour of children. He believed that humans were simply more complicated than animals but operated on the same principles. All animals, he believed, were extremely complex machines that responded to situations according to their "wiring," or nerve pathways that were conditioned by experience. In 1913, he published an article outlining his ideas and essentially establishing a new school of psychology. It was new because Watson disagreed with Freud. He found Freud’s views on human behaviour philosophical to the point of mysticism. He also dismissed heredity as a significant factor in shaping human behaviour. For Watson all behaviour is learned behaviour. Therefore, the environment is central to behaviourism. Behaviourism asserts that it is from the consequences of our action, or from the association between stimuli that we learn.

Because an interaction between stimulus-response can be predicted it would now be possible to control behaviour and learning.

Introspection (the contemplation of one’s own thoughts and feelings) was a feature of structuralism and Freudian psychoanalysis. Introspection was used by Wilhelm Wundt (1832 – 1920) as a method of data collection. However, Watson believed this to be far too subjective i.e. subject to one’s own views – it is not scientific. It was not observable or measurable. Similarly, not everyone is capable of accurately describing the way they feel. Many people simply did not have a sufficient vocabulary and Watson considered it unacceptable as a method of data collection. Introspection is therefore not considered a reliable, repeatable and valid (scientific) means of gathering information.

 

Watson describes his vision of the future of psychology thus:

 

“Psychology as the behaviourist views it is a purely objective experimental branch of natural science. Its theoretical goal is the prediction and control of behaviour. Introspection forms no essential part of its methods, nor is the scientific value of its data dependent upon the readiness with which they lend themselves to interpretation in terms of consciousness. The behaviourist, in his efforts to get a unitary scheme of animal response, recognizes no dividing line between man and brute…” (Watson, J. 1913, p. 158)

 

Watson's behaviourism dismissed at one stroke the entire body of literature on experimental psychology that had been painstakingly built over many decades. Introspection was now out of favour and empirical / scientific / objectivity was in. Titchener (1914), examined Watson's argument carefully and addressed its strengths and weaknesses thus: Watson's reasoning can be stated, in a simplified form, as follows:

(i)                 psychology must be a science (an implicit assumption, unquestioned at the time by advocates and critics alike),

(ii)               a fundamental principle of science is that its data must come from publicly observable phenomena,

(iii)             what is taken to be the subject matter of psychology, namely consciousness, does not satisfy that principle because it cannot be observed publicly,

(iv)              the methods to which psychology must resort for studying consciousness, namely introspection, are not scientific methods,

(v)                therefore, the psychology of the time was not a science.

Watson's embraced Titchener’s thoughts and proceeded directly to propose what must be entailed in a "natural science" of psychology:

(i)                 it must abandon consciousness as the object of its study

(ii)               it must turn only to the study of publicly observable phenomena, namely behaviour, and

(iii)             it must develop methods for publicly observing behaviour.

This, in a nutshell, was the basic doctrine of behaviourism as advocated by Watson in 1913, and it remains so to the present day.

Watson’s most famous experiment involveds a child known as ‘Little Albert’.

The association which takes place in conditioning may offer an explanation as to the development of behaviours such as phobias. A phobia is an irrational and intense fear of some object, event or situation, such as snakes (ophidiophobia), spiders (arachnaphobia) or open spaces (agoraphobia).

Watson and Rayner (1920) demonstrated the cassical conditioning of fear in a young boy. ‘Little Albert’ was an 11 year old boy who was allowed to play with a with a white rat and who showed no fear towards the rat, but as he played a metal bar was struck behing him causing a fear response (an unconditioned response) After several presentations of the noise together with the rat te boy displayed a fear response (conditioned response) to the rat alone. For example:

Rat = No fear

Noise = fear

Rat + Noise = fear

Rat = fear.

Little Albert also showed fear of objects that looked similar to the white rat such as cotton wool. This is known as generalisation.

 

Figure 10.10 from Ryckman (2004) (above) shows an illustrated depiction of the3 stage process used by Watson to condition ‘Little Albert’.

Figure 10.11 (left) from Ryckman (2004) shows the 3 stage process involved in counter-conditioning. This is the process that Watson would have used to return ‘Little Albert’ to his pre-conditioned state.

 

 

 

Following from the work of Pavlov, Thorndike and Watson the history and development of psychology continued with the work of B. F. Skinner who is famous for what was to come to be known as Operant Conditioning.

Burrhus Frederic Skinner (1904 – 1990)

Behavior that is positively reinforced will reoccur; intermittent reinforcement is particularly effective. Skinner likes to tell about how he accidentally came across his various discoveries.  For example, he talks about running low on food pellets in the middle of a study.  So, Skinner had to make his own rat pellets, a slow and tedious task.  So he decided to reduce the number of reinforcements he gave his rats for whatever behaviour he was trying to condition, and, lo and behold, the rats kept up their operant behaviors, and at a stable rate, no less.  This is how Skinner discovered schedules of reinforcement!

Operant conditioning is where we learn through the consequences of our action.

Currently (Sept, 2005) you can hear Skinner talk about his experiments at the following web link: www.fenichel.com/Current.shtml simply type this address into an Internet search engine (such as Google) once it opens press Ctrl and F on your keyboard, type in Skinner and hey presto! You can hear interviews with B. F. Skinner where he talks about operant conditioning.

In the late 1930s and 1940s, behaviourism was revived by B F Skinner (1904 – 1990). Skinner took up Watson's descriptions of the principles of behaviourism. The aspect of behaviourism involving the rejection of consciousness and related terms was hardened by Skinner, who labeled them "mentalistic terms" and advocated their elimination from the language.

Skinner reiterated Watson's principles of behaviourism almost-and in places wholly-verbatim. However, it is important to note that Skinner's lasting contribution to psychology is in his:

Operant conditioning sees learning occur through the consequences of our actions.

 

In operant conditioning the organism is in the process of “operating” on the environment, which in ordinary terms means it is moving around its world, doing what it does.  During this “operating,” the organism encounters a special kind of stimulus, called a reinforcing stimulus, or simply a reinforcer.

The reinforcer encourages a behaviour. This special stimulus has the effect of increasing the operant ­– i.e. the behaviour occurring just before the reinforcer – in the case of the Skinner box experiment – food i.e. the reinforces encourages behaviour which provides us with food.

 

This is operant conditioning:  “the behaviour is followed by a consequence, and the nature of the consequence modifies the organism’s tendency to repeat the behaviour in the future.” (SOURCE: Boeree, 1998)

In operant conditioning the organism can emit responses instead of only eliciting response due to an external stimulus.

Reinforcement is the key element in Skinner's S-R theory. A reinforcer is anything that strengthens the desired response. It could be verbal praise, a good grade or a feeling of increased accomplishment or satisfaction. A great deal of attention was given to schedules of reinforcement (e.g. interval versus ratio) and their effects on establishing and maintaining behaviour.

“All of us are exposed to different environments and to different schedules and arrangements of reinforcement in our daily lives. Some parents, for example, consistently reinforce their children’s behaviour; other supply only intermittent reinforcement. These schedules have a tremendous impact on our responses. Numerous studies with lower animals, for example, have shown that behaviour learned on a continuous reinforcement schedule – that is a schedule in which each response is followed by a reinforcer – produces higher rates of response than behaviour reinforced only intermittently. Behaviour learned on a schedule of intermittent (partial) reinforcement, however, is more resistant to extinction than behaviour acquired on a continuous schedule” (Skinner, 1953 P99) Animals trained on a continuous reinforcement schedule also show signs of emotional reaction or low frustration tolerance when their behaviours are subjected to extinction than do animals trained on intermittent schedules.

Intermittent reinforcement can take many forms. Two of the most common are the fixed-ratio schedule, and the fixed-interval schedule.

In a fixed-ratio schedule, an absolute number of behaviours is required before reinforcement is applied (Ferster & Perrott, 1968 P526). For example, a student might have to complete two class projects before receiving a grade in a course. Or a worker might be placed on a fixed-ration schedule, commonly known as piecework.

In a fixed-interval schedule, the first performance that occurs after an absolute amount of time has elapsed is reinforced (Ferster & Perrott, 1968 P526). There are many examples of the operation of such schedules in our daily lives. We eat at certain times of the day; we go to bed and get up at regular times. Sometimes we get pad by the hour. An interesting feature of behaviour regulated on fixed-interval schedules is that the rate of responding tends to be low just after reinforcement but increases rapidly as the time for reinforcement approaches (Ryckman, RM (2004).

The applications are quite straightforward. Affluent parents who raise their children on a continuous reinforcement schedule should not be surprised that their offspring do not show behaviours that could be labeled persistent, hardworking, ambitious and competitive. These behaviours are more likely to be found in children who have been subjected to partial or intermittent schedules of reinforcement (Carpenter, 1974 P 27-28).

One of the distinctive aspects of Skinner's theory is that it attempted to provide behavioural explanations for a broad range of cognitive phenomena. For example, Skinner explained drive (motivation) in terms of deprivation and reinforcement schedules. Skinner (1957) tried to account for verbal learning and language within the operant conditioning paradigm, although this effort was strongly rejected by linguists and psycholinguists. Skinner (1971) deals with the issue of free will and social control.

Shaping:

Information should be presented in small amounts so that responses can be reinforced ("shaping").  Basically, it involves first reinforcing behaviour only vaguely similar to the one desired.  Once that is established, you look out for variations that are a little closer to what you want, and so on, until you have the animal performing a behaviour that would never show up in ordinary life. For example:

Jackson and Wallace (1974) used shaping and token economy to develop appropriate speech in a 15 year-old girl named Alice who was diagnosed as “severely disturbed, withdrawn, and mildly retarded” by the school diagnostician. The goal was to shape the loudness of her voice until it reached a normal level.

Wearing a microphone to detect the volume of her speech, Alice sat in a private booth, and read to the experimenter single words taken from her classroom reading books. When her voice achieved a specific volume, a token was automatically delivered. At first only slight increases in volume were required to deliver a token. Eventually, however, Alice had to speak louder to activate the relay attached to the microphone sound system that triggered delivery of the tokens. Alice underwent 20 shaping sessions. After each session she was required to read from a book to the experimenter for ten minutes. The tokens Alice earned could be exchanged for several items she wanted, including books, beauty aids, and a photo album.

Once Alice spoke at a normal level, the experimenter attempted to generalise Alice’s new behaviour to her classroom. To promote generalisation, the experimenter rearranged the laboratory setting so that it resembled her classroom and continued her training. Eventually, following intense training, Alice was returned to regular classroom, where she began to behave in a more appropriate way. Her teacher reported that, although she was a long way from being a typical teenager, she had made considerable improvement both in voice loudness and in other social behaviour, such as smiling, playing with others, and initiating verbal interactions with her peers (Ryckman, 2004).

Scope/Application:

Operant conditioning has been widely applied in clinical settings (i.e., behaviour modification) as well as teaching (i.e., classroom management) and instructional development (e.g., programmed instruction).

Imagine a rat in a cage (Skinner box). This is a special cage that has a bar or pedal on one wall that, when pressed, causes a little mechanism to release a foot pellet into the cage.  The rat is bouncing around the cage, doing whatever it is rats do, when he accidentally presses the bar and -- hey, presto! -- a food pellet falls into the cage! The operant is the behaviour just prior to the reinforcer, which is the food pellet, of course.  In no time at all, the rat is furiously peddling away at the bar, hoarding his pile of pellets in the corner of the cage. When the operant is pleasurable, such as a food pellet, positive reinforcement occurs. A behaviour followed by a reinforcing stimulus results in an increased probability of that behaviour occurring in the future. What if you don’t give the rat any more pellets?  Apparently, he’s no fool, and after a few futile attempts, he stops his bar-pressing behaviour.  This is called extinction of the operant behaviour. A behaviour no longer followed by the reinforcing stimulus results in a decreased probability of that behaviour occurring in the future.

Now, if you were to turn the pellet machine back on, so that pressing the bar again provides the rat with pellets, the behaviour of bar-pushing will “pop” right back into existence, much more quickly than it took for the rat to learn the behaviour the first time.  This is because the return of the reinforcer takes place in the context of a reinforcement history that goes all the way back to the very first time the rat was reinforced for pushing on the bar!

However, an aversive stimulus is the opposite of a positive reinforcing stimulus, something we might find unpleasant or painful. Such as; an electric shock. A behaviour followed by an aversive stimulus results in a decreased probability of the behaviour occurring in the future.

This both defines an aversive stimulus and describes the form of conditioning known as punishment.  If you shock a rat for doing x, it’ll do a lot less of x.  If you spank Johnny for throwing his toys he will throw his toys less and less (maybe).

On the other hand, if you remove an already active aversive stimulus after a rat or Johnny performs certain behaviours, you are doing negative reinforcement.  If you turn off the electricity when the rat stands on his hind legs, he’ll do a lot more standing.  If you stop your perpetually nagging when I finally take out the garbage, I’ll be more likely to take out the garbage (perhaps).  You could say it “feels so good” when the aversive stimulus stops, that this serves as a reinforcer! Behaviour followed by the removal of an aversive stimulus results in an increased probability of that behaviour occurring in the future. (SOURCE: Boeree, 1998)

It can be seen therefore that no matter whether a reinforcer is positive or negative – behaviour occurs as a result.

Therefore, behaviour can be modified.

Behaviour modification is a therapy technique based on Skinner’s work.  It is very straight-forward:  Extinguish an undesirable behaviour (by removing the reinforcer) and replace it with a desirable behaviour by reinforcement.  It has been used on all sorts of psychological problems -- addictions, neuroses, shyness, autism, even schizophrenia -- and works particularly well with children.  There are examples of psychotics with learning difficulties who haven’t communicated with others for years who have been conditioning to behave themselves in fairly normal ways, such as eating with a knife and fork, taking care of their own hygiene needs, dressing themselves, and so on.

There is an offshoot of b-mod called the token economy.  This is used primarily in institutions such as psychiatric hospitals, juvenile halls, and prisons.  Certain rules are made explicit in the institution, and behaving yourself appropriately is rewarded with tokens -- poker chips, tickets, funny money, recorded notes, etc.  Certain poor behaviour is also often followed by a withdrawal of these tokens.  The tokens can be traded in for desirable things such as candy, cigarettes, games, movies, time out of the institution, and so on.  This has been found to be very effective in maintaining order in these often difficult institutions.

A token economy is a system (usually in an inpatient setting) in which ‘good’ or ‘appropriate’ behaviour is rewarded with tokens that can be exchanged for desirable luxuries. It works on basic learning principles: behaviours that a therapist wants to encourage are rewarded, and so are more likely to be reproduced.

There is a drawback to token economy:  When an “inmate” of one of these institutions leaves, they return to an environment that reinforces the kinds of behaviours that got them into the institution in the first place.  The psychotic’s family may be thoroughly dysfunctional.  The juvenile offender may go right back to “the ‘hood.” No one is giving them tokens for eating politely.  The only reinforcements may be attention for “acting out,” or some gang glory for robbing a Seven-Eleven.  In other words, the environment doesn’t travel well! (SOURCE: Boeree, 1998).

 

 

 

 

 

REFERENCES:

 

Boeree, CJ (1998) (online) http://www.ship.edu/~cgboeree/skinner.html

 

Carpenter, F (1974) The Skinner Primer New York: Free Press.

 

Davies, R and Houghton, P (1991) Mastering Psychology MacMillan Master Series, MacMillan Education Ltd.

 

Ferster, CB and Perrott, MC (1968) Behaviour Principles New York: Appleton-Century-Crofts.

 

Jackson, DA and Wallace, RF (1974) The Modification and generalisation of voice loudness in a fifteen-year-old retarded old girl Journal of Applied Behaviour Analysis 7, 461-471

 

Roth, I (1990) The Open University’s Introduction to Psychology: Volume 1, Open University, Psychology Press Ltd.

 

Ryckman, RM (2004) Theories of Personality CA USA: Thomson, Wadsworth.

 

Skinner, BF (1953) The Behaviour of Organisms New York: Appleton-Century-Crofts.

 

ANSWER TO PAVLOV EXERCISE:

 

a) The unconditioned stimulus is the electric shock.

b) The unconditioned response is the jerk of the foot.

c) The neutral stimulus is the blue light (prior to pairing with the shock).

d) The conditioned stimulus is the blue light after pairing with the shock.

e) The conditioned response is the jerk of the foot elicited by the blue light.