The Psychology Book
Page 8
IVAN PAVLOV
Ivan Pavlov, the eldest son of a village priest in Ryazan, Russia, was initially destined to follow in his father’s footsteps. However, he quickly abandoned his training at a local seminary, transferring to the University of St. Petersburg to study natural science. After graduation in 1875, he enrolled at the Academy of Medical Surgery, where he gained a doctorate and later a fellowship. In 1890, Pavlov became a professor at the Military Medical Academy, and was also made director of the physiology department at the Institute of Experimental Medicine. It was here that he carried out his famous research into the digestive secretions of dogs, which won him the Nobel Prize in 1904. Pavlov retired officially in 1925, but continued his experiments until his death from pneumonia in February 1936.
Key works
1897 Lectures on the Work of the Principal Digestive Glands
1928 Lectures on Conditioned Reflexes
1941 Conditioned Reflexes and Psychiatry
See also: William James • John B. Watson • B.F. Skinner • Stanley Schachter
IN CONTEXT
APPROACH
Connectionism
BEFORE
1885 In his book On Memory, Hermann Ebbinghaus describes the “forgetting curve”—the rate at which human memories fade.
1890s Ivan Pavlov establishes the principle of classical conditioning.
AFTER
1918 John B. Watson’s “Little Albert” experiments apply conditioning to a human baby.
1923 English psychologist Charles Spearman proposes a single general factor—the “g factor”—in measurements of human intelligence.
1930s B.F. Skinner develops a theory of conditioning from consequences—“operant conditioning.”
At much the same time as Pavlov was conducting his experiments on dogs in Russia, Edward Thorndike began researching animal behavior for his doctoral thesis in the US. He was perhaps the first true “behaviorist” psychologist, although his research took place long before the term was adopted.
Scientific psychology was emerging as a fresh field of study in universities when Thorndike graduated in the 1890s, and he was attracted by the prospect of applying this new science to his interest in education and learning. Thorndike’s original intention had been to study learning in humans, but when he was unable to obtain a suitable subject for his research, he turned his attention to animals, with the aim of examining the processes of intelligence and learning through observation in a series of controlled experiments. Thorndike’s results went much further than this, however, laying down the foundations of behaviorist psychology.
"Psychology helps to measure the probability that an aim is attainable."
Edward Thorndike
Learning environments
Thorndike’s first studies were of chicks learning to negotiate mazes that he designed and built specifically for his experiments. This later became a hallmark of behaviorist experimental technique—the use of a specially created environment in which a subject is given specific stimuli or tasks, now known as “instrumental conditioning” or “instrumental learning.” As his research progressed, Thorndike turned his attention to cats, inventing “puzzle boxes” to observe their ability to learn mechanisms for escape.
A hungry cat was locked inside a puzzle box, and by exploring its environment would come across various devices, such as a loop of string, or a ring, or a button or panel to be pressed, only one of which would be connected to the latch that would open the door of the box. In time, the cat would discover the device, which would allow it to escape and receive a reward of food. The process was repeated and it was noted how long it took for the cat to open the puzzle box each time; this indicated how quickly the animal was learning about its environment.
The experiment was carried out using several different cats, placing each one in a series of puzzle boxes that were opened by different devices. What Thorndike noticed was that although the cats had all discovered the escape mechanism by trial and error in their first attempt, on successive occasions the amount of trial and error gradually decreased as the cats learned which actions were going to be fruitless and which would lead to a reward.
The Law of Effect
As a result of these experiments Thorndike proposed his Law of Effect, which states that a response to a situation that results in a satisfying outcome is more likely to occur again in the future; and conversely, that a response to a situation that results in an unsatisfying outcome is less likely to occur again. This was the first formal statement of an idea that lies behind all behavourist psychology, the connection between stimulus and response and its relevance to the process of learning and behavior. Thorndike proposed that when a connection is made between a stimulus (S) and a response (R), a corresponding neural connection is made in the brain. He referred to his brand of S-R learning as “connectionism,” asserting that the connections made during learning are “stamped in” the circuitry of the brain.
What Thorndike proposed was that it is the outcome of an action that determines how strongly or weakly the stimulus-response connection is stamped in; in the case of the puzzle boxes, whether pulling a string or pushing a panel resulted in escape or frustration. In other words, when particular stimulus-response sequences are followed by a satisfying or pleasant state of affairs (such as escape or a reward), those responses tend to become “more firmly connected with the situation, so that, when it recurs, they will be more likely to recur.” They become “stamped in” as a neural connection. When stimulus-response sequences are followed by an annoying or unpleasant state of affairs (such as continued imprisonment or punishment), the neural connections between the situation and response are weakened, until eventually “profitless acts are stamped out.”
This focus on the outcome of a stimulus and its response, and the idea that the outcome could work back to strengthen the stimulus-response connection, is an example of what would later be called a reinforcement theory of learning. Reinforcement, and the importance of outcomes, was virtually ignored by psychologists in the next generation of behaviorists, such as John B. Watson, but the Law of Effect brilliantly anticipated the work of B.F. Skinner and his theory of “operant conditioning.”
In later research, Thorndike refined the Law of Effect to take into account other variables, such as the delay between response and reward, the effect of repetition of a task, and how quickly a task was forgotten when it was not repeated. From this, he derived his Law of Exercise, which states that stimulus-response connections that are repeated are strengthened, while those that are not used again are weakened. Moreover, the rate at which connections strengthen or weaken can vary. According to Thorndike, “the greater the satisfaction or discomfort, the greater the strengthening or weakening of the bond.”
Interestingly, although Thorndike was studying animal behavior using what were to become standard behaviorist methods—and authoring a book, Animal Intelligence (1911), which was to become a classic of early behaviorism—he considered himself primarily an educational psychologist. He had originally intended to examine animal intelligence, not behavior. He wanted to show, for example, that animals learned by simple trial and error rather than by using a faculty of insight, an idea that was prevalent in psychology at the time: “In the first place, most of the books do not give us a psychology, but rather a eulogy of animals. They have all been about animal intelligence, never about animal stupidity,” he wrote. The fact that his cats in puzzle boxes learned gradually, rather than suddenly gaining an insight into how to escape, confirmed his theories. The animals were forced to learn by trial and error, becau
se they were unable to use reason to work out the link between the door and the operating handle.
The Law of Effect, proposed by Thorndike, forms the foundation of all behaviorist psychology. He demonstrated that animals learn by forging links between actions and results, remembering more positive outcomes and forgetting negative ones.
Human intelligence
After the publication of Animal Intelligence, Thorndike turned his attention to human intelligence. In his opinion, the most basic intelligence is characterized by simple stimulus and response association, resulting in a neural connection. The more intelligent an animal, the more capable it will be of making such connections. Therefore, intelligence can be defined in terms of the ability to form neural bonds, which is dependent not only on genetic factors, but also on experience.
To find a measurement of human intelligence, Thorndike devised his CAVD (Completion, Arithmetic, Vocabulary, and Directions) test. It became the model for all modern intelligence tests, and assessed mechanical intelligence (understanding of how things work), as well as abstract intelligence (creative ability) and social intelligence (interpersonal skills). Thorndike was especially interested in how age might affect learning, and also proposed a theory of learning that remains at the heart of educational psychology to this day, a contribution that is perhaps what Thorndike would have wished more than anything else to be remembered for. However, it is for his enormous influence on the behaviorist movement that Thorndike is most often lauded.
"The intellect, character, and skill possessed by any man are the product of certain original tendencies and the training which they have received."
Edward Thorndike
Adult learners were once thought to be less capable of retaining information than children. Thorndike showed that the only significant difference was in speed of learning, not memory.
EDWARD THORNDIKE
The son of a Methodist minister, Edward Thorndike was born in Williamsburg, Massachusetts, USA, in 1874. He graduated in sciences from Wesleyan University in 1895, proceeding to Harvard to study psychology under William James. In 1897, Thorndike moved to Columbia University in New York City, where he completed his doctorate thesis in 1898.
Thorndike’s interest in educational psychology led to a teaching post at the College for Women of Case Western Reserve in Cleveland, Ohio, but he returned to Columbia just a year later, in 1899, teaching there until his retirement in 1939. In 1912, his peers elected him President of the American Psychological Association. Thorndike continued to research and write until his death, aged 74, in Montrose, New York.
Key works
1905 The Elements of Psychology
1910 The Contribution of Psychology to Education
1911 Animal Intelligence
1927 The Measurement of Intelligence
See also: Hermann Ebbinghaus • Ivan Pavlov • John B. Watson • Edward Tolman • B.F. Skinner • Donald Hebb • Hans Eysenck
IN CONTEXT
APPROACH
Classical behaviorism
BEFORE
1890s German-born biologist Jacques Loeb (one of Watson’s professors) explains animal behavior in purely physical-chemical terms.
1890s The principle of classical conditioning is established by Ivan Pavlov using experiments on dogs.
1905 Edward Thorndike shows that animals learn through achieving successful outcomes from their behavior.
AFTER
1932 Edward Tolman adds cognition into behaviorism in his theory of latent learning.
1950s Cognitive psychologists focus on understanding the mental processes that both lie behind and produce human behavior.
By the beginning of the 20th century, many psychologists had concluded that the human mind could not be adequately studied through introspective methods, and were advocating a switch to the study of the mind through the evidence of behavior in controlled laboratory experiments.
John Watson was not the first advocate of this thoroughgoing behaviorist approach, but he was certainly the most conspicuous. In a career cut short by his marital infidelity, he became one of the most influential and controversial psychologists of the 20th century. Through his work on the stimulus—response learning theory that had been pioneered by Thorndike, he became regarded as the “founding father” of behaviorism, and he did much to popularize the use of the term. His 1913 lecture, Psychology as the Behaviorist Views It, put forward the revolutionary idea that “a truly scientific psychology would abandon talk of mental states… and instead focus on prediction and control of behavior.” This lecture became known to later psychologists as the “behaviorist manifesto.” Before Watson’s research at Johns Hopkins University, in Baltimore, Maryland, the majority of experiments on behavior had concentrated on animal behavior, with the results extrapolated to human behavior. Watson himself studied rats and monkeys for his doctorate but (perhaps influenced by his experience working with the military during World War I) was keen to conduct experiments using human subjects. He wanted to study the stimulus—response model of classical conditioning and how it applied to the prediction and control of human behavior. He believed that people have three fundamental emotions—fear, rage, and love—and he wanted to find out whether a person could be conditioned into feeling these in response to a stimulus.
"Psychology, as the behaviorist views it, is a purely objective experimental branch of natural science."
John B. Watson
Little Albert
With his research assistant, Rosalie Rayner, Watson began a series of experiments involving “Albert B,” a nine-month-old baby chosen from a local children’s hospital. The tests were designed to see whether it is possible to teach an infant to fear an animal by repeatedly presenting it at the same time as a loud, frightening noise. Watson also wanted to find out whether such a fear would transfer to other animals or objects; and how long this fear would persist. Today, his methods would be considered unethical and even cruel, but at the time they were seen as a logical and natural progression from previous animal studies.
In the now famous “Little Albert experiment,” Watson placed the healthy but “on the whole stolid and unemotional” baby Albert on a mattress and then observed his reactions when introduced to a dog, a white rat, a rabbit, a monkey, and some inanimate objects, including human masks and burning paper. Albert showed no fear of any of these animals or objects and even reached out to touch them. In this way, Watson established a baseline from which he could measure any change in the child’s behavior toward the objects.
On a separate occasion, while Albert was sitting on the mattress, Watson struck a metal bar with a hammer to make a sudden loud noise; unsurprisingly, Albert became frightened and distressed, bursting into tears. Watson now had an unconditioned stimulus (the loud noise) that he knew elicited a response of fear in the child. By pairing this with the sight of the rat, he hypothesized that he would be able to condition little Albert to become afraid of the animal.
When Albert was just over 11 months old, Watson carried out the experiment. The white rat was placed on the mattress with Albert, then Watson hit the hammer on the steel bar when the child touched the rat. The child burst into tears. This procedure was repeated seven times over two sessions, one week apart, after which Albert became distressed as soon as the rat was brought into the room, even when it was not accompanied by the noise.
By repeatedly pairing the rat with the loud noise, Watson was applying the same kind of classical conditioning as Pavlov had in his experiments with dogs. The child’s natural response to the noise—fear and distress—had now become
associated with the rat. The child had become conditioned to respond to the rat with fear. In terms of classical conditioning, the rat was initially a neutral stimulus eliciting no particular response; the loud noise was an “unconditioned stimulus” (US) that elicited an “unconditioned response” (UR) of fear. After conditioning, the rat had become a “conditioned stimulus” (CS), eliciting the “conditioned response” (CR) of fear.
However, this conditioning seemed to go deeper than simply a fear of the white rat, and appeared to be far from temporary. In order to test whether Albert’s fear had “generalized,” or spread to other, similar objects, he was reintroduced to white furry things—including a rabbit, a dog, and a sheepskin coat—five days after the original conditioning. Albert showed the same distressed and fearful response to these as to the rat.
In these experiments, Watson demonstrated that human emotions are susceptible to classical conditioning. This was a new finding, because previous stimulus—response experiments had focused on testing the learning of physical behaviors. Watson had discovered that not only can human behavior be predicted—given certain stimuli and conditions—it can also be controlled and modified. A further check of Albert’s reactions to the rat, rabbit, and dog one month later suggested that the effects of this conditioning were long-lasting, but this could not be proven as Albert was soon after removed from the hospital by his mother. It has been suggested that this was a sign of the mother’s distress, but according to Watson and Rayner’s own account, it occurred on a prearranged date.