The word classical in classical conditioning suggests that this was the first type of learning studied by experimental psychologists, but this was not the case. Scientific studies of classical conditioning began during the 1890s with the work of the Russian physiologist, Ivan P. Pavlov, and his colleagues (see Pavlov, 1927), at about the same time as did scientific studies of a second type of learning — instrumental learning — had begun with the work of an American graduate student named Edward L. Thorndike (1874-1949). According to Wozniak (1999), Thorndike’s dissertation for the Ph.D. degree (Thorndike, 1898):
is widely considered to be one of the most influential publications of the first half century of psychological science. In addition to offering a conception of animal intelligence couched solely in terms of the organism’s ability to form new associations, it described ingenious apparatus for the observation of animal learning and demonstrated the use of such apparatus in systematic laboratory research.
For example, Thorndike performed research (summarized in Thorndike, 1911) on the ability of cats to learn to escape from “puzzle boxes” (see Figure 1). Cats placed within a puzzle box had to learn to do one or more of the following things in order to escape: push a lever, pull on a wire loop, pull on a string, turn a “button,” lift a latch, or push aside a door. In some experiments, the cat had to perform two or three of these actions sequentially before the door would open. In still other conditions, the door opened only after the cats licked or scratched themselves. Cats were rewarded for these behaviors by food, which was placed outside the box. In addition, because cats typically do not like being confined in small enclosures (as many cat-lovers already know), Thorndike’s subjects also experienced a reward simply by escaping from the tight confines of the box.
We can use this brief description of Thorndike’s method to show that the type of learning demonstrated by the cats is similar to, but also different from, classical conditioning. The most important similarity is that, in both classical conditioning and instrumental learning, subjects learn to associate paired events. One very important difference is:
- in classical conditioning, the learned response (the CR) is elicited involuntarily by a stimulus that comes before it (the CS);
- in instrumental learning, the learned response (the instrumental response) is emitted voluntarily because of its consequence — that is, because of a stimulus (a reward) that follows it.
The degree to which a response is voluntary is best represented on a continuum:
Involuntary <—————————————–> Voluntary
- Mostly or Fully Involuntary Responses. For most people, it is difficult to voluntarily express a believable smile — that is, to fake a smile that looks genuine to others. This is, in part, because the motor cortex controls the voluntary expression of (fake) smiles, whereas a different part of the brain, the cingulate cortex, controls involuntary (real) smiles. Because different areas of the brain are involved, fake smiles usually look different than real smiles do, although some people are very good at faking smiles. (Go here to see how good you are at spotting fake smiles.)
- More Involuntary Than Voluntary Responses. It is virtually impossible not to salivate when asked to inhibit this response after food has been placed on one’s tongue, although one may be able to voluntarily salivate, perhaps by thinking of food, when asked to do so.
- More Voluntary Than Involuntary Responses. Shaking hands generally is thought to be a voluntary response, and it is, most of the time. However, if someone unexpectedly sticks his hand out in a way that makes it look like he wants to shake your hand, you generally will stick your hand out without thinking (that is, involuntarily). While you’re doing this, the person may, as a joke, pull his hand back, leaving you feeling stupid.
- Mostly or Fully Voluntary. It is quite easy for most people to move their left thumbs when asked to do so; and to not move their left thumbs when asked not to do so. Thus, this is a voluntary behavior. A already stated, the motor cortex is intimately involved in the control of voluntary responses to stimuli.
In classical conditioning, the development of an association between the CS and UCS is indicated by the development of a reflexive (involuntary) response, the CR. Thus, conditioned responses generally are mostly or fully involuntary responses (#1 above). In instrumental learning, on the other hand, subjects learn that, when placed within a particular situation, the performance of a voluntary (nonreflexive) response to the situation is followed by a rewarding (or punishing) consequence. Thus, instrumental responses often are mostly or fully voluntary (#4 above), although there are cases in which one of the other types of responses better reflects the situation. For the purposes of this class, however, we will characterize instrumental responses as mostly or fully voluntary, with the realization that, in future courses, you probably will find that the situation is more complicated.
Another way to think of the difference between classical conditioning and instrumental learning is:
- in classical conditioning, the CR is elicited involuntarily by a stimulus that comes before it, the CS;
- in instrumental learning, the instrumental response is emitted voluntarily because of a stimulus that follows it, the reward.
You may have noticed that the wording here is almost identical to the wording used a few paragraphs back (click here), but with different words bolded. This second difference really is just a different way of thinking about the first difference.
Another important difference between classical conditioning and instrumental learning involves the nature of the association formed in each:
- in classical conditioning, two stimuli are associated — the CS is associated with the UCS after they have been paired repeatedly;
- in instrumental learning, a response is associated with a stimulus that follows it — the instrumental response is associated with the reward after they have been paired repeatedly. (Again, for now, we are ignoring punishment.)
There is a complication with instrumental learning that I haven’t talked about yet. Although it is true that the instrumental response is associated with a stimulus that follows it (the consequence), it’s also true that the instrumental response is a response to a stimulus or stimuli that come before it: the situation in which the response occurs. For example, raising your hand in class is a learned instrumental response: you have learned to raise your hand because it is “rewarded” by the consequence of getting called on by the teacher. However, you probably don’t raise your hand in any situation other than one in which there is a teacher (or some other authority figure) speaking to a group of students (or some other group). You have learned to raise your hand in response to a situation containing the following stimuli: the sight of a teacher in a classrooom. Thus, in addition to associating the instrumental response of raising your hand with the consequence of getting called on, you also have associated it with the preceding stimuli of the sight of a teacher in a classroom. The stimulus that comes before the response may be thought of as a “triggering” stimulus: it tells the person that, in the situation containing that stimulus, the response has been rewarded (or punished) in the past.
It is “more correct,” therefore, to think of instrumental learning as involving the association of a “triggering” stimulus with a response with a rewarding (or punishing) stimulus: the situation is associated with the instrumental response, which is associated with the consequence, as in Figure 2.
INSERT FIGURE 2 HERE
Thorndike and Behaviorism
In the quote below from Wozniak (1999), you’ll notice that he spoke of instrumental learning as involving a stimulus-response association. By this, he meant the development of an association between the situation (the triggering stimulus or stimuli) and the instrumental response emitted in that situation: for example, the teacher in a classroom is the stimulus that triggers the raising of your hand as a response. In the quote, Wozniak stated that Thorndike’s approach to understanding instrumental learning foreshadowed the theoretical approach of behaviorism (Thorndike began his work about twenty years before the emergence of behaviorism):
Thorndike situated himself theoretically within the long tradition of associationism. Unlike his associationist predecessors, however, he construed association not as linking one … [mental] element … with another nor even as linking [mental elements] with movements. Rather, for Thorndike, associations exist between [external] situations in which an organism finds itself and [internal] impulses in the organism to action. In this regard, Thorndike took a step beyond traditional associationism in the direction of the [behavioristic] stimulus-response approach that would eventually come to dominate the field.
Thorndike’s “prebehavioristic” approach, according to Wozniak, is evident in two assertions Thorndike made:
The first, that psychology could be viewed as the science of behavior continuous with physiology, anticipated arguments soon to be advanced by John B. Watson in his famous behaviorist manifesto [Watson, 1913]. The second, that the study of ‘consciousness for the sake of inferring what a man can or will do, is as proper as to study behavior for the sake of inferring what conscious states he can or will have,’ anticipated the general approach to consciousness that would become common among early behaviorists.
In short, behaviorism did not emerge from an intellectual vacuum: a way of thinking gradually developed among some experimental psychologists regarding how best to answer their research questions — a way of thinking that eventually led to the behaviorism of John Watson and others. Thorndike’s solution to the problem of how best to measure learning in his animal subjects — which (of course) were unable to introspect and then report on what was occurring in their minds — was to ignore mental elements and consciousness althogether, and instead to focus on measurable factors: the physical situations in which the animals were placed (the puzzle boxes) and the behaviors they learned in those situations (escaping from the puzzle boxes). In this way, Thorndike’s work was an important influence on the thinking of later behaviorists and has continued to have an important influence on the thinking of researchers to the present day.
Here is a dramatization of Thorndike’s Puzzle Box experiments:
Study Questions for Section 4-15
- What was the first type of learning studied scientifically by early experimental psychologists?
- How did E. L. Thorndike study learning in cats?
- In what way(s) is classical conditioning similar to instrumental learning?
- Is it correct to say that, in all cases of instrumental learning, subjects learn voluntary responses? What will we assume in this course?
- In what way(s) does classical conditioning differ from instrumental learning?
- What is associated in classical conditioning?
- What is associated in instrumental learning? (NOTE: in your answer, discuss all the various associations between stimuli and responses.)
- In what way(s) did Thorndike foreshadow the behavioristic approach?
Pavlov, I. P. (1927). Conditioned reflexes: An investigation of the physiological activity of the cerebral cortex (G. V. Anrep, Trans.). Retrieved October 17, 2011, from http://psychclassics.yorku.ca/Pavlov/
Thorndike, E. L. (1898). Animal intelligence: An experimental study of the associative processes in animals. New York: Macmillan. Retrieved October 17, 2011, from http://www.archive.org/download/animalintelligen00thoruoft/animalintelligen00thoruoft.pdf
Thorndike, E. L. (1911). Animal intelligence: Experimental studies. New York: Macmillan. Retrieved October 17, 2011, from http://psychclassics.yorku.ca/Thorndike/Animal/
Watson, J. B. (1913). Psychology as the behaviorist views it. Psychological Review, 20, 158-177. Retrieved December 12, 2014, from http://people.emich.edu/jtodd/watson_1913.pdf