INSTRUMENTAL LEARNING

INSTRUMENTAL LEARNING
As we have seen, classical conditioning allows an animal to learn about the relationship between events in the environment and so anticipate what will happen next on the basis of stimuli currently present. If there are grey clouds in the sky, then it will probably rain; if the light is presented, then food may well follow. Instrumental learning is the process by which an animal learns about the relationship between its behaviour and the consequences of that behaviour. And it serves a complementary but equally important function in allowing the animal to control (at least partially) the occurrence of environmental events – in other words, to bring about a desired event or to avoid an aversive event by responding in a particular way. Instrumentally trained responses are not entirely elicited by identifiable stimuli. Instead, they are controlled by their consequences, becoming more likely when they produce a positive result and less likely when they lead to an aversive outcome. As Skinner emphasized, this sort o control is the characteristic feature of what we call ‘voluntary’ behaviour. So the study of instrumental learning and performance is important for what it tells us about the nature of voluntary, goal-directed behaviour.

On the other hand, instrumental learning processes can also play a role in establishing and maintaining behaviour that seems, at first sight, anything but voluntary. Patients with the clinical condition known as obsessive– compulsive disorder (OCD) [obsessive–compulsive disorder (OCD) characterized by intrusive unwelcome thoughts (obsessions) and the need repeatedly to perform certain patterns of behaviour (compulsions), such as hand-washing] suffer from persistent, intrusive, unpleasant thoughts (obsessions) and feel compelled repeatedly to carry out certain acts (compulsions) that they know are senseless but which appear to provide some relief (see chapter 15). OCD can be quite disabling. One patient, who believed that contact with everyday objects contaminated her in some way, felt compelled to shower at least six times a day and to wash her hands very systematically every 20 minutes. With hands rubbed raw and half her working day taken up in these activities, her ability to lead a normal life was severely curtailed. OCD patients tend to feel a build-up of extreme anxiety prior to performing the compulsive ritual, which dissipates as the ritual is enacted. This has been measured both by patients’ own reports and by objective indices such as heart-rate (Hodgson & Rachman, 1972). A parallel can be drawn between such cases and a trained rat ‘compulsively’ responding to the presentation of a tone by jumping a hurdle, and continuing to perform this apparently senseless act for a large number of trials in the absence of any obvious reward. Although this behaviour appears senseless, it becomes understandable when the rat’s training history is known – when it becomes clear that the tone evokes fear by virtue of its initial association with shock and that the response avoids a shock that would otherwise occur. In the same way, the rituals performed by OCD patients may well be avoidance responses that are reinforced and maintained because they reduce the sufferer’s state of anxiety. Of course it remains to be explained why the patient has acquired such a fear of dirt, or whatever, in the first place. Nevertheless, this illustration demonstrates the relevance of the analysis of basic instrumental learning processes to an understanding of interesting and important aspects of human behaviour.

INSTRUMENTAL LEARNING

THORNDIKE’S CATS EXPERIMENT
Pavlov was beginning work on classical conditioning in Russia, E.L. Thorndike, in the United States, was conducting a set of studies that initiated a different tradition in the laboratory study of basic learning mechanisms. Thorndike was interested in the notion of animal intelligence. Motivated by an interest in Darwinian evolutionary theory, comparative psychologists of the late nineteenth century had investigated whether non-human animals can show similar signs of intelligence to those shown by humans. Thorndike took this endeavour into the laboratory. In his best-known experiment, a cat was confined in a ‘puzzle box’ (figure 4.3). To escape from the box, the cat had to press a latch or pull a string. Cats proved able to solve this problem, taking less and less time to do so over a series of trials. Cats solved the problem not by a flash of insight but by a gradual process of trial and error. Nevertheless, here was a clear example of learning. Its characteristic feature was that the animal’s actions were critical (instrumental) in producing a certain outcome. In this respect, instrumental learning [instrumental learning the likelihood of a response is changed because the response yields a certain outcome (a reward or punishment) (also called operant conditioning)] is fundamentally different from classical conditioning, in which the animal’s response plays no role in determining the outcome. Subsequent researchers who took up the analysis of this form of learning include the Polish physiologist Konorski (1948), who called it Type II conditioning (as distinct from Pavlov’s Type I conditioning). Another investigator interested in this type of conditioning was Skinner (1938) in the United States, who named it operant conditioning (Pavlov’s version of learning being referred to as respondent conditioning). [respondent conditioning alternative name for classical conditioning] However termed, all agreed that its defining feature was a contingency between a preceding stimulus, a pattern of behaviour (or response) and a subsequent state of the environment (the effect or outcome).