Classical conditioning has been demonstrated in many species—for instance, in newborn human infants (Boiler, 1997; Lipsitt & Kaye, 1964; Reese & Lipsitt, 1970), human fetuses still in the womb (Macfarlane, 1978), laboratory rats (Cain, Blouin, & Barad, 2003), rainbow trout
2 Some psychologists instead use the term respondent conditioning , a label coined by B. F. Skinner to reflect its involuntary-response-to-a-stimulus nature.
3 Pavlov’s original terms were actually unconditional stimulus, unconditional response, conditional stimulus, and conditional response, but the mistranslations to “unconditioned” remain in most classical conditioning literature.
Step 1: (no response) NS (bell) UCR (salivate) Step 2: NS (bell) Step 3: CS (bell) UCS (meat) CR (salivate) Figure 3.1
A classical conditioning analysis of how Pavlov’s dogs learned
(Nordgreen, Janczak, Hovland, Ranheim, & Horsberg, 2010), and snails (Samarova et al., 2005). The applicability of classical conditioning clearly extends widely across the animal kingdom.
As Pavlov’s experiments illustrated, classical conditioning typically occurs when two stimuli are presented at approximately the same time. One of these stimuli is an unconditioned stimu- lus: It has previously been shown to elicit an unconditioned response. The second stimulus, through its association with the unconditioned stimulus, begins to elicit a response as well: It becomes a conditioned stimulus that brings about a conditioned response. In many cases, condi- tioning occurs relatively quickly; it’s not unusual for an organism to show a conditioned response after the two stimuli have been presented together only five or six times, and sometimes after only one pairing (Rescorla, 1988).
Classical conditioning is most likely to occur when the conditioned stimulus is presented just
before (perhaps by half a second) the unconditioned stimulus. For this reason, some psychologists
describe classical conditioning as a form of signal learning . By being presented first, the condi- tioned stimulus serves as a signal that the unconditioned stimulus is coming, much as Pavlov’s dogs might have learned that the sound of a bell indicated that yummy meat powder was on its way.
Classical conditioning usually involves the learning of involuntary responses—responses
over which the learner has no control. When we say that a stimulus elicits a response, we mean that the stimulus brings about a response automatically, without the learner having much influ- ence over its occurrence. In most cases, the conditioned response is similar to the unconditioned response, with the two responses differing primarily in terms of which stimulus elicits the response and sometimes in terms of the strength of the response. Occasionally, however, the CR is quite different—perhaps even opposite to—the UCR (I’ll give you an example in our discus- sion of drug addiction a bit later). But in one way or another, the conditioned response allows the organism to anticipate and prepare for the unconditioned stimulus that will soon follow.
Classical Conditioning in Human Learning
We can use classical conditioning theory to help us understand how people learn a variety of involuntary responses, especially responses associated with physiological functioning or emo- tion. For example, people can develop aversions to particular foods as a result of associating
COME AND GET IT!!
The conditioned stimulus may serve as a signal that the unconditioned stimulus is coming.
those foods with an upset stomach (Garb & Stunkard, 1974; Logue, 1979). To illustrate, after associating the taste of creamy cucumber salad dressing (CS) with the nausea I experienced during pregnancy (UCS), I developed an aversion (CR) to cucumber dressing that lasted for several years.
Classical conditioning is also a useful model for explaining some of the fears and phobias that people develop (Mineka & Zinbarg, 2006). For example, my bee phobia can probably be explained by the fact that bees (CS) were previously associated with a painful sting (UCS), such that I became increasingly fearful (CR) of the nasty insects. In a similar way, people who are bitten by a particular breed of dog sometimes become afraid of that breed, or even of all dogs.
Probably the best-known example of a classically conditioned fear of certain animals is the case of “Little Albert,” an infant who learned to fear white rats through a procedure used by John Watson and Rosalie Rayner (1920). Albert was an even-tempered, 11-month-old child who rarely cried or displayed fearful reactions. One day, Albert was shown a white rat. As he reached out and touched the rat, a large steel bar behind him was struck, producing a loud, unpleasant noise. Albert jumped, obviously very upset by the startling noise. Nevertheless, he reached for- ward to touch the rat with his other hand, and the steel bar was struck once again. After five more pairings of the rat (CS) and the loud noise (UCS), Albert was truly rat-phobic: Whenever he saw the rat he cried hysterically and crawled away as quickly as his hands and knees could move him. Watson and Rayner reported that Albert responded in a similarly fearful manner to a rabbit, a dog, a sealskin coat, cotton wool, and a Santa Claus mask with a fuzzy beard, although none of these had ever been paired with the startling noise. (Watson and Rayner never “undid” their conditioning of poor Albert. Fortunately, the ethical standards of the American Psychological Association now prohibit such negligence.)
Fear of failure is yet another example of a response that may be classically conditioned. In some cases, people who are unusually afraid of failing may have previously associated failure with unpleasant circumstances; perhaps they’ve associated it with painful punishment from an angry parent or ridicule by insensitive classmates. Yet occasional failure is a natural consequence of attempting new tasks, whether in school, at home, or elsewhere. Teachers and parents must be careful that failure doesn’t become such a strong conditioned stimulus that children resist new activities and challenging but potentially risky tasks.
Attitudes, too, can be partly the result of classical conditioning. In one study (Olson & Fazio, 2001), college students sat at a computer terminal to watch various unfamiliar cartoon characters from the Pokemon video game series. One character was consistently presented in conjunction with words and images that evoked pleasant feelings (e.g., “excellent,” “awesome,” pictures of puppies and a hot fudge sundae). A second character was consistently presented along with words and images that evoked unpleasant feelings (e.g., “terrible,” “awful,” pictures of a cockroach and a man with a knife). Other characters were paired with more neutral words and images. Afterward, when the students were asked to rate some of the cartoon characters and other images they had seen on a scale of –4 (unpleasant) to +4 (pleasant), they rated the character associated with pleas- ant stimuli far more favorably than the character associated with unpleasant stimuli. Curiously, a positive attitude toward an initially neutral stimulus doesn’t necessarily emerge only when people experience it in the company of other pleasant things. Simply experiencing it repeatedly in the
absence of un pleasant things can be enough to engender a preference for it (Zajonc, 2001).
These examples of classical conditioning in action will, I hope, help you recognize a classically conditioned response when you see one. We now turn to several general phenomena associated with classical conditioning.