Although there is evidence that attitudes to gender roles are socially learned and can be related to gender, age, socioeconomic class, liberalism, religiousness, and family size (Clarkson, Vogel, Broverman, 8 Broverman, 1970; Ellis 8 Bentler, 1973; Parry, 1983; Smith 8 Bradley, 1980), the exact nature of the learning principles responsible for Stereotyping is open to question. It seems that such learning begins in infancy, with stereotypical attitudes being found cross-culturally at age five (Reiss & Wright, 1982). On the face of it, elementary principles of learning and generalization (as outlined by Hackenberg 8. Hineline, 1989) seem to account for this behavior. For example, when a young Child learns that particular actions in a given situation will produce Certain Consequences, these consequences play a part in determining future behavior. A child who thus learns that the behavior of hitting a doll and hitting another child produce different consequences eventually learns to discriminate between, and behave differently in, the presence of these different stimuli. A child also learns to behave similarly in a range of similar situations. For example, the child may learn to avoid hitting anything that may retaliate. In this way, classes of situations and corresponding classes of behavior develop. Technically, the type of learning described above (ie, discrimination between classes of events or objects and generalization within classes of events or objects) is referred to as concept learning. These are presumably also the principles underlying stereotyping behavior. Concept learning has been studied experimentally, using pigeons as subjects. Porter and Neuringer (1984), for example, trained pigeons to discriminate between 1-minute excerpts of music composed by Bach and 1-minute excerpts composed by Stravinsky; the birds responded differentially in the presence of each piece of music with 80% accuracy. This behavior generalized to novel situations when the pigeons were played pieces of music they had never heard before and were able to classify the pieces, without further reinforcement, according to whether they were composed by contemporaries of Bach or contemporaries of Stravinsky. In these situations, the pigeons' responses were dependent upon the presence or absence of the relevant experimental stimuli, a phenomenon known as conditional discrimination. Because of the complexity of the stimuli used, the characteristic (s) of the music which elicited responses from the pigeons is unclear, but their discriminative behavior was consistent with their having learned the concepts “Bach'and “Stravinsky." With the emergence of verbal and complex conceptual behavior in humans, further, more subtle classes of behavior develop. A deepeľ understanding of the behavioral principles underlying compleX conceptual behavior has become possible with the study of stimulus equivalence, which deals with the relationships between symbolic stimuli. The field of equivalence relations is significant as it provides an account of new emergent behavior that has not been directly reinforced in the past. It is a paradigm that extends the contention of, for example,