The functional substitutability of stimuli in equivalence classes was examined through analyses of the speed of college students' accurate responding. After training subjects to respond to 18 conditional relations, subjects' accuracy and speed of accurate responding were compared across trial types (baseline, symmetry, transitivity, and combined transitivity and symmetry) and nodal distance (one-through five-node transitive and combined transitive and symmetric relations). Differences in accuracy across nodal distance and trial type were significant only on the first tests of equivalence, whereas differences in speed were significant even after extended testing. Response speed was inversely related to the number of nodes on which the tested relations were based. Significant differences in response speed were also found across trial types, except between transitivity and combined trials. To determine the generality of these comparisons, three groups of subjects were included: An instructed group was given an instruction that specified the interchangeability of stimuli related through training; a queried group was queried about the basis for test-trial responding; and a standard group was neither instructed nor queried. There were no significant differences among groups. These results suggest the use of response speed and response accuracy to measure the strength of matching relations. symmetric and transitive properties (combined trials). For example, subjects might select A in the presence of C, based on the BA and CB symmetric and the AC transitive properties.The emergence of these performances is often marked by a transition from inaccurate to accurate or class-consistent test-trial responding. (For ease of exposition, the term accuracy will refer to both correct responses on trained match-to-sample trials and classconsistent responses on probe trials.) After subjects respond in accordance with the tested reflexive, symmetric, transitive, and combined relations, the stimuli are described as a class of functionally substitutable, equivalent stimuli.Despite this description, potential limits to the functional substitutability of equivalent stimuli have been identified. For example, when the baseline conditional discriminations of established equivalence classes were altered in Pilgrim and Galizio's study (1990), subjects responded in accordance with new symmetric relations but not with new transitive relations; rather, they continued to respond in accordance with the transitive relations that were consistent with the originally established equivalence classes. Thus, changes in the relations that defined the class did not uniformly affect the derived symmetric and transitive relations. 643 1996, 65, 643-659 NUMBER 3 (MAY)

Two experiments examined the relation between response variability and sensitivity to changes in reinforcement contingencies. In Experiment 1, two groups of college students were provided complete instructions regarding a button-pressing task; the instructions stated "press the button 40 times for each point" (exchangeable for money). Two additional groups received incomplete instructions that omitted the pattern of responding required for reinforcement under the same schedule. Sensitivity was tested in one completely instructed and one incompletely instructed group after responding had met a stability criterion, and for the remaining two groups after a short exposure to the original schedule. The three groups of subjects whose responding was completely instructed or who had met the stability criterion showed little variability at the moment of change in the reinforcement schedule. The responding of these three groups also was insensitive to the contingency change. Incompletely instructed short-exposure responding was more variable at the moment of schedule change and was sensitive to the new contingency in four of six cases. In Experiment 2, completely and incompletely instructed responding first met a stability criterion. This was followed by a test that showed no sensitivity to a contingency change. A strategic instruction was then presented that stated variable responding would work best. Five of 6 subjects showed increased variability after this instruction, and all 6 showed sensitivity to contingency change. The findings are discussed from a selectionist perspective that describes response acquisition as a process of variation, selection, and maintenance. From this perspective, sensitivity to contingency changes is described as a function of variables that produce response variability.

College students were instructed to press a button for points under a single reinforcement schedule or under a variety of reinforcement schedules. Instructions for a single schedule were either specific or minimal. Instructions on a variety of schedules involved specific instructions on eight different schedules of reinforcement. Subsequent to the varied training, responding under a fixed-interval schedule occurred at a low rate. Both the minimal and specific instruction training led to fixed-interval responding that was similar to the responding exhibited during training. These findings suggest that under certain conditions instructed behavior is sensitive to changes in contingencies.Key words: variety of training, instructed behavior, contingency-shaped behavior, response history, efficiency of responding, reinforcement schedules, button press, adult humans Theoretical and empirical developments in behavior analysis have suggested that behavior acquired by following an instruction may be less sensitive to changes in prevailing contingencies than behavior acquired by shaping (Baron & Galizio, 1983;Baron, Kaufman, & Stauber, 1969;Galizio, 1979;Harzem, Lowe, & Bagshaw, 1978;Matthews, Shimoff, Catania, & Sagvolden, 1977;Skinner, 1966Skinner, ,1969Vaughan, 1985). For example, subjects who have been instructed to respond under one schedule of reinforcement continue to respond as instructed even when the schedule of reinforcement has changed (Baron et al., 1969;Harzem et al., 1978). Insensitivity to changing contingencies is less likely to occur when behavior is shaped by successive approximations, or when instructions are used that do not describe the specific schedules (i.e., minimal instructions; Matthews et al., 1977;Shimoff, Catania, & Matthews, 1981).These findings give rise to the question of which variables determine the sensitivity of human behavior to various and varying contingencies. Weiner (1969Weiner ( , 1970a specific histories of responding under schedules of reinforcement were necessary to bring about sensitivity to fixed-interval (FI) schedules. Training under a differential-reinforcement-of-low-rate (DRL) schedule was sufficient to bring about sensitive performance under FI schedules even when the subjects had a history of responding at high rates under fixed-ratio (FR) schedules. When either no response history or a high-rate response history was provided, high rates occurred under the FI schedule. Weiner's studies, however, did not examine the interaction of reinforcement histories and instructions.Galizio (1979) suggested that under instructed conditions sensitivity occurs only when behavior comes into contact with the change in contingencies. When avoidance behavior was instructed under a point-loss procedure and a schedule was then introduced in which the loss contingency was no longer in effect, behavior did not change. However, when continued responding as instructed resulted in a loss of points, performance quickly adjusted to these conditions. Under the first condition, responses did not...

This study compared three different methods of teaching five basic algebra rules to college students. All methods used the same procedures to teach the rules and included four 50-question review sessions interspersed among the training of the individual rules. The differences among methods involved the kinds of practice provided during the four review sessions. Participants who received cumulative practice answered 50 questions covering a mix of the rules learned prior to each review session. Participants who received a simple review answered 50 questions on one previously trained rule. Participants who received extra practice answered 50 extra questions on the rule they had just learned. Tests administered after each review included new questions for applying each rule (application items) and problems that required novel combinations of the rules (problem-solving items). On the final test, the cumulative group outscored the other groups on application and problem-solving items. In addition, the cumulative group solved the problem-solving items significantly faster than the other groups. These results suggest that cumulative practice of component skills is an effective method of training problem solving.