Human operant studies frequently use points exchangeable for money as reinforcers. Some studies employ more immediately consumable reinforcers to emulate properties of food reinforcers. This study examined demand for points/money and for sound-clips to compare their economic characteristics. Across four participants, demand was often higher and less elastic for points/money than for sounds. During subsequent exposures at each response requirement, demand for sounds often decreased to a greater degree than demand for points/money. Thus, sound-clips seem less durable than points/money across prices and across repeated exposure to the same price. Response rates for points/money were often higher than for sounds, suggesting that reinforcers that generate higher response rates may be less elastic than reinforcers that generate lower response rates.

In recent years, there has been an increasing interest in the study of human operant behavior. One area of study reflecting this interest is the study of the formation of equivalent classes of stimuli by human subjects. The focus of the present research was the study of the conditions under which classes of equivalent stimuli can be inferred to be under conditional control. In Experiment 1-A, three college students were trained to respond to a balanced five-term contingency via a visual-visual simultaneous matching-to-sample task with two choices of comparison stimuli. Probe tests showed that subjects' behavior could be described as being controlled by positive and negative stimulus relations. When the second-order stimulus was removed during subsequent probes, none of the three subjects demonstrated strong correct responses to the four-term unit relations. Also, none of the three subjects demonstrated the expected transitive relations when the second-order (five-term) stimulus was removed. In Experiment 1-B--with the same three subjects--explicit training of the four-term unit relations showed the expected transitive relations in the absence of the second-order stimulus. In Experiments 2 through 5--using a matching-to-sample task similar to that used in Experiments 1-A and 1-B--five subjects were trained to respond to comparison stimuli C and E in the presence of sample A and second-order stimulus X and to comparison stimuli Band Fin the presence of sample D and second-order stimulus X. Likewise, the subjects were trained to respond to comparison stimuli Band Fin the presence of sample A and second-order stimulus Y and to comparison stimuli C and E in the presence of sample D and second-order stimulus Y. Probe tests for transitive relations showed that four of the five subjects eventually demonstrated four three-member classes of equivalent stimuli that functioned separately under the control of the second-order stimuli. The four subjects demonstrating the classes of equivalent stimuli either a) demonstrated the transitive relations immediately orb) demonstrated the transitive relations after explict retraining of the underlying four-term unit relations. The results of all experiments together indicated that the composition of classes of equivalent stimuli can be conditionally controlled by either a) removing the second-order stimulus orb) training subjects to respond to classes of equivalent stimuli under the control of other explicit visual second-order stimuli. The results are discussed in terms of verbal behavior, emergent behavior, and conceptual development.

There are many situations in which human performances appear insensitive to changing contingencies of reinforcement when compared to nonhuman operant performances. Explanations of these discrepancies have appealed to rule-governance and have provided some evidence that instructions produce these differences by restricting response alternatives as well as functioning as discriminative stimuli for other contingencies. In order to further evaluate these potential functions, a canonical study on rule-governance was systematically replicated. Five undergraduate participants were tasked with earning blocks by pressing a button during LED-signaled, fixed-ratio 7 and differential-reinforcement-of-low-rate 5-s schedules of reinforcement. Phase 1 of the experiment switched between these two schedules, with the schedule alternating every 1 minute. Phase 2 added instructions to "Go Fast" and "Go Slow" to the LEDs and programmed the lit LED to switch 30 seconds into each 1-minute session. Phase 3 removed the instructions from the LEDs and returned to the procedures of phase 1, with only one LED lit during each 1-minute session. Results showed that instructions influence the response rates as well as stimulus control over those rates. Results also showed that all participants ignored instructions conflicting with the reinforceable rate by the end of Phase 2. These findings indicate that instances of insensitivity may result from instructions restricting response alternatives and their stimulus control, as opposed to instructions signaling a second contingency. These findings are discussed in terms of the nature of instructional stimulus control, its relation to the operant unit of analysis, and alternative interpretations of other instances of insensitivity.