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Pigeons served in four experiments, each of which involved about 44,000 discrete 1.2‐sec trials under steady‐state conditions. The first experiment scaled a short segment of the visual wavelength continuum; this dimension was then combined in a conditional discrimination with each of three others; time after reinforcement, tone frequency, and line tilt. In the two‐stimulus experiments, the birds' responses were reinforced in the presence of only one stimulus combination: “582 nm” together with “2 min after reinforcement”, “3990 Hz”, or “vertical line”. Many other stimulus combinations also appeared equally often and went without reinforcement. The wavelength stimuli conformed to an equal‐interval scale, and per cent response was generally linear with wavelength, when scaled on cumulative normal coordinates. The components of the compound stimulus were found to interact in a multiplicative fashion; when one component differed greatly from its reinforcement value, changes in the other component had relatively little effect. For the “time”‐“wavelength” compound, this interaction appeared to be modified by the effects of set or attention. Certain response latency data are reported, and other combination rules are discussed.

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A procedure was employed that enabled a teacher to bring inappropriate verbalizations under control in a classroom of approximately 25 fifth‐ and sixth‐grade students. Contingent point loss for inappropriate verbalizations was correlated with a low but steady rate of such verbalizations. Point gain contingent upon quiet behavior produced a marked decrease in inappropriate verbalizations. A return to contingent point loss was accompanied by an increasing rate of inappropriate verbalizations. Verbalizations decreased when quiet behavior was reinforced again. A noteworthy feature of the study was the utilization of students from within the class to act as data recorders. A reliability check indicated satisfactory agreement between the recorders.

Fighting responses were elicited by response‐independent shocks delivered to pairs of rats. Food pellets were presented following different non‐fighting responses to shock: some pairs of rats received pellets dependent upon a specific non‐fighting response to shock; others received pellets dependent upon any non‐fighting response to shock; and control pairs never received pellets. The mean probability of an elicited aggressive response to shock was reduced to 0.2 by food reinforcement for a specific non‐fighting response, and to 0.5 by food reinforcement for any kind of non‐fighting response. These values contrasted with the 0.8 probability of elicited aggression when pairs of rats received no food reinforcement. Consistent findings were obtained when treatment conditions were changed for individual pairs of rats.

Two experiments were conducted to investigate the interaction between response rate and reinforcement frequency in multiple random‐interval avoidance schedules. Responses cancelled delivery of shocks that could be scheduled at different random intervals in each component. When shock‐frequency reduction was taken as the measure of reinforcement, the relationship between response rate and frequency of reinforcement was described by the same equations used by Herrnstein (1970) to describe responding with positive reinforcement.

Thirty five White Carneaux pigeons first received 20 sessions of non‐delayed reinforcement according to a multiple variable‐interval 1‐min variable‐interval 1‐min schedule. For the remaining 15 sessions, subjects were assigned to one of five groups, with seven subjects per group. Four of these groups involved reinforcement according to the same multiple schedule as before, but reinforcement during one of the components was delayed for either 2.5, 5, 10, or 120 sec. The schedule for the fifth group was changed to multiple variable‐interval 1‐min extinction schedule of reinforcement. While some subjects in all groups showed behavioral contrast, it occurred more consistently in the groups involving extinction or the longer delays of reinforcement. Groups involving the various durations of delayed reinforcement or even extinction during the altered component did not, however, show a statistically significant difference in the amount of behavioral contrast. It was suggested that neither a reduction in reinforcement frequency nor response rate during the altered component is necessary to the production of behavioral contrast.

Pigeons were exposed to three stimuli simultaneously with responses reinforced according to differential‐reinforcement‐of‐low‐rate schedules. Responses to one stimulus (the positive stimulus) that were spaced appropriately resulted in food presentation. The variables manipulated were the time parameter of the schedule (5, 10, 20, 30 sec) and the consequences of responding to the other two stimuli (the negative stimuli). The percentage of the total responses that occurred to each stimulus was independent of the schedule value but was dependent on the consequences of responding to the negative stimuli. If responses to both reset the schedule timer, responding was confined largely to the positive stimulus. If responses to neither had scheduled effects, the birds were more likely to respond to those stimuli. Responding to one negative stimulus could be selectively attenuated by having responses to that stimulus alone reset the timer. With the schedule time value held constant, the absolute rate of responding to the positive stimulus was either stable or decreased with maintained exposure; it did not change as a function of increases or decreases in responding to the negative stimuli. Rather than interacting and affecting each other, responses to the three stimuli were controlled independently by their relation to reinforcement. There was no evidence that responses to the negative stimuli mediated the spacing of responses to the positive stimulus.