Motivation in concurrent variable-interval schedules with food and water reinforcers

The lever pressing of four food- and water-deprived rats was reinforced on concurrent variable-interval schedules. Food reinforced one response, and water reinforced the other. Response rates in baseline were higher in the food component than in the water component. After response patterns and body weights had stabilized, the animals were given access to either food only, water only, both food and water, or neither food nor water (baseline) before daily sessions. Giving food before a session decreased per cent time in the food component, decreased overall response rates for food, and increased overall response rates for water. Giving water before a session increased per cent time in the food component, increased overall response rates for food, and decreased overall response rates for water. Giving both food and water before a session resulted in a combination of prefeeding and prewatering effects. More food and more water were consumed when both were available than when only one was available before a session.     

Does school desegregation change occupational goals of Negro males?

Instruments, designed to assess values which affect the motivation to work and aspiration levels, were administered to over 600 Negro male seniors in Texas high schools. Results indicate that the degree and duration of school desegregation these students have experienced, ranging from less than 1 to more than 5 years, have had little effect on work values and occupational aspirations.     

The accuracy of self-administration and scoring on Holland's Self-Directed Search

This study assesed the extent to which Ss commit various types of errors when completing Holland's Self-Directed Search (SDS) entirely on their own. Nearly all Ss made some type of error and approximately half of the Ss made errors which affected their final three-letter summary codes. Almost one-fifth of the Ss made errors resulting in an incorrect high-point code. Whether or not Ss made errors that affected their summary codes was unrelated to the extent to which they were interested in knowing more about occupations or academic majors they might like. Neither were such errors related to whether Ss felt the occupations suggested by their summary codes seemed reasonable. Only slightly over one-third the Ss actually did feel that the occupations seemed reasonable.     

The failure of stimulus control after presence-absence discrimination of click-rate

Pigeons were trained to discriminate a slow click-rate from its absence, or to discriminate it from a faster click-rate. Subsequent click-rate generalization tests produced the usual steepened gradients after the intradimensional discrimination but produced flat gradients after presence/absence discrimination. The occurrence of stimulus control only after intradimensional discrimination, combined with previous results showing stimulus control sometimes after nondifferential reinforcement and sometimes after presence/absence discrimination, argues for a reformulation of the problem of stimulus control. A theoretical framework, relying upon blocking effects inherent in the different discrimination procedures, was presented to account for the diversity of results.     

Elicited responding to signals for reinforcement: the effects of overall versus local changes in reinforcement probability

Pigeons were studied on a three-component multiple schedule where all reinforcement was independent of responding. Two components were cued by different keylights and were associated with different rates of reinforcement. The third was always a no-key period associated with extinction. After a few sessions, pecking was elicited by the keylights signalling the reinforcement and continued to be maintained indefinitely. The duration and sequence of the three components were varied to determine if the primary controlling variable was differences in the overall probability of reinforcement, or if it was the immediate change in reinforcement signalled by the onset and/or offset of the stimulus. Both variables were found to control behavior. When 30-sec components were used, the primary controlling variable was the overall probability of reinforcement, but when 3-min components were used, overall probability had little effect. Control by local changes in reinforcement also occurred, although the type of local control varied both across subjects and experimental conditions. Some behaviors were controlled more by the change in reinforcement signalled by the onset of the stimulus, while others were controlled more by the change signalled by the offset of the stimulus.     

The effect of frustrative nonreward on the attractiveness of the omitted reward

Two experiments were performed to test the hypothesis that omission of a previously received reward is followed by greater motivation to obtain that specific reward, as compared with the case where the reward had been present. In Experiment 1, experimental rats regularly received food rewards (R_a) at one goal, followed by a choice between food and milk (R_b). Control animals received the same choice without food preceding it. Reward magnitudes were manipulated so as to produce a preference for R_b, and additional forced trials were given each day to equalise experience of the two rewards. In the test phase both groups received trials with R_a present (R) or absent (N) at the first goal. The experimental Ss shifted their choice towards R_a on N trials; the controls did not behave differently after R and N. Experiment 2 was similar, except that R_a was milk and R_b food. The same effect of N on experimental animals was obtained. It is argued that the results are relevant to the double-runway ‘frustration effect’, and cannot be explained by existing theories of frustration.