The ambiguous-cue problem: The effects of reduced similarity between trials and the schedule of reinforcement

In a series of seven experiments pigeons were trained on the two-choice ambiguous-cue problem that contains PA and NA trials. On PA trials choice of P (the positive stimulus) was reinforced and choice of A (the so-called ambiguous stimulus) was not reinforced; on NA trials choice of A was reinforced and choice of N (the negative stimulus) was not reinforced. When the two types of trials were distinguished by only the presence of P or N and each trial was terminated by one response, subjects quickly attained high levels of performance on NA trials but showed only chance levels of performance on PA trials. PA performance was markedly improved when a variety of additional stimuli distinguished the two types of trials and when a variety of schedules of intermittent reinforcement were employed; these manipulations had little effect on NA performance.     

Influence of sex-role identity on two indices of social anxiety

The present study was conducted to determine the relationship between sex-role identity and two measures of self-reported social anxiety. The Bem Sex-Role Inventory (BSRI), Social Avoidance and Distress Scale (SAD), and Fear of Negative Evaluation Scale (FNE) were administered to 23 male and 26 female undergraduate students. Generally, sex role was associated with social anxiety for women, but not for men. Androgynous women reported the least anxiety, sex-role stereotyped women reported a moderate amount, and undifferentiated women reported the most anxiety of all groups. Results were interpreted in light of conflicting hypotheses of androgyny rather than masculinity being associated with greater adjustment and the value of a situational analysis of behaviors associated with sex-role orientation.     

Reinforcement rate and force proportional reinforcement

The research examines the consequences of making two reinforcement contingencies simultaneously available for the same bar-pressing response. Specifically, two experiments are described which concern the effects of reinforcement rate upon force proportional reinforcement (FPR). In Experiment 1, reinforcement rate was constrained by combining differential reinforcement of low rate with a force-proportional reinforcement contingency. The group of rats exposed to this regimen eventually showed a significant increase in response force compared to control groups. Experimental vs control response rates were not significantly different. In Experiment 2, reinforcement rate was affected through the expedient of relating the probability of obtaining a single pellet to the response force. The group for which the probability-force relationship was discontinuous came to exert higher forces than either a group for which the relationship was fairly continuous or an ordinary variable ratio control group. Response rate was significantly higher for the control group.     

Preference as a function of the correlation between stimuli and reinforcement outcomes

Pigeons' preferences for stimuli that were to varying degrees correlated with outcomes were studied in two experiments using a concurrent-chain procedure. The pigeons chose between two terminal links, each ending with food reinforcement and with blackout on half of the trials. In the first experiment, one terminal link (nonpredictive or unreliable link) provided stimuli completely uncorrelated with the outcomes while the other terminal link (predictive or reliable link) provided stimuli that were, to varying degrees, correlated with these outcomes. All pigeons showed increasing preferences for the predictive link as the reliability of the stimuli in that link increased. In the second experiment, stimuli in both terminal links were differentially correlated with the outcomes. The pigeons again preferred the more reliably correlated terminal link. The relation between these results and the delay-reduction hypothesis and conditioned reinforcement account is noted. The behavioral value of predictive stimuli may lie in their permitting the organism to more effectively apportion its time between interim activities and terminal responses.     

Response discriminative and reinforcement factors in stimulus control of performance on multiple and chained schedules of reinforcement

Discriminative control of the response rates of two groups of rats was equated by training them to cease bar pressing in light-out no-tone ( + ) and to respond during tone and light. Multiple-schedule subjects received food at the same rate for responding during tone or light as for nonresponding in + . For the chained-schedule subjects responding in tone or light only produced + where food was received for nonresponding. In extinction tests multiple-schedule subjects emitted approximately twice the responses to tone-plus-light as to tone or light presented individually (additive summation). The rats trained on the chained schedule, in which the tone and light each controlled substantial response rates but were never paired with food, showed no summation when the tone and light were presented together. The results indicate that discriminative control of response rates and reinforcement differences between schedule components determine stimulus control.     

Training child abusers in the use of positive reinforcement practices

A parent training program involving reading assignments, practice assignments, role-playing and contingent reinforcement was implemented for two parents identified as child abusers. Measures selected from the Patterson Coding System served as the dependent variables. Several constructive changes in parent-child interactions were observed, some of which were maintained for as long as five months post-training.     

Stimulus control and delayed reinforcement

Pigeons were tested for generalization along the line-orientation dimension, after being trained on various two-component multiple schedules. The first component contained either a variable-interval 1-min schedule of immediate reinforcement or an extinction schedule and was associated with a plain white key (S1). The second component contained a variable-interval 1-min schedule of delayed reinforcement and was associated with a black line on a white background (S2). The major results showed that (a) decremental gradients were obtained around the stimulus associated with the delayed reinforcement component when S1 was associated with extinction, but that incremental gradients were obtained when S1 was associated with immediate reinforcement, (b) the subjects' pretraining did not affect the generalization gradients if sufficient training on the terminal multiple schedule was provided, and (c) changing the S1 schedule from immediate reinforcement to extinction produced behavioral contrast if reinforcement was delayed for 10 sec during S2, but not if it was delayed for 20 sec.     

Behavioral contrast produced by a signaled decrease in local rate of reinforcement

Pigeons' key pecking in the presence of one stimulus (S1) was reinforced according to a response-dependent variable-interval schedule. Pecking rate during S1 increased (behavioral contrast) when a second stimulus (S2) [associated with either a response-dependent fixed-interval schedule (Experiment I) or a response-independent reinforcement schedule in which reinforcement availability was signaled by visual (Experiment II) or temporal (Experiment III) stimuli] alternated with S1. These experiments suggest that a discriminable, signaled decrease in local reinforcement rate during S2 is an antecedent of the behavioral contrast response rate increases during S1.     

Quasireinforcement: Control of behavior by second-order interval schedules

Pigeons were trained on a variable-interval 66-sec schedule of reinforcement that was segmented into either fixed- or variable-interval 10-sec components. Three-second access to food followed some components according to the overall VI 66-sec schedule, but 3-sec periods of nonreinforcement followed the other components. With both FI 10-sec and VI 10-sec segments, overall response rates were generally higher when the completion of unreinforced segments was signaled by a red key (never paired with food) than when it was unsignaled. Response rates during the red-key periods dropped to zero. Brief presentations of the red key engendered the distinctive (FI or VI) patterns of responding which would be expected if each segment were followed by food. These data demonstrate behavioral control by brief stimuli which are not paired with primary reinforcement and show that such control may develop even when the sequences of behavior required to produce food or brief stimuli are variable in duration.     

Choice and amount of reinforcement in rats

Rats were exposed to concurrent-chains schedules in which the terminal links were equal, fixed-interval (FI) schedules terminating in one or a varying number of food pellets. In most rats, choice proportions for the larger reinforcer increased with increases in reinforcer amount (e.g., from one to five food pellets). When log response ratios were plotted against log reinforcer amount ratios, the results indicated that the effects of reinforcer amount depended on the length of fixed-interval terminal links, by showing that rats undermatched their response ratios to reinforcer amount ratios with the shorter terminal links (FI 5 s, Experiment 1), whereas they overmatched with the longer terminal links (FI 20 s, Experiment 2). These results demonstrated that the manipulation of FI terminal-link schedules affected the sensitivity of choice to reinforcer amount, and are consistent with the previous findings that choice proportions for the larger of two reinforcers (one vs three food pellets) increased with increases in the length of FI terminal-link schedules.     

Acquisition and extinction of signaled avoidance as a function of intermittent reinforcement

Signaled, shuttle-box avoidance responding in female rats of the Fischer₃₄₄ strain was examined as a function of four separate contingencies of intermittent reinforcement. In Experiment 1, when avoidance responses during acquisition were reinforced 25% of the time with prompt CS termination, animals responded equally often during acquisition and significantly more often during extinction than animals who received such reinforcement on a 100% schedule. Similar results were found under a trace procedure in Experiment 2 when avoidance responses were reinforced 25% of the time with informational feedback stimuli. In contrast, during Experiment 3, when animals were shocked on only 25% of the trials on which they failed to respond, the level of avoidance responding during both acquisition and extinction was significantly less than it was when animals were shocked on a 100% schedule. Comparable results were found in Experiment 4 when avoidance responses during acquisition averted shock on only 25% of the trials. Thus, intermittent reinforcement contingencies involving response-contingent feedback stimuli and shock have differential effects on avoidance responding during both acquisition and extinction trials under the signaled avoidance procedure.     

Effects of US-Presentation and CS-termination contingencies on avoidance extinction following partial and continuous reinforcement

The present study assessed the role of both the US-presentation (punishment) and CS-termination contingencies on the maintenance of the shuttlebox avoidance responding in gerbils following acquisition under either partial reinforcement (PR) or continuous reinforcement (AV). Following PR, a stronger relationship obtained between delay of CS termination CR frequency than was found between delay of punishment and extinction performance. Following AV training, however, delay of CS termination and delay of punishment were equally effective determinants of avoidance extinction. These results were interpreted in terms of both the enhanced efficacy of the CS-termination contingency, possibly due to its increased informational value, and the attenuation of punishment suppression in PR-trained Ss.     

Effect of CS-US pairings on shock-elicited aggression as a function of US intensity

In two experiments with paired rats, the effect of superimposing CS-US pairings on a baseline of shock-elicited aggression was studied. Baseline shocks (3.0 mA, 0.125-sec duration) occurred at a rate of 20 shocks per min throughout each session. In Experiment I, each independent group of two pairs of subjects received (in addition to baseline shocks) US shocks of 1.0, 3.0, or 5.0 mA and 5-sec duration, each shock signalled by a 1-min CS. At all three US intensities, aggression increased during the CS. In Experiment II, pairs of subjects received each unconditioned stimulus intensity in a within-subjects design. This procedure revealed a direct relationship between rate of responding and unconditioned shock intensity.     

Response elimination in rats with schedules of omission training, including yoked and response-independent reinforcement comparisons

After rats were trained to lever press, response elimination began with factorial combinations of fixed vs variable and adjusting vs constant omission training schedules. A time interval scheduling reinforcement remained the same in a constant schedule, and its length was increased as response rate declined in the adjusting schedule. A variable time (VT) response-independent reinforcement schedule followed response elimination to test the durability of response cessation. Experiment I included groups whose reinforcement was yoked to that received by the omission schedule groups. Rate of response elimination was faster with an adjusting than a constant schedule, and slightly faster with a variable than a fixed schedule. There were no significant differences in rate of response elimination between omission schedule and yoked groups. Shorter delay of reinforcement tended to increase rate of response elimination. In the subsequent VT durability test all groups displayed near-zero response rates. In Experiment II adjusting fixed and variable omission schedules, including yoked groups, were compared with fixed time (FT) and VT reinforcement schedules. Response elimination was slower in the FT and VT groups, and they responded more in a subsequent VT durability test. It was concluded that differential reinforcement of other behavior fails to account for these omission training effects, and suggestions were made for an analysis based on the correlation between response and reinforcement rate.