Response latency as a function of reinforcement schedule

Four Ss were trained to press and hold down a telegraph key in the presence of a light. Subsequent release of the key during a tone was followed by water reinforcement. The schedule of reinforcement for key release was varied, and its effects on the latency (RT) of key release to the tone were studied. Both median RT and variability of RT were found to be inversely related to frequency of reinforcement as determined by the schedule.     

Positive contrast obtained in reacquisition following interpolation of nonreinforced or partially reinforced trials

Two experiments investigated the effects of shifting from either nonreinforcement or partial reinforcement (PRF) to continuous reinforcement conditions (CRF). In the first experiment, three groups of rats were given food reinforcement under CRF conditions in a runway followed by regular extinction trials (RE), extinction trials where Ss were delayed for 30 sec before entering the empty goal box (DE), or CRF trials where Ss were delayed for 30 sec before entering the baited goal box (DF). Then all Ss were run on the delayed reinforcement condition (DF). In the final delayed reinforcement condition, group DE ran significantly faster than group DF, reflecting positive contrast. In the second experiment, four groups of rats were trained in a runway to receive either 4% or 18% sucrose reinforcers under either PRF or CRF conditions. Then all Ss were transferred to a Skinner box and bar presses were continuously reinforced, with each S continuing to receive the same sucrose concentration as before. The former PRF Ss, regardless of the reinforcer, bar pressed at a significantly higher rate in the Skinner box than the former CRF Ss. The evidence seemed to favor the view that the effectiveness of a reinforcer is not an absolute, unchanging quantity but rather depends on the historical context in which the reinforcer occurs.     

Differential reinforcement of low rates performance by impulsive and reflective children

Third-grade boys classified as either cognitively impulsive or reflective were reinforced for key pressing according to a DRL (differential reinforcement of low rates) 6-sec schedule of reinforcement. Half of each group received instructions about the behavioral requirements for obtaining reinforcements. Prior to DRL training, impulsive Ss showed a low probability of key press responding at long interresponse time (IRT) intervals while reflective Ss exhibited an equal probability of terminating either short or long IRTs. During training and in the absence of instructions, impulsives exhibited a less precise temporal discrimination, characterized by a greater predominance of response bursts (0–2 sec IRTs) following reinforcements, than reflective Ss. While impulsive and reflective Ss displayed similar frequencies of collateral behavior between successively reinforced responses, impulsives engaged in the reinforced response more frequently and tended (p < .08) to obtain fewer reinforcements. Instructions served to enhance the DRL performance.     

Delayed reinforcement and delayed choice in symbolic matching to sample: Effects on stimulus discriminability

Six pigeons were trained to peck a red side key when the brighter of two white lights (S₁) had been presented on the center key, and to peck a green side key when the dimmer of two white lights (S₂) had been presented on the center key. Equal frequencies of reinforcers were provided for the two types of correct choice. Incorrect choices, red side-key pecks following S₂ presentations and green side-key pecks following S₁ presentations, resulted in blackout. With 0-s delay between choice and reinforcement, the delay between sample presentation and choice was varied from 0 to 20 s. Then, with 0-s delay between sample presentation and choice, the delay between choice and reinforcement was varied from 0 to 20 s. Both types of delay resulted in decreased discriminability (defined in terms of a signal-detection analysis) of the center-key stimuli, but delayed choice had more effect on discriminability than did delayed reinforcement. These data are consistent with the view that the two kinds of delay operate differently. The effect of a sample-choice delay may result from a degradation of the conditional discriminative stimuli during the delay; the effect of a choice-reinforcer delay may result from a decrement in control by differential reinforcement.     

Effects of operant conditioning on the GSR

Each of nine Ss was run for 11 daily sessions. Except for the first (operant level) and last two (extinction) sessions, 500-ohm drops in skin resistance were followed by reinforcement (light). These reinforcement periods lasted 20 min and were preceded by 10-min control periods during which no reinforcement was administered. Although the results showed no evidence for operant conditioning of the GSR, they did indicate that increased emission of GSR's occurred during the reinforcement period. This effect was shown to hold for Ss with low operant levels of GSR's but not for Ss with high operant levels.     

Comparison of reinforcement and punishment functions produced by the same contingent event in the same subjects

The same event, forced running, was used to reinforce the lever-pressing of six rats in one component of a multiple schedule and to punish their drinking in another component. When the durations of running were converted to probabilities that Ss would not be running at t + n sec, given that the run gegan at t = 0 sec, both reinforcement and punishment were found to be linear (inverse) functions of the probability of not-running. A high concordance (0.90) between slopes of the reinforcement and punishment functions indicated that individual Ss were either sensitive to both reinforcement and punishment or sensitive to neither.     

Warned reaction times of sociopaths

A warned reaction time (RT) task was employed with eight male sociopaths and eight normal male Ss. A warning light appeared at a variable interval preceding a light to which the S responded with a key press. All Ss received both a regular and an irregular series with warning intervals of 1, 2, 4, 8, and 16 sec. In the regular series, blocks of intervals were presented in an ascending order. In the irregular series each interval followed every other interval equally often. Sociopaths obtained reliably slower RTs than did control Ss, showing a constant decrement across all intervals in the two kinds of series.     

Optional shift behavior as a function of age and dimensional dominance

An optional reversal-nonreversal shift task for which the relevant color or form cues were either dominant or nondominant was presented to 320 Ss, 6 through 20 years of age. Dominance, as defined in terms of relative cue similarity, was related to initial learning and shift behavior for kindergarten and third-grade Ss; but not for sixth-grade and college Ss. The speed of initial learning and percentage of reversal shifts was related to age when the nondominant dimension was relevant. There were no developmental differences when the dominant dimension was relevant.     

Informational and motivational components of social reinforcement

Thirty-six four-year-old children of each sex were tested in a two-choice marble dropping task. There were three Ss in each cell of a 3 × 2 × 2 × 2 factorial design. The factors investigated were: reinforcement condition (Contingent, Yoked, Nonreinforcement), sex, base preference level (strong vs weak), Base Rate Level (high vs low). The dependent variables were: base preference ratio, base rate, preference ratio change, rate change. The contingently reinforced Ss had significantly higher preference change scores than Ss in the other two reinforcement conditions but only at the high base preference level. The Ss in both the contingent and yoked groups had higher rate change scores than Ss in the nonreinforcement group. The results were interpreted as indicating social reinforcement may have two effects, one a cue function and the other an effect on S's motivational system. The results indicate that regression effects do not operate in the two-choice task and that crossing baseline levels of performance is an effective way to control baseline differences in analyses of change in the two-choice task.     

Operant Conditioning Effects upon Drawing Content

Abstract

The variability of drawing content classes and the effects of the Ss awareness of contingencies were tested through an experimental reinforcement of human and object content. In three individual sessions 60 Ss completed drawings each time responding to 25 standardized perceptual cues. In the second session, two matched experimental groups were treated with reversed forms of reinforcement. A questionnaire and interview were used to refine the data. Findings show a significant consistency of several content classes; nevertheless, the contingent classes were efficiently conditioned. The male Ss and contingency-aware pairs conditioned better than the nonawareness and female Ss. The relative lack of extinction points to the persistent effects of reinforcement.     

Effects of a coactor's prediction on latencies to predict and indentify stimuli

On each of 300 trials E's confederate (C) verbalized which of two stimuli would occur; then S made a prediction. Following each presentation, S and C pulled a trigger to identify the stimulus. Two latencies were measured: the interval between C's and S's prediction (prediction time), and the interval between stimulus presentation and S's identification response (choice RT). Prediction times were significantly shorter when S's prediction agreed rather than disagreed with C's prediction, when S's preceding prediction was correct rather than incorrect, and when S was female rather than male. Choice RT was influenced by distributions of C's stimulus predictions and C's prediction outcomes in directions supporting an expectancy model.     

Stimulus generalization and the response-reinforcement contingency

Generalization gradients along a line-tilt continuum were obtained from groups of pigeons that had been trained to peck a key on different schedules of reinforcement. In Exp. I, gradients following training on a differential-reinforcement-of-low-rate (DRL) schedule proved to be much flatter than gradients following the usual 1-min variable interval (VI) training. In Exp. II, the value of the VI schedule itself was parametrically studied; Ss trained on long VI schedules (e.g., 4-min) produced much flatter gradients than Ss trained on short VI schedules (30-sec; 1-min). The results were interpreted mainly in terms of the relative control exerted by internal, proprioceptive cues on the different reinforcement schedules. Several implications of the results for other problems in the field of stimulus generalization are discussed.     

Shaping of three-man teams on a multiple DRL-DRH schedule using collective reinforcement

Five three-man teams were conditioned to a multiple DRL-DRH schedule during five daily sessions of 3 hr each. The teams were conditioned on the basis of their cumulative response rate regardless of the contributions of individual members. Two individually conditioned Ss were run under a similar schedule for comparison. Although all teams demonstrated some differentiation of response rate under the two legs of the schedule, this difference was not achieved as rapidly, nor was it as stable, as the differentiation in rates achieved in individually conditioned Ss. Team members displayed a variety of response rates as a result of collective team conditioning. Often, individual response rates interfered with obtainment of team reinforcement. The individual team members displayed little S^D control in comparison with the individually conditioned Ss. In general the results suggest that collective reinforcement is highly inefficient in comparison with procedures employing individual feedback.     

The correlation of EPQ psychoticism with two behavioural measures of impulsivity

The Psychoticism (P) scale of the Eysenck Personality Questionnaire (EPQ) was correlated with performance on two behavioural measures of impulsivity: total number of Errors in a choice reaction-time (RT) task, and number of Taboo Responses in an open-ended creativity test. Experiment 1 employed 20 Ss in an auditory RT situation and using an untimed creativity test. P correlated strongly and positively with a logged Taboo Responses measure but not with a logged Errors score. The correlation of P with Errors reached statistical significance when the biserial correlation of P with Errors/No Errors was calculated. Experiment 2 employed 35 Ss in a visual choice RT situation and using a timed creativity test. Questionnaire scales of Venturesomeness, Impulsiveness and Empathy were also used. Both behavioural indices were significantly correlated with P, but not with Venturesomeness or Impulsiveness. The results constitute further support for the view that the P scale of the EPQ contains a strong impulsivity component.     

Methods and findings in an analysis of a vocal operant

The relations among acoustic parameters of a vocal operant were considered and some methods for their measurement are described. Four human subjects (Ss) and one chick were employed in an experiment on the relations among vocal rate, vocal topography, and schedules of reinforcement. The earlier finding that schedules of reinforcement control human and infra-human vocal responding as they do other operants was replicated and extended to the case of variable-interval reinforcement. An analysis of response amplitude, pitch, and duration showed that the mean and variance of these parameters typically increase from CRF to VI, from VI to EXT and, for a second group of Ss, from CRF to EXT. The topography of the chick's vocal response appears to stand in the same relation to reinforcement operations as does the human vocal response.     

Successive negative contrast after partial reinforcement in the consummatory behavior of rats

Rats given access to a 32% sucrose solution later reject a 4% solution significantly more than controls that have only received the 4% solution. In Experiment 1, this consummatory successive negative contrast (cSNC) effect was attenuated by previous exposure to 50% partial reinforcement. Furthermore, recovery from cSNC was also facilitated by partial reinforcement. In Experiment 2, the attenuating effects of partial reinforcement on cSNC were eliminated by administration of the benzodiazepine anxiolytic chlordiazepoxide (5 mg/kg) before nonreinforced trials. In Experiment 3, the attenuating effect of partial reinforcement was greater after a shift from 32 to 6% solution, than after a shift from 32 to 2% solution. The parallels between the effects of partial reinforcement on consummatory and instrumental behavior are discussed.     

Children's acquisition and reversal behavior in a probability learning situation as a function of programed instruction,internal-external control,and schedules of reinforcement

A three-choice, contingent task was used with 192 fifth and sixth graders in a 2 × 2 × 3 factorial design combining instruction (programed instruction on selected probability concepts vs no programed instruction), locus of control (internal vs external), and schedules of reinforcement (33, 66, and 100%). The dependent measures were the percentage of correct acquisition responses, of correct reversal responses, and of pattern responses, as well as posttests on probability concepts. The major findings of the study were associated with schedule of reinforcement. In acquisition and reversal, Ss under 100% reinforcement during acquisition tended to maximize the greatest, followed by the 66 and 33% conditions, in that order. The ordinal relationship among schedules was the exact reverse of the maximizing approach for the pattern responses. A partial reinforcement effect was obtained in reversal. Evidence indicated that programed instruction and locus of control affected maximizing behavior, patterning behavior, and resistance to extinction (though these variables did not interact with reinforcement schedule in the predicted direction). Finally the posttest data showed that instructed Ss did learn more relative to noninstructed Ss.     

Differential reinforcement of vocal duration

The effects of differential reinforcement of vocal duration were examined in a series of experiments in which each of 28 subjects (Ss) emitted a vowel whenever a light was flashed. In the first phase of each experiment, a penny was dispensed after each of 20 responses. In the second and subsequent phases, only those responses whose durations exceeded a criterion were reinforced; when 10 successive reinforcements were presented, one phase was terminated and the next begun. The criterion for reinforcement in each phase was determined by a different schedule in each of six experiments; it ranged from 80 to 120 per cent of the mean duration of the 10 terminal responses in the prior phase. Differential reinforcement effected a large and systematic change in the duration of vocal responses as long as the responses selected for reinforcement had a sufficiently high probability of occurrence. This requirement was formulated as the difference between the criterion duration and the mean duration of the terminal responses in the prior phase, divided by their standard deviation. This statistic, named the shaping index, was correlated with the number of responses emitted before each phase was terminated. It was found to be large whenever the shaping process failed. Many Ss failed to tact the reinforcement contingency despite marked changes in their vocal behavior and extensive probing by a questionnaire, administered at the end of each session.     

Behavioral definition of minimal reaction time in monkeys

Two monkeys (Macaca mulatta) were trained to press a key after onset of a tone and to release it after a 1-sec fixed foreperiod terminated by a light. The effects of imposing temporal contingencies on key release reaction times were determined by reinforcing only those releases whose latencies from the light fell within a “payoff band”, two time limits 50 msec apart located at some delay following the light. Over several days this delay was first gradually decreased, shortening the interval between light and payoff band, and then gradually increased again. For each delay, the median reaction time and a measure of variability were obtained from the latency distribution. For both animals, median latency could be decreased to 180 msec with the variability remaining small. Moving the payoff band still closer to the light resulted in further decrease in median latency but an abrupt increase in variability. This is in agreement with a model for simple reaction time derived from human research which suggests that this increased variability results from the inclusion of high-variability foreperiod time estimations in the latency distribution. These results indicate that interpretation of monkey response latencies as “minimal reaction times” requires examination of temporal reinforcement contingencies and variability of latencies.     

Effect of prior Pavlovian discrimination training upon learning an operant discrimination

The effect of Pavlovian discrimination training with two stimuli upon subsequent learning of an operant discrimination involving those stimuli was studied. After preliminary lever press training, the lever was removed and thirsty rats received noncontingent pairings between S₁ (a tone or a clicker) and water reinforcements, whereas S₂ (a clicker or a tone) occurred always without reinforcement. This procedure presumably established S₁ as a positive CS for respondent behavior, whereas S₂ was established as an inhibitory CS. Following this training, the lever was reintroduced and the rats were trained on an operant (lever pressing) discrimination involving S₁ and S₂. For the Consistent Ss, S₁ was the S^D and S₂ the S^Δ in the operant discrimination; for the Reversed Ss, S₂ served as S^D and S₁ as S^Δ. The Consistent Ss learned the operant discrimination significantly faster than did the Reversed Ss. The result emphasizes the importance of respondents, conditioned to S^D and S^Δ, which modulate operant performance to these stimuli.