Reinforcer frequency and restricted stimulus control.

Stimulus control was evaluated in 3 individuals with moderate to severe mental retardation by delayed identity matching-to-sample procedures that presented either one or two discrete forms as sample stimuli on each trial. On pretests, accuracy scores on one-sample trials were uniformly high. On two-sample trials, the correct stimulus (i.e., the one that subsequently appeared in the comparison array) varied unpredictably, and accuracy scores were substantially lower, suggesting that both sample stimuli did not exert stimulus control on every trial. Subjects were then given training sessions with the one-sample task and with a new set of four stimuli. For two of the stimuli, correct matching responses were followed by reinforcers on a variable-ratio schedule that led to a high reinforcer rate. For the other two stimuli, correct responses were followed by reinforcers on a variable-ratio schedule that led to a substantially lower reinforcer rate. Results on two-sample tests that followed showed that (a) on trials in which comparison arrays consisted of one high reinforcer-rate and one low reinforcer-rate stimulus, subjects most often selected the high-rate stimulus; and (b) on trials in which the comparison arrays were either two high reinforcer-rate stimuli or two low reinforcer-rate stimuli and the samples were one high reinforcer- and one low reinforcer-rate stimulus, accuracy was higher on trials with the high-rate comparisons. These results indicate that the frequency of stimulus control by high reinforcer-rate samples was greater than that by low reinforcer-rate samples. Following more training with the one-sample task and reversed reinforcement schedules for all stimuli, the differences in stimulus control frequencies on two-sample tests also reversed. These results demonstrate experimental control by reinforcement contingencies of which of two sample stimuli controlled selections in the two-sample task. The procedures and results may prove to be relevant for understanding restricted stimulus control and stimulus overselectivity.     

Individual Behavior Consistencies as Interactive Styles: Their Relation to Personality

Two experimental studies were carried out in order to find within-subject consistencies as individual differences in a concurrent choice situation simulating risk-taking. In a first experiment, six adults were exposed to different values of probability and numbers of reinforcement in a task involving betting on two simultaneous horse races displayed on a microcomputer monitor. In the second experiment, two subjects were exposed to a within-session replication of the first experiment. The results in both experiments support the reliability of within-subject consistencies when experimental tasks are built as open contingencies. The conceptual and experimental implications of the data are discussed in relation to the study of personality.

     

Response selection,sensitivity, and taste-test performance

Tasters selected the odd stimulus from among sets of three samples of party dip. Two samples came from one batch, and one sample came from another batch. The physicochemical difference between the batches consisted of the presence or absence of added salt. Two different tests of discriminability were undertaken by the same subjects with the same stimuli: the triangle test and the three-alternative forced-choice (3-AFC) method. Although different numbers of correct selections were obtained in the two tasks, an index of discriminability,d’, had the same value when the data were analyzed in accordance with the Thurstone-Ura and signal-detection models, respectively. The average data support Frijters’s (1979b) contention that different models of the discrimination process are appropriate to the results of the triangular and the 3-AFC procedures. Further analysis of the data revealed that discrimination was poorer for trios containing one physicochemically weak stimulus and two stronger stimuli than it was for trios containing one stronger stimulus and two weak stimuli. A two-signal 3-AFC task was undertaken by some subjects, andd’ estimates from this task were lower than expected on the basis of performance in the other tasks.     

The use of programmed materials in the analysis of academic contingencies

Programmed handwriting materials were used to examine the effects of different reinforcement contingencies on the academic performance of six public school kindergarten children. The children's responses to these materials provided an educationally relevant dependent variable for the analysis of factors that affected the accuracy of their responses and the attainment of criterion performances. Variations in the complexity of most academic materials, which confound the analysis of contingencies, were eliminated by the programmed sequence so that the differential effects of three reinforcement conditions were observed. The three conditions were: baseline without tokens, tokens contingent on correct writing responses, and noncontingent tokens. It was consistently observed that the children were more accurate when their correct responses produced tokens, and that noncontingent tokens reduced accuracy below baseline levels.     

Aging and individual differences in rapid two-choice decisions

The effects of aging on performance were examined in signal detection, letter discrimination, brightness discrimination, and recognition memory, with each subject tested on all four tasks. Ratcliff’s (1978) diffusion model was fit to the data for each subject for each task, and it provided a good account of accuracy and the distributions of correct and error response times. The model’s analysis of the components of processing showed that aging had three main effects: The nondecision components of processing were slower and the decision criteria were more conservative for 60- to 74-year-old and 75- to 85-year-old subjects than for college students, but the quality of the evidence on which decisions were based was as good for the older subjects as for college students on some of the tasks. Individual differences among subjects in components of processing tended to be preserved across the tasks, as was shown by strong correlations across the tasks in the parameters of the model that represent the components of processing. For example, if the evidence on which a subject’s decisions were based was good in one task, it tended to be good in all four tasks.     

Empirical validation of a procedure to correct position and stimulus biases in matching-to-sample

The development of position and stimulus biases often occurs during initial training on matching-to-sample tasks. Furthermore, without intervention, these biases can be maintained via intermittent reinforcement provided by matching-to-sample contingencies. The present study evaluated the effectiveness of a correction procedure designed to eliminate both position and stimulus biases. Following key-peck training, a group of 6 pigeons had extended exposure to matching-to-sample contingencies without a correction procedure, a group of 4 pigeons was briefly exposed to a simultaneous matching-to-sample procedure to assess biases prior to exposure to the correction procedure, and a group of 5 pigeons was exposed directly to the correction procedure. The correction procedure arranged that every time an incorrect match was made, the trial configuration was repeated on the subsequent trial until a correct match was made. Extended exposure to matching-to-sample contingencies without a correction procedure was associated with reduced biases eventually for most subjects, but rapid development of near-perfect accuracy and bias-free performance was observed upon the implementation of the correction procedure regardless of the type of bias. Bias-free performance was maintained following subsequent exposure to a zero-delay MTS procedure.     

Perception of relative and absolute age in facial photographs

Longitudinal series of photographs of faces of secondary school students were used to evaluate observers’ ability to perceive age. Information in individual stimuli was manipulated by masking out parts of the photographs, while information provided by the relations among stimuli was manipulated by task conditions. The ability to perceive relative age was assessed in two tasks requiring subjects to order photographs by age. Absolute age perception was studied in a third task requiring age estimates in years to photographs presented one at a time. While judgments were beyond chance accuracy in all combinations of masking and task conditions, a decrease in either type of information generally produced a decrease in accuracy.

     

Individual differences,aging, and IQ in two-choice tasks

The effects of aging and IQ on performance were examined in three two-choice tasks: numerosity discrimination, recognition memory, and lexical decision. The experimental data, accuracy, correct and error response times, and response time distributions, were well explained by Ratcliff’s (1978) diffusion model. The components of processing identified by the model were compared across levels of IQ (ranging from 83 to 146) and age (college students, 60–74, and 75–90 year olds). Declines in performance with age were not significantly different for low compared to high IQ subjects. IQ but not age had large effects on the quality of the evidence that was obtained from a stimulus or memory, that is, the evidence upon which decisions were based. Applying the model to individual subjects, the components of processing identified by the model for individuals correlated across tasks. In addition, the model’s predictions and the data were examined for the “worst performance rule”, the finding that age and IQ have larger effects on slower responses than faster responses.     

Cognitive factors affecting sequential dependencies in differential eyelid conditioning

Sequential dependencies were examined as a function of learning, masking, and subject factors in a two-stage differential eyelid conditioning experiment. In Stage 1, all subjects were differentially conditioned to two Vanderplas and Garvin (1959) forms. In Stage 2, the conditional stimuli (CSs) were one of eight words, four reinforced (CS+) and four unreinforced (CS?), with taxonomic category (animalsvs. musical instruments) as the discriminandum, and different subjects were given semantic, physical, or no additional CS processing tasks. The results showed sizeable and highly significant sequential dependencies in the form of greater conditional response probabilities when CS + as opposed to CS? trials were recently experienced. These effects decreased overtrials, were greater in the groups given additional processing loads, and were in some cases greater in C-form responders than in V-form responders and greater in subjects who were unable to verbalize the differential contingencies. It was concluded that the magnitude of sequential dependencies was inversely related to the subject’s awareness of the differential contingencies and/or ability to use the contingency information to respond appropriately to the CS cues.     

Short-term memory predictions across the lifespan: monitoring span before and after conducting a task

Our objective was to explore metamemory in short-term memory across the lifespan. Five age groups participated in this study: 3 groups of children (4–13 years old), and younger and older adults. We used a three-phase task: prediction–span–postdiction. For prediction and postdiction phases, participants reported with a Yes/No response if they could recall in order a series of images. For the span task, they had to actually recall such series. From 4 years old, children have some ability to monitor their short-term memory and are able to adjust their prediction after experiencing the task. However, accuracy still improves significantly until adolescence. Although the older adults had a lower span, they were as accurate as young adults in their evaluation, suggesting that metamemory is unimpaired for short-term memory tasks in older adults.

Highlights:

?We investigate metamemory for short-term memory tasks across the lifespan.

?We find younger children cannot accurately predict their span length.

?Older adults are accurate in predicting their span length.

?People’s metamemory accuracy was related to their short-term memory span.     

Switching or sharing in dual-task line-length discrimination?

In two experiments, we tested whether subjects switched or shared attention between two simultaneously relevant line-length discrimination tasks. Switching models that allowed within- as well as between-trial switching were considered. In the first experiment, stimulus duration was varied randomly from trial to trial. With varied durations, many switching models predict negative contingencies: for a given duration and attentional allocation, accurate responses on one task should be associated with inaccurate responses on the other task. The results, however, showed no negative contingencies, which is consistent with sharing models. In the second experiment, stimulus duration was reduced to 20 msec, yet responses were more than 75% correct overall. This implies that information was obtained about both of the tasks within single trials, contradicting those switching models which predict that information can be obtained from, at most, one task within a period of 20 msec or less. In short, the results of both experiments support sharing models.     

A problem-solving model for teaching remedial arithmetic to handicapped young children

An operant problem-solving model was used to assist two handicapped young boys to learn the concept of number. During the initial baseline condition, with intermittent teacher-attention contingencies in a classroom setting, both boys were performing number concept tasks at about the 50% level of accuracy. The situation was changed to a one-to-one, tutor-pupil arrangement, with continuous reinforcement for correct responses. This alteration failed to increase the subjects' accuracy rates. Training was initiated in which the covert part of the response chain was made overt (e.g., attending and counting out loud) so that mediating responses could be monitored and reinforced. Once the subjects were performing at a high degree of accuracy, the reinforcers for the mediating responses were systematically eliminated and only final solution responses were reinforced. Accuracy of problem solutions remained high after training.This research was supported by the U.S. Office of Education, Division of Research, Bureau of Education for the Handicapped, Project No. 23–2030, Grant No. OEG-0-9-232030-0762(032). Linda S. Berner contributed to the execution of the study. Her assistance is greatly appreciated.     

Sense of Humor and Its Relationship to Personality,Scholastic Aptitude,Emotional Maturity,Height, and Weight

Two experiments were performed having in common the use of sucrose concentration and volume as amount of reinforcement variables, and in situations permitting contrast between concentrations. The following conclusions are reached:

1. It is important to distinguish between the case in which separate subjects are exposed to different concentrations or volumes, and the case in which the same subjects receive different concentrations and volumes.

2. A distinction must be drawn between reinforcement contingencies in which force of response is or is not systematically related to concentration received. In nonforce contingent situations, emitted force is inversely related to concentration, when the same subjects are exposed to the different concentrations. In contingent situations, the relationship tends to be direct.

3. Rate and force of response vary inversely with nonforce contingent volume of sucrose reinforcement, when the same subjects are exposed to the different volumes.

4. Regardless of concentration and volume used, and presumably because of within-session satiation effects, there is a general tendency for rate to decline during nonforce contingent sessions.     

Equivalence classes with requirements for short response latencies

Five adult humans were tested for emergent conditional discriminations under rapid-responding contingencies. During four-comparison matching-to-sample baseline training (AB and AC), limited-hold contingencies for responding to samples and comparisons were gradually restricted to the shortest duration consistent with at least 95% accuracy and no more than 5% failures to respond. The final limited-hold values were 0.4-0.5 s for samples and 1.2-1.3 s for comparisons; mean response latencies were 0.15-0.28 s for samples and 0.59-0.73 s for comparisons; inter-trial intervals were 0.4 s. With these fast-responding requirements, test blocks presented 72 probe trials interspersed among 72 baseline trials, all without programmed differential consequences. Four equivalence test blocks (BC and CB probes, which tested simultaneously for both symmetry and transitivity) were followed by four symmetry (BA and CA probes) test blocks. Three subjects' results documented emergent performances indicative of equivalence classes despite fast-responding requirements that severely limited the time available for mediating vocal or subvocal responses. For these three subjects, mean latencies were slightly shorter in baseline trials than in probes, and shorter on symmetry than on equivalence probes. These differences, however, were usually less than the differences among mean latencies on the different types of trials within the baseline and probed performances.     

The Rapid Establishment of Low-Rate Fixed Interval Responding by Humans in a Single Experimental Session

Subjects responding to receive monetary reinforcement on a fixed interval schedule were read instructions containing varying amounts of information regarding the schedule contingencies prior to their participation in the experiment. In addition, some subjects were exposed to an additional response cost contingency for early responding. The results indicate that reliable low-rate fixed interval responding can be rapidly generated in a single 45-minute experimental session when subjects are provided with explicit instructions together with the response cost contingency.

     

Auditory temporal order and perceived fusion-nonfusion

A pair of pure-tone sine waves, with the first tone presented randomly to either ear, was presented simultaneously or sequentially. The order of occurrence of the tones (temporal order) and the number of tones perceived (fusion-nonfusion) were judged. Three values of stimulus intensity (40, 55, and 70 dB SPL) and 10 values of stimulus onset asynchrony (SOA; 0, 1, 2, and 4 to 28 msec in 4-msec steps) were varied. Of major importance in this investigation was the relationship between the judgmental tasks of temporal order and fusion-nonfusion. Response time and accuracy were the dependent measures used to assess that relationship. The results of two groups of 10 subjects showed an increase in the percentage of correct nonfusion judgments with increases in stimulus intensity and SOA. For correct judgments of temporal order, no significant intensity or SOA effects were noted. Response time for the fusion-nonfusion task was significantly influenced by both stimulus intensity and SOA. For the response times associated with the temporal order task, intensity was significant. More important to this investigation was the observed Intensity by SOA by Task interaction for response time data. These results suggest a hybrid model, with different processes occurring within different stages of this model.     

The noneffects of contingent reinforcement for attending behavior on work accomplished

Past studies have shown that disruptive behavior can be eliminated and attending behavior accelerated in an academic setting. The relationship between these behaviors and academic performance is not well understood. The effects of behavioral and performance contingencies on classroom behavior and on academic performance were investigated. The subjects, third-grade students from an inner city elementary school, were exposed to a series of conditions including baseline, behavior contingencies, performance contingencies, and a mix of behavior and performance contingencies using a reversal design. The students worked 100 randomly selected mathematics problems for 20 minutes each day during each period. Behavioral contingencies improved attending and decreased disruptions but did not improve performance. Performance contingencies increased per cent correct problems but attending declined and disruptions increased. The combined contingencies increased both performance and attending. The experiment was replicated with another class of children varying the sequence of conditions and the amount of token reinforcement that could be earned. The findings emphasized the importance of designing specific contingencies for specific target behaviors. Behavioral contingencies did not have the positive effect on performance often implied, nor were performance contingencies alone able to maintain acceptable classroom behavior.     

Effects of scopolamine on repeated acquisition of radial-arm maze performance by rats.

Rats repeatedly acquired the performance of selecting only the four baited arms in an automated eight-arm radial maze, with the arms containing food pellets randomly assigned prior to each session. During each 14-trial (trial: obtain all four pellets) daily session, the number of errors (selecting nonbaited arms or repeating arm selections) showed a within-session decline, and choice accuracy for the first four arm selections showed a positive acceleration across trials for all rats. An index-of-curvature statistic, calculated for total errors, was used to quantify both the within- and between-session improvement of performance. Scopolamine (0.03 to 0.3 mg/kg, ip), but not methylscopolamine (0.3 mg/kg), reduced the accuracy of the first four selections of each trial and increased total within-session errors for all rats. Session times also were increased by scopolamine. An examination of within-session accuracy showed only slight signs of improvement at the higher dosages of scopolamine. The results indicate that behavior in transition states maintained by reinforcement contingencies in the radial maze is similar to that maintained by extended chained schedules, despite the fact that some of the stimuli controlling behavior in the maze are absent at the moment behavior is emitted.     

Contrast effects in response rate and accuracy of delayed matching to sample

Behavioural contrast is an inverse relation between the response rate in one component of a multiple schedule and the reinforcer rate in an alternated component. To explore possible contrast effects in accuracy as well as response rate, four pigeons were trained in multiple schedules where key pecking produced delayed matching-to-sample trials on a variable-interval schedule. Reinforcer probability for correct matches was constant at .3 in one component, and the conditions of reinforcement were varied in the second component. In Experiment 1, the varied component arranged the same contingencies as the constant component but with reinforcer probabilities of .9 or .1 across conditions. In the varied component, both response rate and accuracy of delayed matching were directly related to reinforcer probability; in the constant component, however, contrast effects on response rate were weak, and there was no evidence of contrast in accuracy of matching. In Experiment 2, the varied component was either variable interval with immediate food reinforcement or extinction. Reliable contrast effects were obtained in both response rate and in accuracy of matching in the constant component, and their magnitudes were correlated within and between subjects. The results of Experiment 2 join previous findings of covariation in the effects of reinforcement on free-operant responding and accuracy of discrimination.     

Developmental dyslexics do not fit in boxes: Evidence from six new case studies

Abstract

Six subjects with a reading problem were tested on a variety of reading and other tasks including tests of phonological awareness and processing, short-term memory, visual analysis and synthesis, memory for faces and pictures, and matching of letters and shapes. The subjects demonstrated differences in their reading strategies, but these showed no relation to any differences in the patterns of deficit on non-reading tasks. Five of them showed severe problems on tasks involving phonological processing and short-term memory but the seventy of these was unrelated to reading strategy. There were some indications of visual weaknesses, but these were severe in only one subject who had a pronounced defect in memory for faces; there was no evidence that the visual weaknesses were consistently related to reading ability or strategy.

It is concluded that all the subjects in this sample (with one 'possible exception) had a deficit in phonological processing but adopted different strategies to cope with this when faced with the task of converting print to sound. Differences in strategy are likely to be affected by the relative efficiency of other cognitive processes, personality and introdctional factors.