Maximizing present value: A model to explain why moderate response rates obtain on variable-interval schedules

In Phases 1 and 3, two Japanese monkeys responded on a multiple variable-ratio 80 variable-interval X schedule, where the value of X was adjusted to ensure equal between-schedule reinforcement rates. Components strictly alternated following the delivery of a food pellet, and each session ended following 50 components. Phase 2 differed from the others only in that the 50 pellets previously earned during the session were delivered together at session's end. Variable-ratio response rates did not decrease across phases, but variable-interval response rates decreased substantially during the Phase 2 procedure. This rate decrease was attributed to the food-at-session's-end manipulation removing the greater immediacy of reinforcement provided by short interresponse times relative to long interresponse times. Without this time preference for short interresponse times, the variable-interval interresponse-time reinforcement feedback function largely controlled response emission, dictating a response-rate reduction. This result was explained in terms of the economic notion of “maximizing present value.”     

A comparison of generalized and modified sample biserial correlation estimators

In a recent paper, Bedrick derived the asymptotic distribution of Lord's modified sample biserial correlation estimator and studied its efficiency for bivariate normal populations. We present a more detailed examination of the properties of Lord's estimator and several competitors, including Brogden's estimator. We show that Lord's estimator is more efficient for three nonnormal distributions than a generalization of Pearson's sample biserial estimator. In addition, Lord's estimator is reasonably efficient relative to the maximum likelihood estimator for these distributions. These conclusions are consistent with Bedrick's results for the bivariate normal distribution. We also study the small sample bias and variance of Lord's estimator, and the coverage properties of several confidence interval estimates.The author would like to thank the referees for several suggestions that improved the paper.     

Key pecking in pigeons produced by pairing keylight with inaccessible grain

In Experiment I, keylight was paired with inaccessible grain delivery (under two conditions of keylight intensity) to determine if autoshaping would occur in the absence of primary reinforcement. In Experiment II, the procedure was repeated with accessible grain, for comparison. In Experiment III, the procedures were repeated with explicitly unpaired presentations of keylight and either inaccessible or accessible grain. The results indicated that key pecking occurred as quickly in the presence of keylight pairings with inaccessible grain as with accessible grain, though (except for one bird) key pecking was not maintained with inaccessible grain. Furthermore, compared to the dim keylight, the bright keylight greatly suppressed key pecking when paired with inaccessible grain, and reduced the rate of key pecking when paired with accessible grain. Little key pecking occurred in groups exposed to explicitly unpaired presentations of keylight (whether bright or dim) and grain (whether accessible or inaccessible). When the birds in Experiment III were retested with explicitly paired presentations of keylight and grain, little key pecking was observed, suggesting suppressive effects of prior explicitly unpaired presentations. It is suggested that the effects of key-brightness manipulation were produced by the association of grain with cues other than the response key, or by distraction produced by partial illumination of the grain hopper.     

Successive discrimination training with equated reinforcement frequencies: failure to obtain behavioral contrast

In two experiments, pigeons were trained on two-component multiple schedules in which responding in one component (S₁) was always maintained by a variable-interval schedule. In Experiment I, low response rates were reinforced in the second (S₂) component for six master subjects. This schedule was adjusted to equate reinforcement frequencies in the two components. These subjects were compared to yoked partners, for which reinforcement in the S₂ component was made available on a variable-interval schedule whose value was determined by the master subjects. A similar procedure was used in Experiment II, where the S₂ schedule for master subjects made reinforcers contingent on the absence of responding. No evidence was found in either experiment for a behavioral contrast effect in the S₁ component attributable to response reduction in the S₂ component. A reliable contrast effect was obtained from a group of pigeons given extinction conditions in the S₂ component, which was compared to a group maintained throughout on a multiple variable-interval schedule. The results suggest that previous indications of behavioral contrast in similar situations were probably caused by uneven reinforcement distributions or reflect uncontrolled fluctuations in response rates.     

A MULTIPLE-BASELINE ANALYSIS OF SOCIAL-SKILLS TRAINING IN CHRONIC SCHIZOPHRENICS

Social-skills training was applied to two male chronic schizophrenics. Component behaviors of social skill requiring modification were identified for each patient by rating videotapes of role-played interactions. Training involved instructions and feedback for one subject and instructions, feedback, and modelling for the second. Target behaviors were treated sequentially and cumulatively in a multiple-baseline format. Training was applied for both positive and negative assertion and for situations involving males and females. The results were positive for all behaviors for both patients. Follow-ups at 2, 4, 6, and 8 weeks after training indicated that most effects were maintained at near-treatment levels.     

A behavioral technology for producing concept formation in university students

Three experiments analyzed the effectiveness of a textbook incorporating "concept programming" in producing concept formation in university students. The concept programming portion of each lesson requires students to determine which concept is illustrated by each of 20 short fictional stories about everyday behavioral situations. The stories are selected to illustrate and contrast the concepts of that lesson. Student responses are heavily prompted during the initial stories of each lesson. The first experiment demonstrated that students generalize to entirely novel examples from the examples in the textbook. The second experiment demonstrated that the concept programming portion of the textbook is a critical component in producing generalization. The third experiment demonstrated that the amount of concept formation produced by the concept programmed textbook is greater than that produced by a widely used standard textbook.     

Note on the squared multiple correlation as a lower bound to communality

It is demonstrated that the squared multiple correlation of a variable with the remaining variables in a set of variables is a function of the communalities and the squared canonical correlations between the observed variables and common factors. This equation is shown to imply a strict inequality between the squared multiple correlation and communality.     

THE GOOD TOOTHBRUSHING GAME: A SCHOOL-BASED DENTAL HYGIENE PROGRAM FOR INCREASING THE TOOTHBRUSHING EFFECTIVENESS OF CHILDREN

There has been a serious lack of experimentally verified, effective dental hygiene programs in the schools. In and of themselves, the instruction-alone programs which comprise children's dental education do not produce proper toothbrushing skills. In the present study, a school-based contingency dental hygiene program designed to increase the effectiveness of children's toothbrushing skills at home was implemented with grade one and two classes. Each class was divided into teams and participated in the “Good Toothbrushing Game.” Each day four children from each team had the cleanliness of their teeth assessed according to the Simplified Oral Hygiene Index (Greene & Vermillion, 1964). The team with the lowest mean oral hygiene score was declared the daily winner. Winning teams received stickers and had their names posted. A multiple baseline across classrooms single-subject group design (Hersen & Barlow, 1976, pp. 228–229) established that the good toothbrushing game greatly increased the effectiveness of children's oral hygiene skills. The treatment terminal level for the grade one scores was 2.0 as compared to a baseline terminal level of 5.0, and for the grade two's was 2.3 compared to 5.7 at the end of baseline. A 9-mo follow-up indicated that these results were maintained. The data strongly suggest that proper implementation of behavioral principles is essential to the success of oral hygiene programs.     

TRAINING FUNCTIONAL EXPRESSIVE LANGUAGE: THE ACQUISITION AND GENERALIZATION OF FIVE-ELEMENT SYNTACTIC RESPONSES1

A single-subject multiple-baseline design using within- and across-subject replication was employed to study the acquisition of expanded “agent-action-object” sentences and the spontaneous generation of this form in the natural environment. Three young language-delayed subjects were trained to describe various agent-action-object relationships with a five-element syntactical form. The language training strategy was a synthesis of the developmental-psycholinguistic and behavioral models. Dynamic interactions between familiar persons and objects were the stimulus events that the children mapped. A five-element syntactical form, previously absent from the children's language repertoires, was trained during individual sessions. Concurrent with baseline, training, and followup, each subject's language was monitored in another setting, the classroom during free play. After onset of training, the core elements of the complex syntactic form were spontaneously emitted by the child in its natural environment. The free-play data reflect individual differences in the emergence and frequency of each child's spontaneous use of the agent-action-object form. The acquisition and maintenance of the specific lexicon and syntax trained were tested by posttraining probes and responses to videotape presentations. These probes revealed generalization and maintenance of both the lexical and syntactical forms acquired in treatment. The main purpose of any language-training procedure should be to provide language that is functional for the child in the natural environment. This study, which documented the spontaneous usage of the core agent-action-object syntactical form in the natural environment, effectively trained a functional syntactical rule.     

EFFECTS OF A PROCEDURE DERIVED FROM THE OVERCORRECTION PRINCIPLE ON MANIPULATED AND NONMANIPULATED BEHAVIORS

Positive practice overcorrection has been shown to be effective in reducing stereotypic self-stimulatory behaviors displayed by retarded and autistic individuals. In addition, the procedure also may increase the occurrence of appropriate behavior through intensive practice. In the present study, several stereotypic and one appropriate behavior (appropriate toy play) displayed by two autistic children were measured before and during treatment by a positive practice in appropriate toy play overcorrection procedure. Overcorrection was introduced for each of the targeted inappropriate behaviors in succession for both children. Results showed that overcorrection reduced all stereotypic behaviors displayed by both children. In addition, one subject displayed marked increases in the behavior practised during overcorrection, appropriate toy play, relative to its baseline rate of occurrence. The results indicate that for some individuals, overcorrection may be effective in teaching and motivating appropriate forms of behavior as well as in reducing stereotypy.