On structural models for analyzing change

The recommendation to base the analysis of multi-wave data upon explicit models for change is advocated. Several univariate and multivariate models are described, which emerge from an interaction between the classical test theory and the structural equation modeling approach. The resulting structural models for analyzing change reflect in some of their parameters substantively interesting aspects of intra- and interindividual change in follow-up studies. The models are viewed as an alternative to an ANOVA-based analysis of longitudinal data, and are illustrated on data from a cognitive intervention study of old adults (Bakes et al , 1986). The approach presents a useful means of analyzing change over time, and is applicable for purposes of (latent) growth curve analysis when analysis of variance assumptions are violated (e.g., Schaie & Hertzog, 1982; Morrison, 1976).     

东莨菪碱所致记忆障碍的脑内突触机制

研究问题是东莨菪碱所致记忆障碍的脑内突触机制,在东莨菪碱所致记忆障碍模型上定量分析屯小鼠海马ＣＡ３区ＧｒａｙＩ突触界面结构参数的变化。     

Fitting multivariage normal finite mixtures subject to structural equation modeling

This paper is about fitting multivariate normal mixture distributions subject to structural equation modeling. The general model comprises common factor and structural regression models. The introduction of covariance and mean structure models reduces the number of parameters to be estimated in fitting the mixture and enables one to investigate a variety of substantive hypotheses concerning the differences between the components in the mixture. Within the general model, individual parameters can be subjected to equality, nonlinear and simple bounds constraints. Confidence intervals are based on the inverse of the Hessian and on the likelihood profile. Several illustrations are given and results of a simulation study concerning the confidence intervals are reported.     

Education and Understanding Structural Causes for Group Inequalities

Group inequalities in the United States are most often attributed to the characteristics of the individuals who belong to these groups; thinking about structural causes of group inequalities is rare. This paper reviews cognitive, cultural, and systemic reasons for this bias. The efficacy of education as a way to increase structural thinking was investigated in two studies of college students' causal thinking about group inequalities. Both studies involved a course on intergroup relations that covered structural sources of racial or ethnic inequalities. Results supported hypotheses that the course would increase structural thinking about racial or ethnic inequality, and that structural thinking would generalize to inequalities not explicitly covered in the course. Both course content and active learning pedagogy were related to structural thinking about inequalities. Active learning was also related to applying structural thinking to targets of change.     

Experimental analysis of academic performance in a classroom setting

We evaluated the effects of specific stimulus prompts on accuracy of academic performance with adolescents who displayed academic problems in a public special education classroom. We conducted analyses of instructional strategies within a multielement design with two students who had mild disabilities. Differential effects of the strategies on reading comprehension were not apparent on demand (independent-level) tasks but were apparent on high-demand (instructional-level) tasks. These results suggested that the application of experimental analysis methodologies to instructional variables may facilitate the identification of stimulus prompts associated with accurate academic performance.     

Concurrent-schedule performance in dairy cows: persistent undermatching.

Performance of dairy cows responding under concurrent variable-interval variable-interval schedules of food delivery was examined, with results analyzed in terms of the generalized matching equation. In Experiment 1, bias measures indicated that crushed barley was preferred over meatmeal when these foods were available under the alternative schedules. For whole-session data, substantial undermatching of response and time-allocation ratios to obtained reinforcement ratios was evident. Postreinforcement pause time ratios approximately matched obtained reinforcement rates. Subtracting these times from total time-allocation values yielded net time-allocation ratios that undermatched obtained reinforcement ratios to a greater degree than did whole-session time-allocation ratios. In Experiment 2, substantial undermatching was evident when the same foods (hay for 2 cows, crushed barley for 2 others) were available under the alternative schedules. Food-related activities and other defined behavior not related to food were quantified by direct observation, and were found to occupy a substantial proportion (roughly 40% to 80%) of experimental sessions. Subtracting the time spent in these activities from the time allocated to each component schedule did not reduce the degree of undermatching obtained. Across all conditions in both experiments, slopes of regression lines relating behavioral outputs to environmental inputs characteristically were below 0.6, which agrees with prior findings and suggests that, contrary to suggestions in the literature, undermatching in dairy cows is not the result of using different foods under alternative schedules or differential pausing under those schedules.     

Multilevel covariance structure analysis of sibling substance use and intrafamily conflict

Conventional covariance structure analysis, such as factor analysis, is often applied to data that are obtained in a hierarchical fashion, such as siblings observed within families. A more appropriate specification is demonstrated which explicitly models the within-level and between-level covariance matrices of sibling substance use and intrafamily conflict. Participants were 267 target adolescents (mean age=13.11 years) and 318 siblings (mean age=15.03 years). The level of homogeneity within sibling clusters, and heterogeneity among families, was sufficient to conduct a multilevel covariance structure analysis (MCA). Parental and family-level variables consisting of marital status, socioeconomic status, marital discord, parent use, and modeling of substances were used to explain heterogeneity among families. Marital discord predicted intrafamily conflict, and parent marital status and modeling of substances predicted sibling substance use. Advantages and uses of hierarchical designs and conventional covariance structure software for multilevel data are discussed.     

THE USE OF IMPOSED AND SELF-SELECTED TRAINING PACKAGES TO ESTABLISH CLASSROOM TEACHING SKILLS1

Although much is known about techniques for teaching elementary pupils in the classroom, no procedures have been consistently effective in training teachers to use these techniques. In the present study, six teacher trainees were observed individually and trained sequentially to use a variety of teaching skills: praise for academic responses, praise for appropriate classroom behavior, correction procedures for incorrect academic responses, and token fines. These skills were examined under four conditions: (1) baseline sessions were taught by the trainees before any instructions on the use of the teaching skills. (2) Instruction sessions were taught by the trainees after they were given instructions describing the use of several teaching skills. (3) During each Imposed-Package session, the trainees received modelling, verbal feedback, graphic feedback, and grade and quiz contingencies on their use of a particular teaching skill. (4) During each Self-Selected Package session, a grade contingency was in effect with the trainees choosing the components (modelling, verbal feedback, graphic feedback, quiz contingency) they wanted included in their training package for a particular skill. The effects of instructions were quite varied. Large increases on three of the four skills occurred with one trainee; almost no changes occurred with another trainee; and changes with the remaining four trainees fell within these extremes. The Imposed and Self-Selected Packages reliably increased the use of teaching skills, including those skills for which instructions had not been effective. The Self-Selected Package was considered to be as effective as the Imposed Package, since the time required for training a teaching skill varied from two to nine sessions with both packages. Under the Self-Selected Package, the trainees chose from modelling, verbal feedback, and graphic feedback, but none chose the quiz contingency. Questionnaire data collected after training showed that all six trainees preferred the Self-Selected Package to the Imposed Package. The effectiveness of the Self-Selected Package, together with the trainees' preference for it, suggests that it may be desirable for teacher training programs to specify the teaching skills, arrange a contingency for performance, and allow trainees to choose which additional components are to be used in each training session.     

COMPARISON OF MODELLING AND REINFORCEMENT PROCEDURES IN INCREASING QUESTION-ASKING OF MILDLY RETARDED CHILDREN1

Questioning is an important skill, particularly for retarded children with deficits in accumulated information. Recent strategies for modifying a variety of verbal behaviors have included both token reinforcement systems and modelling procedures. However, the relative effectiveness (i.e., the rate of behavior change) of certain reinforcement procedures, especially with low base-rate behavior (used alone) have recently been questioned. The present study, using an ABAB design, compared the effect of a Token reinforcement system, a Trainer-Model procedure, and a combination of the two procedures on increasing the rate of question-asking. Each condition was in effect for six sessions. Groups of four mildly retarded children (mean age: 10.1 yr) were prompted to ask questions about large photographs, and each of their questions was immediately answered. For the Model group, the Trainer modelled four questions for each subject for each photograph. For the Token group, each question earned the subject a point, which was exchangeable after the session for various items (e.g., candy, ice cream) from a “store”. For the Modelling plus Token group, the procedures were combined. The Model and the Control groups were yoked to receive the same amount of candy as the Token and the Model plus Token groups for behaviors other than question-asking (i.e., being polite). The results indicated that during Baseline conditions, performance across groups was comparable and that the performance of the Control group did not change across time. The Model procedure had only minimal effects on the rate of question-asking, while both the Model plus Token and the Token groups showed significant performance increments. The only significant difference between the Model plus Token and the Token groups was a faster rate of increase early in the first Training condition for the Model plus Token group. This difference, and the low level of performance change for the Model group, was interpreted as suggesting a facilitory effect of modelling procedures on reinforcement contingencies. The discrepancy between previous findings showing relatively minimal changes following reinforcement of low base-rate responses and the present results were discussed in terms of various procedural differences. Educational implications of the present results were also discussed.     

THE EFFECTS OF MODELLING ON THE CONTINGENT PRAISE OF MENTAL RETARDATION COUNSELLORS

A multiple-baseline design was used to evaluate the effects of a simple modelling procedure on the contingent praise of five counsellors while they conducted hygiene-training sessions in toothbrushing and hand-and-face washing with severely retarded children. After varying numbers of baseline sessions, each counsellor watched a model who conducted a series of toothbrushing sessions, in which he conspicuously praised correct toothbrushing responses and approximations to correct responses. No modelling occurred during hand-and-face washing sessions. As a result of several exposures to the model's performance, levels of response-contingent praise provided by four of the five counsellors during toothbrushing sessions increased sharply over baseline. The levels of counsellor praise showed parallel increases during hand-and-face washing sessions. A two-week followup showed that the levels of praise obtained through modelling were maintained in the model's absence.