Some statistical treatments compatible with individual organism methodology

Consider experimental treatments with consequences so irreversible that baseline performance cannot be recovered. The conventional method of assessing the effects of such treatments by statistical means involves separate experimental and control groups. An alternative proposed here is to administer the experimental treatment to each subject, one subject at a time and in a random order; whenever any subject receives the experimental treatment, those subjects which have not yet received it receive a control treatment. This procedure permits results significant at the one-tailed 0.05 level to be obtained with four subjects; if a two-group procedure evaluated by means of the U test is used, a minimum of six subjects is needed for the same significance level. More generally, the procedure permits equal sensitivity to any experimental effect with over 30% fewer subjects than a two-group procedure. Extensions of the basic method are made to a variety of levels of the experimental treatment and to treatments without irreversible effects, and limitations of the method are discussed.     

THE ROLE OF ATTENTION IN THE TREATMENT OF ATTENTION-MAINTAINED SELF-INJURIOUS BEHAVIOR: NONCONTINGENT REINFORCEMENT AND DIFFERENTIAL REINFORCEMENT OF OTHER BEHAVIOR

Because there are potentially serious limitations to differential reinforcement of other behavior (DRO) (which is probably the most widely used treatment procedure for behavior problems), we examined an alternative procedure—noncontingent reinforcement (NCR). Three females with developmental disabilities, all of whom engaged in severe self-injurious behavior, participated. During a pretreatment functional analysis, each subject's self-injury was shown to be differentially sensitive to social attention as a maintaining consequence. Next, each subject was exposed to a DRO treatment and an NCR treatment. During DRO, attention was delivered contingent on the absence of self-injury for prespecified intervals. During NCR, attention was delivered on a fixed-time schedule that was not influenced by the subject's behavior. Results showed that both procedures were highly effective in reducing self-injury, probably because the functional reinforcer for self-injury was used during treatment. Furthermore, there was evidence that NCR attenuated several of the limitations of DRO. These results are particularly interesting in light of the long experimental history of NCR as a control rather than as a therapeutic procedure.     

Transfer of a memorization strategy in 10-year-old children: study of individual differences]

The spontaneous or induced use of an organization strategy is examined on free recall tasks with 10-year-old children classified as rather global or rather analytical at the Group Embedded Figures test. The experimental procedure include three successive and identical tests followed by two deffered tasks, one requiring a transfer of maintenance and the other a transfer of generalization. The experimental group, who attended a simple illustration of the organization strategy before the second test, applied the strategy quickly and successfully: for these subjects, one does not note differences between global or analytical subjects in the recall performance; however, the global subjects modify their study strategy of the material on the generalization task. For the control group, global or analytical subjects have a different evolution for the performance and the strategic attitude according to the procedure. The analytical subjects are different from global subjects on the generalization task.     

A NOTE CONCERNING THE MATCHED GROUP DESIGN

Despite its strong logical and technical appeal, the employment of the matched group design in applied psychological research has been restricted by practical problems associated with its use. A procedure which circumvents several of the problems of conventional matching was described. Basically, the procedure involves pairing of subjects from two or more treatment pools after the completion of training or other treatment, but without knowledge of the performance of the subjects. Three empirical tryouts of the procedure were summarized. The procedure worked quite well when only two groups were involved and was fairly satisfactory when applied to four groups. Other experimental designs may be better when more than two groups are involved. It was concluded that matching from treatment pools after differential treatment of the pools warrants more extensive use in applied psychological research than it has been accorded in the past.     

Invariance of the weight parameter in information integration

The relative effect of each informational dimension in an information integration task is a joint function of its weight and the range of values over which it is varied. A method is developed for separating these two factors. Weights obtained by this method were compared across variations of stimulus range. Subjects rated the performance of students on the basis of midterm exam scores and final exam scores. For some subjects, the range of scores on the final exam was twice that on the midterm and the reverse was true for other subjects. An averaging model was shown to describe the results, and weights did not differ for different stimulus ranges. This was true for each of two instructional conditions: one in which a particular weighting strategy was prescribed and one in which there was no prescribed weighting. Students who were instructed to use a 2∶1 weighting were found to assign more than twice as much weight to the final as to the midterm.     

Marginal mean weighting through stratification: a generalized method for evaluating multivalued and multiple treatments with nonexperimental data

Propensity score matching and stratification enable researchers to make statistical adjustment for a large number of observed covariates in nonexperimental data. These methods have recently become popular in psychological research. Yet their applications to evaluations of multi-valued and multiple treatments are limited. The inverse-probability-of-treatment weighting method, though suitable for evaluating multi-valued and multiple treatments, often generates results that are not robust when only a portion of the population provides support for causal inference or when the functional form of the propensity score model is misspecified. The marginal mean weighting through stratification (MMW-S) method promises a viable nonparametric solution to these problems. By computing weights on the basis of stratified propensity scores, MMW-S adjustment equates the pretreatment composition of multiple treatment groups under the assumption that unmeasured covariates do not confound the treatment effects given the observed covariates. Analyzing data from a weighted sample, researchers can estimate a causal effect by computing the difference between the estimated average potential outcomes associated with alternative treatments within the analysis of variance framework. After providing an intuitive illustration of the theoretical rationale underlying the weighting method for causal inferences, the article demonstrates how to apply the MMW-S method to evaluations of treatments measured on a binary, ordinal, or nominal scale approximating a completely randomized experiment; to studies of multiple concurrent treatments approximating factorial randomized designs; and to moderated treatment effects approximating randomized block designs. The analytic procedure is illustrated with an evaluation of educational services for English language learners attending kindergarten in the United States.     

Impulsivity,neuroticism, and caffeine: Do they have additive effects on arousal?

The personality dimensions of impulsivity and neuroticism have been linked to differences in basal arousal. The hypothesis tested was whether these personality variables and caffeine have additive effects on arousal. All subjects received three paired-associate trials on each of two neutral control lists, two lists with semantically similar stimuli, and two lists with acoustically similar stimuli. Half of the subjects received caffeine and half placebo. Although significant interactions with personality and drug condition were obtained, the ordering of the conditions was inconsistent with the assumption that the arousal performance curve is single peaked. Further, S. Schwartz's (Journal of Research in Personality, 1975, 9, 217–225) hypothesis that in paired-associate learning high arousal and low arousal subjects process semantic and physical information differentially was not supported. The general issue of how to determine whether individual differences in performance are caused by differences in arousal is discussed.     

Machine definition of ongoing silent and oral reading rate

A procedure is described by which a machine defines the ongoing silent and oral reading rates, and thus subjects them to environmental control and experimental analysis. Reading is considered as a form of monitoring in which response sequences are linear and successive. Applications for other types of monitoring are considered.

A page is projected on a screen, and the subject is required to read, aloud or silently. Through the same optical system, an opaque loop is presented that masks the projection, and a transparent slit on the opaque loop exposes part of a line of type. With each frame, the slit moves linearly and sequentially, exposing successive reading material. Recycling the loop triggers the presentation of another page. The subject controls the loop by pressing a micro-switch to advance the frame, thereby explicitly defining a monitoring response. The procedure is sensitive to variables such as signal-noise ratio, item difficulty, transient and long-term effects, reinforcement schedules (pay-offs), and age. Monitoring rates are extremely steady, suggesting their use as a base line.

Procedures are suggested for training subjects to be differentially attentive to different parts of a complex display.

     

Human concurrent performances: The effects of experience, instructions, and schedule-correlated stimuli

In order to investigate the effects of separate exposures to single schedules, of unique schedule-correlated stimuli, and of independency-informing instructions upon choice under concurrent variable-interval schedules, 28 human subjects were divided into eight groups. Each subject was exposed to a baseline procedure, an experimental procedure, and a return to the baseline procedure. Different combinations of these three manipulations were applied to the different groups only during the experimental phase (except for the independency-informing instructions, which were given to half of the groups at the start of training). For the group of subjects exposed to the combination of all three manipulations, the logarithms of the ratios of response frequencies tended to be linearly related to the logarithms of the ratios of reinforcement frequencies during the experimental phase. These orderly effects were not obtained with subjects in the other groups. The results suggest that human choice was well described by the generalized matching law when the three manipulations were simultaneously in effect, and that unreported differences in the use of these three procedural variables might partly account for contradictions between results in previous studies of human concurrent performance.     

SOCIAL SKILLS TRAINING WITH CHILDREN: PROCEED WITH CAUTION

Three learning disabled children, selected on the basis of peer sociometric ratings and teacher referral, received social skills training. A group training procedure consisting of coaching, modeling, behavior rehearsal, and feedback was used to teach children the target behaviors of eye contact and appropriate verbal responses. A multiple baseline analysis across target behaviors was used to demonstrate treatment effectiveness on role-play scenes trained during treatment sessions. Duration of speech was measured as an untrained, corollary measure. The following measures were also obtained during baseline, posttreatment, and 1-mo follow-up for the experimental subjects and three control subjects: (a) performance on role-play scenes not trained during treatment sessions; (b) behavioral observations in a free play setting, and (c) sociometric ratings. In addition, the trained and untrained role-play scenes were administered by novel experimenters following treatment. The results indicated that socially unskilled, learning disabled children can be taught to respond appropriately to role-play situations. However, improved performance did not generalize to the natural school setting and treatment did not effect ratings of peer acceptance. The implications of these findings for future social skills training with children are discussed.     

An individual differences additive model: An alterating least squares method with optimal scaling features

An individual differences additive model is discussed which represents individual differences in additivity by differential weighting of additive factors. A procedure for estimating the model parameters for various data measurement characteristics is developed. The procedure is evaluated using both Monte Carlo and real data. The method is found to be very useful in describing certain types of developmental change in cognitive structure, as well as being numerically robust and efficient.The work reported here was partly supported by Grant A6394 to the first author by the Natural Sciences and Engineering Research Council of Canada.     

The weighted oblimin rotation

Cureton & Mulaik (1975) proposed the Weighted Varimax rotation so that Varimax (Kaiser, 1958) could reach simple solutions when the complexities of the variables in the solution are larger than one. In the present paper the weighting procedure proposed by Cureton & Mulaik (1975) is applied to Direct Oblimin (Clarkson & Jennrich, 1988), and the rotation method obtained is called Weighted Oblimin. It has been tested on artificial complex data and real data, and the results seem to indicate that, even though Direct Oblimin rotation fails when applied to complex data, Weighted Oblimin gives good results if a variable with complexity one can be found for each factor in the pattern. Although the weighting procedure proposed by Cureton & Mulaik is based on Landahl's (1938) expression for orthogonal factors, Weighted Oblimin seems to be adequate even with highly oblique factors. The new rotation method was compared to other rotation methods based on the same weighting procedure and, whenever a variable with complexity one could be found for each factor in the pattern, Weighted Oblimin gave the best results. When rotating a simple empirical loading matrix, Weighted Oblimin seemed to slightly increase the performance of Direct Oblimin.The author is obliged to Henk A. L. Kiers and three anonymous reviewers for helpful comments on an earlier version of this paper.     

A direct approach to individual differences scaling using increasingly complex transformations

A family of models for the representation and assessment of individual differences for multivariate data is embodied in a hierarchically organized and sequentially applied procedure called PINDIS. The two principal models used for directly fitting individual configurations to some common or hypothesized space are the dimensional salience and perspective models. By systematically increasing the complexity of transformations one can better determine the validities of the various models and assess the patterns and commonalities of individual differences. PINDIS sheds some new light on the interpretability and general applicability of the dimension weighting approach implemented by the commonly used INDSCAL procedure.     

GUEST EDITORIAL MBR: RETROSPECT AND PROSPECT

It was hypothesized that paired-comparison judgments of multiple-cue profiles would be a joint function of instruction set,- cue-inconsistency, and individual differences. Thirty-one subjects judged all possible pairs of 22 profiles containing eight cues in an own-control, counterbalanced design. A comparison of instructions providing no attribute for judging similarity with those which did provide an attribute revealed systematic differences with respect to both the number and kind of perceived profile dimensions. However, within each instruction set individual differences emerged with respect to the perceived profile dimensionality which would have been obscured with a group-averaging multidimensional scaling procedure. Further, more individual difference variability was present in the instructional set providing no attribute for judgment. Finally, many subgroups of response-homogeneous judges were found to base their judgments of profile similarity on discrepant cues whereas others did not. The possibility was raised that resolution of inconsistent cues may involve either weighting of one or the other of the cues or utilizing an entirely new cue for judgment.     

Type A behaviour pattern and attentional bias in relation to anger/hostility, achievement, and failure

Type A subjects are characterised by dysfunctional cognitions related to themes of competitiveness, achievement, and hostility. The present experiment investigated attentional biases for words relevant to the content of these dysfunctional schemata in Type A individuals. After completing the MMPI-2 Type A Scale, subjects completed two alternative versions of a visual probe detection task (administered 4–12 days apart) which contained achievement, failure, and anger/hostility/aggression related words. Prior to testing at time 1, subjects were told that the purpose of the procedure was to collect normative data only. Prior to testing at time 2, subjects were told that performance on the test was known to be closely related to IQ and that they could compare their performance with that of other subjects following completion of the task. Type A subjects directed attention towards anger/hostility/aggression words under low performance motivation conditions but away from such words under high performance motivation conditions. Type A subjects also showed less selective attention to failure words than Type B subjects, and no group differences were detected for achievement related words. The results are discussed with reference to models of dysfunctional cognitive processing, and the role of anger/hostility, in particular, in Type A personality.     

Increasing purposeful activity of severely and profoundly mentally-handicapped adults

A time-series reversal design was used to evaluate the effect of a ‘room manager’ procedure on the level of purposeful activity of severely and profoundly mentally-handicapped people in a residential home. The room manager procedure consisted of systematic prompts to participate in recreational activity and social reinforcement contingent on engagement. Data were collected on group and individual client behaviour and two measures of staff performance were taken to assess whether the procedure was implemented consistently across subjects and in line with the experimental design. The results showed that, as well as a group of subjects who engaged at a higher level during the room manager condition, there were consistently ‘high-engaging’ and ‘low-engaging’ groups, reflecting in part the general level of ability of the subjects. However, data on the independent variables show that the the contingency of staff contact did not vary across conditions and it cannot therefore be assumed that these subjects would not respond to the intervention. Some limitations of the procedure as used are discussed, and areas where further work is needed are indicated.     

Are age differences in consistent-mapping visual search due to feature learning or attention training?

In this experiment, the ability of young and old adults to differentially modify the attention-attraction strength of targets and distractors relative to feature differentiation was examined. Eight young and 8 old subjects were trained for 8,000 trials in conditions that allowed maximal target-distractor strength differentiation, inhibited target-distractor strength differentiation but facilitated feature differentiation, or inhibited both target-distractor strength differentiation and feature differentiation. Age-related performance was assessed between and within conditions during training and with reversal conditions where the roles of targets and distractors were switched. The pattern of data during training and at reversal supports the proposal that age differences in extended-practice visual search are due to differences in the ability to differentially strengthen targets and distractors.     

The Holte Sleeping Technique: An experimental study

The Holte Sleeping Technique is an alternative to medication to facilitate sleep onset in situations of normal stress. The technique is based on a combination of conditioning within the theory of learning, simulation of natural bodily processes, and manipulation of naturally available sleep-releasing stimuli. The author describes the technique and reports on experimental testing of its efficacy. Fifty-six female subjects were selected according to criteria based on questionnaires and sleep logs. The subjects were randomly assigned to a treatment group, a placebo group, and a no-treatment group. A pre-test-post-test design was used. The author questions the generalizability of findings from modern electronic sleep laboratories to the bedrooms of everyday life. In order to optimize the combination of normal stress, objective criteria and generalizability, sleep onset was measured by behavioural criteria based on the "fog-horn procedure" developed by the author. At post-test 67% of the treatment group fell asleep, while only 17% of the placebo group and 25% of the no-treatment group fell asleep. The differences were significant. It is concluded that the Holte Sleeping Technique is highly effective. In a discussion of placebo trials the author argues that traditional medical trials do not take into consideration the differentiating psychological attribution effects occurring by giving the same experimental instruction under different experimental conditions. As a consequence the active treatment is given better conditions than the placebo in traditional clinical trials.     

A two-sample test

In certain investigations involving an experimental group and a control group, the effect of the experimental treatment may be expected to manifest itself by increasing the scores of some subjects but by decreasing the scores of other subjects. Examples arise in the area of defensive behavior. Customary tests of differences between means are inappropriate for assessing the existence of effect of the experimental treatment in such cases. A test based on the ranks of the observations is proposed; it will be sensitive to extreme scores (either large or small or both) for experimentals.