Hierarchical classes: Model and data analysis

A discrete, categorical model and a corresponding data-analysis method are presented for two-way two-mode (objects × attributes) data arrays with 0, 1 entries. The model contains the following two basic components: a set-theoretical formulation of the relations among objects and attributes; a Boolean decomposition of the matrix. The set-theoretical formulation defines a subset of the possible decompositions as consistent with it. A general method for graphically representing the set-theoretical decomposition is described. The data-analysis algorithm, dubbed HICLAS, aims at recovering the underlying structure in a data matrix by minimizing the discrepancies between the data and the recovered structure. HICLAS is evaluated with a simulation study and two empirical applications.This research was supported in part by a grant from the Belgian NSF (NFWO) to Paul De Boeck and in part by NSF Grant BNS-83-01027 to Seymour Rosenberg. We thank Iven Van Mechelen for clarifying several aspects of the Boolean algebraic formulation of the model and Phipps Arabie for his comments on an earlier draft.     

Minimum rank and minimum trace of covariance matrices

This paper considers some mathematical aspects of minimum trace factor analysis (MTFA). The uniqueness of an optimal point of MTFA is proved and necessary and sufficient conditions for a point x to be optimal are established. Finally, some results about the connection between MTFA and the classical minimum rank factor analysis will be presented.     

Evaluating preference for and reinforcing efficacy of fruits and vegetables compared with salty and sweet foods

Children diagnosed with autism spectrum disorder are often more selective in their food preferences than their typically developing peers. Additionally, many preferred food selections have minimal nutritional value. We evaluated the preference for, and reinforcing efficacy of, fruits and vegetables compared with salty and sweet foods, which are often used as edible reinforcers. Multiple-stimulus preference assessments were conducted to identify preferred foods, and reinforcer assessments were conducted to determine the reinforcing efficacy of more preferred foods. Fruits and vegetables were sometimes preferred over salty or sweet foods and often functioned as reinforcers. Future research should incorporate fruits and vegetables into preference assessments when identifying putative reinforcers.     

Progressive-ratio schedules: effects of later schedule requirements on earlier performances

Four rats were studied with variants of a progressive-ratio schedule with a step size of 6 in which different terminal components followed completion of the 20th ratio: (a) a reversal of the progression, (b) a fixed-ratio 6 schedule, or (c) extinction. Responding in the progressive-ratio components of these schedules was compared to performances under conventional progressive-ratio baselines. Under baseline conditions, postreinforcement pauses increased exponentially as a function of increasing ratio size, whereas running rates showed modest declines. The procedure of linking the progressive-ratio schedule to the reversed progression or to the fixed-ratio component resulted in decreased pausing. Linking the progressive-ratio schedule to the extinction component had the opposite effect, that of producing weakened progressive-ratio performances as evidenced by increased pausing. Subjects whose responses were reinforced on half of the ratios also showed exponential increases; however, pauses were substantially shorter following ratios on which the reinforcer was omitted. The results suggested that progressive-ratio pausing reflects the influence of remote as well as local contingencies.     

Effects of anorectic drugs on food intake under progressive-ratio and free-access conditions in rats

The effects of two anorectic drugs, dexfenfluramine and phentermine, on food intake under different food-access conditions were examined. Experiment 1 compared the effects of these drugs on food intake under a progressive-ratio (PR) schedule and free-access conditions. Dexfenfluramine decreased food intake under both conditions, but the doses required to decrease intake under free-access conditions were higher than those required to reduce intake under the PR condition. Intermediate doses of phentermine sometimes increased breaking points, and higher doses decreased them. Phentermine decreased food intake at the same doses under both access conditions. Thus the potency of dexfenfluramine, but not phentermine, to decrease food-maintained behavior depended upon the food-access condition. Experiment 2 used a novel mixed progressive-ratio schedule of food delivery to study the duration of drug effects. Sessions consisted of five components separated by 3-hr timeouts. The ratio requirement reset at the beginning of each component and a new breaking point was obtained. Both dexfenfluramine and phentermine dose-dependently decreased breaking points early in the session. In some rats, compensatory increases in breaking point were observed. That is, breaking points later in the session increased over control levels, resulting in no change in the total number of food pellets earned for the session compared to control. The present findings suggest that the effects of some anorectic drugs depend upon the access conditions for food; increasing the effort to obtain food may enhance their ability to decrease food-maintained behavior.     

Within-session delay-of-reinforcement gradients

Within-session delay-of-reinforcement gradients were generated with pigeons by progressively increasing delays to reinforcement within each session. In Experiment 1, the effects of imposing progressive delays on variable-interval and fixed-interval schedules were investigated while controlling for simultaneous decreases in reinforcer rate across the session via a within-subject yoked-control procedure. Rate of key pecking decreased as a negatively decelerated function of delay of reinforcement within a session. These rate decreases were greater than those during a yoked-interval session in which the rate of immediate reinforcement decreased at the same rate as it did under the progressive-delay procedure. In Experiment 2, delay-of-reinforcement gradients were shallower when the progressive delay intervals were signaled by a blackout than when they were unsignaled. The delay gradients obtained in each experiment were similar to those generated under conditions in which different delays of reinforcement are imposed across blocks of sessions. The present procedure offers a technique for rapidly generating delay-of-reinforcement gradients that might serve as baselines for assessing the effects of other behavioral and pharmacological variables.     

Recurrent Trisomies: Chance or Inherited Predisposition?

Two patients experiencing recurring trisomic pregnancies involving a different chromosome each time are presented. Mechanisms to explain recurrent trisomies include a gene or genes predisposing to nondisjunction in general or to nondisjunction of the acrocentric chromosomes, maternal age effects, and germ-line mosaicism. Genetic counseling is complicated by the lack of a clear explanation for the recurrences, difficulty in quoting a specific recurrence risk, concern regarding the risk for uniparental disomy, and the frustration, grief and guilt reactions of the patients.     

Weak Consistency for Ensuring Priority Vectors Reliability

Consistency and transitivity are important and leading research topics in the study of decision‐making in terms of pairwise comparison matrices. In this paper, we search for conditions that, in case of inconsistency, guarantee ordinal compatibility between ordinal ranking (actual ranking) derived from a transitive matrix and cardinal rankings provided by the most usual priority vectors proposed in the scientific literature. We provide the notion of weak consistency; it is a condition weaker than consistency and stronger than transitivity and ensures that vectors associated with a matrix, by means of a strictly increasing synthesis functional, provide a preference order, on the related set of decision elements, equal to the actual ranking. This notion extends, to the case in which the decision‐maker can be indifferent between two or more alternatives/criteria, weak consistency introduced in previous papers under constraint of no indifference. Finally, we introduce an order relation on the rows of the matrix, that is, a simple order if and only if weak consistency is satisfied; this simple order allows us to easily determine the actual ranking on the set of decision elements. Copyright © 2015 John Wiley & Sons, Ltd.     

A Contemporary View of Applied Relaxation for Generalized Anxiety Disorder

Applied relaxation (AR), originally developed by Lars-Göran Öst, is a long-standing, efficacious treatment for generalized anxiety disorder (GAD). While newer treatments are continuing to be developed, AR remains one of the most efficacious treatments for GAD. However, AR has received less in-depth attention more recently, particularly in terms of potential mechanisms of action. This article is written to honor the development and history of AR and to highlight the ways that it has continued to be adapted. In this article, AR treatment strategies are presented, which include: noticing early signs of anxiety, learning relaxation skills, and applying relaxation at the first sign of anxiety. Then, additional adaptations to AR are presented along with recommendations of how AR may be enhanced by understanding potential mechanisms of change. Finally, recommendations are made for the continued evolution of AR as a powerful and efficacious treatment for GAD.     

Advanced Brief Strategic Therapy: An overview of interventions with eating disorders to exemplify how theory and practice work

This paper aims at introducing some of the central aspects of the evolution that brief strategic therapy has undergone at the Centro di Terapia Strategica of Arezzo, Italy, towards advanced therapeutic strategies which differ from the original Palo Alto model. (Fisch, Weakland, &; Segal, 1982; Watzlawick, 1978 Watzlawick, P. 1978. The language of change: Elements of therapeutic communication, New York: Basic Books.  [Google Scholar]; Watzlawick, Beavin, &; Jackson, 1967; Watzlawick, Weakland, &; Fisch, 1974). We will focus on how the concept of self-deception is central to the formation and the persistence of psychological disorders; and how the usage of non-ordinary logics and the understanding of the individual's perceptive-reactive system are of key importance in unravelling such disorders, allowing the therapist to guide the patient towards an efficacious and efficient solution. Rather than attempting to describe and enlist the theoretical corpus that underlies brief strategic therapy, we have chosen to exemplify some focal concepts that connect theory to practice, and vice versa, by presenting the outline of some therapeutic protocols devised for solving eating disorders which can be specifically tailored for each individual patient.