Comparative evaluation of two superior stopping rules for hierarchical cluster analysis

A split-sample replication stopping rule for hierarchical cluster analysis is compared with the internal criterion previously found superior by Milligan and Cooper (1985) in their comparison of 30 different procedures. The number and extent of overlap of the latent population distributions was systematically varied in the present evaluation of stopping-rule validity. Equal and unequal population base rates were also considered. Both stopping rules correctly identified the actual number of populations when there was essentially no overlap and clusters occupied visually distinct regions of the measurement space. The replication criterion, which is evaluated by clustering of cluster means from preliminary analyses that are accomplished on random partitions of an original data set, was superior as the degree of overlap in population distributions increased. Neither method performed adequately when overlap obliterated visually discernible density nodes.This research was supported in part by NIMH grant 5R01 MH 32457 14.     

The judgment-choice discrepancy: Noncompatibility or restructuring?

The study examines the relative merits of a noncompatibility and a restructuring explanation of the recurrent empirical finding that a prominent attribute looms larger in choices than in judgments. Pairs of equally attractive options were presented to 72 undergraduates who were assigned to six conditions in which they performed (1) only preference judgments or choices, (2) preference judgments or choices preceded by judgments of attractiveness of attribute levels, or (3) preference judgments or choices accompanied by think-aloud reports. The results replicated the prominence effect for choices, but a prominence effect was also found for preference judgments. In accordance with the restructuring explanation, the think-aloud protocols indicated that options were more often restructured in choices than in preference judgments. However, restructuring could not explain the prominence effect observed for preference judgments. A modified compatibility hypothesis is offered as an alternative explanation.     

Towards reflexive practice: Engaging participants as co-researchers or co-analysts in psychological inquiry

This paper considers some of the implications of reflexivity for the practice of psychological research. After a brief consideration of the theoretical background to a concern with reflexivity, the paper goes on to examine how various researchers have attempted to incorporate components of reflexivity in their research practice. While a group of sociologists of science have operationalized reflexivity by self-conscious concern for their own role in the construction of social—scientific knowledge, new paradigm co-operative inquirers interpret a need for reflexivity by including their participants as fully self-reflexive co-researchers. Mulkay's suggestion for a dialogic analytical exchange with one's participants is also considered. The second half of the paper illustrates an attempt at reflexive practice in the authors' own research. This was a project concerned with identity change during the transition to motherhood, and aimed to allow the women a strong hand in helping to shape the project's direction. Preliminary analysis of a woman's data was taken back to her for her comments, and her reflections on the data were incorporated in the final case study. A detailed example of the investigator and participant's discussion of a piece of data is provided.     

Internet resources in applied behavior analysis

Internet communication is becoming an important tool for both academic and clinical areas in psychology and behavior analysis. The Internet, a confederation of thousands of computer systems covering the entire globe (Plaud, 1996b), can significantly enhance behavior analysis in at least three major areas: (a) information exchange and communication among behavior analysts through list servers, (b) dissemination of empirical data and commentary through on-line journals and information servers, and (c) promotion of programs and services in behavior analysis. This commentary provides specific examples in each of these areas and addresses the basics of connecting to the Internet.     

CHOICE-MAKING TREATMENT OF YOUNG CHILDREN'S SEVERE BEHAVIOR PROBLEMS

The choice-making behavior of 5 young children with developmental disabilities who engaged in aberrant behavior was studied within a concurrent operants framework. Experimental analyses were conducted to identify reinforcers that maintained aberrant behavior, and functional communication training packages were implemented to teach the participants to gain reinforcement using mands. Next, a choice-making analysis, in which the participants chose one of two responses (either a mand or an alternative neutral response) to obtain different durations and qualities of reinforcement, was conducted. Finally, treatment packages involving choice making via manding were implemented to decrease inappropriate behavior and to increase mands. The results extended previous applications of choice making to severe behavior disorders and across behaviors maintained by positive and negative reinforcement.     

Decompositions and biplots in three-way correspondence analysis

In this paper correspondence analysis for three-way contingency tables is presented using three-way generalisations of the singular value decomposition. It is shown that in combination with Lancaster's (1951) additive decomposition of interactions in three-way tables, a detailed analysis is possible of the deviations from independence. Finally, biplots are shown to produce powerful graphical representations of the results from three-way correspondence analyses. An example from child development is used to illustrate the theoretical developments.     

Some uniqueness results for PARAFAC2

Whereas the unique axes properties of PARAFAC1 have been examined extensively, little is known about uniqueness properties for the PARAFAC2 model for covariance matrices. This paper is concerned with uniqueness in the rank two case of PARAFAC2. For this case, Harshman and Lundy have recently shown, subject to mild assumptions, that PARAFAC2 is unique when five (covariance) matrices are analyzed. In the present paper, this result is sharpened. PARAFAC2 is shown to be usually unique with four matrices. With three matrices it is not unique unless a certain additional assumption is introduced. If, for instance, the diagonal matrices of weights are constrained to be non-negative, three matrices are enough to have uniqueness in the rank two case of PARAFAC2. The authors are obliged to Richard Harshman for stimulating this research, and to the Associate Editor and reviewers for suggesting major improvements in the presentation.     

Expressed Emotion In The Narrative Context of Family Photographs

This study aims to elucidate cognitive and contextual aspects of the EE (Expressed Emotion) concept. The EE levels of both parents of two first admission psychotic patients were rated from the Five Minute Speech Sample (FMSS), and the emotional responses were further analyzed in narratives of family photographs. The attribution model was found to provide an explanatory framework for understanding relatives' expressed emotions (EE) toward a family member suffering from psychotic disturbances. Four case reports indicated that family photographs induced parents to create narratives in which emotions, attributions, and strategies for coping with stressful aspects of the illness came forward as intertwined phenomena. The method can offer more comprehensive data for intervention strategies aiming to alter the prevailing atmosphere and interaction patterns within the high EE family.     

ASSESSMENT AND TREATMENT OF DESTRUCTIVE BEHAVIOR MAINTAINED BY STEREOTYPIC OBJECT MANIPULATION

In the current investigation, 2 participants with mental retardation displayed property destruction and stereotypy, and both responses involved the same materials (e.g., breaking and tapping plastic objects). Three experiments were conducted (a) to indirectly assess the functions of these two responses, (b) to determine their relation to one another, and (c) to develop a treatment to reduce the more serious behavior, property destruction. In Experiment 1, previously destroyed materials were either present or absent, and their presence reduced property destruction but not stereotypy. In Experiment 2, matched toys (ones that produced sensory stimulation similar to stereotypy) were either present or absent, or were replaced by unmatched toys (for 1 participant). Matched toys produced large reductions and unmatched toys produced small reductions in property destruction and stereotypy. In Experiment 3, attempts to pick up undestroyed objects were either blocked or not blocked while matched toys were continuously available. Response blocking reduced property destruction (and attempts), prevented stereotypy, and increased manipulation of matched toys. These results suggest that the two aberrant responses formed a chain (e.g., breaking and then tapping the object), which was maintained by the sensory consequences (e.g., auditory stimulation) of the terminal response, and that previously destroyed material or matched toys made the initial response (property destruction) unnecessary.