A new computational method to fit the weighted euclidean distance model

This paper describes a computational method for weighted euclidean distance scaling which combines aspects of an analytic solution with an approach using loss functions. We justify this new method by giving a simplified treatment of the algebraic properties of a transformed version of the weighted distance model. The new algorithm is much faster than INDSCAL yet less arbitrary than other analytic procedures. The procedure, which we call SUMSCAL (subjectivemetricscaling), gives essentially the same solutions as INDSCAL for two moderate-size data sets tested.Comments by J. Douglas Carroll and J. B. Kruskal have been very helpful in preparing this paper.     

On various causes of improper solutions in maximum likelihood factor analysis

In the applications of maximum likelihood factor analysis the occurrence of boundary minima instead of proper minima is no exception at all. In the past the causes of such improper solutions could not be detected. This was impossible because the matrices containing the parameters of the factor analysis model were kept positive definite. By dropping these constraints, it becomes possible to distinguish between the different causes of improper solutions. In this paper some of the most important causes are discussed and illustrated by means of artificial and empirical data.The author is indebted to H. J. Prins for stimulating and encouraging discussions.     

Treatment of obsessive-compulsive patients: The contribution of self-instructional training to the effectiveness of exposure

Fifteen obsessive-compulsive patients were given treatment consisting of ten sessions of gradual exposure in vivo. For half of the patients gradual exposure in vivo was preceded by self-instructional training.Treatment resulted in significant improvement on anxiety and avoidance scales, Leyton Obsessional Inventory, Self-rating Depression Scale and on ratings for anxious mood and depression. Neither the post-test nor the follow-ups 1 month and 6 months later indicated a difference between the effects of the two conditions. Self-instructional training did not enhance the effectiveness of gradual exposure in vivo.     

THE SKILL OF PICTORIAL PERCEPTION: AN INTERPRETATION OF CROSS-CULTURAL EVIDENCE*

A theoretical framework is proposed for understanding perceptual skills in their functional context. Pictorial perception is construed as a functionally specialised skill whose pervasive importance in modern education derives from the proliferation of pictorial materials in Western culture. Drawing on cross-cultural research, the major components of the skill are identified as (1) detection of appropriate contexts for its application, (2) selection of a limiting frame of reference, (3) use of conventional criteria of fidelity to recognise depicted items, (4) sensitivity to impoverished depth cues, (5) an expectation of finding in the picture most of the information necessary for its disambiguation, and (6) various assumptions about the range of cognitive inferences that may legitimately be made ‘beyond the information given’. Training studies are interpreted as suggesting that the skill can be enhanced through guided experience.     

TEACHING THE HANDICAPPED TO EAT IN PUBLIC PLACES: ACQUISITION,GENERALIZATION AND MAINTENANCE OF RESTAURANT SKILLS

This study examined classroom-based instruction in restauranting skills for handicapped persons. Three male students were taught each of four skill components in sequential order: locating, ordering, paying, and eating and exiting. Training was implemented in a multiple baseline design across subjects and consisted of modeling and role playing in conjunction with photo slide sequences and a simulated ordering counter. The use of a menu containing general item classes and a finger matching procedure for identifying errors in the delivery of change greatly reduced the reading and math skills necessary to enter and complete the program. Periodic probes were conducted in a McDonald's restaurant prior to, during, and up to one-year following the termination of training. In addition, two probes (overt and covert observation) were conducted in a Burger King restaurant to assess further generalization to a location different from the one depicted throughout training. Results showed that students' performance on restaurant probes improved as a result of training, generalized to novel settings, maintained over an extended period of time, and was comparable to that of a normative sample of nonretarded persons.     

Foveal diplopia thresholds and fixation disparities

Comparison of the magnitude and intrinsic spread of foveal diplopia thresholds with the accuracy of ocular alignment as determined with a subjective alignment method shows that: the accuracy of alignment in the vertical direction (within 1–2 min) is remarkably good and much better than in the horizontal direction; the largest disparities occurring due to restricted alignment accuracy are usually substantially smaller than the foveal diplopia thresholds; interindividual variability in the magnitude of foveal diplopia thresholds is not due only to interindividual variability in the alignment accuracy; and the spread of foveal diplopia thresholds exceeds the spread of ocular alignment, which implies that the noise in the foveal disparity domain is not only due to the restricted alignment accuracy but also to sensory processes. Finally, the data confirm that, unlike the case with diplopia thresholds, the spread of stereoscopic thresholds is not affected by the restricted alignment accuracy.     

The linear utility model for optimal selection

A linear utility model is introduced for optimal selection when several subpopulations of applicants are to be distinguished. Using this model, procedures are described for obtaining optimal cutting scores in subpopulations in quota-free as well as quota-restricted selection situations. The cutting scores are optimal in the sense that they maximize the overall expected utility of the selection process. The procedures are demonstrated with empirical data.     

Attitude extremity,consensus and diagnosticity

Studied the effects of attitude extremity on perceived consensus and willingness to ascribe trait terms to others with either pro or anti nuclear attitudes. Results showed that attitude extremity affected consensus estimates. Trait attributions revealed a clear effect for valence, especially for the extreme attitude groups. Subjects with extreme attitudes also ascribed more traits to both pro and anti others than subjects with relatively moderate attitudes.