MULTIDIMENSIONAL SCALING WITH A PRIORI DIMENSIONS

W aern Y. Multidimensional scaling with a priori dimensions. Scand. J. Psychol., 1972, 13 , 178–189.—This paper presents a method of multidimensional scaling by direct similarity estimates. The method is presented as an alternative to other multidimensional scaling methods, when hypotheses can be made concerning the dimensions underlying the perceptual variation. The method is used with five different sets of stimuli and compared, to an as to dimensions assumption-free component analysis, based on a vector model. The two methods resulted in similar configurations in most cases. One difference was found in a colour material, where the assumed dimensions could be regarded not to be orthogonal to each other. Here the a priori scaling revealed the assumed configuration as projected on the oblique axes whereas the component analysis could not give this information.     

STRUCTURE IN SIMILARITY MATRICES

Waern, Y. Structure in similarity matrices. A graphic approach. Scand. J. Psychol ., 1972, 13 , 5–16.—The present paper proposes a simple method for representing the structure inherent in the similarity matrix, i.e. a graphic representation. The traditional multidimensional scaling methods are compared with each other and with the graphic representation with regard to representation, interpretation and assumptions concerning the subject's performance. The graph gives a topological representation and the derivation of the graph from the similarity matrix may be made so as to reduce the demands on the subjects somewhat. As to interpretation, the graph is able to reveal dimensions, clusters, and hierarchies. Compared with some multidimensional scaling it gives very similar interpretations.     

Suicides among family members of elderly suicide victims: an exploratory study

This exploratory study compares elderly suicides with (n=13) and without (n=72) family member suicide. Previous episodes of suicidal behavior were more common among suicides who lost first-degree relatives by suicide (100% vs. 65%, p = .009). Six persons had lost an offspring by suicide prior to their own deaths. Substance use disorder was more prevalent among those with offspring suicide than those without (100% vs. 25%, p = .000). While informants reported that offspring suicides played a central role in the suicide of the elderly study case, sibbling suicides were not considered precipitating factors.     

What makes a task difficult?

Summary This study explores the relationship between different task requirements and children's task performance and ratings of task difficulty. Four hundred and sixty five children (9 to 13 years old) read texts and answered questions, involving well-defined or ill-defined goals and requiring different thought operations. It was found that rated difficulty and performance were highly related for questions involving a well-defined goal. A simple modus ponens inference was easiest, checking most difficult, and recall of the text ranked in the middle. A question, involving an ill-defined goal was rated to be most difficult, whereas performance was quite high. The results confirm the assumptions that judgment of difficulty relies on two sources of information: 1) perception of goal, and 2) perception of processing effort.