The effect of additional variables on factor indeterminacy in models with a single common factor

Determinate solutions for the indeterminate common factor ofp variables satisfying the single common factor model are not unique. Therefore an infinite sequence of additional variables that conform jointly with the originalp variables to the original single common factor model does not determine a unique solution for the indeterminate factor of thep variables (although the solution is unique for the factor of the infinite sequence). Other infinite sequences may be found to determine different solutions for the factor of the originalp variables. The paper discusses a number of theorems about the effects of additional variables on factor indeterminacy in a model with a single common factor and draws conclusions from them for factor theory in general.     

Constrained least squares estimators of oblique common factors

An expression is given for weighted least squares estimators of oblique common factors, constrained to have the same covariance matrix as the factors they estimate. It is shown that if as in exploratory factor analysis, the common factors are obtained by oblique transformation from the Lawley-Rao basis, the constrained estimators are given by the same transformation. Finally a proof of uniqueness is given.The research reported in this paper was partly supported by Natural Sciences and Engineering Research Council Grant No. A6346.     

A note on the investigation of local and global identifiability

In general, nonlinear models such as those commonly employed for the analysis of covariance structures, are not globally identifiable. Any investigation of local identifiability must either yield a mapping of identifiability onto the entire parameter space, which will rarely be feasible in any applications of interest, or confine itself to the neighbourhood of such points of special interest as the maximum likelihood point.The author would like to thank J. Jack McArdle and Colin Fraser for their comments on this paper.     

The corroboration time measure: An implicit confidence judgement

The corroboration time technique is introduced as a means of eliciting covert confidence judgements. A validation experiment is reported in which three measures based upon the corroboration time are compared with overt confidence judgements. It is concluded that the technique yields a valid, sensitive measure of confidence which is as sensitive as an overt confidence judgement to variations in the independent variable, and which is less intrusive in use. It may be used whenever there is a unique correct response which can given as feedback for corroboration.     

Assessment of mothers' concerns about infants,toddlers, and preschoolers

Only recently has determining the child-rearing concerns of parents been considered an important research objective. Existing efforts have, for the most part, either employed small sample sizes or surveyed parents already in the process of seeking help or advice. It was, therefore, felt that additional, more representative data were needed. In the present study, 583 mothers with children aged 59 months or younger were surveyed regarding their concerns about their children's development. On the „Specific Needs Assessment Report”︁ (SNAR) (copyright © 1975, by Karl F. Riem, J. Jeffrey Crisco, and Kathy Willms), mothers rated their concerns for 60 developmental-behavioral items about their children's health, attending skills, problem behaviors, communication skills, motor skills, cognitive skills, self-help skills, and social skills. Mothers were most frequently concerned to a moderate or major degree about at least one item of the problem behavior category. For this category, parent-child management, crying-whining, and temper tantrums were the individual items of greatest concern. Mothers of girls more frequently indicated health concerns than mothers of boys. These results support those of previous investigations, which suggested the need for parent education programs to help parents manage their children.     

On not "giving psychology away": the Minnesota Multiphasic Personality Inventory and public controversy over testing in the 1960s

Psychological tests, especially the Minnesota Multiphasic Personality Inventory, became the center of public controversy and Congressional scrutiny during the 1960s. This unwanted attention actually helped American psychologists more than they imagined. Assisted by those on Capital Hill, psychologists were able to defend their science in a manner that avoided imposed forms of public accountability. Social questions were reformulated as technical problems. The need to adjust intelligence and aptitude tests reinforced psychologists' control over them. Conversely, personality tests were not made more transparent and nonintrusive, unless psychologists thought these changes were scientifically necessary. This episode prompted tighter regulation of test use and demonstrated that traditional forms of testing were far too important to popularize and "give away".     

Dyslexic students have more everyday cognitive lapses

There is a dearth of information about the everyday performance difficulties of adult dyslexic people. This study investigates the empirical support for anecdotal reports of increased vulnerability to distraction in dyslexia, using the self-report Cognitive Failures Questionnaire (CFQ). Two groups of university students, a dyslexic group and a non-dyslexic control group, were asked to complete the CFQ. The dyslexic group reported a higher frequency of everyday lapses in cognition, scoring significantly higher on a number of CFQ items. Representative problems include distractibility, over-focusing (so that relevant peripheral information is missed), and word-finding difficulties. A similar measure administered to close friends of dyslexic people, the CFQ-for-others, yielded results consistent with those of the CFQ, with major findings being that their friends considered them to be more disorganised, more distractible, and more absent-minded than normal. The results indicate clearly the continuing effects of dyslexia on cognition in adulthood and demonstrate that dyslexic impairments are not limited to "artificial" laboratory tasks or even literacy tasks but, instead, pervade everyday life.     

Performance of Dyslexic Children on Cerebellar and Cognitive Tests

In a previous study (A. J. Fawcett, R. I. Nicolson, & P. Dean, 1996), the authors had found strong behavioral evidence for cerebellar deficit in a panel of children with dyslexia. In the present study, the generality of those results was assessed. A battery of clinical tests for cerebellar dysfunction was administered, together with selected cognitive tests, to a further 59 dyslexic and 67 control children. The dyslexic children showed highly significant impairments on the cerebellar tests, with deficits on postural stability and muscle tone comparable in magnitude with their reading and spelling deficits. Furthermore, over 95&percent; of the dyslexic children showed clear evidence of deficit on muscle tone or stability. The findings provide further evidence of the generality of cerebellar impairment in dyslexia. The implications of the cerebellar tests for screening in dyslexia are discussed.