Modeling individual differences in working memory performance: a source activation account

Working memory resources are needed for processing and maintenance of information during cognitive tasks. Many models have been developed to capture the effects of limited working memory resources on performance. However, most of these models do not account for the finding that different individuals show different sensitivities to working memory demands, and none of the models predicts individual subjects' patterns of performance. We propose a computational model that accounts for differences in working memory capacity in terms of a quantity called source activation , which is used to maintain goal-relevant information in an available state. We apply this model to capture the working memory effects of individual subjects at a fine level of detail across two experiments. This, we argue, strengthens the interpretation of source activation as working memory capacity.     

Intraindividual variability in perceived locus of control in adults: P-technique factor analyses of short-term change

Multivariate correlational methods such as P-technique factor analysis provide a way to structure intraindividual change by identifying dimensions of covariation in intensive longitudinal measurements. For example, for 20 years or more researchers have acknowledged that some major personality constructs such as anxiety exhibit both trait (relatively stable, interindividual) and state (intraindividual) variability. However, the consideration that state variability might be quite general and can “intrude” in the measurement of putatively more stable attributes has not generally entered into construct validation work and other manifestations of theoretical development. Locus of control, as with many personality constructs, is considered to be a dimension of relatively stable interindividual differences. Levenson's three-dimensional locus of control scale was adapted for use in a measurement-intensive P-technique study involving 10 participants (5 mothers and fathers who were expecting their first child) to examine the extent to which responses manifested systematic liability. The data indicated that perceived locus of control exhibits coherent, day-to-day variability; especially the dimensions identified as internality and powerful others. Such state variation manifestations are discussed in relation to their important implications for measurement, long-term prediction, and theorizing about the nature of personality.     

Models and Personality Traits in Occupational Psychological Testing

From a study of methods of test construction – criterion-keying, item analytic, factor analytic and using item characteristic curves – it is shown that, in the sphere of personality tests, only factor analytic methods can ensure univariate measures. A further scrutiny of factor analytic methodology reveals various technical defects which have created a chaos of different findings and factors in personality inventories. It is finally demonstrated that rotation to simple structure yields reliable and replicable factors and that when this is done, four or five factors account for most of the variance in personality inventories. It is concluded that in occupational testing only tests measuring these factors, or primary factors clearly related to them, should be used.     

Methodological considerations in the evaluation of the convergence of psychiatric diagnoses and parent-informant checklists

Psychiatric diagnoses and objective parent checklists are alternative ways to describe child adjustment problems. There has recently been interest in evaluating the degree of agreement or convergence between these sources of information. This paper addresses three issues neglected by researchers in this area. The appropriateness of the use of indices of sensitivity and specificity to describe the correspondence of diagnoses and checklist scores is questioned. Implications of failure to consider the reliability of diagnoses in interpreting diagnosis-checklist agreement are discussed. Also, possible parameters of diagnosis-checklist agreement that should be identified by researchers are reviewed. Suggestions for improving research in this area are offered.     

Age differences in target identification as a function of retinal location and noise level: examination of the useful field of view

Foveal and peripheral target detection were compared in young adults (M age = 22 years) and older adults (M age = 66 years) who were optically corrected for the viewing distance. In a two-alternative, forced-choice task, target letters were presented at 0 degree to 10.5 degrees from fixation. Targets were presented alone, flanked on each side by one noise element (i.e., nontarget letter), or embedded in a horizontal row of 19 noise elements. An Age X Noise Level X Location interaction was obtained, wherein age differences were largest for peripheral targets presented in noise. Slope analyses of latency data showed that the performance of young adults in the high-noise condition was most similar to that of older adults in the low-noise condition. At the functional level, results indicated that aging is associated with a restricted useful field of view. In addition, the data suggest that age differences in search can be described by a model in which older adults take smaller perceptual samples from the visual scene and scan these samples more slowly than do the young adults.