Evaluation of a “mental effort” hypothesis for correlations between cortical metabolism and intelligence

Previous research indicates that low scores on the Raven's Advanced Progressive Matrices (RAPM) test are associated with increased cortical glucose utilization during problem solving. We hypothesized that previous results may reflect the neurophysiological consequences of patterns of effort requirements; that is, high-effort expenditure from lower aptitude participants (for whom the problems are hard) and low-effort expenditure from higher aptitude participants (for whom the problems are easy). In this experiment, positron emission tomography (PET) data were gathered on participants (N = 28) who solved easy and hard problems that were tailored to the participants' own ability levels, thereby eliminating aptitude group differences in effort requirements. Contrary to previous results, high aptitude was associated with high cortical glucose use. Average aptitude participants showed diminished glucose use in the hard condition. A significant Group X Condition X Hemisphere Effect was also noted, with greater right hemisphere activation in the hard condition for the high-aptitude group. These results demonstrate that the relation of cerebral glucose use and cognitive ability is sensitive to participant and task selection.     

Dimensional and metric structures in multidimensional stimuli

The present experiments investigated two characteristics of subjects’ multidimensional representations: their dimensional organization and metric structure, for both analyzable and integral stimuli. In Experiment 1, subjects judged the dissimilarity between all pairs of stimuli differing in brightness and size (analyzable stimuli), while in Experiment 2, subjects made dissimilarity judgments for stimuli varying in width height, and area shape (integral stimuli). For the brightness size stimuli, the findings that (a) brightness judgments were independent of size (and vice versa) and (b) the best fitting scaling solution was one that depicted an orthogonal structure are strong evidence that subjects perceived brightness size as a dimensionally organized structure. In contrast, for the rectangle stimuli, neither width height nor area shape contributed additively to overall dissimilarity. The results of the metric fitting were more equivocal. For all stimulus sets, the Euclidean metric yielded scaling solutions with lower stress values than the city block metric. When bidimensional ratings were regressed on unidimensional ratings, the city block metric yielded a slightly higher correlation coefficient than the Euclidean metric for brightness size stimuli. The two rules of combination were equivalent for the width-height stimuli, but the Euclidean metric provided a better approximation for the area shape stimuli. The results were discussed in terms of how subjects integrate physical dimensions for the case of integral stimuli and the superiority of dimensional vs. metric structure as an indicator of stimulus analyzability.     

Color categories and color appearance

We examined categorical effects in color appearance in two tasks, which in part differed in the extent to which color naming was explicitly required for the response. In one, we measured the effects of color differences on perceptual grouping for hues that spanned the blue-green boundary, to test whether chromatic differences across the boundary were perceptually exaggerated. This task did not require overt judgments of the perceived colors, and the tendency to group showed only a weak and inconsistent categorical bias. In a second case, we analyzed results from two prior studies of hue scaling of chromatic stimuli (De Valois, De Valois, Switkes, & Mahon, 1997; Malkoc, Kay, & Webster, 2005), to test whether color appearance changed more rapidly around the blue-green boundary. In this task observers directly judge the perceived color of the stimuli and these judgments tended to show much stronger categorical effects. The differences between these tasks could arise either because different signals mediate color grouping and color appearance, or because linguistic categories might differentially intrude on the response to color and/or on the perception of color. Our results suggest that the interaction between language and color processing may be highly dependent on the specific task and cognitive demands and strategies of the observer, and also highlight pronounced individual differences in the tendency to exhibit categorical responses.     

Liability,culpability, and luck

Philosophical Studies - This paper focuses on the role of culpability in determining the degree of liability to defensive harm, and asks whether there are any restrictions on when culpability is...     

The effect of corpus size in predicting reaction time in a basic word recognition task: Moving on from Kučera and Francis

Word frequency is one of the strongest determiners of reaction time (RT) in word recognition tasks; it is an important theoretical and methodological variable. The Ku?era and Francis (1967) word frequency count (derived from the 1-million-word Brown corpus) is used by most investigators concerned with the issue of word frequency. Word frequency estimates from the Brown corpus were compared with those from a 131-million-word corpus (the HAL corpus; conversational text gathered from Usenet) in a standard word naming task with 32 subjects. RT was predicted equally well by both corpora for high-frequency words, but the larger corpus provided better predictors for low- and medium-frequency words. Furthermore, the larger corpus provides estimates for 97,261 lexical items; the smaller corpus, for 50,406 items.     

Fabry disease in genetic counseling practice: recommendations of the National Society of Genetic Counselors

The objective of this document is to provide health care professionals with recommendations for genetic counseling and testing of individuals with a suspected or confirmed diagnosis of Fabry disease, with a family history of Fabry disease, and those identified as female carriers of Fabry disease. These recommendations are the opinions of a multicenter working group of genetic counselors, medical geneticists, and other health professionals with expertise in Fabry disease counseling, as well as an individual with Fabry disease who is a founder of a Fabry disease patient advocacy group in the United States. The recommendations are U.S. Preventive Task Force Class III, and they are based on clinical experience, a review of pertinent English-language articles, and reports of expert committees. This document reviews the genetics of Fabry disease, the indications for genetic testing and interpretation of results, psychosocial considerations, and references for professional and patient resources. These recommendations should not be construed as dictating an exclusive course of management, nor does use of such recommendations guarantee a particular outcome. The professional judgment of a healthcare provider, familiar with the facts and circumstances of a specific case, will always supersede these recommendations.     

Psychometric Study of the Child and Adolescent Functional Assessment Scale: Prediction of Contact with the Law and Poor School Attendance

The predictive validity of the Child and Adolescent Functional Assessment Scale (CAFAS) is investigated using the data set generated by the national evaluation of the demonstration service grants funded by the Center for Mental Health Services. Logistic regressions were performed separately for contact with the law and poor school attendance, which were both assessed at 6 months postintake. Other variables included in the model besides the CAFAS total score at intake were age, gender, and family risk factors. The results show that the CAFAS total score at intake was a positive predictor of the likelihood of contact with the law and poor school attendance, even after controlling for age, gender, and risk factors. Furthermore, the CAFAS total score was predictive even after excluding scores on CAFAS subscales, which may have been influenced by absenteeism or delinquency. These findings are consistent with recent research indicating that the CAFAS predicts recidivism in juvenile delinquents.This research was conducted while the author was a Research Associate at the Population Studies Center, University of Michigan, Ann Arbor, MI