Examining workgroup diversity effects: does playing by the (group-retention) rules help or hinder?

Group diversity researchers are often faced with the problem of calculating diversity indices for groups that are incomplete due to participant nonresponse. Because participant nonresponse may attenuate the correlations that are observed between group diversity scores and outcome variables, some researchers use group-retention rules based on within-group response rates. With this approach, only those groups that have a within-group response rate at, or higher than, the rate prescribed by the group-retention rule are retained for subsequent analyses. We conducted two sets of experiments using computer simulations to determine the usefulness of group-retention rules. We found that group-retention rules are not a substitute for a high response rate and may decrease the accuracy of observed relations, and consequently, we advise against their use in diversity research.     

Exploring how symptoms of attention-deficit/hyperactivity disorder are related to reading and mathematics performance: general genes, general environments

Children with attention-deficit/hyperactivity disorder (ADHD) tend to perform more poorly on tests of reading and mathematical performance than their typical peers. Quantitative genetic analyses allow for a better understanding of the etiology of ADHD and reading and mathematics outcomes, by examining their common and unique genetic and environmental influences. Analyses were conducted on a sample 271 pairs of 10-year-old monozygotic and dizygotic twins drawn from the Western Reserve Reading and Mathematics Project. In general, the results suggested that the associations among ADHD symptoms, reading outcomes, and math outcomes were influenced by both general genetic and general shared-environment factors. The analyses also suggested significant independent genetic effects for ADHD symptoms. The results imply that differing etiological factors underlie the relationships among ADHD and reading and mathematics performance. It appears that both genetic and common family or school environments link ADHD with academic performance.     

Parental Depression and Divorce and Adult Children’s Well-Being: The Role of Family Unpredictability

We examined how parental depression and divorce are associated with anxiety and depression among college students (N = 126; 83% female; 89% Caucasian). Participants provided retrospective recollections of their parents’ depression, and they completed The Center for Epidemiologic Studies-Depression Scale and portions of the Trait Anxiety Scale. In addition, they filled out the brief Marlow-Crowe Social Desirability Scale and the Retrospective Family Unpredictability Scale. Parental depression related to students’ depression, and aspects of family unpredictability (unpredictable money, maternal discipline, and paternal nurturance) mediated this relationship. Parental depression also related to students’ anxiety, however family unpredictability was not a strong mediator of this relationship. Finally, students reporting parental divorce did not report elevated depression or anxiety scores, although parental divorce did relate to perceptions of parental depression. We discuss implications and ideas for treatment and future research.     

Saccades compress space, time and number

It has been suggested that space, time and number are represented on a common subjective scale. Saccadic eye movements provide a fascinating test. Saccades compress the perceived magnitude of spatial separations and temporal intervals to approximately half of their true value. The question arises as to whether saccades also compress number. They do, and compression follows a very similar time course for all three attributes: it is maximal at saccadic onset and decreases to veridicality within a window of approximately 50ms. These results reinforce the suggestion of a common perceptual metric, which is probably mediated by the intraparietal cortex; they further suggest that before each saccade the common metric for all three is reset, possibly to pave the way for a fresh analysis of the post-saccadic situation.     

Essentialism in the absence of language? Evidence from rhesus monkeys (Macaca mulatta)

We explored whether rhesus monkeys (Macaca mulatta) share one important feature of human essentialist reasoning: the capacity to track category membership across radical featural transformations. Specifically, we examined whether monkeys – like children ( Keil, 1989 ) – expect a transformed object to have the internal properties of its original category. In two experiments, monkeys watched as an experimenter visually transformed a familiar fruit (e.g. apple) into a new kind of fruit (e.g. coconut) either by placing a fruit exterior over the original, or by removing an exterior shell and revealing the inside kind of fruit. The experimenter then pretended to place an inside piece of the transformed fruit into a box which the monkey was allowed to search. Results indicated that monkeys searched the box longer when they found a piece of fruit inconsistent with the inside kind, suggesting that the monkeys expected that the inside of the transformed fruit would taste like the innermost kind they saw. These results suggest that monkeys may share at least one aspect of psychological essentialism: They maintain category‐specific expectations about an object’s internal properties even when that object’s external properties change. These results therefore suggest that some essentialist expectations may emerge in the absence of language, and thus raise the possibility that such tendencies may emerge earlier in human development than has previously been considered.     

Danger ideation reduction therapy for obsessive-compulsive checking: preliminary findings

Danger Ideation Reduction Therapy (DIRT) is a cognitive treatment package developed in the mid-1990s to treat obsessive-compulsive (OC) washing. DIRT is solely directed at decreasing threat expectancies and does not involve direct or indirect exposure. The effectiveness of the DIRT package for OC washers has been examined, and to date a number of publications, including two randomised controlled trials, support its efficacy. Recently, the DIRT package was modified to treat people with the OC checking subtype. In the current study, three adult OC checkers received DIRT in 12 to 14 individual 1-hr sessions conducted by a clinical psychologist. At posttreatment, substantial and clinically significant reductions in scores on a range of standardized outcome measures of obsessive-compulsive disorder symptom severity were apparent for all three participants. Crucially, these improvements were maintained at 4-month follow-up. Although further research is clearly warranted, these preliminary findings suggest that DIRT for checkers may prove as effective as DIRT for OC washers.     

Estimating confidence intervals for eigenvalues in exploratory factor analysis

Exploratory factor analysis (EFA) has become a common procedure in educational and psychological research. In the course of performing an EFA, researchers often base the decision of how many factors to retain on the eigenvalues for the factors. However, many researchers do not realize that eigenvalues, like all sample statistics, are subject to sampling error, which means that confidence intervals (CIs) can be estimated for each eigenvalue. In the present article, we demonstrate two methods of estimating CIs for eigenvalues: one based on the mathematical properties of the central limit theorem, and the other based on bootstrapping. References to appropriate SAS and SPSS syntax are included. Supplemental materials for this article may be downloaded from http://brm.psychonomic-journals.org/content/supplemental.     

On the common stimulus condition and explanation of the Müller‐Lyer,Poggendorff and Zöllner illusions: The basis for a class of geometrical illusions

Although the Müller‐Lyer, Poggendorff and Zöllner figures and the illusions with which they are associated– those of length, misalignment and non‐parallelism, respectively – are quite different, all three are attributable to the same basic effect, that of the difference in the apparent length of equal lines forming acute and obtuse angles. The role of this basic affect, reported originally by Müller‐Lyer but overlooked by him and others as a possible cause of the three illusions, is identified and discussed. It is suggested that the demonstration of a basic stimulus condition (acute and obtuse angles) and its associated illusion (difference in apparent length) generating a class of “higher order” geometric illusions has implications not only for a closer understanding of the three illusions under consideration but for other classes of illusory phenomena that might also share a common basis.     

The Irreducibility of Personal Obligation

It is argued that claims about personal obligation (of the form “s ought to ϕ”) cannot be reduced to claims about impersonal obligation (of the form “it ought to be the case that p”). The most common attempts at such a reduction are shown to have unacceptable implications in cases involving a plurality of agents. It is then argued that similar problems will face any attempt to reduce personal obligation to impersonal obligation.