Family and psychosocial predictors of obsessive compulsive disorder in a community sample of young adolescents

A two-stage epidemiologic study conducted between 1986 and 1988 in the southeastern United States investigated family and psychosocial predictors of obsessive compulsive disorder (OCD) and subclinical OCD in young adolescents. In the first stage, a life-event schedule and a family adaptability and cohesion scale were administered to a community sample of 3,283 adolescents. In stage two, the Schedule for Affective Disorders and Schizophrenia in School Age Children and the Children's Global Assessment Scale were administered to 488 mother-child pairs. In multivariable models family cohesion was the only significant correlate of OCD (odds ratio=0.95, 95% confidence interval 0.91–0.98). Gender, race, age, socioeconomic status, guardian status, adaptability, undesirable life events and desirable life events were not found to be significant predictors of OCD in models adjusting for cohesion. Note of the above variables were significantly associated with subclinical OCD. However, separate analyses of the 41 individual life events indicated seven specific events were significantly associated with OCD or subclinical OCD. These findings are at odds with the theory that overinvolvement of family members is a risk factor for OCD, though an association with overly rigid family structure cannot be eliminated based on these data. Further exploration of family characteristics is warranted.     

Undesirable life-events and depression in young adolescents

We compared the relationship between individual undesirable life-events and comprehensive life-event factors, as well as major depression in adolescents. Students in four public suburban middle schools were screened for depressive symptomatology and life-events by a self-administered questionnaire. Seven of 21 individual events (parents' divorce, parental job loss, problems between parents, problems between the adolescent and his/her parents, failing a grade in school, school suspension, death of a close friend) and three of six life-event factors (conflict/disappointment, marital discord, maladjustment) were significantly related to depression in univariate models. A multivariate examination of the individual events was difficult to interpret, but examination of the event factors found maladjustment and conflict/disappointment significant. Analyses using the undesirable life-event factors provided a clearer picture of the relationships investigated by grouping related events into a more manageable number of independent categories. Specific combinations of life-events suggest stronger associations with adolescent depression than others. Clinicians may identify youths at risk for depression when specific combinations of undesirable life-events occur.     

Conditional probability judgments: Effects of imagining vs experiencing the conditioning event

Applications of Bayesian conditionalization often involve two temporal aspects: a probability judgment is based on knowledge at a point in time and is revised over time in light of added information. Let t, t′, and t″ designate three chronological points in time. E designates a target event which occurs or not at t″, and C designates a conditioning event which occurs or not at t′. Suppose that an individual judges P(EC) at t. If C occurs, Bayesian conditionalization requires that a judgment of P(E) at t′ is equal to the earlier judgment of P(EC). However, inconsistencies may result because a judgment of P(EC) at t is based on imagining C, while a judgment of P(E) at t′ is based on experiencing C. This study examines two sources of such inconsistencies. First, C normally is an abstraction of what might happen between t and t′. What actually happens may differ, such that an individual observes extraconditional information which affects a judgment of P(E) at t′. Second, experiencing C may change an individual's affective state, leading to greater optimism or pessimism about the occurrence of E. We report an experiment which documents both effects.     

The operant control of vocalization in the dog

Control over the vocal responses of three dogs was established using operant-conditioning procedures. Several points of interest were observed in the data. First, fixed-ratio schedules of reinforcement generated a vocal response topography which was similar in detail to that of a “motor” bar-nosing response. Second, vocal responding was brought under the control of external visual stimuli as a result of differential reinforcement. Third, good stimulus control was maintained on a multiple schedule containing a vocal-response component and a bar-response component. Fourth, the stimulus control on the multiple schedule transferred with minimal disruption to a chain schedule requiring a sequence of 10 bar responses followed by 10 vocal responses. Fifth, because vocal and bar responses are not mutually exclusive, concurrent responding tended to develop on the chain schedule.

These results were discussed with reference to the advisability of applying the terms operant and respondent to unconditioned behavior, and, particularly, to unconditioned verbal behavior.

     

Handwriting as an operant

An apparatus was designed to monitor handwriting behavior. Two subjects were studied under various schedules of monetary reinforcement for handwriting. The different schedules engendered and maintained distinctive response patterns but the rates of sustained responding did not vary across schedules. The development of fixed-interval performance following continuous reinforcement resembled the same transition in lower animals. In one subject, availability of reading material interacted with the schedule to determine response pattern. It was suggested that handwriting may be a more appropriate response for the experimental analysis of human behavior than the more frequently used button-pushing or lever-pulling responses.     

Individual differences in spatial learning from computer-simulated environments

A multivariate study examined relationships between the following factors: paper-and-pencil assessments of verbal and spatial ability, ability to form an accurate spatial representation of a large real-world environment, gender, computer attitudes and experience, proficiency with the navigational interface of a virtual environment (VE), and the ability to acquire and transfer spatial knowledge from a VE. Psychometrically assessed spatial ability and proficiency with the navigational interface were found to make substantial contributions to individual differences in the ability to acquire spatial information from a VE. Gender influenced many VE-related tasks, primarily through its relationship with interface proficiency and spatial ability. Measures of spatial knowledge of a VE maze were highly predictive of subsequent performance in a similar real-world maze, suggesting that VEs can be useful for training people about real-world spaces.     

Fungible Correlation Matrices: A Method for Generating Nonsingular,Singular, and Improper Correlation Matrices for Monte Carlo Research

For a fixed set of standardized regression coefficients and a fixed coefficient of determination (R-squared), an infinite number of predictor correlation matrices will satisfy the implied quadratic form. I call such matrices fungible correlation matrices. In this article, I describe an algorithm for generating positive definite (PD), positive semidefinite (PSD), or indefinite (ID) fungible correlation matrices that have a random or fixed smallest eigenvalue. The underlying equations of this algorithm are reviewed from both algebraic and geometric perspectives. Two simulation studies illustrate that fungible correlation matrices can be profitably used in Monte Carlo research. The first study uses PD fungible correlation matrices to compare penalized regression algorithms. The second study uses ID fungible correlation matrices to compare matrix-smoothing algorithms. R code for generating fungible correlation matrices is presented in the supplemental materials.