Stimulus-independent thought depends on central executive resources

Stimulus-independent thoughts (SITs) are streams of thoughts and images unrelated to immediate sensory input. Four experiments examined the contribution of aspects of working memory to production of SITs. In Experiments 1 and 2, interventions that were targeted on, respectively, phonological and visuospatial components of working memory both interfered with production of SITs, but there was evidence that these tasks also made demands on central executive resources. Experiments 3 and 4 specifically examined the hypothesis that production of SITs and control of nonproceduralized tasks both depend on central executive resources, and so should show mutual interference. In Experiment 3, prior practice on pursuit rotor and memory tasks reduced the interference with SITs from concurrent task performance. In Experiment 4, randomness within a task involving random-number generation was less when SITs were being produced concurrently than it was when they were not. The results suggest that production of SITs depends on central executive resources.     

The Diagnostic Interview Schedule for Children (PC-DISC v.3.0): Parents and Adolescents Suggest Reasons for Expecting Discrepant Answers

To identify reasons for discrepancies between parent and child reports of child/adolescents's psychiatric symptoms, parents and adolescents (51 pairs) were asked to guess what the other would answer to questions from the PC-DISC about the adolescent's psychiatric symptoms, and to explain why they expected disagreement when the answer they provided for the other was different from their own. Adolescents' explanations for expecting (1) parental denial of symptoms the adolescent reported were: the parent was unaware of, forgot about, assumed the adolescent could not have, or trivialized the symptom; and (2) parental report of symptoms the adolescent denied were: the parent misread or exaggerated the adolescent's symptom, had too high expectations for the adolescent's behavior, put a negative label on or did not trust the adolescent. Parents' reasons for expecting their children to (1) deny symptoms the parents reported were: the adolescent did not remember how s/he felt, lied, did not recognize or minimized the importance or frequency of the symptom; and (2) report symptoms the parents denied were: the adolescent lied, exaggerated the importance of or interpreted the symptom differently.Support for this work was provided by National Institute of Drug Abuse grant number DA-05585 (Dr. Cottler, P.I.), and National Institute of Mental Health grants numbers MH-31302 (Dr. R. C. Cloninger, P.I.) and MH-17104 (Dr. Cottler, P.I.).Address all correspondence, including reprint requests, to Michelle Bidaut-Russell, Ph.D, MPH, MPE, Department of Psychiatry, Box 8134, Washington University School of Medicine, 4940 Children's Place, St. Louis, Missouri 63110.     

The relationship between locus of control and long-term stuttering treatment outcome in adult stutterers

The present study was designed to investigate the extent to which adult stutterers' scores on the Locus of Control of Behaviour (LCB) scale are predictive of their ability to maintain speech fluency immediately following intensive treatment and approximately 2 years later. Twenty-one subjects participated in a 3-week intensive treatment program based on the Precision Fluency Shaping Program. Thirteen subjects could be contacted again 2 years later to participate in a follow-up evaluation. While most subjects showed a significant long-term improvement in fluency, no predictive relationship was found between scores on the LCB scale and the level of fluency, measured in percentage of words stuttered, post-treatment or at follow-up. However, LCB scores were found to be predictive of the subjects' fluency self-evaluation measured post-treatment and at follow-up. Overall, the present study suggests that while the LCB scale may contribute to the prediction of long-term treatment outcome, particularly as perceived by the client, other client and process variables will need to be considered as well.     

Perceptual scaling of synthesized musical timbres: Common dimensions,specificities, and latent subject classes

To study the perceptual structure of musical timbre and the effects of musical training, timbral dissimilarities of synthesized instrument sounds were rated by professional musicians, amateur musicians, and nonmusicians. The data were analyzed with an extended version of the multidimensional scaling algorithm CLASCAL (Winsberg & De Soete, 1993), which estimates the number of latent classes of subjects, the coordinates of each timbre on common Euclidean dimensions, a specificity value of unique attributes for each timbre, and a separate weight for each latent class on each of the common dimensions and the set of specificities. Five latent classes were found for a three-dimensional spatial model with specificities. Common dimensions were quantified psychophysically in terms of log-rise time, spectral centroid, and degree of spectral variation. The results further suggest that musical timbres possess specific attributes not accounted for by these shared perceptual dimensions. Weight patterns indicate that perceptual salience of dimensions and specificities varied across classes. A comparison of class structure with biographical factors associated with degree of musical training and activity was not clearly related to the class structure, though musicians gave more precise and coherent judgments than did nonmusicians or amateurs. The model with latent classes and specificities gave a better fit to the data and made the acoustic correlates of the common dimensions more interpretable.     

The numbers game: Gender and attention to numerical information

Research suggests that males outperform females on standardized tests of math ability from early adolescence onward. Several explanations for this difference focus on the different experiences of females and males with numerical information. We reasoned that males have more experience with numerical information than females because typical male interests (e.g., sports) are more likely to involve numerical information than typical female interests (e.g., physical appearance). Thus, we predicted that males would attend more to numerical information than would females, at least when the information was presented in a male-related or gender-neutral context. Females were expected to attend more than males when the context was female-related. Results using White/Caucasian subjects provided some support for these predictions. Implications for future research on the relationship between the gender-linkage of math materials and gender differences in math performance are discussed.     

An investigation of the effects of comorbid Axis II pathology on outcome of inpatient treatment for unipolar depression

DSM-based research on comorbidity has suggested thatdepression andpersonality disorder frequently occur together and that the combination of syndromes is associated with a poor response to treatment for depression. The present study was designed to explore the effect of comorbid Axis II pathology for a sample of 45 inpatients who received treatment for major depression. Both categorical and dimensional ratings of personality disorder were used in the statistical analysis. Positive categorical diagnosis of Cluster C (anxious-avoidant) disorder, as well as higher dimensional rating of Cluster A (odd-eccentric) pathology, was predictive of a poor response to treatment (p<.05), as measured by change in pre-post clinical ratings on the Montgomery-Asberg Depression Rating Scale. These results were construed as indicative of a significant Axis II comorbidity effect in the context of an inpatient, multimodal treatment setting for depression. The results also spotlight the influence of techniques of measurement in determining the outcome of statistical analysis.     

An investigation of the relationship between self-efficacy and the communication effectiveness of product manual formats

Product manuals have been virtually ignored in published research despite their relevance to consumer satisfaction and marketplace safety. This study examines self-efficacy (perceptions of capabilities related to operating a product) and how it influences the effectiveness of and is also influenced by three safety message formats commonly used in product manuals (i.e., 1. safety messages presented in list format at the front of the manual; 2; safety messages presented by semantic similarity interspersed throughout the manual—chunked format, and 3. safety messages presented in a combined format—both list and chunked). As anticipated, pre-exposure self-efficacy was a significant covariate which was found to be positively related to post-exposure self-efficacy and negatively related to information evaluation. Further, controlling for pre-exposure self-efficacy, post-exposure self-efficacy was significantly lower in the combined (list plus chunked) condition. Findings of this research have important implications for the practice of repeating safety warnings and future research in the consumer information domain.Authors are listed in alphabetical order. This study was supported by an Illinois State University Research Grant.     

Modifications of the Poggendorff effect as a function of random dot textures between the verticals

In the present research, we investigated the modification of the strength of the Poggendortf illusion as a function of different densities ofrandom dot textures failing the space between the verticals. The results ofExperiment 1 show that the illusory effect is a nonlinear function ofthe texture parameterr, the ratio of black pixels to white and black pixels, with a minimum forr=0.5, approximately, and a maximum forr=0 andr=1. The results may be interpreted by an analytical model of perceptual space dynamics, in which the effect dependson the amount of interaction between points of different light intensity. A computer simulation performed by applying the analytical model to different values ofr shows a good agreement between the predictions and the experimental data. To test the hypothesis underlying the model, a second experiment was carried out to measure the magnitude of the expansion ofthe space between the verticals as a function of the parameterr. The results are consistent with the hypothesis of the model. The overall data are discussed in terms of their implications on various theories proposed for the Poggeadorff illusion.