A comparison of two response time models applied to perceptual matching

Two models, a Poisson race model and a diffusion model, are fit to data from a perceptual matching task. In each model, information about the similarity or the difference between two stimuli accumulates toward thresholds for either response. Stimulus variables are assumed to influence the rate at which information accumulates, and response variables are assumed to influence the level of the response thresholds. Three experiments were conducted to assess the performance of each model. In Experiment 1, observers performed under different response deadlines; in Experiment 2, response bias was manipulated by changing the relative frequency ofsame anddifferent stimuli. In Experiment 3, stimulus pairs were presented at three eccentricities: foveal, parafoveal, and peripheral. We examined whether the race and diffusion models could fit the response time and accuracy data through changes only in response parameters (for Experiments 1 and 2) or stimulus parameters (for Experiment 3). Comparisons between the two models suggest that the race model, which has not been studied extensively, can account for perceptual matching data at least as well as the diffusion model. Furthermore, without the constraints on the parameters provided by the experimental conditions, the diffusion and the race models are indistinguishable. This finding emphasizes the importance of fitting models across several conditions and imposing logical psychological constraints on the parameters of models.     

Assessing adolescents' personality with the NEO PI-R

The suitability of the Revised NEO Personality Inventory (NEO PI-R) to assess adolescents' personality traits was investigated in an unselected heterogeneous sample of 469 adolescents aged 12 to 17 years. They were further administered the Hierarchical Personality Inventory for Children (HiPIC) to allow an examination of convergent and discriminant validity. The adult NEO PI-R factor structure proved to be highly replicable in the sample of adolescents, with all facet scales primarily loading on the expected factors, independent of the age group. Domain and facet internal consistency coefficients were comparable to those obtained in adult samples, with less than 12% of the items showing corrected item-facet correlations below absolute value .20. Although, in general, adolescents reported few difficulties with the comprehensibility of the items, they tend to report more problems with the Openness to Ideas (05) and Openness to Values (06) items. Correlations between NEO PI-R and HiPIC scales underscored the convergent and discriminant validity of the NEO facets and HiPIC scales. It was concluded that the NEO PI-R in its present form is useful for assessing adolescents' traits at the primary level, but additional research is necessary to infer the most appropriate facet level structure.     

Dimensionen der Gefühle

Zusammenfassung Es war das Ziel der Untersuchung, ein System der Gefühlsqualitäten zu finden, das im Unterschied zu früheren Klassifikationsversuchen nicht auf der Anwendung formaler Kategorien oder anderer, gewissermaßen von außen an den Gegenstand herangetragener Gesichtspunkte beruhte, sondern aus den Erlebnisinhalten selbst hervorging.Nach verschiedenen Methoden wurden drei Versuche unternommen, in denen die Versuchspersonen auf Grund der Vergegenwärtigung des Erlebnisses Urteile über die Ähnlichkeit und über bestimmte Eigenschaften von Gefühlsqualitäten abzugeben hatten.Aus den Ergebnissen aller drei Versuche konnten Ordnungssysteme der verwendeten Gefühlsqualitäten gebildet werden. Trotz der Verschiedenheit der angewendeten Methoden besteht zwischen den drei Systemen in den vergleichbaren Punkten eine nahezu vollkommene Übereinstimmung.Die Gesamtheit der Gefühlsqualitäten ordnet sich nach dem Resultat dieser Untersuchung in drei Dimensionen an, denen die Bezeichnungen Angenehm—Unangenehm, Unterwerfung—Überhebung und Grad der Motivierung gegeben wurden.Nach einigen Betrachtungen über die der Beurteilung von Gefühlsqualitäten zugrunde liegenden subjektiven Prozesse werden methodische Folgerungen gezogen, die besagen, daß die Voraussetzungen für die Untersuchung der Gefühle weit günstiger sind, als dies nach der vorherrschenden Meinung der Fall ist. Schließlich wird die Anwendungsmöglichkeit der Resultate auf einige Fragestellungen der Gefühlsforschung an Hand von Beispielen erörtert.     

Explicit and implicit attitudes towards food and physical activity in childhood obesity

This study investigated differences in the explicit and implicit attitudes towards food and physical activities between children with obesity (n=38) and a matched control group (n=38). The implicit attitude was assessed using the Extrinsic Affective Simon Task (EAST; J. Exp. Psychol. (50) (2003) 77), a modified version of the Implicit Association Test (IAT; J. Personality Social Psychol. (74) (1999) 1464). It was expected that both groups would report a positive explicit attitude towards healthy food and intense physical activities, and a negative explicit attitude towards unhealthy food and sedentary activities. Of particular interest was the hypothesis that children with obesity would have a more positive implicit attitude towards unhealthy food and sedentary activities than the control group. Results revealed no differences between groups in the explicit attitude towards food and physical activity. Children and adolescents with obesity had a more pronounced positive implicit attitude towards food in general. The relevance of these findings in terms of prevention, treatment and further research is discussed.     

Luminance edges are not necessary for visual completion

Luminance edges seem to have an important role in visual feature binding and, more specifically, in visual completion because luminance differences are important for the perception of depth. We investigated this claim in two experiments in which the primed-matching paradigm was used. In Experiment 1, we investigated conditions under which either a partly occluded shape or an occluder was isoluminant with respect to the background. In Experiment 2, the partly occluded shape and the occluder were isoluminant with respect to each other. Evidence was found for visual completion in all cases, and we therefore conclude that luminance edges are not essential for visual completion.     

A conceptual and psychometric framework for distinguishing categories and dimensions

An important, sometimes controversial feature of all psychological phenomena is whether they are categorical or dimensional. A conceptual and psychometric framework is described for distinguishing whether the latent structure behind manifest categories (e.g., psychiatric diagnoses, attitude groups, or stages of development) is category-like or dimension-like. Being dimension-like requires (a) within-category heterogeneity and (b) between-category quantitative differences. Being category-like requires (a) within-category homogeneity and (b) between-category qualitative differences. The relation between this classification and abrupt versus smooth differences is discussed. Hybrid structures are possible. Being category-like is itself a matter of degree; the authors offer a formalized framework to determine this degree. Empirical applications to personality disorders, attitudes toward capital punishment, and stages of cognitive development illustrate the approach.     

Willingness to seek help for psychosocial problems among Latino and white American college students

This study compared 50 Latino and 50 White American students' perceptions of the severity of 25 psychological problems, their willingness to seek help for these problems, and their preferences for caregivers. Each group received a modified version of the Personal Problems Inventory. Latino students rated depression, financial concerns, and discrimination as more severe problems; their preference for mental health workers consistently significantly exceeded those of White students, although both groups preferred seeking help from family and community resources. Findings suggest the possibility of a greater role for therapists serving Latino students than currently exists.     

Variability of the MAX and MIN Statistic: A Theory of the Quantile Spread as a Function of Sample Size

The maximum and minimum of a sample from a probability distribution are extremely important random variables in many areas of psychological theory, methodology, and statistics. For instance, the behavior of the mean of the maximum or minimum processing time, as a function of the number of component random processing times (n), has been studied extensively in an effort to identify the underlying processing architecture (e.g., Townsend & Ashby, 1983; Colonius & Vorberg, 1994). Little is known concerning how measures of variability of the maximum or minimum change with n. Here, a new measure of random variability, the quantile spread, is introduced, which possesses sufficient strength to define distributional orderings and derive a number of results concerning variability of the maximum and the minimum statistics. The quantile spread ordering may be useful in many venues. Several interesting open problems are pointed out. This work was supported by an NIH Grant R01 MH57717 to the first author. Some of the collaboration took place during the year 2000 while J.T. Townsend was a Fellow at the Hanse Institute for Advanced Study (HWK), sponsored by H. Colonius at Oldenburg University.