Tall is typical: Central tendency, ideal dimensions, and graded category structure among tree experts and novices

Many accounts of categorization equate goodness-of-example with central tendency for common taxonomic categories; the best examples of a category are average members--those that are most similar to most other category members. In the present study, we asked 24 tree experts and 20 novices to rate goodness-of-example for a sample of 48 trees and found (1) that the internal structure of the category tree differed between novices and experts and (2) that central tendency did not determine goodness-of-example ratings for either group. For novices, familiarity determined goodness-of-example ratings. For experts, the "ideal" dimensions of height and weediness, rather than average similarity to other trees, were the primary predictors of goodness-of-example ratings for experts. The best examples of tree were not species of average height, but of extreme height. The worst examples were the weediest trees. We also found systematic differences in predictors of goodness-of-example as a function of type of expertise. We argue that the internal structure of taxonomic categories can be shaped by goal-related experience and is not necessarily a reflection of the attributional structure of the environment. Implications for models of category structure and category learning are discussed.     

What is free association and what does it measure?

This paper reports the results of a study of free association in which participants were asked to produce the first two words to come to mind. The findings were used to estimate the reliability of indices of strength and set size for different types of items and to model free association as a retrieval task. When confined to first responses, reliability was generally high for both indices, particularly for words with smaller sets of associates and stronger primaries. When second responses were included, reliability declined. A second response added new but weak items to the set, and, when the primary associate was not produced on the first opportunity, it tended not to be produced on the second. Relative to when multiple responses are requested, first-response free association provides more reliable indices of the relative strength and set size for a word's strongest associates. A model of free association assuming that a strength distribution underlies each response provided a good fit to the data.     

Examining the utility of the PCL:SV as a screening measure using competing factor models of psychopathy

The correspondence between the Hare Psychopathy Checklist: Screening Version (PCL:SV; S. D. Hart, D. N. Cox, & R. D. Hare, 1995) and the Hare Psychopathy Checklist-Revised (PCL-R; R. D. Hare, 1991, 2003) was examined in forensic (N = 175) and correctional (N = 188) samples. Intermeasure correlations for Total scores (.95 forensic, .94 correctional) and the original 2-factor, D. J. Cooke and C. Michie's (2001) 3-factor, and R. D. Hare's (2003) 4-facet models (range = .87-.95) were high. Area under the curve values for the PCL:SV were .98 in both samples (cutoff = PCL-R Total score of 25). The PCL:SV performed well as a screen, maximizing false positive relative to false negative errors. Close correlations for prediction of violent recidivism in the correctional sample were obtained for the PCL-R (.42) and PCL:SV (.37). Results indicate the robust relation between the measures is maintained whether they are completed on the basis of file review only or file plus interview and whether the same or different raters score the measures.     

Comparative analysis of movement characteristics during dead-reckoning-based navigation in humans and rats

Human and rat movement organization was investigated as they searched for randomly located rewards without access to visual information. Under dark conditions, rats foraged for randomly located food pellets (Experiment 1). Blindfolded humans were instructed to search for an ostensible hidden coin using a metal detector (Experiment 2). After locating the food pellet, rats carried it back to the refuge, and after a designated searching time, humans were instructed to return to the start location. Although both species exhibited a high degree of similarity in searching path movement organization and ability to return to the start location, disruption of human searching path organization was associated with impairments in returning to the start location. These results support the vestibular "gain" account of movement organization during dead-reckoning-based navigation.     

Pharmacotherapy of delusional disorders in the context of offending and the potential for compulsory treatment

Delusional disorder is an uncommon mental illness with an estimated prevalence of 0.03%. Its low prevalence has likely contributed to the paucity of research interest in this area, leading to substantial gaps in knowledge concerning its treatment and management. In the absence of a robust literature, most clinicians rely on their experience and guidelines for treating schizophrenia when treating patients with delusional disorder. This article reviews the available literature that is specific to the treatment of delusional disorder. In addition, it focuses on specific forensic and medicolegal aspects of managing patients with delusional disorder.     

Clustering, seriation, and subset extraction of confusion data

The study of confusion data is a well established practice in psychology. Although many types of analytical approaches for confusion data are available, among the most common methods are the extraction of 1 or more subsets of stimuli, the partitioning of the complete stimulus set into distinct groups, and the ordering of the stimulus set. Although standard commercial software packages can sometimes facilitate these types of analyses, they are not guaranteed to produce optimal solutions. The authors present a MATLAB *.m file for preprocessing confusion matrices, which includes fitting of the similarity-choice model. Two additional MATLAB programs are available for optimally clustering stimuli on the basis of confusion data. The authors also developed programs for optimally ordering stimuli and extracting subsets of stimuli using information from confusion matrices. Together, these programs provide several pragmatic alternatives for the applied researcher when analyzing confusion data. Although the programs are described within the context of confusion data, they are also amenable to other types of proximity data.     

Assessing family-of-origin functioning in Mexican American adults: retrospective application of the family environment scale

Although both theoretical and empirical literature suggests that individuals' family-of-origin experiences affect subsequent relationship functioning as adults, few studies have examined the appropriateness of family assessment techniques when applied retrospectively for use in either theory development or clinical applications. This study examined psycho-metric characteristics of the Family Environment Scale (FES) when used retrospectively with Mexican Americans to assess their families-of-origin. Findings provided qualified support for the internal consistency of the FES and showed significant mean profile differences for this population across gender and when compared to the normative sample for this measure. Retrospective reports on the FES related to independent measures of family history of distress and, to a lesser extent, with current relationship functioning, providing preliminary support for the criterion-related validity of the FES when adapted for retrospective assessment. Limitations and implications of findings for further research are discussed.     

Incremental validity analyses of the violence risk appraisal guide and the psychopathy checklist: screening version in a civil psychiatric sample

This study compares two instruments frequently used to assess risk for violence, the Violence Risk Appraisal Guide (VRAG) and the Psychopathy Checklist: Screening Version (PCL:SV), in a large sample of civil psychiatric patients. Despite a strong bivariate relationship with community violence, the VRAG could not improve on the predictive validity of the PCL:SV alone, even though the VRAG includes several ostensible violence risk factors other than psychopathy. Moreover, incremental validity analyses indicated that the remaining VRAG items accounted for little or no variance in violent outcomes once psychopathy scores were controlled. Conversely, the PCL:SV continued to account for considerable variance after controlling for the VRAG. These results reflect the limited validity of the VRAG items in civil psychiatric samples beyond the variance that is explained by the PCL:SV alone.