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; we 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.

The Construct of Internalization: Conceptualization, Measurement, and Prediction of Smoking Treatment Outcome. Depression symptoms and diagnosis are associated with failure to quit smoking in most studies but not all. A new measure of internalization (i.e., symptoms of depression or anxiety, or poor mood) was created to investigate whether internalization would predict smoking cessation in 549 smokers from three randomized clinical trials with inconsistent findings. Predicted item locations based on a map of the construct of internalization agreed with empirical locations based on item response theory. Internalization was highly correlated with neuroticism. Logistic regressions showed that internalization improved upon the predictions of other affect-related measures. High baseline internalization decreased abstinence from smoking at end-of-treatment and 3 months thereafter. History of major depression (single-episode or recurrent) failed to predict abstinence. The broad, dimensional construct of internalization as conceptualized herein appears to be an important predictor of smoking cessation.

Measurement of Impulsivity in a Hierarchical Model of Personality Traits: Implications for Substance Use. This review describes how measures of a prominent three-dimensional hierarchical model of personality traits relate to substance use. H. J. Eysenck proposed a biologically based model of personality that gave rise to related models such as those of J. A. Gray, C. R. Cloninger, and M. Zuckerman. The varying role of impulsivity--a trait related to disinhibition, approach motivation, novelty seeking, and sensation seeking--in successive self-report measures of this model, including the Eysenck Personality Inventory (EPI) and Eysenck Personality Questionnaire (EPQ), is described. It is argued that certain findings in experimental, cross-sectional, and longitudinal research using these measures point to the importance of impulsivity as a temperamental vulnerability factor for substance use.

Interpersonal Personality Measures Show Circumplex Structure Based on New Psychometric Criteria. The importance of the interpersonal circle in organizing the interpersonal domain is complemented by its empirical relations with broader personality taxonomies and with more specific personality variables. Yet circumplex structure in interpersonal measures has often been investigated using the "eyeball test" rather than using circumplex criteria of known effectiveness. Simulations (Acton, 1999) showed the effectiveness of 5 exploratory criteria (3 entirely new) that assess the properties of equal spacing, constant radius, and no preferred rotation. Along with Browne's (1992) criterion, these were applied to the Interpersonal Checklist (ICL; Laforge & Suczek, 1955; N = 763), Interpersonal Adjective Scales (IAS; Wiggins, 1979; Ns = 716 and 187), Revised IAS (IAS-R; Wiggins, Trapnell, & Phillips, 1988; N = 474), Inventory of Interpersonal Problems Circumplex Scales (IIP-C; Alden, Wiggins, & Pincus, 1990; Ns = 616 and 1,381), and Inventory of Interpersonal Goals (IIG; Horowitz, Dryer, & Krasnoperova, 1997; N = 318). In corroboration of interpersonal theory, all showed circumplex structure.

Evaluation of Ten Psychometric Criteria for Circumplex Structure. This study tested for sensitivity to circumplex structure in six existing and four new psychometric criteria that assess the circumplex properties of interstitiality, equal spacing, constant radius, and no preferred rotation. Simulations showed one criterion to be sensitive to equal versus unequal axes (Fisher Test) and four to be sensitive to interstitiality versus simple structure (Gap Test, Variance Test 2, Rotation Test, and Minkowski Test). Five criteria were ineffective (Squared Loadings Index, Gap* Test, Gap Difference Test, Cosine Difference Test, and Variance Test 1). Deviation scoring improved the effectiveness of most criteria and is thus recommended for assessing circumplex structure. This study provides new and effective means for discovering complex interrelations of variables where they exist. The circumplex, which falls in the middle of a hierarchy of models in degree of parsimony, may most accurately reflect a complex domain.

The Interpersonal Principle of Complementarity: A Meta-Analysis. According to the interpersonal principle of complementarity, dominance invites submission, submission invites dominance, hostility invites hostility, and friendliness invites friendliness. Narrative reviews of the literature on the principle of complementarity have turned up contradictory and inconclusive results. The present meta-analysis is meant to determine the overall effect size of the principle of complementarity and to find those factors, if any, that mediate this effect size. The effect size of complementarity was found to be large, but homogeneity was achieved only after eliminating half of the studies as "outliers." Possible mediating factors examined include global or summative ratings versus sequence of behaviors, and document source (published versus unpublished). Effect sizes differed significantly based on these mediating variables.

Differential Item Functioning in a Chinese Translation of the Fagerstrom Test for Nicotine Dependence. This study compared a Chinese translation of the Fagerstrom Test for Nicotine Dependence (FTND) with the English version. A community sample of 409 American smokers completed the assessment in either English (n = 241) or Chinese (n = 168). Internal-consistency coefficients for the FTND in English (.96) and Chinese (.90) were good. Item response theory (IRT) analyses indicated differential item functioning (DIF) based on language, implying that the two language groups are not directly comparable on the FTND. Item locations, person distributions, and a score equivalence index for converting raw scores into latent person locations for each version are presented. This study--the first to apply IRT to the FTND--illustrates how DIF analyses can be used to determine the comparability of groups on translated instruments, which the international nature of clinical assessment and the increasing ethnic diversity of the U.S. population make increasingly vital.

Depression and Stages of Change for Smoking in Psychiatric Outpatients. This article reports on the relations between depression and stages of change for smoking cessation. A convenience sample of 205 psychiatric outpatients (68% female, mean age 41) completed measures of depression (Primary Care Evaluation of Mental Disorders [PRIME-MD] and Beck Depression Inventory-II [BDI-II]), all transtheoretical model constructs related to smoking (stages and processes of change, pros and cons of smoking, and situational temptations), and thoughts about abstinence. As hypothesized, patients who had never smoked showed substantially lower rates of currently diagnosed major depressive disorder (MDD) than those who had ever smoked. Patients in early stages of change did not show more MDD or depressive symptoms but, as hypothesized, showed more negative thoughts about abstinence. Findings are consistent with the documented association between smoking and depression and suggest the appropriateness of building smoking cessation interventions based on the transtheoretical model of change for use with psychiatric populations.

Classification of Psychopathology: Goals and Methods in an Empirical Approach. Many have criticized the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994), and few regard it as a vehicle of truth, yet its most serious limitation is that its frank operationism in defining manifest categories has distracted attention from theories about what is going on at the latent level. We sketch a Generalized Interpersonal Theory of Personality and Psychopathology and apply it to interpersonal aspects of depression to illustrate how structural individual differences combine with functional dynamic processes to cause interpersonal behavior and affect. Such a causal account relies on a realist ontology in which manifest diagnoses are only a means to learning about the latent distribution, whether categorical or dimensional. Comorbidity of DSM diagnoses suggests that dimensionality will be the rule, not the exception, with internalization and externalization describing common diagnoses.

Classification of Psychopathology: The Nature of Language. This article criticizes the approach to language underlying the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; American Psychiatric Association, 1994). Concepts from the philosophy of language illuminate taxonomic problems that vex users of the DSM nosology: lack of coverage, comorbidity, and within-category heterogeneity. Exception is taken to the operationism that results in a highly artificial DSM nomenclature, raising the specter of non-referential criterion sets. A dimensional approach is recommended because it would better correspond to an objectively seamless reality.

Sensory Discrimination as Related to General Intelligence. The hypothesis, originally proposed by Galton and elaborated by Spearman, that there is a functional correspondence between sensory discrimination and general intelligence (g) continues to spark debate. Previous findings suggest that pitch discrimination and tactile discrimination are only weakly correlated with g. This study sought to replicate the pitch discrimination findings and to expand them to the modality of color discrimination in a large sample (N = 899) by correlating two sensory discrimination measures with the general factor from a battery of 13 cognitive-ability tests. The modest correlations found between g and measures of pitch discrimination (r = .21) and color discrimination (r = .31) suggest that sensory discrimination is relatively distinct from general intelligence. Although consistent with the neural processing speed explanation of g, these results cast doubt on a strong form of the sensory discrimination explanation of g.

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