Keywords

These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Synonyms

SNAP-2

Definition and Introduction

The Schedule for Nonadaptive and Adaptive Personality, 2nd edition (SNAP-2), is a factor analytically derived self-report measure to assess personality traits ranging from the healthy to the pathological range (Clark et al. 2014). Its 390 items emphasize the extreme ends of traits, which are at the core of personality disorder (PD) and associated with maladaptive functioning. The SNAP-2 was normed on community adults from three US cities/metropolitan areas. The sample was gender balanced and represented a wide range of age, race/ethnicity, socioeconomic status, geographic region, and urban/rural settings.

The SNAP-2 assesses 15 trait dimensions in three broad domains: negative affectivity (NA), positive affectivity (PA), and disinhibition (vs. constraint; DvC). The core scale of the NA domain is negative temperament; other traits in this domain are mistrust, manipulativeness, aggression, self-harm, eccentric perceptions, and dependency. The core scale of the PA domain is positive temperament; other traits in this domain are exhibitionism and entitlement, with detachment assessing the opposite end of the higher-order dimension. The core scale of the DvC domain is disinhibition; the impulsivity scale also assesses this end of the higher-order domain, whereas propriety and workaholism assess the opposite end. All 15 scales are lower-order scales that tap specific aspects of three broad domains they comprise, with the core scales assessing the most central aspect of each. Scales to assess four of the “Big-Five” (neuroticism, extraversion, conscientiousness, and agreeableness) dimensions of personality (e.g., Digman 1990) (see NEO Inventories) also have been developed (Calabrese et al. 2012).

In addition to its trait scales, the SNAP-2 provides seven validity scales including an overall invalidity index, which help to identify profiles that may be invalid due to such factors as response biases, carelessness, or deliberate distortion. Finally, the instrument contains items to assess the PD criteria in Section II of DSM-5 (see Diagnostic and Statistical Manual of Mental Disorders (DSM-5); American Psychiatric Association 2013), which are the same as those in the DSM-IV (APA 1994, 2000).

Historical Background

The SNAP was developed as an alternative to the DSM’s categorical conceptualization of PD, describing personality pathology as continuous trait dimensions. The categorical system of PD diagnosis has many documented shortcomings (Clark 2007). The SNAP was developed to provide researchers with a method of improving diagnostic criteria and investigating the validity of specific PD diagnoses and has proven useful in clinical settings as well.

The first complete version of the SNAP consisted of the 15 trait scales, 6 validity scales, and 13 diagnostic scales for DSM-III-R PDs (Clark 1993). In the SNAP-2, the trait and validity scales remain unchanged. The diagnostic scales were updated to assess DSM-IV (APA 1994; now DSM-5-II) PDs, and a validity scale was added. Research using the SNAP-2 has been and continues to be instrumental in advancing the field of personality assessment (e.g., Morey et al. 2012; Stepp et al. 2012), addressing both the conceptual and empirical challenges of assessing personality pathology (Clark and Ro 2014).

Psychometric Data

Reliability. All 15 SNAP-2 trait scales are highly reliable per various indices (Clark et al. 2014). They demonstrate strong internal consistency in community adult, student, and patient samples (coefficient alphas ranged from 0.78 to 0.92). Dependability (short-range temporal stability; Chmielewski and Watson 2009) was high in both a subset of the SNAP-2 norming sample (n = 67; median r = 0.88 for 7–30 days) and an inpatient sample (N = 52; median 1-week retest r = 0.81). Medium-range temporal stability was also high in a subset of the SNAP-2 norming sample (n = 203; median r = 0.86 for intervals ranging from 31 to 131 days). Pre/post test-retest reliability was appropriately lower in two treatment samples: back pain patients in a 6-month functional treatment program (median r = 0.70; range = 0.49–0.82; Vittengl et al. 1999) and depressed patients in a 20-session course of cognitive-behavior therapy (median r = 0.74; range = 0.57–0.85; Clark et al. 2003).

Structural and external validity. Factor analyses of the 15 SNAP-2 trait scales indicate that its three higher-order personality factors broadly replicate the structure of “Big Three” personality measures (see Eysenck Personality Questionnaire [Eysenck and Eysenck 1975]) (Eaton et al. 2011). Most scales have strong loadings on a single factor, but several have significant empirically predicted cross loadings (e.g., manipulativeness often cross loads on NA and DvC). Cross loadings are typically higher in patient than non-patient samples, due to the interrelations of dimensions of psychopathology.

The SNAP-2’s correlations with a wide range of other measures of personality pathology provide considerable support for its validity. It correlates in predictable ways with chart-based ratings of PD-relevant behaviors (Clark et al. 1993), interview-based PD diagnoses (e.g., Morey et al. 2003; Reynolds and Clark 2001), the MMPI classic and restructured scales (see Minnesota Multiphasic Personality Inventory; Restructured Clinical Scales (MMPI-2-RF) (Simms et al. 2005), clinician ratings of medium- and long-term outcomes (e.g., Hopwood et al. 2007; Morey et al. 2007, 2012), and myriad self-report and interview measures (e.g., see Markon et al. 2005; contact the SNAP-2’s author for a reference list).

The SNAP “Family” Measures

Several versions of the SNAP-2 have been developed to assess personality for various purposes and in diverse populations. The SNAP-Youth Version (SNAP-Y; Linde et al. 2013) assesses adolescent personality using the same trait dimensions as the SNAP-2, with items adapted for younger respondents. The SNAP-Y is useful for assessing both community and clinical youth (e.g., Kushner et al. 2013; Latzman et al. 2013).

The SNAP Self-Description Rating Form (SNAP-SRF; Harlan and Clark 1999) is an alternative-format, short form of the SNAP-2 that assesses only the 15 trait scales of the full-length measure. The SNAP Other-Description Rating Form (SNAP-ORF; Harlan and Clark 1999) was developed to obtain informant reports of an individual’s personality. These two measures are parallel in structure, with the only difference being that the SNAP-SRF is a self-report measure, whereas SNAP-ORF respondents provide ratings for another individual. Both measures have acceptable reliability and convergent/discriminant validity with the original SNAP-2.

Clinical Utility

The SNAP-2 measures are self-administered and can be used individually or in group settings. Their reading level is approximately sixth grade. They are available in two print formats (reusable, with responses recorded on a separate answer sheet, and one-time use, with responses recorded on the test booklet or sheet) and also electronic format for computer administration. SAS, SPSS, and Excel scoring programs are available.

The SNAP-2 offers an easy-to-use, informative way of assessing a subject’s adaptive and maladaptive personality traits in a range of clinical settings. The SNAP-2 characterizes patients using both traits and traditional diagnostic dimensions, providing a multifaceted description of an individual’s (mal)adaptive style associated with personality (dys)function. Given the broad scope of the instrument, clinicians are able to gain a large amount of information regarding patients and develop more effective treatment plans.

Availability

The SNAP-2 measures, scoring programs, and manual are freely available for both clinical use, providing that clients are not charged, and for use in unfunded, noncommercial research. They also are available on a sliding scale for other uses (e.g., billed clients, funded research) upon completion of a clinical or research license in all cases. Materials are available in various formats. Translations of the SNAP-2 have been developed in Russian and Estonian, and an Italian translation is being developed. Individuals interested in using and/or translating any of the SNAP-2 measures should contact its author for a research, clinical, and/or translation license: la.clark@nd.edu

Conclusion

The SNAP-2 measures provide comprehensive assessment of the full adaptive-to-maladaptive range of personality traits for both researchers and clinicians. The measures are used widely both clinically and in research and exist in a variety of formats to suit diverse assessment needs. The scales are reliable and have undergone extensive validation. They are compatible with the alternative model of personality disorder in DSM-5’s Section III, and the primary SNAP-2 also assesses the DSM-5, Section II personality disorders.

Cross-References