How useful are personality tests in employment and forensic settings? Personality tests are widely used in many different settings, including psychological research, employment screening, diagnostic and clinical purposes; and even in criminal legal proceedings and forensic settings (Funder, 2013; Kramer, 2007). While many employers will use pre-employment testing to determine which applicants are most likely to be successful employees, in settings such as policing, employers will screen out high-risk applicants to reduce the possibility of employing individuals with psychopathologies (K. R. Black, 1994). In forensic assessments of individuals committed to stand trial, personality tests can be used to determine the defendant’s competence to stand trial, and make predictions about the possibility of re-offending and response to rehabilitation (Carrasco, Barker, Tremblay, & Vitaro, 2006; Cooke & Thorwarth, 1978; Gendreau, Goggin, & Law, 1997).
There are a number of ways in which personality may be tested and in psychological literature most measures are classified as either projective or objective (K. R. Black, 1994). Projective tests typically use a person’s response to an ambiguous stimulus to discern personality characteristics, based on the assumption that such responses reflect unconscious desires and motives (K. R. Black, 1994). In contrast, objective tests usually require the person to answer a questionnaire with the responses compared against an established standard (K. R. Black, 1994). Tests may be designed in a number of different ways, although each is built on a theoretical framework or set of assumptions (K. R. Black, 1994). For example, the NEO PI-R is based on the Big Five model of personality traits (Costa & McCrae, 1992), while the MMPI and MMPI-2 are not based on a trait model of personality as such, rather these tests are based on the assumption that people with similar personality characteristics tend to answer certain questions in similar ways (Colligan, 1985).
Personality tests face a huge number of potential limitations and so design is a crucial factor in the success of a test (K. R. Black, 1994). One of the first such hurdles that must be cleared when designing a test is ensuring construct validity; that is, a test must be measuring what it is intended and assumed to measure, and the theory or assumption on which that test is based must hold true (Reis & Judd, 2000). A test must also have content validity, meaning that items on the test are relevant to and cover all aspects of the measures the test was designed to assess (Reis & Judd, 2000). Criterion (particularly predictive) validity – the extent to which the test results can be used to make predictions about a person – is also of great importance in personality testing because arguably without criterion validity, personality tests would have no purpose (Reis & Judd, 2000). The extent to which a test satisfies these requirements will determine the extent to which results obtained from the test are meaningful, and in practice there are limits to how well a test can satisfy such requirements.
Many criticisms of personality testing are levelled at how well the test actually measures personality and whether personality measures are even indicative of job performance or criminal responsibility (among others) (Morgeson et al., 2007). Numerous meta-analyses have been conducted on the literature regarding personality testing for employment screening. Among them, Hurtz & Donovan (2000) reviewed 26 studies to determine the extent to which job performance could be predicted by the Big Five measures of personality. Data comprised of personality measures from 5,525 to 8,083 people (not all measures were collected from all people) and job performance assessed in most cases by subjective ratings. Across all conditions, conscientiousness was the most highly correlated with job performance with a correlation coefficient of 0.22, while correlations for emotional stability, agreeableness, extraversion, and openness were 0.14, 0.13, 0.10, and 0.07 respectively.
Hurtz and Donovan (2000) noted that the results were similar to other analyses in this area, and also stated that these correlations were quite low. This study was influenced by, and as a result remarkably similar to, an earlier meta-analyses by Barrick and Mount (1991) of 117 studies regarding the Big Five measures and job performance (the specific personality tests were not reported). Barrick and Mount (1991) had found that while occupational groups (professionals, police, managers, sales staff, and skilled or semi-skilled workers) did differ in correlations between Big Five traits and performance, these correlations were mostly less than an absolute value of 0.10. The exceptions were extraversion for managers and sales staff (correlations of 0.18 and 0.15 respectively), emotional stability in police and skilled workers (0.10 and 0.12), agreeableness in police and managers (both 0.10), while conscientiousness correlations were, across all categories, between 0.20 and 0.23.
One area in which personality testing is used almost worldwide is law enforcement recruitment, undoubtedly because of the potential consequences of failing to do so (Lee, 2006). In the United States, many jurisdictions are required by law to use empirically proven personality tests to screen potential officers in peace roles (police, correctional staff, federal agents etc.) to limit liability of government departments (Caillouet, Boccaccini, Varela, Davis, & Rostow, 2010; Lee, 2006). The MMPI-2 is one of the most commonly used pre-employment screening test for police officers, however was originally designed as a diagnostic test for psychological disturbances. To determine how well the PSY-5 (Personality Psychopathology) scale of the MMPI-2 predicted officer misconduct, Caillouet et al. (2010) assessed sample of 600 police officers in the United States.
These officers had been administered the MMPI-2 during the application process, and the test results (from the PSY-5 scale only) were correlated with later career outcomes to assess the predictive validity of the PSY-5 scale in such a setting. Measures taken from the MMPI-2 PSY-5 included aggression, risk taking, impulsivity, disconnection from reality, self-criticism, worry, guilt, and experience of joy (Caillouet et al., 2010). Outcomes were measured based on supervisor ratings of misconduct including citizen complaints, inappropriate use of force, weapons, and/or vehicles, and receipt of reprimand or suspension (Caillouet et al., 2010). Factors significantly correlating with on duty misconduct (correlation coefficients shown in parentheses) were assertiveness (0.22), impulsivity (0.21), psychotic experiences (-0.13), negative emotionality (0.14), irritability (-0.13), phobias (-0.17), and disengagement (-0.18).
The results indicate that in this study, measures from the PSY-5 are small to medium strength predictors of later misconduct in these police officers (the largest correlation, assertiveness, gives a binomial effect size display of only about 11% greater than chance level). The implications of this study are limited by the original sample of officers – mostly Caucasian (76.4%) males (90.2%) – and the researchers acknowledge this, along with limitations regarding the validity of supervisor ratings, and not having access to more MMPI measures from the officer’s tests. The Inwald Personality Inventory (IPI), in contrast to the MMPI, was specifically developed for the role of assessing peace officer (and similar role) applicants. Wisniewski (2004) investigated how IPI and MMPI-2 scores could be used to predict performance (assessed by supervisor scores) in 91 correctional officers from county jails in the United States. To do this, three regression models were created; one based on MMPI-2 scores alone, the second on IPI scores alone, and the third on both MMPI-2 and IPI scores together.
The regression for the IPI alone was significant, accounting for close to 39% of the variance in scores, much higher than Morgeson et al. (2007) proposed personality scores could account for. Other outcomes were also assessed in this manner; disciplinary action against a correctional officer, and awards for outstanding performance. However no model utilising the MMPI-2 and IPI either alone or together was significant. Recently the NEO PI has become a target of interest for the purpose of screening peace officers (Chibnalltt & Detrick, 2003). J. Black (2000) reported that the Big Five personality traits could be used to a limited degree to predict performance of police recruits during training. In a sample of New Zealander Police College recruits, conscientiousness was generally the highest correlate of performance in areas such as practical scenarios and examinations, while neuroticism (impulsiveness, vulnerability) correlated negatively with most aspects of performance.
Sub traits including assertiveness, activity, ideas, and trust were all positively correlated with performance. Absolute values of all significant correlations were in the range from 0.14 to 0.25, similar to the aforementioned studies and analyses. The studies of personality testing in pre-employment settings that have been presented to this point have a common flaw: participants had successfully passed pre-employment screening for their job (Caillouet et al., 2010). As a result there is a massive bias in all the literature reviewed here towards people that are deemed suitable for employment in their chosen field (Caillouet et al., 2010). This is a common obstacle that is not easily overcome in such research and acknowledged as one of the biggest limitations (Caillouet et al., 2010).
Therefore, when considering the outcomes of the aforementioned studies, it is important to realise that rather than testing how well scores on personality tests correlated with job performance etc., such studies are actually testing how well scores on personality tests correlate with job performance in people who are deemed suitable for that job. In addition to pre-employment screening, personality testing is used in forensic assessments with the goal of determining important issues such as a defendant’s competence to stand trial, need for psychiatric rehabilitation; or likelihood of reoffending (Cooke & Thorwarth, 1978; Gendreau et al., 1997).
The MMPI-2 and similar objective tests are the most commonly used for these purposes, while projective testing is used to a much lesser extent (Borum & Grisso, 1995). Gendreau, Goggin, and Law (1997) performed a meta-analysis of 39 studies between 1940 and 1995 to determine which factors significantly predicted inmate misconduct during incarceration. The analysis was severely limited by the studies on which it was based: Few had reported important methodological and demographic information or characteristics of the prisons. The outcomes of the study showed that MMPI (and MMPI-2) scores were significant at predicting misconduct, however the correlation was small (0.11) compared to institutional factors (0.26). The MMPI has also been used to determine the probability that a mentally ill offender will escape from a psychiatric hospital, and in one study of 60 participants yielded correct predictions 68% of the time, 18% higher than the chance rate of 50% (Cooke & Thorwarth, 1978). Such results are important for judges and hospitals to consider when determining how much security is required for patients, however it is questionable whether an error rate of 32% is acceptable in such settings.
Determination of potential for rehabilitation is also a consideration for judges during sentencing, and for this reason Edwards (1963) investigated the relationship between MMPI scores and success of rehabilitation. Seventy-two inmates provided data for this study, and they were grouped according to how successful the outcomes of rehabilitation were. Results were presented in a poor fashion, however it was reported that MMPI scores were able to predict outcomes significantly. Patient demographics and the accuracy and reliability of the predictions were not reported. One of the most important questions that must be raised when discussing personality testing is how strong correlations and criterion validity must be for the test to be considered a useful measure (Morgeson et al., 2007). In research settings, correlations of 0.2 to 0.3 might be sufficient for the researcher to develop testable theories, especially when large quantities of data are being collected and random effects diminish in accordance with probability theory.
However this sort of correlation may not be high enough to provide meaningful predictions in recruitment or legal settings when the sample size is one person, and so statistical uncertainties are much higher (Morgeson et al., 2007). This is an important consideration because the consequences of over relying on personality tests could include test results overriding other highly informative data (based on behavioural observations, personal history, life achievements and outcomes, statements of character etc.) made about job candidates or defendants (Morgeson et al., 2007). As such it is important that there continues to be scepticism towards the results of personality tests when used in any setting. The literature reviewed in the present essay suggests that personality tests only correlate a small to medium extent with job performance (Morgeson et al., 2007) however these findings are plagued by limitations that could seriously have undermined conclusions.
The biggest limitation was inherent in the way that samples were selected: participants must have already passed pre-employment screening and been deemed suitable for employment so that ratings of job performance could be obtained (Caillouet et al., 2010). As such, even if personality tests were able to eliminate ‘bad employees’ with near perfect precision, this would not be reflected in the studies reported here (Caillouet et al., 2010). Personality testing may be useful to a limited extent in forensic applications for determining potential misconduct during incarceration, risk of escape from a mental health hospital, and response to rehabilitation programs (Cooke & Thorwarth, 1978; Gendreau et al., 1997).
This information would be useful to a judge, and also to administrators of facilities that house inmates or mentally ill offenders. Personality testing has a huge potential in the fields highlighted in the present essay. New tests designed for specific purposes are likely to prove more useful and valid predictors of job performance, or forensic assessment, than existing (and more general) tests such as the MMPI. Furthermore, situational effects might be better accounted for by utilising interactionist models of personality and so could have much higher criterion validity. Continued research in personality psychology will undoubtedly result in better personality tests being developed and so those using the tests can be more confident that the results are valid and reliable.
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