Personality test results can be affected by factors other than faking. Situational states such as mood and motivation may influence results, and scores can change slightly over time. People may also differ in how well they know and understand their own behaviour.

For more information, read Precision of personality scores and Stability of personality traits.

These factors are often considered part of the test’s measurement error, which is captured by its reliability coefficient.

Faking is different. It is commonly defined as intentional misrepresentation in self-report (Holden & Book, 2011). This means that a person’s scores when faking would differ from their scores when responding without faking.

Researchers can study faking by asking the same people to complete an assessment under different conditions and comparing their scores.

Operational studies have examined candidates who were offered the opportunity to retake a personality assessment after failing it the first time. The average differences between the first and second attempts varied considerably, ranging from -0.02 in Hogan, Barrett and Hogan (2007) to 0.86 in Landers et al. (2011).

In practice, however, it is difficult to separate faking from other sources of uncertainty. Candidates may also have different goals when responding, including:

Some candidates may focus more on impressing a potential employer, while others may be more concerned about being dishonest or being “caught” by a supervisor or colleagues after being hired.

The oldest and most common approach is to use scales designed to measure social desirability or lying. This method has been studied extensively, and there is broad agreement among researchers that it is not useful (Sackett, 2011). Social desirability scales should therefore not be used to detect faking.

More recent approaches include:

These methods have not been studied extensively, so caution is advised when considering them for operational use.

The most reasonable conclusion is that there are currently no methods for detecting faking that are suitable for operational use (Sackett, 2011). Test scores should not be adjusted on the basis of suspected faking.

In candidate selection, the main concern is often an assessment’s predictive validity: how well it differentiates between candidates who are likely to perform well and those who are likely to perform poorly in the job.

Evidence indicates that the predictive validity of personality assessments is relatively robust to faking (Sackett, 2011). Faking may therefore be less relevant if the assessment continues to predict job performance effectively.

Hiring decisions are also rarely based on personality assessments alone. The highest predictive validity is achieved by combining several measurements, such as:

When personality results are considered alongside other measurements, the effect of faking on the overall assessment is relatively small.

The research discussed above supports the following conclusions:

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