Attributes of True and Deceptive Statements Made in Evaluations of Criminal Defendants

ABSTRACT

Court-ordered psychological evaluations of criminal defendants generally include two types: mental status (competence or sanity) versus risk assessment. When defendants are deceptive in mental status evaluations, lies of commission, in which symptoms of psychopathology are feigned (malingering), are most likely. When defendants are deceptive in risk assessments, lies of omission, in which antisocial impulses are concealed or denied, are most likely. Four research conditions, consisting of the true and false statements of two men accused of sex offenses and two men claiming an insanity defense, were rated by participants on a test of truthfulness containing eight items derived from Criterion-Based Content Analysis and Reality Monitoring. All items, as well as the collective test score, significantly differentiated between true and false statements. Further, the lie of commission was rated as significantly more false than the lie of omission, and a confession was rated as more truthful than a true statement involving only exculpatory information, which is in accordance with the theory of cognitive load. Factor analyses provided support for the construct validity of the test of truthfulness and two subscales. Further, the data suggests that statements judged true are characterized by the presence of attributes of truthfulness, while statements judged false are characterized by the absence of attributes of truthfulness along with the presence of attributes of untruthfulness.

KEYWORDS:

• Clinical Interviewing
• detecting deception
• forensic psychology
• insanity defense
• sex offenders

Notes

¹ Three items from the previous study that failed to significantly differentiate between the true and false statements—reproduction of conversation, the expression of affect in the statement, and gratuitous, self-serving statements—were excluded from this study, leaving the eight most theoretically coherent and reliable items.

² For the purpose of this study, the terms false and untrue are synonymous.

³ The score of the truthful accused sex offender represents one of the only two examples in the data of a statement being rated on the unpredicted side of the scale midpoint, that is, a true statement receiving an average score below three.

⁴ The primary reason for the inclusion of the perceptual details and contextual details items in the FACT is because, notwithstanding their relative psychometric weakness, they still differentiated true from false statements in the predicted direction in every test in which they were involved.

⁵ In fact, this score was the single lowest mean score on any of the FACT items for all research conditions.

⁶ The results in Table 1 indicate that the participants rated the statements more in the deceptive than truthful direction (i.e., the average rating of the false statements was 5.7 points below the FACT midpoint of 24, while the average rating for the true statements was 4.8 points above the FACT midpoint). It appears that the participants in this research, perhaps as a result of taking a class in forensic psychology, exhibited a deception bias rather than a truth bias.

⁷ Much discussion during the class dealt with threats to the reliability and validity of forensic evaluations as well as study of the different populations typically of concern in these evaluations, that is, psychopathic individuals, individuals with pedophilic disorder, mentally ill offenders, and so forth. While the topic of client deception had been discussed throughout the class term, this was the first time these eight specific variables were discussed regarding their connection with deception detection.