Clinical Myths of Forensic Neuropsychology

Abstract

Clinical myths and lore are unfounded beliefs that still influence practice decisions. I examine the validity of six beliefs commonly encountered in forensic neuropsychology practice: the admissibility of test batteries; avoidance of practice effects; forewarning insures good effort; average deficits in bright persons; 15% chronic impairment in mild brain injury; and examiner bias causing malingering. I show these beliefs are invalid because of material misunderstandings of case law and literature, falsification by empirical findings, and lack of authoritative sources. The benefits, costs, and persistence of clinical myths are discussed.

Keywords:

• Myths
• Neuropsychology
• Forensic
• Clinical folklore.

Acknowledgments

This review paper is unfunded. Part of my practice includes defense-selected evaluations in personal injury matters. A portion of this paper derives from a book chapter (Greiffenstein, 2008). I wish to thank Laurence Binder and Glenn Larrabee for their preliminary reviews and helpful criticisms.

Notes

¹ There was a Daubert challenge in this case to the testimony of a “vocational specialist” who speculated about the minor plaintiff's future job prospects. The judge excluded that intuitive testimony.

² As this article went to production, the New Hampshire Supreme Court struck down the “only a fixed battery is admissible” position. In Baxter v. Temple, a lead exposure case, the initial trial court ruled as inadmissible any testimony based on flexible battery evidence. The state's supreme court reinstated the evidence, finding the “fixed battery” argument to be fallacious and inconsistent with accepted practice.

³ Diaz-Asper reported a mean effect size of 0.73 for the low to average group, and the above average group showed a mean effect size of 0.41.