Test of Memory Malingering (TOMM)

The issue of malingering is becoming increasingly important in the field of forensic psychology, particularly in cases involving traumatic brain injury, where alleged memory impairment is often used to seek personal compensation or as a defense against prosecution for various types of crimes. The Test of Memory Malingering (TOMM) was developed by the author to provide an objective, criterion-based test that is able to discriminate between individuals with bona fide memory impairment and those with feigned symptoms of impaired memory. The acronym TOMM was selected to emphasize that the test was developed with a definite, preconceived notion—to determine whether or not an individual is feigning or malingering a memory impairment. Thus, the TOMM should not be viewed as a malingering test per se.

The TOMM consists of two learning trials and a retention trial. The learning trials consist of a learning phase and a test phase. The study portion of each learning trial contains 50 line-drawn pictures (targets), each presented for 3 seconds with a 1-second interval between pictures. The same 50 pictures are used on each learning trial. However, they are presented in a different order on the second trial. During the test phase, each target is paired with a new line drawing (distractor). The position of the target is counterbalanced for the top and bottom positions. The person is required to select the correct picture (i.e., target) from each panel. For each answer, the examiner provides feedback about the correctness of the response. A delayed retention trial, consisting only of the test phase, is administered approximately 15 to 20 minutes after completion of the two learning trials. The TOMM is available in a computerized as well as a paper-and-pencil format.

Development and Validation

The TOMM was initially validated with 475 community-dwelling adults ranging in age from 17 to 84 years and 187 neuropsychological assessments from patients classified as follows: no cognitive impairment (n = 13), cognitive impairment (n = 42), aphasia (n = 21), traumatic brain injury (TBI) (n = 45), depression (n = 26), and dementia (n = 40). Inspection of the distribution of correct responses for the cognitively intact participants and the clinical patients showed that most nondemented individuals achieved a perfect score on Trial 2 and the retention trial. Moreover, rarely did a nondemented patient obtain a score lower than 45. In view of these results, the criterion score of 45 on Trial 2 or on the retention trial was selected. That is, any score lower than 45 should raise concern that an individual is not putting forth the maximum effort and is likely malingering. The criterion score correctly classified 100% of the community-dwelling participants and 95% of the nondemented clinical patients (cognitively impaired = 90%; aphasia = 95%; TBI = 98%; depressed = 100%; and dementia = 73%). Thus, the only clinical sample with a relatively low sensitivity score was the dementia group. Even these individuals still obtained a score of greater than 92% on Trial 2. The finding that the scores on the TOMM were less than 95% for the dementia group is not particularly negative since it is unlikely that feigning memory impairment is a major issue when dementia patients undergo neuropsychological assessment.

It should be noted that “below-chance” performance (<18 correct at the 95% confidence level) also can be used as a statistical decision rule. However, experience has shown that malingerers or individuals simulating malingerers do not ordinarily obtain below-chance scores on the TOMM on any trial. Of course, if they do, the decision rule can be applied.

Five experiments using different types of participants and different types of experimental designs provide evidence that the TOMM readily differentiated between malingering and nonmalingering individuals and show that the TOMM is a useful psychometric test for detecting exaggerated or deliberately faked memory impairment. In this context, it should be noted that the TOMM meets all the guidelines established in Daubert v. Merrell Dow Pharmaceuticals (1993) to define the generally accepted standards for judges to use in determining the scientific admissibility of evidence, particularly when presented by expert witnesses.

Interpreting the TOMM

Interpretation of the TOMM should never be made solely on the basis of the TOMM score that a patient achieves. It depends on many factors, starting with the basic conceptual issues on how malingering is defined. The TOMM does not measure a general trait called “malingering.” In forensic assessments, the TOMM is not an appropriate test to evaluate whether or not a person is faking a psychiatric disorder any more than it would be appropriate to use it to determine if a person is faking a back injury. Moreover, the interpretation of the TOMM should not be used to identify a “malingerer” but rather to indicate that a person is putting forth less than the maximum effort. Although individuals malinger, malingering cannot be legitimately viewed as a personality trait. Malingering in one situation does not necessarily mean that the person will always malinger or, in fact, will ever malinger again. In many, if not most, instances, individuals with TBI who malinger are “good” people caught in “bad” situations. It must also be remembered that malingering is not an all-or-none phenomenon but that it exists in different degrees, ranging from minor exaggeration of existing symptoms to flagrant faking of nonexistent symptoms.

References:

  1. Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993).
  2. Lynch, W. J. (2004). Determination of effort level, exaggeration, and malingering in neurocognitive assessment. Journal of Heat Trauma Rehabilitation, 19, 277-283.
  3. Multi-Health Systems. (2006). Test of Memory Malingering (TOMM). Research monograph: Summary application in clinical and research settings. Toronto, ON, Canada: Author.
  4. Tombaugh, T. N. (1996). The Test of Memory Malingering (TOMM). Toronto, ON, Canada: Multi-Health Systems.
  5. Tombaugh, T. N. (2002). The Test of Memory Malingering (TOMM) in forensic psychology. Journal of Forensic Neuropsychology, 2, 69-96.
  6. Vallabhajosula, B., & VanGorp, W. G. (2001). Post-Daubert admissibility of scientific evidence on malingering of cognitive deficits. Journal of the American Academy of Psychiatry and the Law, 29, 207-215.

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