Faking amnesia and how to detect it

IMPORTANT NOTE: A revised version of this article has been published in the journal ESTRO. You can access the pdf HERE, or the full issue HERE (page 11).

Have you ever wondered if someone can fake amnesia? You might have seen the movie Memento where they suspect a patient to be faking. Well, believe it or not but people do try to fake memory loss. This is called malingering, but in this article I will generally refer to it as faking. The most usual reason is to avoid criminal punishment or gain money through insurance fraud (Binder & Rohling, 1996). For example, imagine you have an accident and get a minor head injury. If you fake amnesia perhaps you could get more money from your insurance claim. In terms of crime, in 1994 29% of all criminals sentenced to life imprisonment claimed amnesia at their trials and later some admitted feigning their memory loss (Pyszora et al., 2003). The question then becomes: how do you detect fakers?

First, there are two types of amnesia: retrograde and anterograde amnesia. Retrograde amnesia means that you can’t remember anything that happened before whatever incident caused the memory loss (usually an injury). This kind of memory loss can typically be seen in movies such as the Bourne movies, Cowboys and Aliens, X-Men, and Unknown. The other kind of memory loss is called anterograde amnesia, which is when you are unable to learn anything new. You might be less familiar with this kind of amnesia, but it is famously portrayed in the movie Memento. Doris in Finding Nemo also displays a kind of anterograde amnesia. As far as fakers go, it is more common to fake anterograde amnesia (Kapur, 1999). Most likely this is because people find it easier to pretend they can’t learn anything new compared to forgetting everything they already know. Fortunately it is also easier to detect fakers with this condition because more tests are available.

Cues for spotting a faker
One aspect that is common in all fakers is a tendency to exaggerate their symptoms. In other words, they tend to put effort into performing bad. For example, if I ask you to remember which of my hands is concealing a coin, then even after a short break you would probably get 100% right. Amnesiacs, however, can’t remember and are forced to guess, meaning they will score about 50% (Hanley et al., 1999). Fakers, on the other hand, will exaggerate their bad performance. They will remember which hand the coin is in and deliberately choose the wrong one, scoring below chance.

There are tests that are specifically aimed at detecting amnesia fakers, such as the TOMM (Tombaugh, 1997), but there is some debate as to whether these kind of tests are the most appropriate to use because they are not useful in assessing patients with real amnesia (Meyers & Volbrecht, 2003).  The tests are also not very effective if the patient suffers from dementia (Teichner & Wagner, 2004).

Since faking is a form of deception it is possible to use neuro-imaging to look for clues of lying. Fakers use different areas of the brain compared to genuine amnesiacs (Spence et al., 2004). Fakers who take the TOMM test also have higher brain activity (Browndyke et al., 2008). By the way, you may think that surely brain scanners can detect whether brain injury exist or not, but it is not that simple. Not all amnesia is due to brain damage, it can also be due to psychological trauma or stress.

There are other implicit measures that can be used to detect fakers: People who fake amnesia perform slower on reaction time tests (Van Hooff et al., 2009), and on memory test they tend to show a primacy effect while genuine amnesiacs don’t (Wiggins & Brandt, 1988). A primacy effect is a tendency to remember items at the beginning of a list. So if I give you the numbers 9,6,4,5,7 to remember, a primacy effect means you are likely to remember the number 9. Fakers show this effect too, but people with amnesia don’t. Also, if I were to give you this same list of numbers along with some new ones and ask you which you recognise, your pupils will dilate more when you recognise something. In other words, if you were to fake amnesia it would still be possible to check you pupil dilation to see if you are lying (Heaver & Hutton, 2010).

Anterograde amnesia
The good thing about detecting people who fake anterograde amnesia is that there is a wide variety of tests available. In fact, practically any memory test will do: fakers will typically score either below chance or worse than real amnesiacs.

Greiffenstein et al. (1994) used a variety of tests on amnesiacs and simulators (participants told to feign amnesia) to see which were suitable to detect fakers. One such test is the AVLT (Invik et al., 1990), a five-trial learning procedure where participants read a list of 15 words followed by free recall. Participants then do the same with a second list before finally the initial list is recalled again. People who fake will perform worse than patients with real amnesia on this task. A variety of other tests were used as well, but the details of the tests are not important. What is important is that on the majority of the people who fake amnesia would score worse than people with genuine amnesia. In other words, the fakers are sabotaging their own performance.

So, if someone pretends to be unable to learn new information, give them a memory test. If the person performs below chance or below the average of an actual amnesiac, then this is indication that he is faking. Be careful, though, because the performance may have been bad by chance, or there could be other reasons such as previous neurological conditions (Schretlen et al., 1991).

Retrograde amnesia
It is more problematic to assert whether a patient is feigning retrograde amnesia as this involves loss of memory prior to the onset of the condition. The variables in question are therefore largely out of the examiner’s control. For this reason there are relatively few tests that show promise of malingering detection within retrograde amnesia assessment. Jenkins (2009, cited in Jenkins et al., 2009) is one of few studies to compare performance between brain injured patients, controls, and instructed simulators on retrograde amnesia. Among the tests used was the Autobiographical Memory Interview (AMI), which uses samples of personal semantic memories across the lifespan, such as information from schooldays (Kopelman et al., 1989). Another test was the dead/alive test, which is a test of recognising whether a famous person is still alive or dead, and if the participant knows the circumstances of the death (Kapur et al., 1992). Jenkins (2009) found that simulators typically scored lower on both the AMI and the dead/alive test compared to brain injured patients.

Other tests exist that are designed to assess retrograde amnesia, such as the Famous Events Tests (Leplow & Dierks, 1997, cited in Fujiwara et al., 2008), which involve recall and recognition of public news events. However, few tests have been used in the context of retrograde amnesia patients who may be faking. Even if strong suspicions occur it is difficult to make accurate conclusions without patient confessions, which are rare. Fujiwara et al. (2008) tested five patients on a series of memory tests and strongly suspected that one of the patients was simulating functional retrograde amnesia, but was unable to conclude that this was so without the patient’s confession.

Conclusion
To summarise, a wide variety of tests are available to assess if a patient is faking anterograde amnesia. Performance worse than chance or below the baseline of genuine amnesiacs is cause for suspicion, especially if factors such as dementia and reduced cognitive functioning are ruled out. Feigning retrograde amnesia is relatively harder to assess, but there are tests available and trends suggests that simulators perform worse than patients with genuine amnesia. The best way to investigate faking is to use a combination of tests and see if the patient reliably scores below chance or the genuine amnesia baseline across the tests. In other words, do not rely on the results of only one test, but use several. Should a patient show signs of poor performance compared to real amnesiacs across the tests, then this is strong reason to suspect the patient is feigning. Ultimately, however, one cannot say with absolute certainty that the patient is simulating without a confession.

  • Note: This article is an extensive rewrite of a longer essay on malingering in amnesia. This essay has subsequently been published and is accessible via ResearchGate.
  • A more elaborate review on faking amensia is currently in prep.

References:

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4 thoughts on “Faking amnesia and how to detect it

  1. Pingback: “Faking Amnesia” article published in ESTRO | I am alive, p < .05.

  2. Pingback: How To Fake Amnesia | Information

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