DMT – A reliable and sensitive test for combat pilot selection

Defense Mechanism Test (DMT) ad modum Neuman

A reliable and sensitive test for combat pilot selection

By Jaan Suurküla, M.D.


This test is used worldwide as a combat pilot selection instrument and has drastically reduced the frequency of pilot errors, the most common cause for flight accidents. It detects defence mechanisms, that prevent the pilot from assessing the situation realistically in acute stressful conditions. These defences bring about a distorsion of the perception, like ignoring a warning signal, or interpreting it to be irrelevant or changed (eg from red to green).

This behavior occurs in people with trait anxiety, a disturbance caused by anxiety-provoking situations or traumas often in childhood. To alleviate anxiety, subconsciously these people acquire the habit of using defence mechanisms that reshapes the perception of the situation so as to appear less threating. This disturbance is very common in modern society.

The test is also being used for selection of civil pilots by some companies including SAS. It has also been used successfully for selection of top managers and other people who must act realistically under stressful conditions. It is suggested that it should be used for eliminating unsuitable world leader candidates, including presidents.


A great problem in combat pilot training all over the world has been that common psychological tests have not been able to reveal the deeply seated disturbances that make persons unable to keep the mind cool in highly stressful situations. In Sweden, a major part, sometimes even 80% of the pilot trainees, failed year after year. With few exceptions, the reason was psychological inaptitude revealed under demanding flight situations. The situation has been similar in other air forces, which meant great economic losses considering the high costs of pilot training.

Therefore the Swedish Air force sponsored the development of a test designed to reveal hidden psychological disturbances. The test used was the “Defence Mechanism Test” (DMT) originally created by Ulf Kragh. It was modified in important respects by the psychologist Thomas Neuman and was introduced in the Air Force 1970. As there are fundamental differences between Kragh’s method and the way Neuman applies it, we will call it “DMT-Neuman”.


DMT-Neuman detects disturbances in the perception of threatening pictures presented in a fraction of a second. It is experienced as a very brief flash that one only gets a very vague idea about. This is called subliminal perception. Persons with pronounced defence mechanisms react spontaneously with anxiety (indicated a/o by pronounced galvanic skin responses etc) that makes them distort what they perceive.

This test turned out to be very useful. There was a high correlation between the test points and inadequate behaviour or mistakes in demanding flight situations, which made it greatly superior to MMPI and other common tests used in pilot selection. The most important reason is that, differently from such tests, it does not depend on verbal responses to questions but is an objective detector of defence mechanisms.

The test reveals deep-seated disturbances

According to psychology, the proneness to use psychological defence mechanisms in threatening situations is closely related to the presence of deeply seated, often early acquired memories of anxiety-provoking and otherwise traumatic or insecurity-causing experiences. These memories uphold an increased level of conscious or often subconscious anxiety, called trait-anixety in psychology.

When a situation somehow appears threatening to such a person, this anxiety tends to break through. The defence mechanisms serve to suppress these anxiety provoking impressions. So, differently from secure and harmonious people who perceive the threat realistically and handle it adequately, the disturbed person immediately mobilizes reality-distorting defence mechanisms.

It is important to note that the defence mechanisms are often so strong that people are not even aware of having any anxiety at all, and they appear perfectly normal psychologically. This is the reason why paper-pencil tests where people are asked to tell about their symptoms have failed completely in pilot selection. Actually, it is the experience in psychoterapy, that those who are totally anxiety-free tend to be the most disturbed ones. It has been suggested that the reason is that they carry so painful anxiety-provoking memories that, in response, they have developed extra strong defence mechanisms to suppress the anxiety. So paradoxically, a nervous person may be more psychologically healthy than a completely anxiety-free one.

Great decrease of flight accidents with DMT-Neuman

In the Swedish Airforce, there has been a great decrease (to almost zero) of accidents and incidents caused by pilot mistakes since the introduction of the test in 1970 (1). Formerly, such pilot mistakes were the major cause for serious incidents and crashes, and there were 10-20 people or more killed every year because of this. The same is the experience from the other air forces that now are using this test for selection of combat pilots (for more, see footnote 1)

Furthermore, before DMT-Nueman was used for pilot selection, about 55-80% of the pilot trainees failed every year due to inappropriate flight behavior (making mistakes in stressful situations provoked by the teachers). But after the test was introduced, virtually no Swedish pilot trainee has been discarded for this reason, although the pilot trainers systematically expose them for the same “stress tests” in flight action that made a major part of trainees drop out formerly.

Defence mechanisms are remarkably common

Experience from DMT-Neuman studies has objectively verified the experience of psychologists that most people with these disturbances behave normally, except for in threatening situations. Therefore, barring reliable detection methods, their presence in the population was greatly underestimated before DMT appeared.

Extensive testing using DMT indicates that a very small proportion of the population is free from such defence mechanism-activating disturbances (see footnote 2). This concurs with experiences from psychoterapy and developmental psychology that indicates that very few people, not even one percent of the population, have a high level of inner security, which is associated with a high level of self-actualization. High inner security is associated with low trait anxiety and thus no propensity for using defence mechanisms.

Experience from many hundreds of thousands of cases of psychotherapy has shown that it takes often 20-25 years or more of psychotherapy to access and cure these deeply seated subconscious anxiety-provoking disturbances.

DMT-Neuman should be used to select leading decisionmakers

Considering that defence mechanisms are so common, and can have devastating effects on the judgement in critical situations, this test should be used for the selection of decisionsmakers. This goes especially for people like presidents and top managers who often have to make vital decisions under great stress. Under such circumstances, an anxiety-prone person is very likely to make fatal mistakes because of the reality-distorting effect of defence mechanisms.

An effective remedy

The Swedish airforce launched a search for methods that might restore normality in disturbed pilots who had been grounded due to bad DMT performance. As they found that conventional methods were far to slow in curing this condition, they looked for unconventional alternatives. They found one method that deserves mentioning due to the remarkable result.

They first made a minor pilot study using this method on 5 grounded airforce pilots. After one year of regular use of it, the pilots improved in a manner corresponding to 20-30 years of psychoterapy, according to Thomas Neuman. The result was confirmed in a controlled study.

The method producing this result was Transcendental Mediation (TM), introduced by Maharishi Mahesh Yogi, a mental technique which differs fundamentally from relaxation techniques and other meditation methods, for whom such effects have not been reported. This remarkable effect of TM concurs with several other studies, reporting profound effects of the technique. For more information of the effects of TM, see for example The Swedish Phycisians for TM and their American counterpart, “Ask the Doctors”.

Acknowledgement: I want to thank Air Force Colonel Lieutenant Folke P Sandahl, who supervised the Air Force DMT development project, for checking and confirming the correctness of this manuscript and for valuable suggestions and advice. 


  1. The validity of Neuman’s interpretation methodUlf Kragh, the inventor of DMT suggested the responses to subliminally presented threatening pictures could be interpreted as projections of psychological states of the subject. However it is difficult to reliably establish the psychological significance of a certain response.

    Because of this, Neuman avoided any evaluation of psychological states with his version of DMT. His mission was to develop a stringent quantitative test for selection of Air Force pilots. The Air Force demanded it should have a high reliability and validity. To achieve this, Neuman found it was useful to assess only the presence of Defense Mechanisms. The number of different Defense Mechanisms present and some other stringently quantifiable criteria were used for calculating test points.

    In a systematic manner, Neumann developed his evaluation method using mistakes in combat pilot performance as the criterium of validity. He arrived at a correlation above 0,7 between the test points and error-proneness in pilot performance. The validity of this method has been further confirmed in extensive practical use in the Swedish and other air forces. As said above, since the introduction of the test, there has been a very great decrease (to almost zero) of accidents and incidents found to be caused by pilot mistakes.

    Neuman did additional in-depth studies that further confirmed the validity of his method, demonstrating the connection between presence of defence mechanisms as revealed by his test and traumatic memories. He found that TM first normalized responses associated with recent traumatic memories and then gradually worked backward in the “record” of traumas. Unfortunately, the Air Force decided these reports should be confidential as they revealed intimate personal details of the subjects, some of whom still are active in the Air Force. In assessing anxiety he did not use projective psychology interpretations but objective criteria like galvanic skin responses.

    Conclusion: While the Kragh system uses a projective test approach for assessing the psychological response with important uncertainities due to interpretation problems, DMT-Neuman is a scientifically stringent quantitative method determining the amount of defense mechanisms with a high level of validity and reliability.

  2. High proportion of the population found to have trait anxietyThe Swedish Airforce submits about 700-800 air force pilot training applicants to testing every year. The proportion that has passed DMT without showing a dangerous propensity for using defence mechanisms has been about 1 on 30-40, that is about 2,5-3,0%.

    However, it must be pointed out that the applicants were not a random sample from the population. It consisted of persons interested in undergoing pilot training. To be eligible, they had to be approved for military service by the drafting organization, which dismisses a significant proportion every year, including pepople with behavioral disturbances, alcohol- and drug additiction and other problems. Also people with pronounced psychosomatic and stress-relatd disorders are eliminated.

    Therefore, the applicants for pilot training are most probably, at an average, more healthy than the population in general. This may indicate that the real proportion not having trait anxiety and the associated propensity for defence mechanisms is even less than 0,25%.





1. Sandahl, F.P.: The Defence Mechanism Test DMT as a Selection Instrument when Testing Applicants for Training as Military Pilots. Stockholm: Kungl Krigsvetenskapsakademiens Handlingar och Tidskrift (Proceedings and Journal of the Swedish Military Academy) nr 4, p 132-154, 1988.

2. Sandahl, F.P.: Inverkan av tm-utövning på neurotiseringsgrad. Stockholm: Läkartidningen (Journal of the Swedish Medical Association), vol 77, nr 34, p 2808 ff, 1980. (Swedish)

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