An empirical look at the Defense Mechanism Test (DMT): reliability and construct validity

Although the Defense Mechanism Test (DMT) has been in use for almost half a century, there are still quite contradictory views about whether it is a reliable instrument, and if so, what it really measures. Thus, based on data from 39 female students, we first examined DMT inter-coder reliability by analyzing the agreement among trained judges in their coding of the same DMT protocols. Second, we constructed a "parallel" photographic picture that retained all structural characteristic of the original and analyzed DMT parallel-test reliability. Third, we examined the construct validity of the DMT by (a) employing three self-report defense-mechanism inventories and analyzing the intercorrelations between DMT defense scores and corresponding defenses in these instruments, (b) studying the relationships between DMT responses and scores on trait and state anxiety, and (c) relating DMT-defense scores to measures of self-esteem. The main results showed that the DMT can be coded with high reliability by trained coders, that the parallel-test reliability is unsatisfactory compared to traditional psychometric standards, that there is a certain generalizability in the number of perceptual distortions that people display from one picture to another, and that the construct validation provided meager empirical evidence for the conclusion that the DMT measures what it purports to measure, that is, psychological defense mechanisms.     

In defence of the Defence Mechanism Test (DMT)—a reply.

A paper by I. Zuber and B. Ekehammar in this Journal (38, 1997) is reviewed. The paper advocates that the non-veridical contents in the series of reports in the DMT should preferably be referred, not to psychoanalytic defence mechanisms, but to factors of stimulus order. The methods and the arguments of this investigation are critically examined.     

An empirical look at the Defence Mechanism Test (DMT) Stimulus effects

Based on a sample of non-clinical subjects (N=74) the study examines the Defence Mechanism Test (DMT) by focusing on when perceptual distortions, called ‘signs of defence’ in DMT terminology, occur (distribution in exposure duration), which part of the picture is involved (distribution in localisation), and which ‘signs’ go together (using correlation and factor analyses). The results disclosed that the occurrence of perceptual distortions (‘signs of defence’) was related to exposure duration (some ‘defences’ are more frequent at brief exposures, some others at longer exposure durations), and to localisation on the picture. The location of misperceptions to the central person (hero) or the peripheral person (pp) of the picture was the major explanatory principle for the distribution of ‘signs’ on factors. Rather than capturing psychodynamic defence mechanisms, which is the theoretical basis of the test, the analyses imply that the DMT seems to measure misperceptions which are a function of the localisation of persons on the stimulus picture and of exposure durations.     

In defence of the criticism of the Defence Mechanism Test (DMT): A reply to Kragh (1998)

Kragh ( Scandinavian Journal of Psychology , 1998, 39, 123–124) criticises a recent empirical study of the Defence Mechanism Test (DMT) conducted by the present authors (Zuber & Ekehammar, 1997) concerning methodological and other shortcomings. The present paper reviews and responds to Kragh's critical points. As to the most serious criticism, the methodological, the main conclusion is that Kragh's own published empirical studies of the DMT, and also those of other researchers, can be criticised along similar lines. Furthermore, and surprisingly, in contrast to our study, Kragh's main DMT studies do not employ the DMT picture(s) at all.     

The Wechsler Adult Intelligence Scale (WAIS), but not the Defence Mechanism Test (DMTm), separates schizophrenics and normal controls in a factorial cluster analysis

Ten schizophrenic patients and ten healthy control subjects matched with respect to sex, age and education were tested by a psychological test battery including WAIS, WCST, FAS and a modified version of the tachistoscopic Defence Mechanism Test (DMTm). In a Q-factor analysis two factors were derived in the analysis of DMTm test scores. The distribution of cases among these factors was wholly at random. On the other hand, when analysing WAIS scores, five factors were derived and schizophrenic cases as well as control subjects were almost unequivocally clustered by different factors. It is argued that also if an unequivocal categorisation of cases had been achieved in the analysis of DMTm data, such a finding might well have been interpreted as an effect of anomalies in cerebral structures assumed to be of critical importance in the filtering of signals in the stream of visual perception. The existence of such anomalies in schizophrenics is now well established by neuroimaging as well as postmortem studies, and findings are also well in accordance with phenomenological and physiological data. The failure of DMTm to separate schizophrenic and control subjects does thus make the second and important step in a discussion on validity entirely superfluous, namely whether signs recorded really measure what they are assumed to measure, in this case defence mechanisms in a psychoanalytic sense.     

Psychological defense mechanisms and electroencephalographic arousal

The aim of this study was to examine the relationship between psychological defense as measured by the Kragh tachistoscopic Defense Mechanisms Test (DMT), and general arousal properties of the individual as measured with electroencephalogram (EEG). The DMT assesses defense by presenting neutral and threatening pictures with very short exposure times. EEG characteristics were measured in the 8–12 Hz EEG frequency band during DMT testing. Twenty-one male subjects participated in the study. All were US Air Force personnel on active duty. Personnel with high defense mechanisms, defined in this connection as slow perception of the threat, tended to have higher cortical arousal after Stimulus exposure than the subjects with low defense mechanisms. The differences occurred mainly with new stimulus material without any threatening content. The differences in arousal response to novel stimuli may contribute to an understanding of the relationships between the Kragh DMT test and performance in life-threatening situations.     

Defense mechanisms and morality: a link between isolation and moralization

The relationship between morality and perceptual defense mechanisms was studied. Three new scales were constructed to measure different aspects of morality: moralism (the tendency to evaluate everything in terms of right and wrong), conscience (strength of feelings of right and wrong) and reparation (inclination to repair the damage one has caused). Perceptual defense mechanisms were measured with Kragh's Defense Mechanism Test (DMT). Three hypotheses about relationships between morality and defense mechanisms, derived from psychoanalytical literature, were tested on 54 male University students. Results show positive correlations between the defense mechanism isolation of affect and moralism, and between identification with the aggressor and reparation. Total amount of perceptual defense correlated positively with moralism. It is argued that the psychological study of morality should take unconscious processes into consideration.     

Effects of psychological defense on processing of neutral stimuli indicated by event-related potentials (ERPs)

The Defense Mechanism Test (DMT) is claimed to identify personnel with a high risk for accidents. A new explanation for why the DMT seems to predict performance when survival depends on split second decisions is proposed. Sixteen right-handed, adult male students were tested with the DMT and with an ERP paradigm (two sine wave tones, presented binaurally). Each subject was tested with a one-stimulus paradigm, and a passive and an active oddball paradigm. Under the passive oddball condition, High defensive subjects differed from Low, having significantly smaller N2 amplitudes (low immediate perception), and significantly larger P3 amplitudes (rely on later associative mechanisms). High defensive subjects seem to have less ability to perceive the environment correctly immediately. This slowness may be fatal when life depends on split second decisions. The fundamental neurophysiological difference may also be the basis for the very complex cognitive and perceptual mechanisms involved in psychological defense mechanisms.     

Personality organization defined by DMT and the Structural Interview

The psychoanalytic concept of Personality Organization (PO) may be operationalized by means of a Structural Interview as well as by means of psychological tests. The present study utilized the Structural Interview and a projective test called the Defence Mechanism Test (DMT) to operationalize the PO concept on a sample of 50 psychiatric inpatients. The reliability of the PO judgements were found to be acceptable for both the Structural Interview and the DMT. The validity, which was estimated as the correlation between the two methods, was also found to be substantial. The conclusion is that the concept of PO may be reliably operationalized for psychiatric patients and seems to have concurrent validity. Both the DMT and the Structural Interview may be used for differential diagnosis of PO.