Personality and Health Psychology Laboratory
Reverend Michael Wm. MacGregor, Ph.D., R.D.Psych.

Defense Mechanism Research

Defense Mechanisms 
One of the most important and lasting contributions that psychoanalytic theory has made to psychology is the concept of defense mechanisms (Vaillant, 1992).  An issue of the Journal of Personality (1998) set forth the status of defense mechanism research and provided the definitional criteria for defenses.  This issue of the Journal of Personality brought together a diverse body of literature and provided a uniform theoretical foundation for the understanding of defenses.  The research presented in the issue not only provided the reader with an understanding of the current state of defense mechanism research, but also with an understanding of research yet to be conducted.  For example, the issue discussed the reliable and valid assessment of defenses, research assessing the relation between defenses and physical health outcomes, and research assessing the relation between defenses and mental health outcomes.  If defense mechanisms is to be useful and of value to clinicians and researchers alike, there must be a reliable and valid method by which to assess defenses.  Only with a reliable and valid instrument can some of the theoretical hypotheses relating to defenses and psychopathology (or physical health) be tested.  It is the assessment, validation, and hypothesis testing related to defense mechanisms that forms my first line of research.  In particular it is the relation between defenses and mental health that forms the basis of my most recent research.

There are a number of different methods by which to assess defenses (e.g., observer-report, laboratory report, self-report), each with its own strengths and limitations.  To date my research has focused on an observational and self-report approach to the assessment of defense mechanisms.  Given that my future research will build upon my past and current research, I will briefly describe my recent efforts without attempting to provide a complete literature review.  


Reliable Assessment
Until recently one of the most serious limitations associated with defense mechanism assessment was the lack of uniform terminology.  That is, inconsistencies in the definitions and conceptualizations of defenses have hindered their reliable assessment (Vaillant, 1992).  For defense mechanisms to be useful concepts to clinicians and researchers they must first be operationally defined, and second, it must be demonstrated that defenses can be reliability observed and rated.  Part of the research I have been involved with has been focused on the operationalization and reliable assessment of defense mechanisms.  In an attempt to correct for the limitations associated with alternative measures of defenses (e.g., no operationalization) I have been involved in the development of a Q-sort approach (the Defense-Q) to assessing defenses (Davidson & MacGregor, 1996; MacGregor & Davidson, 1998).  As part of the development of this instrument we have operationalized the defenses that we assess, and we have developed a standardized manual of definitions, clinical examples, and information on coding.  In addition to the training manual we have also developed a standardized training procedure along with a standardized set of training tapes. The Defense-Q Manual has just undergone a text revision.

Using the Defense-Q as an instrument and following our training procedures we have trained both undergraduate and graduate students in the reliable assessment of defenses.  Our findings demonstrated that the coder reliability, individual defense mechanism reliability, and averaged coder reliability across all defenses mechanisms using the Defense-Q instrument was equal to or better than other existing measures of defenses.  This article demonstrates the ability to achieve reliable assessment of defenses using the Defense-Q.  


Construct Validity
In order to demonstrate the construct validity of defenses in general and of the Defense-Q in particular we have conducted a number of investigations looking at the predictive validity of defenses assessed by the Defense-Q.  As well, we have looked at the ability of the Defense-Q to better predict outcome measures compared to other measures of defenses.  In three studies we assessed participants' characteristic patterns of defense use with the Defense-Q and determined the similarity of each person's defense pattern to a prototypical adaptive defense profile (ADP) to achieve an ADP similarity score.  Consistent with theory, higher ADP similarity scores were significantly related to lower self-reported depression and hostility, higher informant and observer ratings of levels of empathy and competency, and lower resting cardiovascular measures.  These results were found both for undergraduate and for population-based samples.  In additional studies we compared defenses assessed with the Defense-Q to defenses assessed with a self-report measure of defenses and again, consistent with theory, higher ADP similarity scores were predictive of both higher informant ratings of empathy and competency and of lower cardiovascular measures. That is, those person's with higher ADP similarity scores were more likely to be rated by observers to be empathic and competent and more likely to have lower resting systolic and diastolic blood pressure.  Using a self-report measure of defenses, those person who reported using more adaptive defenses were not judged to be more empathic or competent but those persons who reported using more image-distorting defenses were.  Defenses assessed by self-report were unrelated to blood pressure.  These results are consistent with the idea that defenses assessed with the Defense-Q are theoretically related to expected outcomes, and are more predictive of theoretically expected outcomes than defenses asses by an alternative self-report measure.  


Defenses and Physical Health
In order to test some of the hypotheses relating to defenses and physical health I have been involved in a study aimed at determining the relation between defense use and blood pressure.  In 1939 Alexander introduced the idea that use of less adaptive defense mechanisms may contribute to the development and maintenance of high blood pressure.  Using the Defense-Q we tested whether adaptive defense use (i.e., those persons with higher ADP similarity scores) had an impact on resting blood pressure in older compared to younger adults.  We determined the interaction between age, sex, and defense use in a subsample of persons from a population-based sample of adults over the age of 18 and stratified on age and sex.  We found that there was a significant age by sex by defense use interaction for both systolic and diastolic blood pressure.  The results revealed that adaptive defense use predicted lower resting systolic and diastolic blood pressure in 65+ year old women.   


Defenses and Health Care Costs
As health care costs are an important consideration in light of shrinking health care budgets, we investigated the relation between adaptive defense use and physician health care costs.  Using a subsample of persons from a population-based sample of Canadian adults (where all persons belonged to one health care provider) the relation between defense use and physical health care costs over a three-month period was determined.  More adaptive defense use predicted lower physical health care costs.  As well, more adaptive defense use predicted lower reports of physical illness such as peripheral-vascular disease, lower reports of self-reported depression, and fewer days of work missed due to illness.  These results were similar when all persons with major medical illness (e.g., heart disease) or mental illness were removed from analyses.  


Future Research:  Defenses and Mental Health
My most recent research ideas have expanded my focus to include the relation between defenses and psychopathology.  I am involved in an ongoing study investigating the relation between defenses and anxiety and depression.  Specifically, we are attempting to differentiate anxiety and depression on the basis of defenses.  We are using an outpatient psychiatric population for this investigation.  Also using an outpatient population we are investigating the relation between defenses and borderline and histrionic personality disorders.  We are attempting both to test some of the theoretical assumptions regarding which defenses underlie these disorders (e.g., splitting in borderline personality disorder) and to differentiate the two disorders on the basis of defenses. Additionally, I have recently proposed to investigate the relation between defenses and psychopathology as assessed by the Personality Assessment Inventory (PAI).  I have proposed to not only assess each person's personality using the PAI but also to assess each person's defenses.  In that way we can again test some of the theoretical assumptions relating to defenses and psychopathology (e.g., Turning Against Self as a key defense in depression) as well as test the ability of defenses to differentiate between disorders.  For the proposed sixth axis of the DSM-IV to be useful we must not only be able to reliably and validly assess defenses, but the process of assessment must also be clinically meaningful and add to our conceptualization and understanding of disorders.   
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