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In order to use the Myers-Briggs Type Indicator® (MBTI®) appropriately and effectively, professionals need an authoritative source of advice and guidance on how to administer, score, and interpret this test. Written by Naomi Quenk-who coauthored the 1998 revision of the MBTI® Manual and the MBTI® Step II Manual-Essentials of Myers-Briggs Type Indicator® Assessment, Second Edition is that source.
Like all the volumes in the Essentials of Psychological Assessment series, this book is designed to help busy practitioners, and those in training, to quickly acquire the knowledge and skills they need to make optimal use of major psychological assessment instruments. Each concise chapter features numerous callout boxes highlighting key concepts, bulleted points, and extensive illustrative material, as well as test questions that help you gauge and reinforce your grasp of the information covered.
Completely revised and up to date with discussion of new versions of the MBTI® such as MBTI® Step II and MBTI® Complete, Essentials of Myers-Briggs Type Indicator® Assessment, Second Edition provides expert assessment of the instrument's relative strengths and weaknesses, valuable advice on its clinical applications, and several illuminating case reports.
The book contains no figures.
Series Preface ix
1 Overview 1
2 How to Administer the MBTI® Instrument 31
3 How to Score the MBTI® Instrument 43
4 How to Interpret the MBTI® Instrument 53
5 Strengths and Weaknesses of the MBTI® Assessment 93
6 Clinical Applications of MBTI® Step ITM and Step IITM Assessments 105
7 Illustrative Case Reports 151
Annotated Bibliography 179
About the Author 195
Note: The Figures, References, and/or Tables mentioned in this sample chapter do not appear on the Web
The Myers-Briggs Type Indicator (MBTI) personality inventory is firmly grounded in C. G. Jung's theory of psychological types, first presented in his book Psychological Types (1921/ 1971). MBTI assessment of type has been available in published form since 1956, though its development began some 15 years earlier. A wealth of information has since been generated about the instrument's theoretical basis, its reliability and validity, and its practical application in widely diverse areas. There are three editions of the MBTI manual (Myers, 1962; Myers & McCaulley, 1985; Myers, McCaulley, Quenk, & Hammer, 1998), as well as a comprehensive review of research in seven application areas (Hammer, 1996 ). These and many other sources contain valuable information about the theory, psychometric characteristics, research relationships, and applications of the MBTI. The sheer magnitude of what is available can be daunting to those new to the instrument as well as to experienced practitioners seeking practical guidance for administering and interpreting the MBTI.
Essentials of MBTI Assessment encapsulates the overwhelming amount of MBTI information by providing all key information in a manner that is straight-forward and easily accessible. Each chapter includes several "Rapid Reference," "Caution," and "Don't Forget" boxes that highlight important points relevant to each topic. Chapters end with a series of questions designed to solidify what you have read. The primary emphasis is on clinical uses of the MBTI; however, professionals in any area of application will find the basic information they need to effectively administer and interpret the MBTI in their setting.
HISTORY AND DEVELOPMENT
Jung's Psychological Types (1921/ 1971) was translated into English in 1923. Interest in the work was generally limited to Jungian and psychoanalytic circles in both Europe and America. It was fortuitous, if not remarkable, that two women, Katharine C. Briggs and her daughter, Isabel Briggs Myers (neither of whom had credentials in Jungian analysis or psychological test development), read Jung's work, spent 20 years studying it, and devised an instrument-- the MBTI-- to assess typology. Their years of intensive reading of Jung and careful observation of individual behavior led to their conclusion that typology could provide a useful way of describing healthy personality differences and, importantly, that such assessment could be put to practical use in people's lives.
Jung's interest in types emerged from his observation of consistent differences among people that were not attributable to their psychopathology. At first he believed that two basic attitude types-- extraverts and introverts -- adequately explained the differences he found. Further observation convinced him that other differences must be at work and that his two-category typology was inadequate. He subsequently added opposite mental functions to his descriptive system: two opposite functions of perception, sensation (called Sensing in the MBTI) versus intuition, and two opposite functions of judgment, thinking versus feeling.
Briggs's early interest had been in the variety of ways that people achieved excellence in their lives. Prior to discovering Jung's work, she had studied biographies in an effort to develop her own typology. In addition to opposites similar to those described by Jung, she observed that individuals differed in the way they habitually related to the outside world. Her early observations ultimately led to the addition of a fourth pair of opposites to Jung's system, a Judging versus a Perceiving attitude toward the outer, extraverted world. Although Jung did not explicitly identify this pair of opposites, Briggs and Myers found it to be implicit in his writings.
Published forms of the MBTI have been in existence since 1956. Until 1975, when its publication moved from Educational Testing Service to Consulting Psychologists Press, it was used primarily by a small number of enthusiastic researchers. Consulting Psychologists Press made the MBTI available to all professionals who were qualified to purchase Level B instruments. Since 1975 over 30 million people have taken the Indicator, more than 10 million in the past 5 years. About 2 million people fill out the MBTI annually, making it by far the most widely used instrument for assessing normal personality functioning.
Rapid Reference 1.1 gives a chronological listing of significant events in the history of MBTI development.
A major reason for the popularity of the MBTI is its relevance in many quite diverse areas-- education, career development, organizational behavior, group functioning and team development, psychotherapy with individuals and couples, and in multicultural settings. Because of its long history and prevalence as a research instrument, there are well over 4,000 articles listed in an ongoing MBTI bibliography (Center for Applications of Psychological Type, 1999), including more than 1,300 dissertations. The bibliography is updated monthly. The Journal of Psychological Type has published 49 volumes primarily devoted to typological research efforts.
Essentials of MBTI Assessment focuses on MBTI Form M, the standard form of the instrument that was introduced in 1998. Users who are familiar with Form G, the previous standard form, may be particularly interested in the similarities and differences between the two forms, which are briefly described in Rapid Reference 1.2.
There are two extended forms of the MBTI, Forms J and K, along with associated scoring methods and reports (Mitchell et al., 1999; Quenk & Kummerow, 1997; Saunders, 1987, 1989), which yield additional individualized typological information. The development and uses of these forms, scoring methods, and reports are beyond the scope of this book. Interested readers can find relevant information in the references cited. There is also a type indicator designed for children aged approximately 8 through 14, the Murphy-Meisgeier Type Indicator for Children (Murphy & Meisgeier, 1987 ), which rests on the same assumptions as the MBTI but contains different items, scoring method, and guidelines for interpretation.
THEORETICAL FOUNDATION OF THE MBTI
The Jung/ Myers theory of psychological types is a way of describing and explaining certain consistent differences in the ways that normal people use their minds. The MBTI purports to identify these differences through a 93- item, self-administered, paper-and-pencil questionnaire. Results show the respondent's preferences on each of four pairs of opposite categories, which are called dichotomies. According to the theory, all eight categories, or preference poles, included in the MBTI are used at least some of the time by every person. However, individuals have an innate disposition toward one category (pole) of each dichotomy. The goal of MBTI assessment is to accurately identify preferences by sorting respondents into the categories to which they are already disposed. To elicit preferences between categorical poles rather than the degree of liking for or use of each opposite pole, all items are presented in a forced-choice format. This question format requires the respondent to choose between two mental functions or two attitudes in order to identify which is naturally preferred. If respondents were instead asked to indicate their use of or liking for each pole separately (as with a Likert-type rating scale), preference for one over the other could not be readily distinguished. Forcing respondents to choose between two legitimate ways of using their minds most directly and clearly elicits a preference.
The mental functions and attitudes that are the basic elements of the Jung/ Myers theory follow.
The Opposite Functions of Perception: Sensing and Intuition
Sensing perception uses the five senses to become aware of facts and details occurring in the present. When Sensing perception is being used, the perceiver is grounded in and trusting of the evidence of the senses, focusing on concrete reality, and the gathering of facts and details. There is trust in what is known and can be verified. With little conscious effort, a person who prefers Sensing has a memory that is specific, detailed, literal, and complete. Without exercising considerable conscious effort, he or she is less likely to give credence and be interested in hypotheses, the unknown, and future possibilities. Sensing is a process that avoids inferences and conjecture and prefers instead to make decisions based on verifiable facts. People who prefer Sensing can experience any requirement to speculate on an unknown future as a pointless distraction from what is important.
Intuitive perception looks at patterns, meanings, and future possibilities that are believed to be implicit in current reality. When Intuition is being used, the perceiver focuses on concepts, ideas, and theories, inferring connections among diverse pieces of information. With little conscious effort, Intuitive perception moves quickly and easily from what is present in the here and now to what is implied and possible in the future. Without exercising considerable conscious effort, a person who prefers Intuition has difficulty memorizing and using facts without putting them into an interesting context. Intuition is a process that is less experienced and interested in acquiring , remembering, and using facts and details for their own sake. People who prefer Intuition can experience such a focus as inhibiting to their free flow of ideas and as a pointless distraction from what is important.
The Opposite Functions of Judgment: Thinking and Feeling
Thinking judgment applies specific criteria and principles in a linear, logical analysis of Sensing or Intuitive information. The goal is to arrive at the objective truth or a reasonable approximation of truth. When Thinking judgment is being used, the person making the judgment takes an objective and dispassionate approach to the available data. With little conscious effort, individuals who prefer Thinking can maintain an objective stance and personal distance by keeping issues of their own and others' personal values and well-being separate from their decision making. Typically, only after a Thinking conclusion has been arrived at can conscious effort be devoted to considering issues of welfare and harmony.
Feeling judgment applies specific, usually personally held values to assess the relative importance of the Sensing or Intuitive information available. When Feeling judgment is being used, there is concern for the impacts and consequences of a decision on individuals or groups of people. The goal of a Feeling decision is to maximize harmony and well-being for people and situations. Without conscious effort, people who prefer Feeling take into account their own and others' feelings, values, and welfare. They use personal connections and empathy with the people affected by a decision to arrive at a conclusion. People who prefer Feeling can readily recognize logical principles and objective criteria for decision making. However, without exercising considerable conscious effort, they avoid using such criteria if harm and disharmony will result.
The terms chosen by Jung and retained by Myers for these two opposites have some unfortunate potential "surplus meanings." Therefore it is important to recognize that in the MBTI Thinking judgment does imply the absence of emotion but rather an automatic setting aside of value considerations for the sake of impartiality and objectivity. Feeling judgment does not refer to the experience and expression of emotion. Emotion is separate from Feeling judgment in that emotion is accompanied by a physiological response that is independent of decision making. Thinking types and Feeling types can be equally passionate about a favored position in spite of contradictory evidence that violates certain logical principles (for Thinking types) or certain values (for Feeling types).
Similarly, a Thinking judgment is not more intelligent or correct than a Feeling judgment. In the Jung/ Myers theory, Thinking and Feeling describe rational processes that follow laws of reason; that is, they evaluate data using definite criteria --logical principles for Thinking and personal values for Feeling.
The Opposite Attitudes of Energy: Extraversion and Introversion
Extraversion as an attitude directs psychic energy to and receives energy from the outer world of people, things, and action. When in the Extraverted attitude, a person interacts with the environment, receives energy through actively engaging with people and activities, and takes a trial-and-error approach to acquiring new experiences and skills. People who prefer Extraversion tend to think most effectively when interacting and talking to others and it takes little conscious effort for them to approach others and explore the outer world. Without conscious effort, it is hard for them to think only internally, since they often become aware of what they are thinking only when they are verbalizing. Spending too much time without external activity can result in fatigue and low motivation.
Introversion as an attitude directs psychic energy to the inner world of ideas, reflection, and internal experiences and is energized by operating in that realm. When in the Introverted attitude, a person spends time reflecting on and reviewing ideas and experiences, and observes and thinks about whether or not to interact with new people or try new outside activities. People who prefer Introversion tend to think internally before expressing their thoughts to others. It takes little conscious effort to keep what they are thinking to themselves. Without conscious effort, it is uncomfortable and difficult for them to express their thoughts without first reflecting on them. Spending too little time alone and too much time interacting with people and the environment can result in fatigue and low motivation.
The Two Opposite Attitudes Toward the Outside World:
Judging and Perceiving
A Judging attitude involves the habitual use of one of the judging functions, Thinking or Feeling , when interacting with the outer world. When a Judging attitude is being used, there is a desire to reach a conclusion (use judgment) and make a decision as quickly and efficiently as possible. Without conscious effort, individuals who prefer a Judging attitude are organized, structured, effectively work within schedules, and begin tasks sufficiently early so that deadlines can be comfortably met. Without exercising considerable conscious effort, they resist putting off decision making, working without a set plan, and operating in an environment where there are frequent interruptions and diversions.
A Perceiving attitude involves the habitual use of one of the perceiving functions, Sensing or Intuition, when interacting with the outer world. When a Perceiving attitude is being used, there is a desire to collect as much information (i. e., perceive) as possible before coming to a conclusion. Without conscious effort, a person who prefers a Perceiving attitude is flexible, adaptable, and spontaneous when operating in the outside world, works comfortably and effectively when there is pressure of an imminent deadline, and welcomes interruptions and diversions because they stimulate new energy and may provide additional useful information. Without considerable conscious effort, it is difficult for him or her to start on tasks very far in advance of a deadline, operate within set schedules, and be orderly and methodical in pursuing desired goals.
A frequent source of misunderstanding for people with regard to the Judging and Perceiving attitude is knowing that these attitudes describe ways of relating to the outside, extraverted world regardless of one's preference for Extraversion or Introversion. People who prefer a Judging attitude behave in a Judging manner while extraverting (extraverting either Thinking or Feeling , whichever they prefer); people who prefer a Perceiving attitude behave in a Perceiving manner while extraverting (extraverting either Sensing or Intuition, whichever they prefer).
Rapid Reference 1.3 summarizes the four dichotomies that constitute a four-letter type and indicates their designation as either attitudes or functions. The order of presenting the dichotomies in this Rapid Reference is the one typically used when presenting type to clients, rather than the one used in the preceding discussion. It also corresponds to the order used in the standard type code. Alternative strategies for presenting the functions and attitudes are considered in Chapter 4. Like all definitions and descriptions of MBTI preferences and types, the brief definitions presented here are designed to be neutral and positive in tone, conveying that neither pole of any dichotomy is favored over its opposite.
An individual's preferences can be summarized in a four-letter code, each letter standing for one of the eight preferences, such as ISTJ for Introverted, Sensing, Thinking, Judging or ENFP for Extraverted, Intuitive, Feeling , Perceiving. All possible combinations of preferences yield 16 different types. All 16 types are seen as valid and legitimate ways of being psychologically healthy, adapted, and successful, though their interests, talents, and general outlooks are likely to be quite different.
Dynamic Personality Type
Personality type is the result of the interplay of a person's four preferences, represented by one pole of each dichotomy. This interplay is of a dynamic and interactive nature rather than a static or additive one: The whole type is hypothesized to be greater than the sum of the four preferences it encompasses. It is assumed that every individual has access to all eight preference poles-- Extraversion and Introversion, Sensing and Intuition, Thinking and Feeling , a Judging attitude and a Perceiving attitude. The underlying rationale for this assumption is that each of these functions and attitudes is necessary for psychological adaptation and therefore is present in every person's psychological makeup. However, each is likely to be used with greater or lesser comfort and facility by an individual, depending on its dynamic status within his or her type.
Dynamic status is represented in the Jung/ Myers theory as the likely use and development of the system's four functions, or processes (Sensing, Intuition, Thinking, Feeling), which may be dominant (most used, capable of development, and under conscious control), auxiliary (second in use, development, and conscious access), tertiary (third in use and development, and relatively unconscious), or inferior (least used and developed, and primarily unconscious). The theory also specifies that the auxiliary function must be the "other kind" of mental function to that of the dominant; that is, if the dominant function is one of the perceiving functions (Sensing or Intuition), then the auxiliary function must be one of the judging functions (Thinking or Feeling); if the dominant function is one of the judging functions (Thinking or Feeling), then the auxiliary function must be one of the perceiving functions (Sensing or Intuition). By conceptualizing the psyche in this way, an individual has reasonable conscious access to one kind of perception and one kind of judgment so that two critical human endeavors can be directed and controlled.
Both Jung and Myers specified that people who by nature prefer the Extraverted attitude and are most comfortable in that attitude, tend to use their dominant, most consciously accessible function when extraverting; people who by nature prefer the Introverted attitude and are most comfortable in that attitude, tend to use their dominant, most consciously accessible function when introverting. Jung, with Myers and Briggs concurring, were also clear that the fourth, inferior function, operated primarily in the opposite, less preferred attitude of Extraversion or Introversion. It should be noted that Jung's use of the term inferior function was in contrast to his alternative term for the dominant function, which was the superior function. The fourth function is "inferior" only in the sense of being last in its accessibility to conscious control.
Jung did not provide clear guidelines regarding the attitude of the auxiliary and tertiary functions. Myers and Briggs amplified and extended Jung's theory by specifying that for sound and healthy adaptation, the auxiliary function operated in the less preferred attitude. In extending Jung's system in this way, they provided for a comfortable and effective way of extraverting and introverting , both of which are necessary for human functioning.
With regard to the attitude of the tertiary function, Myers and Briggs assumed it was opposite to that of the dominant function, as were the auxiliary and inferior functions. This convention was followed in all three MBTI manuals, although there are alternative views regarding the issue. Because there is relatively little theoretical or empirical evidence favoring one attitude or the other as habitual for the tertiary function, an attitude is not specified in this book.
The assumptions of a hierarchy and habitual attitudinal direction are reflected in the designation of each type, for example, Introverted Intuition with Extraverted Thinking. The first term identifies the type's dominant function and attitude whereas the second term specifies the auxiliary function and attitude. The tertiary and inferior functions do not appear in the type code or title of the type, but they are implicit opposites: The tertiary is opposite to the auxiliary in function, and the inferior is opposite to the dominant in both function and attitude.
The hierarchy of functions and associated attitudes is also implicit in the type description of the four-letter type in question. The type description is a detailed narrative that is the primary way that type results are presented. The most theoretically grounded type descriptions (Myers, 1998; Myers et al., 1998) are an orderly presentation of the personality qualities that result from having a dominant function operating in the preferred attitude, an auxiliary function in the less preferred attitude, a tertiary function that is relatively unconscious, and an inferior function that takes the less preferred attitude and is largely unconscious.
Rationale for Determining Type Dynamics
The method for determining type dynamics can seem confusing to people new to type, but it is actually straightforward once the basic assumptions detailed earlier are recognized. The following points reinforce the theoretical assumptions underlying the method:
Recall that the J-P dichotomy identifies which function the type uses in the Extraverted attitude-- regardless of whether or not Extraversion is the preferred attitude: A person with a Judging ( J) preference extraverts either Thinking or Feeling , whichever of the two is preferred; a person with a Perceiving (P) preference extraverts Sensing or Intuition, whichever one of the two is preferred. Because the Jung/ Myers theory specifies the use of the dominant function in the preferred attitude and the auxiliary in the less preferred, it follows that (a) for extraverts the function that is extraverted is the dominant function, and the function that is introverted is the auxiliary function; and (b) for introverts the function that is extraverted is the auxiliary function, because their dominant function is used in their preferred attitude of Introversion.
Rules to Determine Type Dynamics
The assumptions of type dynamics lead to a logical procedure for determining the dynamics of any four-letter type. Remember that the first letter of the code shows the energy preference, the second letter the perception preference, the third letter the judgment preference, and the fourth letter the preference for using judgment or perception while extraverting. We will illustrate the procedure using two types who differ only in their J or P preference, INFJ and INFP:
Rule 1. One of the two middle letters is the dominant function; the other is the auxiliary function. Example: For both INFJ and INFP, N or F is dominant; N or F is auxiliary.
Rule 2. One of the two middle letters is extraverted; the other is introverted. Example: For both INFJ and INFP, N or F is extraverted; N or F is introverted.
Rule 3. The last letter ( J or P) always tells us which of the two middle letters is extraverted. If the last letter is J, Thinking (T) or Feeling (F) is extraverted because Thinking and Feeling are the two judging functions. Example: For INFJ, F is extraverted, and applying Rule 2, N is introverted (i. e., Ni Fe ).
If the last letter is P, Sensing (S) or Intuition (N) is extraverted because Sensing and Intuition are the two perceiving functions. Example: For INFP, N is extraverted, and applying Rule 2, F is introverted (i. e., Ne Fi ).
Rule 4. The first letter tells us what the preferred attitude is, either Extraversion (E) or Introversion (I). Example: For INFJ, the preferred attitude is Introversion (I) (i. e., I Ni Fe J). For INFP, the preferred attitude is Introversion (I) (i. e., I Ne Fi P).
Rule 5. The dominant function is typically used in the preferred attitude of Extraversion or Introversion. Example: For IN i Fe J, the middle letter that is introverted is N for Intuition. The dominant function of INFJ is therefore Introverted Intuition ( N i ). For INe F i P, the middle letter that is introverted is F for Feeling. The dominant function of INFP is therefore Introverted Feeling ( F i ).
Rule 6. Following Rule 1, the "other letter" (the one that identifies the auxiliary function) for IN i Fe J is Feeling, which, according to Rule 2, is extraverted. Example: The auxiliary function for INFJ is Extraverted Feeling. The dynamics of INFJ are stated as dominant introverted Intuition with auxiliary extraverted Feeling. The "other letter" (the auxiliary function) for INe F i P is Intuition, which, according to Rule 2, is extraverted. The auxiliary function for INFP is extraverted Intuition. The dynamics of INFP are stated as dominant introverted Feeling with auxiliary extraverted Intuition.
Rule 7. The tertiary function is opposite to the auxiliary function. We won't specify an attitude for the tertiary function. Example: For INFJ, Thinking (T) is the opposite of auxiliary F and is the tertiary function (i. e., I N i Fe J T ). For INFP, Sensing (S) is the opposite of auxiliary N and is the tertiary function (i. e., I Ne F i P S ).
Rule 8. The inferior function is opposite to the dominant function and takes the opposite attitude. Example: For IN i Fe J, Extraverted Sensing is the opposite of dominant introverted Intuition and is therefore the inferior function (i. e., I Ni Fe Se J ). For INe F i P, Extraverted Thinking is the opposite of dominant introverted Feeling and is therefore the inferior function (i. e., I Ne Fi P Te ).
Note that INFJ and INFP have three type preferences in common, I, N, and F, so we might reasonably expect that these two types are very much the same. But according to type theory, their dynamics-- the nature and direction of flow of energy of their mental functions-- are quite different. These differences show up in the behavior of these two types and are in accord with these types' dynamic differences. This important information can be put to practical use in the assessment of their personalities and functioning during the course of counseling and psychotherapy.
To further illuminate the effects of type dynamics, let's contrast the type ENFP with INFP, two types that also have three letters in common. Will these two types be as different in dynamics as the INFJ and INFP? Briefly, ENFP extraverts the preferred perceiving function, N. Since Extraversion is the preferred attitude, Ne (Extraverted Intuition) is the dominant function. ENFP introverts the preferred judging function, F. Since Introversion is the less preferred attitude, Fi (Introverted Feeling ) is the auxiliary function. The tertiary function is opposite to the auxiliary, and is therefore T. The inferior function is opposite in function and attitude to the dominant function, and is therefore Si (Introverted Sensing). The total dynamics for ENFP are E N e Fi P, S i T . The total dynamics for INFP are I Ne F i P S Te .
In an important way, INFP and ENFP could be considered more similar to each other than INFP and INFJ because they use their two conscious functions, the dominant and auxiliary in the same attitudes. Yet their more unconscious expressions can be expected to be rather different, because for ENFP, Introverted Sensing is the inferior function and Thinking is the tertiary function, whereas for INFP, Extraverted Thinking is the inferior function and Sensing is the tertiary function. This and the differential availability of energy for their respective functions account for some important observable differences between these two types.
Similar differences occur for other types who share middle letters but differ on either J and P, or E and I-- or both. Chapter 4 discusses some of the dynamic differences between types, and Chapter 6 includes examples of their effects in relation to clinical applications of the MBTI.
You can test your understanding of type dynamics by following the steps in Don't Forget 1.1 (page 18), which focuses on two other types that differ only in their preference for E or I, ESTP and ISTP. You can also figure out the dynamics of any other type and check your accuracy by consulting Rapid Reference 1.4, which shows each four-letter type, its dynamic designation, and its specified tertiary and inferior function.
A Fundamental Theoretical Distinction
The chief advantage of a theoretically based assessment device is that it provides a cohesive structure within which personality differences can be described, explained, and predicted. However, this puts extra construction and validation requirements on the developer and an added burden on the user, who must understand the theory well enough to apply the instrument appropriately. A fundamental feature of Jung's theory-- and therefore the construction and accurate interpretation of the MBTI-- is that it postulates qualitatively distinct categories rather than more familiar behavioral traits that vary along a continuum.
Don't Forget 1.2 shows the differences between MBTI type assessment and contrasting trait approaches. Caution 1.1 (page 20) lists the dangers of misinterpreting type categories as trait variables. Avoiding these errors is essential for accurate administration (Chapter 2) and interpretation (Chapter 4) of the instrument.
Throughout its long history, the MBTI has undergone continuous and meticulous research-- on its construction, the various ways of estimating its reliability, and the abundant and varied studies regarding its validity in diverse areas of interest.
Construction of Items and Scales
nstruction of the four MBTI scales. Items ask about simple surface behaviors and attitudes that are designed to reflect the presence of an underlying preference for one or the other mental function (S or N; T or F ) or attitude (E or I; J or P). Because the goal was to identify slight as well as clear preferences on each dichotomy, items were not worded extremely. Because using logically opposed wording on some items could engender adverse social desirability (e. g., "convincing" versus "unconvincing"), opposite choices were designed as "psychological equivalents" that would be meaningful to people holding the preference in question (e. g., "convincing" versus "touching"). The major concern in scale construction was to achieve maximum accuracy in the placement of the midpoint separating the poles of each dichotomy, since the goal was to sort people into categories rather than measure the amount of a trait. As will be seen in Chapters 2, 3, and 4, item wording and scale construction have an impact on administration, scoring, and interpretation of the MBTI, and they are discussed further in those contexts.
Norms are appropriate for trait measures but inappropriate in a type-based instrument. Norms are therefore not reported for the MBTI. Instead, type tables are typically used to report the frequency and percent of each of the 16 types in a sample of interest. To draw meaningful conclusions about the frequency of the types in a particular sample, an appropriate base population is used for comparison. For example, if one wishes to know which types, if any, are over-or underrepresented among Ph. D. psychologists, the comparison base population would be holders of the Ph. D. degree in a wide range of disciplines; if interest was in the types of college students who are likely to seek personal counseling, the appropriate base population would be a general sample of college students. The statistic used to show over-and under-representation of types is called a self-selection ratio (SSR), and type tables that show SSR data are called selection ratio type tables (McCaulley, 1985). The SSR, also referred to as the Index of Attraction, is calculated by dividing the percentage of a type in the sample of interest by the percentage of that type in the base population to obtain a ratio. Ratios greater than 1.00 indicate overrepresentation of the type relative to the base population, ratios of less than 1.00 show underrepresentation of the type, and ratios around 1.00 reflect about the same representation as the base population. The statistical significance of SSRs is estimated using a chisquare technique. For example, research on educationally oriented leisure activities for each of the 16 types (DiTiberio, 1998) reported an SSR of 2.64 ( p < .01) for INFJs for the category Writing , and an SSR of 0.45 ( p < .05) for this same type for the category Watching Sporting Events; ISTJs showed an SSR of 1.21 ( p < .01) for Watching Sporting Events and an SSR of 0.52 ( p < .01) for Writing. Thus a leisure activity that is quite attractive to INFJs is significantly unattractive to ISTJs, and one that significantly attracts ISTJs is significantly unattractive to INFJs. (See Appendix A for an example of a Selection Ratio Type Table for a large sample of counselors.)
Internal consistency and test-retest reliability have been reported for each scale of the MBTI and vary somewhat depending on the nature of the sample studied. Coefficient alpha results available for the largest and most general sample of male and female adults (N = 2,859) tested with Form M are .91 for the E-I and T-F scales and .92 for the S-N and J- P scales (Myers et al., 1998). Test-retest reliabilities are given for each scale separately and for whole four-letter types. Because type is hypothesized to remain stable over the life span, this latter measure of reliability is the most important. Test-retest reliabilities vary somewhat with the interval between administrations and also with the age of sample members; younger samples tend to have somewhat lower reliabilities, a result in accord with the theory, which hypothesizes that type develops over the life span and is more likely to be incompletely developed in younger individuals. The developmental hypothesis and its empirical verification are relevant to both administration and especially interpretation of type to clients in different ages and stages of life. With a 4-week interval between administrations, using the most general sample available (N = 258), 66% reported all four letters the same and 91% were the same on three out of four preferences. Detailed information on these estimates and additional reliability information can be found in the most recent MBTI manual (Myers et al., 1998).
A theory-based test must demonstrate that it adequately reflects the theory it purports to represent. For the MBTI, this entails demonstrating that the preference poles of each dichotomy correspond to Jung/ Myers definitions and, most important, that the dynamic interactions hypothesized by Jung and Myers occur. Years of correlational and behavioral research demonstrate the correspondence of the eight preference poles to theoretical prediction (Hammer, 1996; Myers & McCaulley, 1985). More recently, several different forms of evidence supporting the dynamic hypothesis have been reported (Myers et al., 1998).
A variety of statistical methods have been utilized in MBTI research, including the SSR method described earlier. Correlational research looks at one dichotomy at a time and treats MBTI data as though they varied along a continuum, a method that contradicts the MBTI assumption of qualitatively distinct categories. These and other studies of individual dichotomies do not address the dynamic aspect of the MBTI, although they can provide useful information for practitioners about some of the behavioral traits that develop as a result of the exercise of underlying type preferences. The most fruitful lines of research look at the behavior of whole types and dynamic qualities of those types. Chapter 6 applies some of the results of studies of whole types and type dynamics to clinical issues.
MBTI Manual: A Guide to the Development and Use of the Myers-Brig gs Type Indicator (Myers et al., 1998) provides the most complete and detailed theoretical, psychometric, and research information on the MBTI, as well as practical guidance for its use in five areas of application.
MBTI Applications: A Decade of Research on the Myers-Brig gs Type Indicator (Hammer, 1996 ) contains contributed chapters summarizing the reliability and validity of the MBTI as well as research that was completed in the decade after publication of the 1985 MBTI manual.
CAPT Bibliography for the Myers-Brig gs Type Indicator is a frequently updated bibliography of published and unpublished work on the MBTI. It is available in printed form and on disk from the Center for Applications of Psychological Type. A library of type resources is housed in the same location.T
he Journal of Psychological Type is published quarterly and is devoted entirely to research and application articles and reviews on psychological type. The journal was first published in 1978 as an annual. Rapid Reference 1.5 provides basic information on the MBTI and its publisher.