For the most part, cognitive differences between individuals and the manner in which they are expressed have been much overlooked in generating and appraising personality traits. With an occasional, notable exception or two, little of the recent "revolution" in cognitive science that has profoundly affected contemporary psychology has impacted on the study of personology. Historically, the realms of intellect, aptitude, and ability have not been considered to be personality-related spheres of study.

Now, the focus of personology has been broadened to encompass the "whole person," an organically unified and unsegmented totality. Consequently, there is a growing recognition that cognitive dimensions and their various "styles" not only should be included but also may have significance equal to motivational and behavioral styles as a source of personality traits and differences (Millon, 1986, 1988).

The various features and styles of cognition have not been included as central elements in most personality instruments. Nonetheless, in the author's judgment, they comprise what may be viewed as the fourth and most recent phase of evolution. The capacity to think abstractly, that is, to transcend the immediate and concrete, to interrelate and synthesize diversity, to represent events and processes symbolically, to weigh, reason, and anticipate, signify a quantum leap in the evolutionary potential of organisms for change and adaptation.

With the mind emancipated from the real and present, unanticipated possibilities and novel constructions may be created by particular styles of cognitive processing. The capacity to sort and recompose, to coordinate and arrange the symbolic representations of experience into new configurations, is, in certain ways, analogous to the biological processes of random recombinant replication, although more focused and intentional. To take more liberty with the analogy, genetic replication represents the recombinant mechanism underlying the adaptive progression of phylogeny, whereas abstract reasoning represents the recombinant mechanism underlying the cognitive progression of ontogeny.

The uses of physical replication are limited, constrained by the finite potential inherent in parental genes. In contrast, experiences, internalized and recombined through cognitive processes, are infinite. Over one lifetime, innumerable events of a random, logical, or irrational character transpire and are construed and reformulated time and again, some ideas and behaviors proving more, and others less, adaptive than the ideas and behaviors their originating circumstances may have called forth. Whereas the actions of most subhuman species derive from successfully evolved genetic programs, prompting behaviors of a relatively fixed nature that are suitable for a modest range of environmental settings, cognitive processing both implicit and intentional, gives rise to adaptive competencies that are suited to radically divergent ecological circumstances, which themselves may be the result of far-reaching acts of symbolic and technological creativity.

The human mind may mirror outer realities, but it also reconstructs them, reflectively transforming perceptions into subjective modes of phenomenological reality and rendering external events subject to individualistic designs. Every act of apprehension is transformed by elements of projection. Not only are images of self and others emancipated from direct sensory realities, allowing them to become mental entities, but time also loses its immediacy and impact, becoming as much a construction as a tangible reality. Cognitive abstractions bring the past effectively into the present, and their power of anticipation brings the future into the present, as well. With past and future embedded in the here and now, humans can encompass, at once, not only the totality of the cosmos but also its origins, nature, and evolution. Most impressive of all are the many visions humans have of life's indeterminate future, where no reality exists as yet.

As noted previously, we view cognitive functions to be the most recent stage of evolution's progression and, hence, as consonant with our biosocial formulations concerning the fundamental architecture that undergirds human functioning. We also judge cognitive processes to be the second step in our tripartite sequence that represents how organisms approach their environments. Rather than giving primacy either to the "driving" motivational and emotional roots of personality style (as in the author's formulation of the personality disorders), or to the overt behavioral expressions of personality (as explicated, for example, in a lexical approach that generates the Big-Five factor model; Goldberg, 1993), the MIPS approach seeks to conjoin these components of style by linking them to cognitive functions, thereby integrating all three expressions of personality into a single coherent whole.

JUNG'S CONTRIBUTIONS AND THEIR CURRENT PARALLELS

The Cognitive Orientation of Jung's Typology Through the years, several bipolar dimensions have been proposed as the basis for a schema of cognitive styles. Contrasting terms such as "leveling versus sharpening," "narrow versus broad," "analytic versus synthetic," "constricted versus flexible," "inductive versus deductive," "abstract versus concrete," and "convergent versus divergent," have been used to illustrate the stylistic differences among cognitive functions. Although each of these pairs contributes to distinctions of importance in describing general cognitive processes, few were conceptualized with personality differences in mind, although they still could prove productive in that regard.

By contrast, one well known bipolar schema intentionally formulated to serve as a basis for generating personality types was composed essentially of cognitive concepts. Although Jung did not speak explicitly of cognitive processes, it would not he unjustified to view his three bipolarities of Extraversion-lntroversion, Thinking-Feeling, and Sensing-Intuiting as being anchored more firmly in a cognitive than in a motivational or behavioral domain.

To illustrate this thesis, we may ask, What did Jung mean by "Extraversion" and "Introversion"? The view commonly held by lung's interpreters is that these terms refer to behavioral aspects of sociability, with Extraversion signifying social outgoingness, and Introversion signifying social reservation. It is the author's view that Jung intended something appreciably different: His was essentially a cognitive orientation, so that Extraversion and Introversion signified not a person's social style but the direction of his or her attentions and interests. Extraversion indicated that these attentions were extraceptive-oriented more toward the outer than the inner world; the person was inclined to trust "objective" events and to seek external sources of inspiration. Introversion denoted intraceptiveness -- an internally oriented direction of attention and interest, involving a subordination of external sources of knowledge to those emanating from one's inner life and an attentiveness to inner promptings and "subjective" inspirations. In sum, Extraversion and Introversion, Jung's most accepted and durable personality concepts, do not pertain to types of motivation or to interpersonal behaviors but, rather, to cognitive styles.

It is even clearer that the other two bipolarities formulated by Jung -- Sensing versus Intuiting, and Thinking versus Feeling - are distinctly cognitive in both their character and grounding. They represent not so much the reasons people act or their actions, but the "attitudes" individuals take in attending to their environments and the "functions" they employ to interpret and transform their perceptions.

TOWARD THE MIPS APPROACH

As noted, numerous researchers and theorists have proposed useful dimensions and polarity schemas to represent cognitive styles, several of which remain as potentially important grounds for establishing personality traits. The author's earliest writings on the topic (Millon, 1969) focused essentially on styles of cognition characterizing and differentiating the personality disorders that eventually comprised Axis II of DSM-III (American Psychiatric Association, 1980). For example, the histrionic type was noted for cognitive dissociation, the narcissistic type for cognitive expansiveness, the antisocial/aggressive type for cognitive projection, the obsessive-compulsive type for cognitive constriction, and so on. Aspects of these cognitive styles were arranged in a circumplex model, along with aspects of self-image; in both domains of cognitive activity, therefore, a rough framework was provided for a bipolar schema.

A similar, but more developed, format of cognitive styles was proposed a decade and a half later (Millon, 1984, 1986b). Once again, the disorders were organized with reference not to basic personality styles but to the distinctive cognitive characteristics of each clinical type -- for example, the schizoid was characterized as cognitively impoverished, the avoidant as cognitively distracted, the dependent as cognitively naive, the histrionic as cognitively flighty, and so on.

Descriptively useful as these cognitive conceptualizations might have been, they were targeted to explicate pathological rather than "normal" styles; they expressed cognitive differences among core clinical types but did not express latent dimensions or fundamental polarities. Also problematic was the fact that pathologically oriented descriptions included cognitive content along with cognitive style, confounding further the desire to devise a schema of "pure" stylistic features.

Finally, a model was formulated by the author that separated cognitive activities into two superordinate functions. The first pertained to the contrasting origins from which cognitive data were gathered, or what have been termed "information sources"; the second pertained to the methods by which these data were reconstructed by the individual, or what have been labeled "transformational processes.

These two functions -- the initial gathering and subsequent reconstruction of information -- were further subdivided into two bipolarities each. As will be elaborated shortly, the sources of information" were separated into (1) external versus internal, and (2) tangible versus intangible. "Transformational processes" were divided into (1) intellective versus affective, and (2) assimilative versus imaginative. The resulting four cognitive bipolarities of the MIPS are by no means exhaustive. Rather surprisingly and pleasantly, however, they turned out to be highly consonant with the model formulated in 1921 by Jung (1921/1971).

THE MIPS EXTRAVERSING AND INTRAVERSING MODES

An Evolution-Based Information-Processing Model The first two contrasting functions considered significant to personality styles in the cognitive domain relate to the sources used by individuals in gathering knowledge about their world. Given our view that the two central elements that comprise the environmental field of an organism are itself and others, it should not be surprising that these very same components serve as the two primary sources from which an organism gathers information. Hence, turning attention to matters either internal or external to self is a key distinction in cognitive activity.

Although related materially to the Individuating versus Nurturing distinction drawn in the previous section on Motivating Aims, the correspondence is neither simple nor clear-cut, nor are individual score correlations between these bipolarities necessarily high. Because the two sets of constructs interrelate in more ways than one, and belong to broader configurations composed of different intensity levels, correspondences may be much more variable than their common point of origin would suggest. Thus, Individuating, for some people, may be best achieved by attending to external sources, whereas Nurturing may be enhanced by drawing inspiration primarily from internal sources.

It should be noted that useful parallels may be drawn between evolutionary processes and cognitive functions; the evolutionary model that undergirds our formulation is no less apt in this realm than it was in the sphere of motivation.

Information is seen by many as the opposite of entropy. Further, what energy or nutrients are to physical systems, information is to cognitive systems. A physical system sustains itself by "sucking order" from its environs, taking in energy or nutrients and transforming them to meet tissue needs; a cognitive system does something similar by "sucking information" from its environs--that is, taking in data and transforming it to meet its cognitive needs.

In much the same way as any other open system, a cognitive structure needs to maintain itself as an integrated and cohesive entity. In the physical world, the integrity of a system is achieved by making adaptations that preserve and enhance the physical structure, thereby precluding the entropic dissipation of its ordered elements. Similarly, a cognitive system achieves its integrity through a variety of preserving and enhancing adaptations that reduce the likelihood of events that may diminish the order and coherence of its knowledge base.

Moreover, an open cognitive system is purposefully focused, as is a physical system. Just as a physical system must be selective about its nutrition sources in order to find those suitable to meet its tissue needs, so, too, must a cognitive system be selective about information sources, choosing and processing particular raw inputs according to specific cognitive goals. A cognitive system can no more process random input than a physical system can ingest random material. Hence, information (negative entropy) must be acquired selectively rather than randomly or diffusely; some sources of information will be heeded and others ignored or suppressed.

Coherence may be optimized by adopting and maintaining a preferred and regular information source, thereby ensuring a consistent confirmatory bias in favor of a cognitive structure's "world view" and organizational architecture. Conversely, a cognitive structure that is exposed to dissonant or contradictory sources, or that heeds diverse or multitudinous sources, ultimately may be challenged successfully or may be exhausted beyond its ability to maintain coherence. In other words, burdensome processing and discordant sources are likely to result in increasing cognitive entropy. A more structured and coherent focus that strengthens and confirms prior sources of information becomes useful in ensuring optimal cognitive survivability.

ONTOLOGICAL TRANSLATION

In light of the preceding argument, in sum, we see two primary sources of information, that which originates external to the self and that which originates internally. Whether this polar cognitive orientation is termed external versus internal, extraceptive versus intraceptive, or extraversing versus introversing, each bipolarity provides a replicable reservoir for cognitive information--a selectively narrowed wellspring of knowledge to which the person will continue to be exposed.

Extraversing. A few lines from Jung may be of value in highlighting core features of his conception of the externally oriented attitude:

Extraversion is characterized by interest in the external object, responsiveness, and a ready acceptance of external happenings, a desire to influence and be influenced by events, a need to join in and get "with it," the capacity to endure bustle and noise of every kind, and actually find them enjoyable. (Jung, 1936/1971, p.550)

Introversing. Similarly, the following brief excerpt from Jung's writings clearly states his view of the internally oriented attitude:

The introvert is not forthcoming, he is as though in continual retreat before the object. He holds aloof from external happenings, does not join in. For him self-communings are a pleasure. His own world is a safe harbour, a carefully tended and walked-in garden, closed to the public and hidden from prying eyes. His own company is the best. He feels at home in his world, where the only changes are made by himself. His best work is done with his own resources, on his own initiative and in his own way. (Jung, 1936/1971, pp. 550-551)

THE MIPS SENSING AND INTUITING MODES

Information, whether its source is internal or external to the self, can be classified in numerous ways. A core distinction can be drawn between information that is tangible versus that which is intangible. By "tangible" is meant identifiable by the human sensory capacities, well-defined, distinctive, recognizable, and knowable--referring to phenomena that are concrete, factual, material, realistic, or self-evident. In contrast, information that is termed "intangible" takes in phenomena that lack an intrinsically distinctive order and structural clarity; they are inherently ambiguous, abstract, insubstantial, vague, mysterious, and obscure. Such phenomena usually can be fathomed only by means that are unknown, unconscious, and percipient, or by glimmerings into their diffuse and elusive nature that are materially tenuous or psychical in form.

The readiness of some individuals to be receptive to information that is well-structured and tangible, and of others to receive information that is obscure and intangible, constitutes, in our view, a fundamental difference in cognitive style that is of appreciable personological significance. Although Jung's language is only partially formulated in cognitive terms, close parallels again can be seen between the bipolarity presented here and that offered by Jung in his distinction between Sensing and Intuiting:

Here we should speak of sensation when sense impressions are involved, and of intuition if we are dealing with a kind of perception which cannot be traced back directly to conscious sensory experience. Hence, I define sensation as perception via conscious sensory functions, and intuition as perception via the unconscious.

Sensation and intuition ... make us aware of what is happening, but do not interpret or evaluate it. They do not proceed selectively, according to principles, but are simply receptive to what happens. (Jung, 1931/1933, pp.538-539)

Sensing. Favoring tangible, structured, and well-defined sources of information that call upon one's five senses will, no doubt, correlate with a wide range of associated behaviors, such as choosing actions of a pragmatic and realistic nature, preferring events in the here and now, and attending to matters calling for facts and quantitative precision. As Jung conceived it:

There are people for whom the ... accent falls on sensation, on the perception of actualities, and elevates it into the sole determining and all-overriding principle. These are the fact-minded men, in whom intellectual judgment, feeling, and intuition are driven into the background by the paramount importance of actual facts. (Jung, 1936/1971, p.554)

Intuiting. In contrast, preferring the intangible, unstructured, and ambiguous is likely to be associated with actions inspired by possibilities, challenges, potentials, and thoughts of an abstract, complex, connotative, and symbolic character, as well as by matters that depend on novelty, mystery, and speculation. To quote Jung:

On intuition actual reality counts only in so far as it seems to harbour possibilities which then become the supreme motivating force, regardless of the way things actually are in the present. (Jung, 1936/1971, p.554)

THE MIPS THINKING AND FEELING MODES

The first two pairs of cognitive functions were grouped according to sources and styles of gathering information. The next two pairs of bipolarities represent transformational processes, referring to what is done to information once it has been received. Cognitive science has articulated a number of concepts related to registering, encoding, and organizing life experiences. These concepts pertain to various questions, such as: Through what cognitive mode will information be received--intellective or affective? How shall information be organized; will it be assimilated into preformed memory systems or will it be recast through imagination into novel schemas? Although individuals may be positioned on several other continuums or bipolarities--e.g., convergent versus divergent, serial versus hierarchical, primary versus secondary, verbal versus visual--it is the author's view that the most fruitful cognitive transformational distinctions relevant to personality are the pairs selected in this and the following section.

Simplifying matters, there are essentially two pathways through which experiences pass once recorded by our senses, if they are of sufficient magnitude to activate an encoded response. The first pathway evaluates whether information is objective and reasoned, eliciting a thought-based judgment that signifies in an articulate and organized way that the registered experience "makes sense"--that is, it is intellectually logical and coherent, The second pathway elicits a subjective, emotional response, a feeling reaction, signaling, in a less organized and often diffuse and global way, that the registered experience was recorded as affectively neutral, positive, or negative.

Thinking. The intellective pole, what Jung meant by "thinking," indicates a preference for interpreting experience in light of reason and logic. Although life events may derive from internal or external sources, and may be of a tangible or intangible nature, the interpretive and evaluative process is inclined toward the objective and impersonal, as events are analyzed by means of critical reason and the application of rational and judicious thought. By increasing affective detachment-reducing the unruly emotional input of others and the upsetting effects of one's own emotional state--it may be possible to sustain a high degree of cognitive cohesion and continuity. Objective analysis and affective detachment protect against unwanted incursions upon cognitive stability, but often at the price of promoting behavior that is rigid, overcontrolled, and unyielding.

Feeling. In contrast, experiences processed affectively will activate subjective states such as liking versus disliking, feeling good versus feeling bad, comfort versus discomfort, attracted versus repelled, valuing versus devaluing, and so on. Through empathic resonance, the route of affectivity inclines the individual to record not so much what other people think hut, rather, how he or she feels about matters. The individual who inclines toward the Feeling pole uses "psychic vibrations" to learn more from the emotional tone words convey than from their content or logic. The usual modality for those who exhibit an affective style is that of subjective reality, a more or less "gut" reaction composed of either global or differentiated positive or negative moods. There are, of course, individuals who are notably introspective, inclined to pursue inner affective states with an intellective cognitive style. These individuals are not merely psychological-minded; they may exhibit an obsessive search for self-insight. For the most part, however, the affective transformational style indicates individuals who evince modest introspective analysis, combined with an open and direct empathic response to others, and a subconscious susceptibility to the emotional facets of experience in as pure a manner as possible.

THE MIPS SYSTEMATIZING AND INNOVATING MODES

The final cognitive transformational bipolarity addresses the question whether new information is shaped to fit preformed memory schemas (assimilated within preexisting cognitive systems), or is organized through the imagination and cast into more novel forms. Evolutionary theory suggests that the best course may be to reinforce (cognitive) systems that have proved stable and useful. On the other hand, progress will not he made unless promising new possibilities are explored. A beneficial tension in evolution clearly exists between conservation and change, between adhering to the habitual and unleashing the creative. These two contrasting cognitive styles demonstrate the two options--assimilating experiences into already established systems versus exploring innovative ways to structure them.

Systematizing. In the MIPS schema, systematizers are akin in certain features to those who exhibit the 'Judgment preference," which Katherine Briggs and Isabel Briggs Myers abstracted from Jung's notions (Meyers, 1962). Both Systematizing and having a Judgment preference indicate persons with well-structured memory systems, to which they routinely attach new cognitive experiences. Disposed to operate within established perspectives, systematizers assimilate new information to previous points of view, exhibiting thereby a high degree of dependability and consistency, if not rigidity, in their functioning. Typically, such people are predictable, conventional, orderly, planful, decisive, methodical, exacting, formal, disciplined, conscientious, faithful, loyal, and devoted. Hence, in evolutionary terms, the assimilative polarity leads to continuity and tradition, or to the maintenance of existing levels of cognitive entropy; this cognitive style promotes an architectural cohesion that remains unchallenged by risky variations that could potentially diminish established levels of order.

Innovating. In contrast, those at the Innovating pole are characterized by an openness to forming new and imaginative cognitive constructions of an impromptu character. They are inclined to search for creative ideas and solutions, to find novel ways to order information, and to accumulate negative entropy, so to speak, by stepping outside of what is known and given so as to establish a new or higher level of cognitive organization. Innovators stretch beyond confirmed perspectives, seeking to broaden interpretations of experience, and are not concerned with demonstrating their reliability. The imaginative mode is typically associated with being open-minded, spontaneous, extemporaneous, informal, adaptable, flexible, resilient, impressionable, creative, inventive, and resourceful.