Several other researchers have traversed territory similar to personality theorist Ernest Hartmann over the past two decades. Psychologist Elaine Aron has illuminated various facets of what she calls the "highly sensitive person" or HSP (Aron 1996)... Harvard professors Jerome Kagan and Nancy Snidman have studied the differences between "high reactive" and "low reactive" individuals (Kagan and Snidman 2004)... educator Mary Sheedy Kurcinka has profiled what she terms the "spirited child" (one who exhibits high energy as well as sensitivity) (Kurcinka 2006)... researchers Sheryl Wilson and Theodore Barber have profiled the "fantasy prone" person (Wilson and Barber 1983)...psychologist Sharon Heller has examined what makes someone "sensory defensive" (Heller 2002)...and physicians James J. Lynch and Gabor Maté have chronicled "Type C" people who seem unwilling or unable to acknowledge their feelings (Lynch 1985, Maté 2003).

Of late, researcher Susan Cain's book on introversion has grabbed popular attention. In Quiet: The Power of Introverts in a World that Can't Stop Talking, the author draws an important distinction between shyness and introversion. (Cain 2012) Shyness, she says, is the fear or social judgment whereas introversion is "really a preference for less stimulation." This interpretation is consistent with what Aron has found - that high sensitivity is not the same thing as shyness. Indeed, approximately 30% of highly sensitive people are gregarious. But, as they still tend toward being careful and deep thinkers, highly reactive, and easily over-stimulated, they need much more downtime than do extroverts to recover.

Value of Knowing Your Boundary Type

All of these conceptions are helpful, and all point to the same basic kind of person - the "orchid" - who can thrive or wilt based on the quality of her or his emotional environment. Hartmann's boundary concept, though, goes to the heart of what actually drives the formation of that particular personality. In a word, it's stimulation...what kind (positive or negative), how much (not enough, just right, too much)...and, most important, how the person handles said stimulation (acts as if it's not happening, reacts immediately, stores away for future rumination). The person's boundary type - thick or thin or any degree in between - mediates with the outside world and, internally, mediates the flow of feeling.

That flow, that characteristic style of processing emotional stimuli, has a direct bearing on what kind of illnesses the person will experience. We have already noted that highly sensitive (i.e., thin boundary) people are especially susceptible to anxiety disorders. This class of chronic illnesses can be seen to reflect a ‘hyper' style of feeling. Similarly, highly thick boundary people, who aren't nearly so sensitive to environmental changes, are much slower to recognize what they're feeling. It stands to reason that they would manifest different forms of chronic illness. Based on my assessment of the research literature, ulcer, hypertension, and phantom pain are examples of thick boundary conditions. (Jawer and Micozzi 2011)

The implications are quite remarkable. Based on where you fall on the boundary spectrum, you'll have a sense for what forms of chronic illness you're most susceptible to. And you don't need a genetic workup to determine boundary type. All you need is Hartmann's Boundary Questionnaire (BQ) - of which there's, handily, an 18-question short form. (You can take the BQ yourself in the last installment of this series.)


Aron, Elaine. The Highly Sensitive Person: How to Thrive When the World Overwhelms You. New York: Carol Publishing Group, 1996.

Cain, Susan. Quiet: The Power of Introverts in a World that Can't Stop Talking. New York; Crown, 2012.

Heller, Sharon. Too Loud, Too Bright, Too Fast, Too Tight: What to Do If You Are Sensory Defensive in an Overstimulating World. New York: HarperCollins, 2002.

Jawer, Michael A. and Micozzi, Marc S. Your Emotional Type. Rochester, Vermont: Healing Arts Press, 2011.

Kagan, Jerome and Snidman, Nancy. The Long Shadow of Temperament. Cambridge, Massachusetts: Belknap Press, 2004.

Kurcinka, Mary Sheedy. Raising Your Spirited Child, 2nd ed. New York: Harper, 2006.

Lynch, James J. The Language of the Heart: The Body's Response to Human Dialogue. New York: Basic Books, 1985.

Maté, Gabor. When the Body Says No: Understanding the Stress-Disease Connection. Hoboken, New Jersey: John Wiley & Sons, 2003.

Wilson, S.C. and Barber, T.X. "The Fantasy-Prone Personality: Implications for Understanding Imagery, Hypnosis, and Parapsychological Phenomena." In Imagery: Current Theory, Research and Application, ed. Anees A. Sheikh. New York: John Wiley & Sons, 1983, 340-87.

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