I. Zebra Cards serve as a motivating force.
Enjoyment of a subject stimulates intellectual exploration and growth.
Flipping through the Cards immediately discloses that they are
fun; this is inherent in the notion of astonishment underlying them.
Given the important role that motivation plays in the challenging,
occasionally tedious task of learning medicine, it is my hope that the
mental stimulation and enjoyment derived from the cards (and the Extracts)
will become transformed into an eagerness to study mainstream medicine
independently using more conventional sources.
II. Zebra Cards teach medical facts.
This is the raison d'être for most medical textbooks and, ultimately, for Zebra Cards as well. But because the facts presented in Zebra Cards are likely to be ignored or glossed over (or even mis-stated) in many textbooks, some colleagues have labeled these cards as a medical equivalent of "Trivial Pursuit." Make no mistake, triviality is a comparative term, applied appropriately to populations and inappropriately to individuals. As McKusick (7) has noted in commenting about rare diseases, "It is no consolation to the victim of the disorder that he is one in a million. He still has a right to as thoughtful management as the patient with a run-of-the-mine condition."
III. Zebra Cards will sharpen clinical skills.
By example and by repetition, Zebra Cards attempt to modify subtly the way a physician thinks during the interview and examination of a patient; that is, to make him or her aware that anything could be a clue to the identity of the patient's malady. The same sentiment was well expressed by the English neurosurgeon Wilfred Trotter (8):
We come ... to the question of what aspects of human faculty it is necessary for the good doctor to cultivate. ... The first to be named must always be the power of attention, of giving one's whole mind to the patient without the interposition of oneself. It sounds simple, but only the very greatest of doctors ever fully attain it. It is an active process and not either mere resigned listening or even politely waiting until you can interrupt. Disease often tells its secrets in a casual parenthesis.
Zebra Cards help attune the physician's ear to the casual parenthesis by showing how the most inconsequential, outrageous, innocuous, or inconsistent statement or observation may be a manifestation of disease. It is well known that a common cause of incorrect diagnoses is failure to consider the proper diagnosis (9). The flash-card format forces the reader to repeatedly think at the boundaries of his or her knowledge. Thus, after a few passes through Zebra Cards, the habit of continously asking oneself "What am I missing?" or "What haven't I considered?" will develop. In this way the physician automatically begins using all the available data in decision making, and, with this questioning attitude, takes nothing for granted.
That there is a need for reinforcing this manner of thinking is clear: The accelerating pace of activities demanded by the practice of medicine today is the natural enemy of the casual parenthesis. I suspect most (if not all) physicians, of whatever age, are haunted by a feeling that one's professional forebears were somehow vastly more adept than he or she at interpreting the signals of disease (10). Certainly, bemoaning a perceived contemporary decline in clinical skills is not a new practice. For example, Dressler (11), in a 1960 article about the value of percussion in detecting pericardial effusions, quotes the 1936 lament of Sir John Parkinson: "No longer shall we tell of the professor who by knocking at the front door could find out who was in the drawing room."
IV. Zebra Cards convey the boundless subtlety of the human organism.
Because common things occur commonly, it is easy in any type of medical practice to fall into an unthinking routine. Osler warned against this brand of hubris (12):
We, the doctors, are so fallible, ever beset with the common and fatal fallacy of reaching conclusions from superficial observations and constantly misled by the ease with which our minds fall into the ruts of one or two experiences.
Zebra Cards convincingly show, not only at an intellectual level, but at a visceral level as well, that there are subtleties in even the most mundane situations and that no two experiences are ever identical. This knowledge results directly in better patient care and a more enriched practice of medicine (13).
V. Zebra Cards help train the mind to remember disjoint facts.
Unlike some of the physical sciences, where a basic set of laws captures a large proportion of the knowledge about a field, medicine lacks grand unifying principles (14). As a result, physicians are required to memorize thousands of facts, too many of which are little used and exist in isolation, with no contextual associations to assist recall. For example, either you know that shoulder pain may be referred from the diaphragm or you do not. Extended work with Zebra Cards, I have found, helps develop a facility for remembering unconnected facts that is useful in both medicine and other endeavors.