Why is yawning more contagious for some people and not others? The reason may be empathy. Researchers have found that people who score high on empathy are more likely to stretch their jaws when they see others doing so. The same research found that people with mild schizotypal traits— healthy individuals that exhibit traits associated with schizophrenia—were less likely to yawn when they see others do it. Steven Platek, Ph.D., at Drexel University in Philadelphia, Pennsylvania, had 65 subjects watch videos of people laughing, yawning and staring blankly. "Those who showed contagious yawning were more likely to perform better on our empathy test than those who did not," says Platek. Forty percent of the subjects yawned in reaction to the videos; while subjects who were less likely to yawn showed some schizotypal traits. While none of the subjects were found to be schizophrenic, Platek notes that a yawn test may help identify some people with the disorder.

One interesting study on the cause of yawning hypothesized that, "contagious yawning occurs as a result of a theory of mind, the ability to infer or empathize with what others want, know, or intend to do. Seeing or hearing about another person yawn may tap a primitive neurological substrate responsible for self-awareness and empathic modeling which produces a corresponding response in oneself" (2). Researchers tested this hypothesis by observing individuals that exhibited schizotypal personality traits. They felt that those traits would inhibit a person's ability to process information about the self and would therefore lower their tendency to yawn contagiously (2). Their lowered ability to identify with another's state of mind would prevent them from 'catching the yawns' as a result of empathizing with someone seen yawning. The researchers' findings were consistent with their hypothesis and could aid in explaining why schizophrenics rarely catch the yawns (3). Another experiment conducted at New York State University's Department of Psychology declared similar findings stating, "We have also shown that individuals who score higher on schizotypal personality traits are less likely to show contagious yawning because of a fundamental impairment of self-processing" (9).

There are evolutionary theories for yawning. Robert Provine, professor of psychology at the University of Maryland Baltimore County, suggests that yawning is about "transitions in the body's biology" (5). This theory might support observations that suggest fetal yawning. Perhaps it aids in maintaining the balance of amniotic fluid. Provine goes on to say that yawning can occur not only when transitioning from a state of alertness to a state of sleepiness, but also from a transition from sleepiness to alertness (5). He makes the point that, "at track and field events, sometimes you'll find participants in the race of their life will be standing around on the sidelines or in the starting block and they may be yawning. Or before a concert, a musician may yawn to prepare for an increasingly energized state" (5). The evolutionary theory behind this is that yawning is a result of synchronizing behavior based on these changing states of alertness (5). The changes in your body that "are brought about by yawning are synchronized in everyone that's doing it" (5). The associate professor of physiology at the Lake Erie College of Osteopathic Medicine suggested a similar theory, stating that, "the contagious nature of yawning is most likely a means of communication within groups of animals, possibly as a means to synchronize behavior; therefore in humans it is most likely vestigial and an evolutionarily ancient mechanism that has lost its significance" (8). Just as our teeth have gotten smaller as we have evolved, so has the significance and meaning of the yawn. Continuing along the lines of evolution, one might consider the yawn in term of a link to our "furrier days"

A big yawn I was talking with Chris last night before dinner and he kept breaking into big yawns from his comfortable position in the easy chair. His whole face contorted, he opened his mouth wide and he sucked in air. In other words, a typical yawn. He yawned three or four times, enough to make me wonder if I was boring him. Why is this so interesting? Well, for one, a yawner he is not. Apparently, people with a diagnosis of schizophrenia do not yawn. Based on my knowing Chris, by golly that's right. I had never seen Chris yawn. Maybe he did as a baby. If so, I've forgotten, but for sure I never saw him yawn as a child, teen and adult. A few weeks after Chris underwent the assemblage point therapy, I caught him yawning. Haven't seen much since. Chris has told me repeatedly recently that his life lacks fun. It appears that he is beginning to be uncomfortable in his role of stay-at-home guy with little fun in his life. Here's a partial explanation for what's going on, from the Bulletin of the Menninger Clinic. I don't necessarily agree with the final paragraph's hypothesis about chronicity.

YAWNING A homeostatic reflex and its psychological significance Heinz E. Lehmann, Professor of Psychiatry, McGill University Clinical Observations : It is an old clinical observation (Russell 1891; Geigel 1908) that persons suffering from an acute physical illness never yawn as long as their condition is serious. Nurses have learned to recognize the return of yawning as a sign of patients' convalescence, particularly in those patients who have infectious diseases. The literature, however, reports few observations regarding yawning in psychotic patients, although Hauptmann (1920) made mention of its possible significance. Some time ago I was struck by the conspicuous scarcity of yawning among mental patients. I informally recorded the incidence of people yawning in public gatherings, on buses, in restaurants, at scientific meetings, and on mental hospital wards. These observations confirmed my impression that yawning among the mentally ill is unusually rare. There were two exceptions: patients receiving large doses of sedatives and those diagnosed as suffering from organic brain syndrome. Of course, the absence of yawning in patients with psychoses associated with constant psychomotor excitement or increased nervous tension was not surprising since excitement or emotional tension usually excludes the occurrence of yawning in normal individuals. However, the majority of patients I observed were quiet, inactive, indifferent persons suffering from schizophrenia. Their failure to yawn requires an explanation. One of the most consistent physiological findings about patients with schizophrenia is defective homeostasis. The schizophrenic patient's ability to adjust to changes in the internal milieu is impaired. Slight reductions of the schizophrenic subject's brain metabolism would, therefore, provoke a homeostatic response less easily than in a normal person. Yawning might not be elicited unless the yawning provoking stimulus assumes an unusual strength such as that provided by hypoglycemia or by barbiturates. As I have mentioned, the principal psychological agent to produce yawning-boredom-is an affect characterized by an extraverted attitude, a searching tendency toward reality. The schizophrenic subject's typical withdrawal from reality and his affective blunting make it almost impossible for him to be truly bored; his passivity, indifference, and daydreaming must not be confused with boredom. In addition, the schizophrenic individual can hardly be expected to imitate unconsciously the yawning of another person since he is not likely to transfer sufficient interest to other persons in his surroundings. Therefore, when a schizophrenic patient yawns as a result of boredom or unconmous imitation, it shows that the patient's contact with reality is not entirely lost and that he is making an effort to maintain it. In fact, when any psychiatric patient yawns, it is a signal that he is in an accessible mood, regardless of his general mental state or diagnosis. Of course, yawning is by no means completely absent in schizophrenic patients. Its incidence, however, appears to be much lower in schizophrenia than in normal mental conditions or in other mental diseases. The occurrence of yawning in early schizophrenia may be evaluated as a favorable sign; however, it seems to be of ominous significance in chronic schizophrenia. One may theorize that yawning in the acute schizophrenic patient is the reflection of a fairly intact homeostatic system and possibly the expression of the patient's efforts to retain his contact with reality. In the chronic stages of the disease, yawning may be indicative of structural brain changes and the formation of a new, permanent, and pathological relationship to the outside world, characterized by complacency and the complete loss of the inner stress and tension that should accompany even partial insight.