Evidence for the Health Claim
Robert Provine, a leading researcher on yawning, has conducted various studies to determine if and when yawning is contagious. One experiment divided 360 college students into 12 groups. Some students watched video clips of yawning faces, while others observed featureless or smiling faces. Significantly more students yawned after being exposed to the yawning faces than did those watching faces exhibiting other expressions.
Further research by Provine and his colleagues found that observing, hearing, reading about, or thinking about yawns stimulates people to yawn. Although most vertebrate (having a backbone) animals yawn, studies have shown that yawning is only contagious between humans and possibly chimpanzees.
The reasons and mechanisms behind contagious yawning have been examined, and various theories have been proposed. From an evolutionary standpoint, the absence of contagious yawning in other species suggests that human primates yawned as a way to coordinate social behavior, such as signaling an event that requires alertness, or preparing for sleep.
With the advent of new imaging techniques a few studies were done in recent years that try to answer the question of contagious yawing by observing the brain function in subjects who observe other people yawn. One study identified an area of prefrontal cortex as the one involved in the processing of contagious yawning.
The Empathy Factor
Some researchers suggest that contagious yawning is linked to certain psychological traits. Platek and fellow researchers conducted a study to see if there was a connection between subjects’ susceptibility to contagious yawning and self-processing skills (as measured by the ability to recognize one’s own face) and schizotypal personality traits (which signal a deficiency in interpersonal relationships). They found that people with strong self-processing performance and weak schizotypal personality traits were the most likely to yawn contagiously.
Further research linked contagious yawning to empathy and affinity for social cues. Schürmann and colleagues studied brain activation of subjects observing videos of people yawning, and found that contagious yawns seem to be automatic behavioral acts as opposed to a more complex imitation of another person’s actions, which would require understanding, deliberation, and decision-making.
Evidence Against Health Claim
Although it may seem illogical that a physical action could be contagious (in the absence of a spreading infection), few studies have been conducted that refute the claim that yawning is contagious. Granted, yawning is not a problem for most people, so limited research has been done on the topic.