Roughly 40 to 60 percent of all people are susceptible to contagious yawning. People who tend to be more self-aware and are able to relate to the point of view of other people appear to be more likely to experience contagious yawning. At the same time, people who have emotional disorders that interfere with these abilities are less likely to succumb to an episode of contagious yawning. As an example, individuals who suffer from schizophrenia are less likely to yawn after seeing another person yawn.
More facts about contagious yawning:
- Contagious yawning usually develops when a person is 4 years old. This is because children at that age begin to empathize with others, triggering deep-seated desires to bond with others in the social circle. Depending on the level of development, it is possible for a child to develop contagious yawning as early as the age of 2.
- All vertebrates yawn, but only a few experience the phenomenon of contagious yawning. In addition to humans, chimpanzees have exhibited the ability to yawn after seeing other chimps or even humans yawn. There also are some studies that suggest that dogs also might be susceptible to contagious yawning.
- Contagious yawning can be triggered by factors other than observing someone else yawn. Reading about yawning or even thinking about yawning in general might trigger the desire to yawn.