In a research study titled "Emotional Contagion", scientists revealed that emotions can be transmitted to subsequent receivers as fast as the blink of the eye, according to a study findings published in The Washington Post.

Elaine Hatfield, a professor of psychology at the University of Hawaii and co-author of the study, says that emotions whether positive or negative are passed from person to person without even the notice of the receiver.

In a study at Uppsala University in Sweden, the volunteers were shown the pictures of happy or angry faces for 30 milliseconds, immediately followed by neutral faces.

Without even realizing the volunteers responded by giving a corresponding facial muscle reaction of their own.

Hatfield explains that those incremental muscle movements then trigger the actual feeling by causing the same neurons to fire in the brain as if you were experiencing the emotion naturally.

The researchers rule that degree to which people become emotionally in sync with each other depends partly on the level of intimacy and emotional bond between the them.

John T. Cacioppo, professor of psychology and director of the Center for Cognitive and Social Neuroscience at the University of Chicago says that the people who are more expressive spread their emotions more powerfully and the ones who are calm on outside but respond strongly to emotional events are most susceptible.