Study shows why scratching and itching also have a contagious effect

Scratching: Itching is as contagious as yawning
When other people start to laugh, you often have to do it yourself. And yawning is contagious. The situation is similar with itching. Researchers have now found out why you have to scratch yourself when you see others. It does not seem to have anything to do with empathy.

Itching is very contagious
Be it fatigue or boredom, when we see someone who yawns gleefully, we can barely suppress their own yawning. According to experts, the emotional closeness we feel towards a person plays an important role. Therefore, the yawning of people close to us is much more contagious than strangers. Although itching is also contagious, empathy is unlikely to play a role here, as researchers have now discovered.

When you watch others scratching, you often have to itch yourself. It has nothing to do with empathy, researchers have now discovered. (Image: Astrid Gast / fotolia.com)

No form of empathy
"Itching is very contagious," said Zhou-Feng Chen of the Washington University School of Medicine in St. Louis. "Sometimes it's enough just to mention itching and then you start to scratch yourself." Why this is so, was not clear so far.

"Our experiments show that it is a predisposed behavior and not a form of empathy," said the study author in a statement.

The researchers have now published their results in mice in the journal Science.

Experiments with mice
The team of scientists showed each mouse a mouse in a closed room videos of another mouse scratching.

"Within a few seconds, the mouse in the enclosure began scratching, too," Chen explained.

"That was very surprising because mice are known for their poor vision. They use smell and touch to explore the environment, so we did not know if a mouse would notice a video. Not only did she see the video, but she could also see the mouse scratching in it. "

Innate and instinctive behavior
The researchers also found that a particular brain region is particularly active in scratching, which also controls falling asleep and waking up.

In this region, a substance was simultaneously released, which the scientists had identified in previous work as one of the main messengers for the transmission of itching signals between the skin and spinal cord.

"The mouse does not see another mouse scratching and thinks it could scratch," Chen said. Rather, the brain starts to send signals.

So this is not a form of empathy. The expert assumes that the animals can not control the contagious itching behavior. "It's innate behavior and instinct," Chen said. (Ad)