Reposting messages on social media makes people stupid, a new study suggests.

Researchers from Cornell and Beijing universities found that the simple act of “retweeting” interfered with people’s understanding of the contents of the message.

Professor Qi Wang, a human development expert at Cornell in the US, said: “Most people don't post original ideas any more. You just share what you read with your friends.

“But they don't realize that sharing has a downside. It may interfere with other things we do.”

Two groups of Chinese students were shown a series of messages on Weibo, a Twitter-like social media platform in China.

One group was then given the choice whether to repost the message or move on to the next one. The other group were not able to retweet.

The students were then tested about the contents of the messages. The group that had to decide whether to repost or not got almost twice as many wrong answers as the students who simply read the messages. The reposters scored particularly badly for messages they chose to share.

The researchers, who published a paper on their work in the journal Computers in Human Behaviour, said the problem could be caused by “cognitive overload” about the decision whether or not to share the message.

The two groups were also given a test to see how well they understood an article from the New Scientist magazine. The group who had been reposting messages performed less well than the others.

“The sharing leads to cognitive overload, and that interferes with the subsequent task,” Professor Wang said.

“In real life when students are surfing online and exchanging information and right after that they go to take a test, they may perform worse.”