The team looked at a specific bunch of trolls who like to swap notes about the abduction of three-year-old Madeleine McCann from her family’s holiday villa in Portugal.

Most of the trolls are focused on insulting McCann’s parents, celebrating their daughter’s disappearance and gloating over their misery.

The team of shrinks bashed out a paper called Online Trolling , where they tried to engage with this troll community, to study their attitudes and behaviour, and to work out what makes them tick.

Once the goal of their study was exposed by others in the anti-McCann community, “you need better English to do a PHD luv!” was among the politer messages sent in response to questions from “the psychology student studying trolls”.

The comments became even more toxic when the scientists tried to introduce some science into the debate. One of the psychologists posted a reference to an academic paper showing that tracking dogs might have made mistakes in finding a body because of the hot weather.

The trolls became more insulting and started attacking on the researcher’s motive, labelling them a “shill” and blocking them when they tried to steer conversations back to the findings.

The researchers discovered that the trolls has identified key phrases that act as calling cards and draw activity. In this study, the word ‘shill’ implying that the researcher was paid by the McCann family to protect its reputation was a red rag, and led to more and more trolls circling the discussion and piling in.

The paper shows trolls have some powerful psychology at play. One theme of the anti-McCann messages is motherhood and how the trolls argue that they would have behaved differently, both before and after the abduction.

This is “disassociation” and arises from an irrational belief that parents who explicitly distance themselves from the plight of the McCann family somehow keep their own children safer.

Although most of the trolls argued that they were fighting for justice, the researchers conclude that this was thin cover for being able to hurl insults anonymously.

Most of the abusive and offensive messages sent and received were against the rules of the social-media provider, yet no action was taken. Saying ‘do not feed the trolls’ does not work as they are cultural scavengers who feast on alternative facts and false news already in the system, the report said.