Flat Earth conspiracy theorists are being indoctrinated after falling down a “rabbit hole” of videos on YouTube, a scientist has warned.

The popular site’s habit of recommending related videos to viewers is drawing in people who are vulnerable to believing in outlandish ideas, according to Dr Asheley Landrum at Texas Tech University

Subscribers to the ideology tend to believe the government is covering up the fact the Earth is flat, not a round spinning sphere.

While this seems like a fringe idea, in recent years it has appeared to grow in prominence as celebrities like the rapper B.o.B have emerged as advocates for it.

A poll conducted by YouGov last year found only two-thirds of young people surveyed “firmly believed” the Earth was round.

Dr Landrum said the spread of this phenomenon can largely be attributed to YouTube and its habit of suggesting videos to keep viewers engaged.

“YouTube really has propagated the Flat Earth movement in a way I don’t think has been done before with any conspiracy community,” she said.

Dr Landrum has attended the last two Flat Earth International Conferences, both held in the US, to interview people and establish how they arrived at their conclusions.

All 30 people she interviewed at the first conference had learned about the phenomenon directly from YouTube, apart from one whose daughter had told him about it after watching YouTube.

“There was a real spread and we were very surprised by that. Many had college degrees, there was an engineer, a social worker, a substitute teacher,” she said.

Everybody Dr Landrum and her colleagues talked to believed in other conspiracy theories including those concerning 9/11, “chemtrails” and the Holocaust.

However, she said belief in a flat Earth in particular was a “YouTube-centric” phenomenon.

“It comes down to the way that the algorithms work,” said Dr Landrum. “Under normal circumstances that might not be problematic. But it means that if someone’s looking up conspiracy videos, it’s going to suggest more conspiracies.”

This creates the impression among viewers that there is an enormous amount of evidence for the flat Earth theory, she suggested.

One man Dr Landrum talked to at the convention said he had been sceptical about the idea for a long time, but after repeatedly being drawn to the videos after watching other conspiracy theories, he was eventually converted.

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After that, he said he struggled to find any evidence to disprove the flat Earth idea.

Dr Landrum, who was discussing her work at the American Association for the Advancement of Science meeting, said while many of these people did not trust institutions, scientists must try to fight back against the flow of misinformation on YouTube.

“There are a lot of people out there who are questioning, who are curious, who want to understand – and we can’t let the only information that’s out there that’s accessible from YouTube be coming from conspiracy theorists,” she said.

The Independent has contacted YouTube for comment.