As Fred Astaire and Ginger Rogers once sang, the difference between British and American English used to come down to whether someone said “tomato” or “tomAto”.

Now though the lines are becoming increasingly blurred as the words, intonation and accent used by US internet stars are adopted by their young British fans.

A survey of 3,000 childcare providers and teachers for Childcare.co.uk, an online platform for childcare providers, parents, schools and tutors, has found that a quarter of primary school teachers are now familiar with the “YouTube accent” phenomenon – when children adopt an American accent or slang as a result of watching YouTube videos and television shows during lockdown.

Jane Setter, professor of phonetics at the University of Reading and author of Your Voice Speaks Volumes: It’s Not What You Say, But How You Say It, suggested some children could be seeking “covert prestige” – when a group deliberately adopts non-standard or non-prestige speech forms to demonstrate a group identity.

She cited the example of working-class and lower middle-class men in the UK using dialect and swear words to demonstrate their masculinity.

Other children could be seeking a form of “accommodation”, Setter suggested.

“For children, it could simply be because everyone is watching a particular trending YouTube influencer or group of influencers, or playing particular online interactive games, through word of mouth and a desire to fit in with their friends, that these people speak in a particular way, and the kids are using the features of those speakers with other kids to show they “belong” to that group.”

American influencers such as nine-year-old Ryan Kaji, who has his own YouTube channel, Ryan’s World; Leah Ashe, 27, a gaming and vlogging YouTuber; and James Charles, 21, an online makeup artist have become multimillionaires because of the army of young fans they attract.

“We do naturally gravitate towards and accommodate the speech styles of people we admire or feel positive towards,” said Dr Rob Drummond, reader in linguistics at Manchester Metropolitan University. “We all do it. Only slightly, but it’s there.”

However, he questioned whether teachers were simply picking up on a few words and drawing overarching conclusions.

“It’s very easy to overstate the effect and impact of very small changes in speech. For example, maybe a child has picked up the pronunciation of a particular word such as ‘letter’ using a more American-sounding ‘ledder’; a parent hears this and says ‘Oh my goodness, she’s got an American accent!’. When really she is simply repeating one single pronunciation of one single word.”

Either way, Drummond pointed out the phenomenon was hardly new. “Young people have always leaned towards whatever is deemed attractive and ‘cool’ at the time. Be that American culture, Jamaican culture, hip-hop culture, Japanese culture or K-pop culture.”

Dr Punit Shah, associate professor of cognitive psychology at the University of Bath, suggested parents should not unduly worry (or get “salty”) if their children have started speaking like YouTube stars.

“Compared with adults, children are much better at picking up language and linguistic tone and features – that’s why it’s actually really hard to learn a second language as an adult. But when you are a child the way you hear sounds in the context of language is far more malleable and that most likely explains what’s going on here.

“If you are exposed to a greater amount of YouTube accents and Americanisms, it’s no surprise we are seeing children pick up these linguistic features in the way they speak.”

Shah said children “learning and being adaptable” was “almost always going to yield positive results”. The real issue, he suggested, was what children were watching.

“The thing people should be more concerned about is the content they picked up on YouTube rather than the way they are speaking as a result of engagement with such content.”

The phenomenon appears to provide further proof of the hegemony of American – as opposed to British-English. “American English has certainly risen in status above British English in many domains, and this could be for a number of different reasons,” Setter said.

“The sheer number of speakers of American English, the political and economic rise of the US while the UK’s influence has declined.”

She suggested that schools had a role to play in exposing children to a range of accents, so that they did not discriminate against a person because of how they spoke.

Online platforms should also step up, Setter says. “Platforms like YouTube have a huge role to play in the presentation of diversity in a positive way. But with YouTube, it’s largely about who puts the content up.

“While Google might police the platform, I don’t believe it has any power to stop one group posting more than another – so if a particular YouTuber/influencer gains a following, as long as they are operating within the guidelines, how they speak could be going to have some kind of … er … influence.”