A controversial experiment on children was carried out in 1939, earning it the nickname “Monster Study” and resulting in recompense years later for those who survived.

There has been a lot of study into what causes stuttering and stammering, as well as how people can overcome speech impairments.

However, in one experiment conducted by Dr. Wendell Johnson on 22 orphaned youngsters in Iowa, some of them suffered long-term consequences.

We divided the 22 children into two groups: those who stammered and those who did not, and then further divided them within those groups.

Five stuttering youngsters were informed that they were speaking fluently and without stuttering, while another five were told they had speech issues and were given speech treatment.

In the other group, six fluently speaking children were told that they could speak well and were complimented on their ability to do so, while another six who could speak without stuttering were told that they were terrible speakers who were developing stutters and were barred from speaking until they could do so easily.

These final six youngsters quickly moved from being able to communicate fluently to hardly being able to speak at all.

Researchers reported that in the instance of a five-year-old girl, it ‘was quite difficult to persuade her to speak, although she talked very freely the month before,’ while a nine-year-old was recorded as almost refusing to communicate.’.

They also noticed that a 15-year-old stopped talking and began saying ‘a’ a lot, and when questioned why, she told researchers she was terrified of not uttering the following word.

All six of the youngsters in this group’s academic aptitude deteriorated, and their problems persisted even after the trial was over.

Academics never published the study’s findings, but they were aware of them and dubbed it the “monster study.” The findings remained at the University of Iowa until 2001, when an investigative journalist discovered them stowed away.

When Jim Dyer of the San Jose Mercury News reached out to the experimentees, they revealed to him that they had experienced long-term psychological effects.

In 2007, the state of Iowa decided to compensate the orphans for $925,000 (£730,000).

NBC reported at the time that Hazel Potter Dornbush, an 84-year-old lady who had previously been the 15-year-old girl who was worried she wouldn’t be able to say the next syllable, said, “It was awful stressful all these years.” I am simply relieved that it has come to an end.

“How would you like them to go over your whole past in the previous 80 years?

“I call it brainwashing. I don’t care what others name it; that’s my language. I was aware of it immediately, but I cooperated.

“You know, we weren’t in a position to debate with anybody. We had no one to turn to for aid.”

The University of Iowa’s speech and hearing facility is still named after Wendell Johnson.