If, like me, you spend far more time in airports than is good for you, then you will be familiar with the television sets dotted around the lounges, largely silent but with the subtitles or closed captionson. Usually tuned to a news program, the captions themselves become hypnotic, and you cannot help but read them:

I’m told that the same thing also happens in sports bars, but obviously I have far less practical knowledge of such establishments myself.

It seems that the mere appearance of the words forces you to read. This phenomenon was first formally observed by Brij Kothari, an Indian then studying at Cornell in the States. He was trying to learn Spanish, but the local cinemas that showed films from Spain put English subtitles on them. It made it much harder to hear the original language. He realized that if they had Spanish captions it would be much easier to learn the language, with the written script reinforcing the sound of the spoken words.

“Then it occurred to me that if all Indian television programming in Hindi was subtitled in Hindi, India would become literate faster,” recalled Kothari, now professor at the Indian Institute of Management.

Today one of the most popular programs on Indian television is the Sunday night sing-along: Bollywood hits with same-language subtitles. Not only do people read, listen, sing and learn, but children copy the lyrics down so they can sing them with their friends later.

This karaoke-for-literacy effort reaches 200 million viewers a week. In the last nine years, functional literacy in the areas covered has more than doubled. A researcher focusing on one particular town found that newspaper reading has risen by more than 50%, so the population is better informed. Women are now capable of reading bus timetables so social mobility is boosted. Literacy is liberating in so many ways.

Now here is the killer message: this does not only work in developing countries. Research in the USA by Nielsen’s ORG Center for Social Research found that same language subtitling doubles the number of functional readers among primary school children.

Across the developed world there is a huge number of adults who, while not being illiterate, cannot read fluently. According to the World Literacy Foundation, one in five adults in the UK struggles with basic reading. If they do not feel they can pick up a newspaper, or read a bus timetable, they cannot take a full role in society.

I’m not suggesting that same-language subtitling of every MTV broadcast is the complete solution. But it looks like it would help, and with today’s technology it is a low-cost win. Literate viewers are more responsive to advertising, too, so there are potential returns.

So next time you find yourself in an airport, or even a bar, remember that same-language subtitling is not just for those who cannot hear the words, for whatever reason. It could – and should – be changing peoples’ lives.