According to 2006 research from the European Commission, more than 80 percent of people from the Netherlands, Denmark and Sweden say they can hold a conversation in English. But that falls to below 60 percent in nearby Germany.

In Spain, those who sit the Test of English as a Foreign Language (TOEFL) score on average 89, whereas in neighboring Portugal the average score is 95. What could account for these apparent disparities in different pockets of Europe? New research published in the Journal of Economic Behavior and Organization claims to have the answer: TV subtitles.

The researchers posit that countries where English-language television and films are subtitled rather than dubbed into the local language see a boost to the English-speaking skills of their people. "The magnitude of our effect is large, equivalent to 16.9 percent … of the average level of English skills," of a TOEFL score, the research states. Subtitling is particularly helpful with viewers' English listening skills, the study suggests.

This is by no means the only factor. A country's investment into education and how similar its native language is to English are very important. But the effect may be pronounced enough to account for much of the difference between otherwise similar countries.

The researchers highlight the Netherlands and Austria as two small countries with similar expenditure on education. In the Netherlands, 87 percent of the population say they can hold a conversation in English, whereas in Austria this number is 53 percent. The Netherlands subtitles much of its English-language programming, whereas Austria tends to use dubbed German.

Interestingly, the researchers suggest that, typically, the choice of particular countries to opt for subtitling over dubbing tends to date back to around World War II, and be influenced either by cost (subtitling is cheaper) or the tendency towards subtitling in countries with a native language less widely used internationally. This is important, because the researchers argue that countries that opted for subtitling would not have had a higher baseline for English proficiency to begin with. In other words, they argue causation, not correlation.

And according to separate research, no country in the OECD (Organisation for Economic Co-operation and Development) has made the switch from subtitling to dubbing, or vice versa, since the war. Poland comes closest, with the switch to subtitling made for its TV channel TVP2, aimed at young people. (A more widespread switch was met with strong opposition.)

Polling various populations, the European Commission found a strong preference for dubbing in countries that dub, and subtitling in countries that subtitle, which would help to explain why switches from dubbing to subtitling haven't happened.

But in light of this research, and with English still an increasingly influential language on the world stage, the researchers even suggest that governments could encourage subtitling as a means of improving English language proficiency and potentially increasing trade.

The team's research, TV or not TV? The impact of subtitling on English skills, was published January 14. The paper was authored by Ainoa Aparicio Fenoll, AlbertBanal-Estañol, Arturo Brise and the late Augusto Rupérez Micola, to whom it is dedicated.