Luis von Ahn helped develop the CAPTCHA and reCAPTCHA tests that tell whether humans or bots are entering information online. But the Guatemala-born computer scientist says his passion is education.

He followed the sale of the CAPTCHA technology to Google with Duolingo, a language-learning app that gets better as more people use it. Duolingo now has more than 120 million users worldwide.

As our series on science in America wraps up, Here & Now‘s Jeremy Hobson talks with von Ahn about CAPTCHA, Duolingo and how computer programs could some day bring the educational benefits of one-on-one tutoring to anyone with an internet connection.

Hear more from our series on science in America

Interview Highlights: Luis von Ahn

On how most people interact with CAPTCHA

“I think most everybody has seen in a sense the distorted characters that you have to type all over the internet whenever you’re trying to get an account on Facebook, for example or trying to buy tickets on Ticketmaster. You get these distorted, annoying characters that you have to type. That thing is called a CAPTCHA, and the reason it’s there is to make sure that you, the entity filling out the form, are actually a human and not a computer program that was written to submit the form millions of times.”

On the inspiration behind Duolingo

“What we wanted to do was to work on something related to education. I was in a very fortunate time in my life. I had just sold my second company to Google and it was these distorted characters, the company for CAPATCHAs, was sold to Google. So what I wanted to work on was something related to education, because it’s my passion, I’m a professor. My views on education are very related to where I’m from. I’m from Guatemala, which is a very poor country. And a lot of people talk about education as being something that brings equality to different social classes. But I always saw it as something different. I always saw it as something that brings inequality to different people, because what happens is that the people who have a lot of money can buy themselves the best education in the world and, because of that, they continue having a lot of money. Whereas the people who don’t have very much money, especially in countries like Guatemala, they barely learn how to read and write and therefore, they continue not having very much money.

So what I wanted to do is that I wanted to have something that would give equal access to education to everybody. Now, education is very general, so we decided to start with one type of education which is learning a foreign language. And so what I wanted to do was to make a free way to learn languages for everybody. So we launched four years ago this app called Duolingo, and today it’s the most-used method to learn language in the world. We have about 120 million people learning languages on Duolingo.”

On how he’s using Duolingo to answer language teaching questions

“At first it was a funny thing, we actually neither I nor my co-founder Severin, knew anything about teaching languages. We were just a couple of engineers trying to come up with the best way to teach languages, or build the best way to teach languages. So we just wanted very, answers to very specific questions, like, ‘Should we teach plurals before adjectives?’ for example.

The different books that we were reading actually contradicted each other, so what we did is that we just launched our app, but then we realized we were actually in a pretty great position, because we started getting so many users that we started figuring out that you could actually determine the answer to all the questions we originally had with our own users. So, for example, if we want to know whether we should teach plurals before adjectives, the next 50,000 people that sign up for Duolingo, half of them you teach them plurals before adjectives, and to the other half you teach them adjectives before plurals. And then you measure which ones learn better.”

On his future plans

“I mean I think for me right now my passion is really being able to educate everybody. I think the educational system in the world could be massively improved, so we know how to do better, it’s basically by giving everybody a one-on-one human tutor. The problem with that is that that is not scaleable. So we can’t do that. But I believe that computers are something that can really help. I’m not talking about substituting teachers, I think teachers do a lot of great things in motivating students and being able to answer questions. But, what I want to do, you know, in the near future, is come up with a system that is as adaptable as a one-on-one tutor would be.”

Guest

Luis von Ahn, an associate professor of computer science at Carnegie Mellon. He co-founded reCAPTCHA and created Duolingo. He tweets @LuisvonAhn.

Copyright 2016 NPR. To see more, visit NPR.