"Usability of CAPTCHAs Or usability issues in CAPTCHA design", Jeff Yan and Ahmad Salah El Ahmad (Newcastle University, UK)
http://homepages.cs.ncl.ac.uk/jeff.yan/soups08.pdf Pages 3 and 4: "Friendly to foreigners? In theory, text-based CAPTCHAs are intuitive to world-wide users and have little localization issues – these were recognised by many researchers (e.g. [5]) as major advantages of text-based CAPTCHAs over other schemes. However, in a small scale test carried out with 20 students in the first author’s class in October 2007, we observed that many foreign students whose mother tongue does not use the Latin alphabet performed much worse than those whose first language is based on Latin alphabet (e.g. native English speakers), when asked to recognise distorted challenges generated by BaffleText [6], an early text-based scheme. The former found it hard to recognise (or even guess) distorted letters in the scheme." [...] "The performance difference between foreigners and natives does not appear to be large in the case of reCAPTCHA. However, given the size of population using this service (hundreds of thousands websites serving millions of people at least, for example, popular sites such as Facebook and Twitter are amongst subscribers of this service), this “being friendly to foreigners” issue can be a serious usability concern. Moreover, for schemes whose designers were unaware of this issue, usability problems caused can be even worse." [...] In the conclusion: "Contrary to the common belief, text-based CAPTCHAs can be difficult for foreigners." It is worth reading and likely the same for references there in. The first sentence is similar to what I have experience in 3 classes. And people begin to get anxious and usually say "If I type wrongly again, I'll give up". I've seen 3 students saying this to me. Even if hypothetically had in an experiment that only 1% of foreigners will face difficulties with CAPTCHA in a foreign language (I bet it's much more from real life experience), how much users this would represent in one of the most accessed sites in the world? Tom -- Everton Zanella Alvarenga (also Tom) Wikimedia Brasil Wikimedia Foundation _______________________________________________ Wikitech-l mailing list Wikitech-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikitech-l
