How to learn a foreign language better? Watch movies with subtitles in that language

“We’ve all probably tried to learn a new language at some point. Foreign films can help you learn those words and accents, but a recent study suggests that subtitles can help a lot.
Your first instinct is probably to turn on subtitles in your native language (English subtitles on a Spanish movie for example). But ideally, you’d watch with the subtitles in the foreign language as well. In the study, students learned the accents better and were able to understand new material easier. Plus, it helps you pick up individual words when people talk quickly.”
Source – Learn a Foreign Accent by Watching Films With Subtitles

The study (Foreign subtitles help but native-language subtitle… [PLoS One. 2009] – PubMed – NCBI) says:

Understanding foreign speech is difficult, in part because of unusual mappings between sounds and words. It is known that listeners in their native language can use lexical knowledge (about how words ought to sound) to learn how to interpret unusual speech-sounds. We therefore investigated whether subtitles, which provide lexical information, support perceptual learning about foreign speech. Dutch participants, unfamiliar with Scottish and Australian regional accents of English, watched Scottish or Australian English videos with Dutch, English or no subtitles, and then repeated audio fragments of both accents. Repetition of novel fragments was worse after Dutch-subtitle exposure but better after English-subtitle exposure. Native-language subtitles appear to create lexical interference, but foreign-language subtitles assist speech learning by indicating which words (and hence sounds) are being spoken.

Personally, I always watch movies in English with English subtitles only. Now I have some material to backup my thesis. :)