WIRED did an article in 2014 that pegs the number at 2.5 seconds. Amusingly, the professor cited in the article has the last name of "Cutting", which makes the

WIRED did an article in 2014 that pegs the number at 2.5 seconds. Amusingly, the professor cited in the article has the last name of "Cutting", which makes the article a little jarring to read to me (since I keep seeing the verb "cutting" and thinking about "cutting together" a movie).