Does watching YouTube at 2x speed hurt learning?

Quick answer

Half the internet watches at 2x and the other half thinks they're psychos. Turns out there's actual research on this.

What 125x is: 125x is a web app at 125x.app. You connect your YouTube subscriptions, and it gives you a feed of the latest videos from the channels you follow, each with a summary: a verdict, the 5 key takeaways, and the spoiler, plus Actionable and Lessons tabs with more tips. You read that and decide what's actually worth opening.

Open 125x

What the study found

Researchers at UCLA had students watch lecture videos at 1x, 1.5x, 2x and 2.5x and then tested them. Speed had little effect on comprehension until it went past 2x. On the immediate test, the normal speed group averaged 26 out of 40 and the 2x group 25.

The 2.5x group dropped to about 22 (UCLA Newsroom). The paper is Murphy et al., Applied Cognitive Psychology, 2022.

The same UCLA write-up says 85% of the UCLA students surveyed reported speed-watching lecture videos (UCLA Newsroom).

The catch

A week later, the normal speed group averaged 24 and the 1.5x and 2x groups 21 (UCLA Newsroom). The researchers' advice was to use the time saved for extra studying, like flashcards or rewatching close to a test, and to stay at 2x or below. They also said it may work less well for really complex material.

Tips from people who speed-watch

Start at 1.25x and creep up. Your ear adjusts in a few days.
Drop to 1x for the hard parts, then speed back up.
Fast talkers at 2x are rough. Slow talkers at 2x sound normal.
Turn on captions at high speeds.

Our take

Speed helps, but you're still sitting through the filler, just faster. Reading the summary first tells you which videos deserve the time at all. That's what 125x does for your subscriptions, and then you can watch the keepers at whatever speed you like.

FAQ: questions people ask

Is watching YouTube at 2x speed bad for learning?

A UCLA study found little drop in comprehension up to 2x, and a clearer drop at 2.5x, for lecture videos.

Can you watch YouTube faster than 2x?

Some devices let you set a custom speed above 2x, but the UCLA study saw comprehension drop past 2x.

Should I watch twice at 2x or once at 1x?

In the study, watching twice at 2x right in a row was about the same as once at 1x. Spacing the second watch closer to the test helped.