lectures double speed

Students can still retain information when watching their lectures at up to twice the speed, as recorded lectures have expanded during the pandemic

A study, with 85% of college students surveyed who “speed-watched” their lecture videos, shows that students can still retain information quite well.

Recorded lectures have become a routine part of course instruction during COVID-19, and so this study set out to identify how faster speeds affected learning.

As people generally speak at a rate of about 150 words per minute, previous research has shown that comprehension begins to decline as speech is doubled in speed at 275 words per minute. However, researchers stated their surprise that students could learn, and retain knowledge, at some of the faster speeds.

Students were involved in a series of experiments to test this question, as it is reported that college students often try to pack more learning into a shorter span by watching their recordings at double their normal speed or even faster.

Does comprehension suffer as a result?

Student understanding of their courses is not too affected by doubled lecture speed. However, it was found that once students exceed that limit, lectures begin to get become less comprehensive.

In one of the experiments used to test retainability in students, the researchers divided 231 UCLA undergraduates into four groups and had them watch two 13-to-15-minute lecture videos – one on the Roman Empire and another on real estate appraisals. One group watched at normal speed, one at 1.5 times normal speed, another at double speed and the final group at 2.5 times normal speed. They were instructed not to pause the videos or take notes.

After the videos, students were given comprehension tests on the individual videos, each comprising 20 multiple-choice and true-or-false questions. The normal-speed group averaged 26 correct answers out of 40, while the double-time group scored 25 (about the same as the 1.5-speed group). The 2.5-speed group didn’t do as well, answering only about 22 questions correctly.

The same groups of students were given different tests related to the two videos to assess what they’d retained a week after the first tests. The normal-speed group averaged 24 out of 40, the 1.5-speed and double-speed group averaged 21, and 2.5-speed students averaged 20.

Lead author Dillon Murphy, a doctoral student in psychology at UCLA, stated: “Surprisingly, video speed had little effect on both immediate and delayed comprehension until learners exceeded twice the normal speed.”

Different combinations of speed-watching had different results

Researchers from other experiments tested various combinations of speed-watching and normal-speed viewing of the two videos.

One group of students watched the videos at double speed twice in succession and another watched them just once at normal speed. Of which they found that both groups answered an average of 25 of the 40 questions correctly immediately following their viewings.

Similarly in another experiment, one group watched the videos once at normal speed while another viewed them initially at double speed, then a week later at double speed again. When tested a week after the first group watched the videos – and shortly after the second group viewed the videos a second time – the speed-watchers actually performed better, averaging 24 out of 40, in comparison to 22 for the one-time, normal-speed group.

Murphy added: “College students can save time and learn more efficiently by watching pre-recorded lectures at faster speeds if they use the time saved for additional studying, but they shouldn’t exceed double the normal playback speed.

“While our study didn’t reveal significant drawbacks to watching lecture videos at up to double the normal speed, we caution against using this strategy to simply save time. Students can enhance learning if they spend the time saved on activities such as reviewing flashcards or taking practice tests.”

The researchers highlight that different course which may have more complex material could outcome in different results depending on speed watched at.


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