In light of the recent announcement that Netflix was introducing a test feature that allows viewers to accelerate the playback speed of films and television shows, a lot of people have been asking about the impact of speed on comprehension. Is there a link? Let’s explore each of the major media in turn.
Speed reading
Despite the hype, speed reading is largely a myth. Due to the physical constraints of the eyeball and ocular muscles, humans can focus on approximately seven letters per eye-glance and can make only about four eye-glances per second. Assuming the average word length is six letters, this puts a hard bottleneck on reading at about 280 words per minute. Any person reading faster than this is simply skimming.
To be fair, reading speed can increase with topic familiarity. However, this boost relies on the ability of the reader to make deep and accurate predictions of skimmed material based on prior knowledge.
Reading speed can also increase when texts contain frequent recursion (when the same names, events, and ideas are presented multiple times throughout a piece). But this boost is simply because readers are more likely to catch repeated key ideas while skimming.
Unfortunately, most educational reading is neither deeply familiar nor highly recursive. As such, when reading for learning, there is a stark and undeniable speed/comprehension trade-off: the faster students read, the less they remember and understand.
Speed listening
It has become common for people to listen to podcasts at 2x or 3x speed (which sounds hilarious). Most skilled narrators can speak at approximately 150 words per minute. Most skilled listeners can process approximately 280 words per minute before degradation occurs. This means most individuals can hear most words in podcasts sped up to 2x (as before, this value can increase when individuals are deeply familiarity with content and can make accurate predictions for missed words).
Unfortunately, although individuals can process audio at higher speeds, there appears to be a late-order speed/comprehension trade-off. When presented with material at 1x, 1.25x or 1.5x speed, individuals can typically remember and comprehend similar amounts. Once the speed jumps above 1.5x, however, comprehension drops markedly and memory suffers significantly. Luckily, it appears many students recognise this decline and, when listening to audio for learning purposes, they prefer slower speeds (~1.4x).
Speed watching
When it comes to videos, the same speed/comprehension trade-off occurs as with pure audio. More specifically, at speeds of less than 1.5x, learning appears to be largely unimpaired. But, once speeds jump above 1.5x, recall and comprehension decline significantly. Luckily, when learning is the ultimate goal, students appear to prefer - and show greater satisfaction with - slower video speeds (between 1x and 1.25x).
Interestingly, learning is best supported when the visual element of educational videos contains simple and relevant images only. When the visual element of these videos includes written text that supplements or mirrors the audio narration (closed captioning), memory and comprehension suffers significantly, regardless of video playback speed.
So our modern love affair with speed may not matter much when enjoyment is the ultimate goal, but can be a detriment when learning is the ultimate objective.
Learning takes time. Believe it or not, students will learn faster if they slow down, settle in and devote complete attention to a learning task than if they speed through it multiple times with minimal or degraded attention.
For list of references, see tes.com. Ask our resident learning scientist a question: AskALearningScientist@gmail.com
Jared Cooney Horvath is a neuroscientist, educator and author
This article originally appeared in the 10 January 2020 issue under the headline “Does speeding up videos, podcasts or reading affect learning?”
