Many of us have fallen into the habit of listening to podcasts, audiobooks, and other online content at double speed. For young people, this may have become the norm. For example, a survey of students in California, USA, showed that89% of students will watch recorded videos of online lectures at double speed.Meanwhile, there have been numerous media articles describing the prevalence of double-speed browsing.
The benefits of speeding up are obvious: you can consume more content in the same amount of time, or gain a deeper understanding by watching the same content over and over again.
This is particularly important at the educational level, as students can free up time to consolidate knowledge, take mock exams, etc. Moreover, driving at double speed may also allow people to concentrate and be fully engaged throughout the process and avoid being distracted.
But what are the downsides? In fact, quite a few.
Researchers have found that a person needs to go through three stages to receive spoken information and form a memory:Encoding information, storing information, and later retrieving information.In the encoding stage, the brain needs a certain amount of time to process and understand the speech just input. The brain must extract words and their contextual meanings from memory in real time.
People typically speak at around 150 words per minute, and even speaking at twice that rate (300 words/minute) or three times that rate (450 words/minute) is still within the range of human intelligibility. butThe main issue is the quality and durability of the memories we form.
The information we receive will be temporarily stored in a file calledworking memory(working memory) memory system. It can convert and combine large amounts of information into a form that can be stored in long-term memory. Since the capacity of working memory is limited,If we receive too much information in a short period of time, we may overload it.This can lead to cognitive overload and information loss.
Double-speed browsing and brain information extraction
A recent meta-analysis in memory research examined 24 studies of learning from lecture videos. The designs of these studies varied, but generally divided participants into two groups, one group watched the lecture video at original speed (1x), and the other group watched the same lecture video at multiple speeds (1.25x, 1.5x, 2x, and 2.5x).
Like randomized controlled trials used in medicine to test efficacy, participants are randomly assigned to one of two groups. After watching the video, both groups completed the same test to test their mastery of the video material. The tests either require them to recall information, test memory with multiple-choice questions, or a combination of the two.
This meta-analysis showed thatThe higher the speed when watching videos, the worse the test performance.The impact is minimal at 1.5x speed, but significant at 2x speed and above.
Specifically, if the average score for a group of students is 75%, and typically fluctuates by 20%, then watching the video at 1.5x speed will bring the average down by 2%. And 2.5x speed will result in a 17% drop.
elderly group
Interestingly, one of the studies included in the meta-analysis also looked at older adults (ages 61 to 94) and found that they were more affected by watching videos at double speed than younger adults (ages 18 to 36). This may reflect the fact that memory capacity also declines with age in healthy people, suggesting thatElderly people should watch videos at full speed or even slow down to make up for the shortcomings.
However, it's not clear whether the disadvantages can be reduced by frequently playing videos at double speed. That is to say,One possibility is that younger people are simply driving at double speed more often and are therefore better able to cope with the increased cognitive load.Likewise, this means we cannot be sure whether young people can mitigate the negative impact of this behavior on their ability to retain information by regularly speeding up.
Another point that remains unclear is whether playing videos at double speed has long-term effects on mental function and brain activity. In theory, these effects could be positive, such as improving a person's ability to cope with cognitive load. These effects may also be negative, such as greater cognitive load that may trigger mental fatigue, but we still have no scientific evidence to answer these questions.
The final phenomenon is that although turning up to 1.5x speed does not affect memory performance, there is evidence that people's viewing experience will be degraded. This may affect people's motivation and experience in learning new things, and may allow them to find more excuses to avoid learning. On the other hand, doubling up has become the norm, so maybe once people get used to it, it won't be such a big deal - hopefully we'll understand these processes better in the coming years.