This tendency extends to video as well, as experiments with video lectures and even Discovery Channel shows have shown. Increasing the tempo of a recording seems to stave off boredom and help people stay engaged. “With the slower pace, my attention span actually wavered, and I focused on too much detail,” one subject told researchers at Microsoft.
Sometimes, people don’t even notice that they are watching on fast-forward. Cable companies will slightly speed up shows to make room for more ads, but the difference can be hard to detect — in part because the brain adapts to the higher speeds.
In the 1970s and 1980s, the Defense Department began investigating compressed speech as a way to boost learning. Military-funded experiments showed that people can be trained to better understand accelerated recordings. Just a few weeks of regular exposure seemed to alter how people perceived and processed language, causing them to prefer faster and faster listening rates.
Some of those changes happen within minutes. An experiment in 1997 found that listening to just five sentences of accelerated speech boosted subsequent comprehension rates by 15 percent. This process may be related to how our brains adjust to unfamiliar accents. Have you ever noticed that it becomes easier and easier to talk to someone with a foreign accent? It’s not them. It’s your brain making short-term adaptations.
Our brains also make long-term adaptations to accelerated speech. Continued training increases people’s accuracy rates and their comfort with sped-up recordings. Functional MRI scans show changes in how their brains respond to speech. Anecdotally, many subjects found that repeated exposure to accelerated speech caused speech at regular speeds to sound strange.