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  • This episode is sponsored by Blinkist.

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  • [♩INTRO]

  • If you've reached a certain age,

  • you might notice you're not plowing through books the way you used to.

  • And like so many things about getting older,

  • thatcertain agecomes sooner than you expect.

  • It gets worse in your 60s or 70s, but some researchers have noticed

  • a decline in reading ability starting in your 40s.

  • So why do people read more slowly as they get older?

  • Well, we're not totally sure -- the reasons seem to vary.

  • But understanding some of the details might actually help us tell

  • the difference between healthy aging and Alzheimer's disease.

  • Most people experience a decline in reading speed as they get older.

  • That's the case even though other mental factors tend to stay pretty strong,

  • as long as you're otherwise healthy.

  • Which makes it tough to pin down

  • what's causing reading to slow down, specifically.

  • Like, most people on average tend to have their overall mental processing

  • slow a bit as you get older.

  • But your memory for word meaning stays pretty consistent into old age.

  • It's also possible that declining vision could slow you down.

  • But studies show that's a separate factor

  • in other words, people slow down their reading even if their vision is fine.

  • Researchers have also proposed that maybe people slow down on purpose.

  • That even if they don't realize it, they're slowing down to be a little more cautious

  • about what they're taking in -- so as to avoid mistakes.

  • But studies haven't borne that out, either.

  • In a 2018 study, researchers had both young and old people read

  • at their own pace.

  • Then, they tested their comprehension after making them double their speed.

  • If older adults deliberately set a slower pace than the younger people

  • in the study, they should make fewer mistakes when forced to speed up.

  • The older group did pace themselves a little more slowly,

  • and made more mistakes overall, as expected.

  • But doubling their speed made everyone, young and old, equally worse.

  • So it seems like the mistakes weren't a result of their self-paced speed.

  • So if we've ruled out things like declining vision or going slower on purpose,

  • why does reading speed decrease?

  • It kind of depends on how old you are.

  • Early on, between young adulthood and middle age,

  • reading slows because all kinds of processing slows.

  • Generally, we get a little bit worse at processing incoming information,

  • and our executive function gets a little worse.

  • If you control for things like working memory and processing speed,

  • middle-aged adults can read just as quickly as younger adults.

  • One thing in particular that can trip you up a little more

  • is an effect called visual crowding.

  • Most people can identify a letter sitting on its own more quickly

  • than a letter surrounded by other letters.

  • That's especially true for your peripheral vision.

  • And reading requires some anticipation of what's in your peripheral vision,

  • as your eyes move from word to word.

  • A 2017 study published in Scientific Reports found a relationship

  • between age, crowding, and reading speed.

  • The researchers reported that older adults experience a bigger crowding effect.

  • That means letters don't need to be as close

  • for people to start making mistakes because of crowding.

  • And this was related to their reading speed.

  • The researchers found that adults over 50 read more slowly than those in their 20s.

  • And the younger group likewise had a smaller crowding zone.

  • That means older adults might be more distracted by other things on the page

  • skipping ahead to irrelevant things

  • instead of focusing on the part they need to process next.

  • So that may be part of what slows us down.

  • The shift in reading comprehension with age might also be related

  • to a specific kind of memory called your phonological loop.

  • Imagine a conversation where you're not really paying close attention,

  • and then you notice the other person is waiting for you to respond.

  • So you quickly think of the last few words they said

  • so you can rephrase it as a question.

  • That's the phonological loop in action.

  • It's like a buffer of a few moments of auditory information your mind keeps ready

  • in case you need to go back,

  • like if you need to repeat a phone number to yourself before you dial.

  • And that's really useful when you're reading.

  • Researchers in the year 2000 found this was part of the decline

  • in reading comprehension with age.

  • Basically, once they controlled for how much people can keep

  • in their phonological loop, readers in their 40s and 50s

  • showed about the same reading comprehension as those over 60.

  • And that suggests the phonological loop is the key factor

  • it stores less as you age.

  • So at the very least, you can take comfort in the fact that

  • this is a typical part of healthy aging.

  • But another reason why this research is important

  • is because of that key word, “healthy.”

  • Because focusing on the details of your reading ability might

  • also help distinguish typical aging from Alzheimer's disease.

  • Like we said before, this phenomenon is surprising because most people

  • keep a fairly consistent level of word knowledge and memory as they age.

  • But that's not the case for people with Alzheimer's disease.

  • For them, meanings are impaired, too.

  • They perform worse at naming words that fall in specific categories

  • like things at a grocery store.

  • A 2016 study identified a few key brain regions that help distinguish

  • those with Alzheimer's from others, such as the amygdala.

  • In people with Alzheimer's, their verbal ability was related to

  • how much gray matter they had in those regionsbut not the control group.

  • Older studies have had a hard time distinguishing Alzheimer's patients

  • from controls based on verbal abilities alone.

  • Understanding the differences, paired with brain scans,

  • may help us understand the unique features of Alzheimer's.

  • So if your reading is slowing down as you get older, don't worry.

  • You're not alone -- and you'll still enjoy that novel

  • just as much as those kids are enjoying that dance challenge online.

  • But if you want a little help finding the time to get your reading in, there's Blinkist.

  • Blinkist is an app that takes the best insights, the need-to-know information

  • from over 3,000 nonfiction books and condenses them into just 15 minutes.

  • For example, you might enjoy The Mystery of the Exploding Teeth,

  • a collection of bizarre stories from the history of medicine.

  • It will help you appreciate just how far science and medicine have come!

  • The first 100 people to go to Blinkist.com/scishowpsych

  • will get unlimited access for 1 week to try it out.

  • You'll also get 25% off if you want the full membership.

  • You can get started with a 7-day free trial at the link in the description.

  • [♩OUTRO]

This episode is sponsored by Blinkist.

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