You 2.0: Did That Really Happen?

Our memories are easily contaminated. We can be made to believe we rode in a hot air balloon or kissed a magnifying glass — even if those things never happened. So how do we know which of our memories are most accurate? This week, psychologist Ayanna Thomas explains how we remember, why we forget, and the simple tools we all can use to sharpen our memories.

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Did That Really Happen

/ December 17, 2019

Our memories are easily contaminated. We can be made to believe we rode in a hot air balloon or kissed a magnifying glass — even if those things never happened. So how do we know which of our memories are most accurate? This week, psychologist Ayanna Thomas explains how memory works, how it fails, and ways to make it better.

Transcript

*The transcript below may be for an earlier version of this episode.
Our transcripts are provided by various partners and may contain errors or deviate slightly from the audio.*

SHANKAR VEDANTAM, HOST: From NPR, this is HIDDEN BRAIN. I'm Shankar Vedantam. Almost a century and a half ago, a young German philosopher named Hermann Ebbinghaus picked up a curious book at a used bookstore. It was called "Elements Of Psychophysics" and it described how to gather data on invisible mental processes. The book gave Ebbinghaus an idea.AYANNA THOMAS: And he thinks about, OK, well, we all have this experience of learning information and forgetting information. How can I study that?VEDANTAM: Psychologist Ayanna Thomas - she says Ebbinghaus wanted to answer a big question. How does memory work?THOMAS: He really wanted to understand memory at its most basic core. How quickly can we learn new information that we've never been exposed to? And how quickly does that information degrade?VEDANTAM: This was the late 1800s. There was no protocol on how to run a psychology experiment. Most insights about memory came from philosophers and theologians. So Ebbinghaus came up with a plan. He would run an experiment on himself. First, he needed something to memorize. He came up with the idea of nonsense syllables - three random letters strung together. He put them on some cards.THOMAS: So more than 2,000 of these.VEDANTAM: Then he shuffled the cards, divided them into groups and set about learning them in a variety of controlled conditions. Sometimes he read the cards aloud...UNIDENTIFIED ACTOR #1: (As Hermann Ebbinghaus) Leg, muf, vok, dal, sen, cap, nud, suk (ph)...VEDANTAM: ...Forcing himself to read them at the exact same rate in the same soft tone of voice keeping time to a ticking metronome.(SOUNDBITE OF METRONOME)UNIDENTIFIED ACTOR #1: (As Hermann Ebbinghaus) Dal, sen, kep, nud, suk, kas, leg (ph)...VEDANTAM: He would read a group of cards aloud once, hide it, and then try to recite it from memory. Every time he made a mistake, he would stop, note it in his records...(SOUNDBITE OF WRITING)VEDANTAM: ...And start over.UNIDENTIFIED ACTOR #1: (As Hermann Ebbinghaus) Leg, muf, vok...(SOUNDBITE OF WRITING)VEDANTAM: He kept doing this - stopping and starting over, stopping and starting over - until he could recite a group of syllables perfectly.UNIDENTIFIED ACTOR #1: (As Hermann Ebbinghaus) Suk, suk...VEDANTAM: He repeated this process periodically to see how much he could remember 20 minutes later, an hour later, nine hours, a day and so on.(SOUNDBITE OF WRITING)VEDANTAM: Stopping, starting over, stopping, starting over - for more than six months.UNIDENTIFIED ACTOR #1: (As Hermann Ebbinghaus) Vok, dal, sen, kep, nut (ph)...VEDANTAM: The experiments were highly precise and monotonous and required a huge amount of self-discipline. His greatest enemy was boredom. Years later, Ebbinghaus told a group of psychologists about the tedium of his most celebrated accomplishment.UNIDENTIFIED ACTOR #1: (As Hermann Ebbinghaus) I shall not go into the agonies that months on end of such study engendered in me. I attempted to...Lek, muf, vok, dal, sen, kep, nut, muf, ton, gen (ph)...And with that respect, the magnitude of the task seemed staggering to me.THOMAS: And you might ask, why would anyone want to do that? Well, his motivation was he wanted to see what information was remembered but also how much information was forgotten.(SOUNDBITE OF MUSIC)VEDANTAM: This week on HIDDEN BRAIN - the science of memory from the early ideas of Ebbinghaus to the latest discoveries of modern psychologists.(SOUNDBITE OF MUSIC)VEDANTAM: How do our minds hold on to the events of the past? What are the most common ways our memories fail us? Can we ever really know for sure that our memories are telling us the truth?(SOUNDBITE OF MUSIC)VEDANTAM: How we remember, why we forget and the simple lessons we can all learn to make our memories sharp and vivid.(SOUNDBITE OF MUSIC)VEDANTAM: Hermann Ebbinghaus remembered thousands of three-letter strings and then tried to see how many he remembered the same day, the next week, the next year. He discovered something that many of us experience. Over time, he started to forget things. But since he was running an experiment, it allowed him to actually measure how much he was forgetting and how quickly. It led him to discover something that is today called the forgetting curve.THOMAS: That forgetting curve, if you look at it, you see an exponential decline in what he can accurately remember as time passes.VEDANTAM: This, again, is Ayanna Thomas, a psychologist at Tufts University who studies memory.THOMAS: You see a really quick drop off, so by the time you get out to a week and then a month, there's a lot of information that's been lost. But I also think what's really neat is a month later, there's quite a bit of information that still has been retained.VEDANTAM: What I find really interesting about this story, Ayanna, is that it reveals two things that at some level feel intuitively true to us. All of us have this experience of remembering something and then finding a week later we can't remember what we remembered. And also realizing that if we try and relearn what it is that we have forgotten, it is quicker the second time around than the first. So at one level, he is telling us things that we all experience in our life. But was he also, in some ways, putting on the map the idea that you can actually study these things empirically, that there was a science to memory, that it was amenable to measurement and to precision?THOMAS: Indeed. He was the first to bring this in to a laboratory where he has a hypothesis about how memory is going to operate. And he operationalizes the construct of memory. So I think about memory as a really broad construct - a really broad term. And that term can encompass so many different things. Right now, I'm using memory to communicate with you, right? I'm bringing things up from my long-term memory and I'm using my working memory to communicate that information. But that's not how Ebbinghaus operationalized it. So he thinks about, OK, well, we all have this experience of learning information and forgetting information. How can I study that?And in order to study memory and what Ebbinghaus introduced us to is that we have to figure out what our construct is, we have to define that construct, and then we have to develop tasks that are appropriate to the definition of that construct. You can think about memory in a whole host of different ways. I know how to ride a bike, but I can't tell you exactly how to do it. I just know how to do it. That's still an element of memory and not the one that Ebbinghaus was studying.(SOUNDBITE OF MUSIC)VEDANTAM: After Hermann Ebbinghaus, other researchers came along and said, OK, we can study memory systematically. Through careful observation and measurement, we can see how memory works and when it fails. In the 1930s, Frederic Bartlett set up an experiment that revealed a very interesting aspect of memory. The experiment revolved around a story - a Native American legend called "The War Of The Ghosts."(SOUNDBITE OF RUNNING WATER)UNIDENTIFIED PERSON: One night, two young men from Egulac went down to the river to hunt seals, and while they were there, it became foggy and calm. Then they heard war cries, and they thought, maybe this is a war party. They escaped to the shore and hid behind a log. Now canoes came up, and they heard the noise of paddles and saw one canoe coming up to them. There were five men in the canoe...VEDANTAM: Fre

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