Cosmic Habituation

Summary

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Episode Overview

Radiolab’s episode “Cosmic Habituation” explores a baffling scientific mystery: why do certain scientific results seem to diminish or even vanish with repeated experimentation? Hosted by Jad Abumrad and Robert Krulwich, the episode unpacks the so-called “decline effect”—a phenomenon where early scientific findings become less reliable or pronounced over time. Through investigative storytelling and an engaging conversation with psychology professor Jonathan Schooler, the hosts delve into the scientific, psychological, and philosophical implications of these fading effects.

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Key Discussion Points & Insights

1. The Verbal Overshadowing Experiment

• Origin Story: Jad and Robert introduce Jonathan Schooler's now-classic psychology study.
  • Schooler had participants watch a video of a bank robbery and asked half to write detailed descriptions of the robber's face.
  • Later, all participants tried to identify the robber from a lineup.

"We found those people who had been asked to describe the face in great detail, they were actually less good at recognizing the face than if they didn't engage in any description at all."
— [03:28, Science Contributor/Guest]

• Surprising Result: Describing what they saw reduced accurate recognition—by 30-40%.

• Naming the Effect: Schooler coined this the "verbal overshadowing" effect because "the words overshadow the truth." ([04:06, Jad Abumrad])

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2. The Mysterious Decline

• Replication Attempts: Schooler noticed the effect diminished over time.

  • Each attempt to replicate the original study showed a weaker result.
  • [05:08] "As we kept trying to replicate this study, the effect size got smaller and smaller and smaller."
    — Science Contributor/Guest

• Statistical Questioning: Schooler and the hosts discuss “regression to the mean”—the tendency for extreme findings to moderate with more data ([06:38, Narrator/Advertiser]).

  • But this doesn’t explain the gradual, consistent decline witnessed.

• Possible Causes Considered:

  • Experimental procedures subtly changing (e.g., different room colors, less charismatic grad students) ([08:06, Narrator/Advertiser]).
  • Schooler: “There might be some little thing off to the side that you're not even thinking about.” ([08:03, Jad Abumrad])
  • Ultimately, he gave up on the line of research due to its elusiveness.

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3. A Widespread Problem: The Decline Effect Beyond Psychology

• Not Isolated: Schooler discovers his experience is widespread.

  • The “decline effect” appears in biology and medicine.

• Example—Biology:

  • Early ‘90s studies: Female birds prefer symmetrical male mates—early success, but later studies often failed to replicate.
  • [09:52] "It was a very exciting idea. …Until by the end of the 90s, you're going one for 13."
    — Narrator/Advertiser

• Example—Medicine:

  • Second-generation antipsychotics: Initially twice as effective as the first generation. Over time, new studies showed diminished advantages ([10:45, Narrator/Advertiser])
  • Antidepressant studies: Both drug effects and placebo responses changed, possibly due to public awareness and drug advertising ([11:11, Narrator/Advertiser]).
  • Birds, obviously, do not read scientific journals—so public awareness couldn't explain all decline effects.

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4. Struggling for Explanations

• Multiple Theories
  • Statistical quirks like regression to the mean ([12:37, Science Contributor/Guest])
  • Unnoticed variables in methodologies or sampling
  • The power of observation itself changing reality—a radical speculation by Schooler

"I say this with some trepidation, but I think we can't rule out the possibility that there could be some way in which the act of observation is actually changing the nature of reality."
— [13:03, Science Contributor/Guest]

• Cosmic Habituation Hypothesis
  • Maybe reality "habituates," like how we stop feeling a constant sensation (e.g., a hand resting on a leg) ([13:47, Science Contributor/Guest])
  • Possibility (however wild) of a kind of 'collective consciousness' influencing outcomes
  • "The notion that the laws of reality are unchangeable is an assumption…we don’t know it for a fact." ([14:16, Science Contributor/Guest])

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5. If All Reality Is In Flux…

• Disquieting Implications

  • If observer effects can change results, scientific certainty itself is at risk.
  • "The problem with this idea is if you really believe it, then you can never really know anything."
    — [14:47, Jad Abumrad]
  • Robert: "By this logic, you could never really know for sure because reality could change based upon the observer's position, habits, biases, information, whatever." ([14:52, Robert Krulwich])

• Meta-Decline?

  • Schooler jokes: If you studied the decline effect, would it also decline? And would a study of that effect make it return?
    ([15:39, Science Contributor/Guest]; [15:48, Jad Abumrad])

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Notable Quotes & Memorable Moments

• “The words overshadow the truth.” ([04:06, Jad Abumrad])
• “Turns out it’s not just me who has experienced this peculiar decline effect.” ([09:17, Science Contributor/Guest])
• “You haven’t been around chickadee conversation. Word passes quickly amongst the chickadees.” ([12:03, Robert Krulwich & Jad Abumrad]—humorous moment)
• “In this most radical conjecture, there could be some sort of collective consciousness that's habituating… Keep in mind the notion that the laws of reality are unchangeable is an assumption." ([14:16, Science Contributor/Guest])
• "You're just stuck forever in the great seesaw of the universe." ([15:57, Robert Krulwich]—a fitting, playful close to the episode’s theme)

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Timestamps for Key Segments

• [02:20-04:09] — Jonathan Schooler’s Verbal Overshadowing discovery
• [05:08-07:08] — The mysterious decline in statistical effect sizes
• [09:22-10:28] — The decline effect in biology and animal studies
• [10:43-11:35] — The decline effect in psychiatry and the rise of placebo effects
• [13:03-14:47] — Speculation: Does observation change reality? The idea of “cosmic habituation”
• [14:47-15:39] — Philosophical implications: Can we ever really know anything for sure?
• [15:48-16:01] — Closing banter about the decline effect’s meta-implications

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Conclusion

Cosmic Habituation is a classic Radiolab exploration at the boundary of science and philosophy. What begins as a psychological curiosity—why describing a memory makes you worse at remembering—spirals into a provocative meditation on the nature of scientific knowledge, the quirks of statistics, and the possibility that the act of observation may alter reality itself. While the explanations remain elusive, the episode captures the profound mystery and beauty at the heart of scientific inquiry.

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For deeper dives and additional context, listeners are pointed to On the Media’s special episode on data, recorded in collaboration with Radiolab.

Transcript

[Narrator/Advertiser]

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[Jad Abumrad]

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[Science Contributor/Guest]

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[Jad Abumrad]

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[Robert Krulwich]

I'm Robert Krulwich.

[Jad Abumrad]

This is Radiolab, the podcast. And this week on the podcast, we did a collaborative thing with our friends at on the Media, a wonderful show produced here at wnyc.

[Robert Krulwich]

We decided to give them a headache. It was a very provocative idea brought to us by Joan o', Learer, one of our regular contributors. And we just couldn't get it out of our heads. It was such spooky. Yes.

[Jad Abumrad]

Begins with the work of a psychology professor, Jonathan Schooler, who many years ago, to great acclaim, got a bunch of people in a room together and he had them watch a video.

[Science Contributor/Guest]

They basically watch this bank robber walk into a bank and he hands a note to the clerk and he says, don't press the alarm and you won't get Hurt clerk then hands him some money and he exits.

[Jad Abumrad]

And these people watching the video, do they get a good look at the guy?

[Science Contributor/Guest]

You get a straight on look at the bank robber? Absolutely.

[Jad Abumrad]

And here was the test. After everybody watched this thing, he had half the subjects, only half, write down.

[Science Contributor/Guest]

In as much detail for five minutes everything they could remember about the appearance of the bank robber.

[Jad Abumrad]

So they'd write, you know, curly brown hair, mustache, thick glasses, whatever it was. Yeah, they just described the guy that they just seen. Now, only half of them did this, the other half did nothing. And then later, he had all the subjects look at a police lineup and try and identify the robber.

[Robert Krulwich]

Pick the bank robber. See if you can pick them.

[Jad Abumrad]

Yeah. Now, you would think that the people who had to describe the guy right after seeing him the first time, they would do really well at this, you know, because they had kind of set the memory. Yeah, that's not what they found.

[Science Contributor/Guest]

We found those people who had been asked to describe the face in great detail, they were actually less good at recognizing the face than if they didn't engage in any description at all.

[Jad Abumrad]

Not just a little less good. They were like 30 or 40% less good.

[Science Contributor/Guest]

So it was pretty whopping and just odd.

[Jad Abumrad]

Yeah. Even more odd is that as he did more studies, he found it wasn't just a face thing. It happens when you try to remember all kinds of stuff.

[Science Contributor/Guest]

We found the effect with colors. We found it later on with tastes choices.

[Jad Abumrad]

The effect was so strong and in so many different places that he gave it a name.

[Narrator/Advertiser]

Verbal.

[Science Contributor/Guest]

Overshadowing verbal.

[Jad Abumrad]

The words overshadow the truth.

[Science Contributor/Guest]

Yeah.

[Robert Krulwich]

So there's some association here. When you talk about it, you get it wrong.

[Science Contributor/Guest]

Exactly. So.

[Jad Abumrad]

And we should say these studies made Schooler into kind of a rock star.

[Science Contributor/Guest]

Yeah, it did get. It got some press at the time.

[Jad Abumrad]

And he appeared everywhere, really, including on a little show called Radiolab.

[Robert Krulwich]

He was even here.

[Jad Abumrad]

And this is where our story really begins. Because just as people like us were getting very excited about his work, the.

[Robert Krulwich]

Data began to go a little funny on him.

[Science Contributor/Guest]

That's right.

[Jad Abumrad]

And it all began when he tried to replicate that original experiment.

[Science Contributor/Guest]

Yes.

[Robert Krulwich]

As you kept doing it, what happened?

[Science Contributor/Guest]

Well, over the years, over the next five or six years, when I attempted to do it again, I would get the effect, but not to the same degree that I did initially.

[Narrator/Advertiser]

And this is a little troubling for him.

[Jad Abumrad]

That's Joan Allaire, a science writer, one of our contributing editors. He turned us onto this story, and it went like this. He says the first Time Schooler tries to replicate that study, that effect falls by 30%. And so he tried it again and again.

[Science Contributor/Guest]

And as we kept trying to replicate this study, the effect size got smaller and smaller and smaller.

[Robert Krulwich]

Meaning that big difference between the people who wrote about the bank robber and got it wrong and people who didn't write about the bank robber and they got it right, that big difference began to decline.

[Narrator/Advertiser]

This slow downward trajectory, it did sort.

[Science Contributor/Guest]

Of gradually get smaller. It wasn't as if all of a sudden it disappeared.

[Narrator/Advertiser]

Now, it's still significant, it's still publishable, but it's not nearly as exciting as it was that first time.

[Jad Abumrad]

So as you can imagine, Jonathan Schoolers was sitting in his office and he was like, what is happening here? I mean, it was so good the first time, and then it started to fade.

[Robert Krulwich]

He's a very good experimental psychologist. So he's not sloppy or anything.

[Jad Abumrad]

No. So he's thinking, what's happening here? And the first theory he has to.

[Science Contributor/Guest]

Really wrestle with is something known as regression to the mean.

[Jad Abumrad]

I mean, those are three of the most uninspired words put together.

[Robert Krulwich]

There are four words, though. It's regression two, the meme.

[Jad Abumrad]

But, Jonah, can you make it concrete for us?

[Narrator/Advertiser]

Sure. So you flip a coin, right? Let's say you'll flip a coin 10 times. You may get eight heads and two tails, and you may say, oh, my gosh, I've discovered a new law of coin flipping. When I flip coins in this room, they are almost always heads. But if you kept on flipping that coin for, say, a thousand times, your data would show almost certainly. Unless you really had discovered something very peculiar about that room, the results would get closer to the true result, which is about 50%.

[Jad Abumrad]

The results would regress to the mean. Sorry. Any case, his first thought was, maybe that's what's going on here.

[Science Contributor/Guest]

Yeah. Meaning when we first did the study, for whatever reason we got lucky, or.

[Jad Abumrad]

Unlucky as the case may be, you saw an outlier.

[Science Contributor/Guest]

Exactly.

[Narrator/Advertiser]

And reality is full of quirky surprises we can't explain. But over time, and this is the miracle of the scientific process, you regress to the true effect size.

[Science Contributor/Guest]

But one thing about the regression to the mean account is it doesn't really explain why the effects gradually get smaller. Regression to the mean, you predict one big effect and then it should basically totter around the actual value. This gradual decline doesn't naturally fall out of the regression to the mean account.

[Jad Abumrad]

Yeah, I mean, the effect could just go away, in which case you knew you were wrong. But why would it slowly get worse?

[Science Contributor/Guest]

Well, one possible explanation is that there was some aspect to the procedure that was important that we never really realized was important, and somehow we were gradually not including whatever that secret ingredient was.

[Jad Abumrad]

Meaning, you know, as a scientist, when you try and do an experiment, you try and do it the same way every time, down to the. To the floss that you floss your teeth with before you did the experiment.

[Robert Krulwich]

But there are too many things that you may not pay attention to.

[Jad Abumrad]

Yeah, there might be some little thing off to the side that you're not even thinking about.

[Narrator/Advertiser]

The color of the room in which he was conducting the experiments. It could have been how charming his grad student was who was actually asking the students to describe the bank robber. Totally making up a story here. Let's say that grad student was so charming, so good looking, so charismatic that he distracted the students. Then that grad student goes off, leaves the lab. Now he's got a much less exciting grad student. It's not nearly as distracting. And now the effect size of verbal overshadowing has gone down.

[Robert Krulwich]

The only problem with that is that that little sound that Jed and I made means that you have to have your charming grad student at the beginning and your less charming grad student in the middle and your even less charming grad student on your back.

[Jad Abumrad]

Yeah, they have to get slowly less charming.

[Science Contributor/Guest]

That's right.

[Jad Abumrad]

And so if you're thinking something is changing here, what is it? What is it? What is it? Did you go on some kind of mad search to figure out what you might be doing differently?

[Science Contributor/Guest]

We tried lots, a lot of different things, and in the end, I just moved to another area of research you got out of.

[Jad Abumrad]

And apparently one of Schooler's colleagues told.

[Narrator/Advertiser]

Him, don't worry about it. The only mistake you made was trying to replicate it in the first place.

[Robert Krulwich]

Really?

[Narrator/Advertiser]

Yeah.

[Jad Abumrad]

But here's the problem.

[Science Contributor/Guest]

Turns out it's not just me who has experienced this peculiar decline effect.

[Jad Abumrad]

As he started to look around, he realized what was happening to him was happening all over the place.

[Robert Krulwich]

Other scientists in all kinds of other sciences were having the exact same problem.

[Science Contributor/Guest]

In biology, there was a meta analysis of many different biological findings, showing there.

[Jad Abumrad]

Are a ton of examples, he says, and here's one. In the 90s, there were a bunch of studies about animals using symmetry to find mates, like birds, females, female birds, choosing their sexual partners based on how even the male's tail feathers were.

[Narrator/Advertiser]

It was a very exciting idea. And the first year there were eight tests of it, and all Eight found that. Yep. Fluctuating asymmetry, that's what the phenomenon is called, is real. We also got an effect size.

[Jad Abumrad]

So it seemed true.

[Narrator/Advertiser]

Yeah. That all over the world and all these different species, females had evolved this unconscious tendency to prefer symmetrical males. The next year it's tested 12 times and nine of the 12 confirm it. And then things start to fall apart. You can make the sound effect. Yeah, exactly. Until by the end of the 90s, you're going one for 13.

[Jad Abumrad]

One for 13.

[Narrator/Advertiser]

One. One for 13.

[Robert Krulwich]

Now, of course, these studies are not black and white. Yes. No studies. There's some gradation. But this was the basic trend that Jonah saw.

[Jad Abumrad]

And just in case birds seem a distant, here's another example, and I think.

[Narrator/Advertiser]

This is for me the most troubling area of the decline effect. Because you see, like second generation antipsychotics.

[Robert Krulwich]

Second generation antipsychotics.

[Narrator/Advertiser]

These are drugs used to treat people with schizophrenia, bipolar. When they first came out in the late 80s, early 90s, some studies found that they were about twice as effective than first generation antipsychotics. And then what happened is the standard story of the decline effect. Cue the sound effect, which is clinical trial after clinical trial. The effect size just slowly started to fall apart.

[Jad Abumrad]

And that's not all.

[Narrator/Advertiser]

You see a similar decline with things like Prozac and antidepressants. The effect of the drugs have gotten weaker, but the placebo effect has also gotten stronger. I was talking to one guy at a drug company who, he was kind of interesting. He blamed that on drug advertising. He said that they started to see their placebo effect go up in the late 90s when these drug companies started advertising.

[Jad Abumrad]

But then wouldn't that actually offer an explanation for this decline thing? Because, you know, some. If you know about what this drug is supposed to do, maybe it works differently somehow.

[Science Contributor/Guest]

Certainly there are areas of psychology where that can change the outcome in one way or another. But it's very unlikely that, you know, in say, these female preferences for symmetrical feathers that the, you know, the birds got wind of this symmetry finding and now all of a sudden are not. Not into it anymore.

[Jad Abumrad]

I don't know.

[Robert Krulwich]

You haven't been around chickadee conversation.

[Jad Abumrad]

Word passes quickly amongst the chickadees.

[Robert Krulwich]

And so does that mean that you. Can you explain why what you found at the beginning is not what you.

[Jad Abumrad]

Find now and why it gradually went away? Gradually is still puzzling?

[Science Contributor/Guest]

I tell you, I find it very puzzling too. I'm personally baffled.

[Narrator/Advertiser]

It's tough to come up with an all purpose Explanation or some easy fix.

[Jad Abumrad]

It could be a lot of different things bundled together into one phenomenon. He says, you know, maybe in some cases it really is statistics.

[Science Contributor/Guest]

Progression to the almost sure to be a part of it.

[Jad Abumrad]

Or maybe in some cases it's, you.

[Science Contributor/Guest]

Know, this gradual change in the procedure in something that we just don't know what it was that happened.

[Jad Abumrad]

Can't rule it out.

[Science Contributor/Guest]

But I would probably be less shocked than most people if something unconventional was actually involved in this as well.

[Robert Krulwich]

Unconventional? Like.

[Science Contributor/Guest]

Like I. I say this with some trepidation, but I think we can't rule out the possibility that there could be some way in which the act of observation is actually changing the nature of reality. That somehow in the process of observing effects, we change the nature of those effects.

[Robert Krulwich]

You're in real trouble.

[Jad Abumrad]

Essentially, what he's saying, we think, is that when he discovered that thing with the bank robber experiment, that maybe the discovery itself somehow set in motion a series of events that made the thing he discovered start to sort of run away.

[Science Contributor/Guest]

Well, I'm not going to say that. I'm certainly not going to say that there's some sort of intentionality to these effects disappearing more that it's almost. And again, this is just speculation, some sort of habituation. So just as when you put your hand on your leg, you feel it, and then as you leave it there, it becomes less and less noticeable somehow, there may be some kind of habituation that happens with respect to these findings.

[Jad Abumrad]

What is the hand and what is the leg in this?

[Science Contributor/Guest]

Well, in this most radical conjecture, there could be some sort of collective consciousness that's habituating. Again, radical speculation. Keep in mind the notion that the laws of reality are unchangeable is an assumption. It's a reasonable assumption, but we don't know it for a fact. And there have been physicists who have even speculated that perhaps the rules change as time goes on.

[Jad Abumrad]

The problem with this idea is if you really believe it, then you can never really know anything.

[Robert Krulwich]

We're sliding into that kind of territory. Like, you know, by this logic, you could never really know for sure because reality could change based upon the observer's position, habits, biases, information, whatever.

[Science Contributor/Guest]

Well, so far we have not really seen these types of things in the domain of physics, but an aspirin might not do what it used to. There's a question that you haven't asked, which is, let's say that we were to do a study and demonstrate this decline effect. That when you keep running experiments, that they get smaller. Well, what happens when you Try to replicate that effect. Does the decline effect decline?

[Jad Abumrad]

Yeah, that's a good question.

[Science Contributor/Guest]

Maybe we could just get rid of the decline effect by studying it.

[Jad Abumrad]

But then if you were to study the decline of the decline effect, then it would undecline and it would come back. Do you see what I'm saying?

[Robert Krulwich]

I see what you're saying. You're just stuck forever in the great seesaw of the universe.

[Jad Abumrad]

We should thank our friends at OnTheMedia. On the media is a show that analyzes the media, as I'm sure you know. And it's an amazing show. I mean, it's an amazing show. Brooke and Bob, who host the show are, are funny, hysterically funny and brilliantly smart. And it's the kind of show that it's just kind of essential. It's one of those shows. I could not recommend it more on themedia.org all one word onthemedia.org check it out.

[Robert Krulwich]

They're going to do an entire hour on the subject of data and we have sort of snuck this issue that we've just talked about into the middle of that show. So it's the same thing, but in a very different context. You can go to their podcast on Friday 13th May and there it and.

[Jad Abumrad]

We shall be until it and we decline.

[Robert Krulwich]

Yep.

[Jad Abumrad]

Into oblivion. I'm Jad Abumran.

[Robert Krulwich]

I was and will continue to be.

[Jad Abumrad]

I hope, for the moment. Robert Bye.

[Robert Krulwich]

Hi, this is Colin von Heering. I'm a Radiolab listener from Portland, Oregon. Radiolab is supported in part by the Alfred P. Sloan foundation, enhancing public understanding of science and technology in the modern world. More information about Sloan at www.sloan.

[Science Contributor/Guest]

End of message.

[Jad Abumrad]

Radiolab is supported by the National Forest Foundation, a non profit transforming America's love of nature into action for our forests. Did you know that national forests provide clean drinking water to 1 in 3Americans? And when forests struggle, so do we. The National Forest foundation creates lasting impact by restoring forests and watersheds, strengthening wildfire resilience and expanding recreation access for all. Last year they planted 5.3 million trees and led over 300 projects to protect nature and communities nationwide. Learn more at nationalforests.org Radiolab for delicious.

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