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.

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])

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.

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.

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])

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])

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)

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

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.

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