All Podcasts / The Rest Is Science / Your Brain Invents Pain. Here's Why.
The Rest Is Science
The Rest Is Science

Your Brain Invents Pain. Here's Why.

July 05, 2026 • 51m

Summary

⏱️ 8 min read

Overview

Hannah Fry and Michael Stevens explore the science of pain, from testing their own pain thresholds in ice water to examining people who feel no pain at all. They discuss how pain is constructed by the brain rather than being a direct readout of tissue damage, the mechanisms behind pain perception, and promising research into new pain treatments that could target specific neural pathways without the side effects of opioids.

Testing Pain Thresholds with Ice Water

The hosts begin by plunging their hands into ice water, a standard research method for measuring pain tolerance. This uncomfortable experiment demonstrates how pain is both a physical sensation and a psychological experience. Michael's bowl has minimal ice, while Hannah's is well-stocked, creating an unequal challenge. They discuss how distraction affects pain perception and how redheads may experience pain differently due to genetic variations.

  • Ice water submersion is a standard method researchers use to measure pain thresholds in people
  • Redheads have a mutation that causes them to feel pain in a different magnitude and require different anesthesia
  • The burning sensation from extreme cold activates the same pain pathway as actual burning
  • Talking about pain makes it hurt more, while distraction reduces the sensation
" I would say I'm enjoying the distraction of talking about hot dogs. "
" Suddenly my hand actually hurts way more when I'm saying burning. "

The Thermal Grill Illusion: Tricking the Brain into Feeling Pain

Hannah describes the thermal grill illusion, where alternating warm and cold frankfurters create an excruciating burning sensation despite neither temperature being dangerous. Michael has experienced this firsthand. The illusion works because warm objects prevent the brain from registering the cold as safe, so only the burning alarm activates. This demonstrates that pain is not a faithful readout of damage but a verdict the brain constructs.

  • The thermal grill illusion uses alternating hot and cold objects (like frankfurters at 40°C and 5°C) to create intense pain
  • Warm objects block the 'cool reporter' signal, leaving only the burning alarm to reach the brain
  • The brain only receives signals from both hot and cold receptors simultaneously during extreme tissue damage
" Your brain's getting a signal from both cold and warm receptors. And that's only that only happens when you're like literally having your arm cut off. "

📚 6 more sections below

Sign up to unlock the complete summary with all insights, key points, and quotes

Listen on Apple Podcasts More Episodes from The Rest Is Science