The Current

Scientists are tricking our senses to learn more about the brain

A new documentary about the secrets of the senses on CBC's The Nature of Things will have you questioning whether you can believe what you see, hear, taste, touch and smell.

Myth or Science: The Secrets of Our Senses – Disappearing Ball Illusion

55 years ago
Myth or Science: The Secrets of Our Senses – Disappearing Ball Illusion

Read story transcript

Jennifer Gardy learned a lot about how our senses fool us by watching a scientist stab a rubber arm with a fork.

The host of a this week's episode of The Nature of Things played guinnea pig in research about the senses and the brain. 

She sat with her right arm behind a screen and a rubber arm in front of her, where her eyes would expect her real arm to be. When a researcher touched that rubber arm, her brain felt it as her own.

The myth about senses

"We all grew up hearing about the five senses and thinking that these are five distinct senses," Jennifer Gardy tells The Current's Anna Maria Tremonti.

"They each exist in their own little box. They each have their own portion of the brain that governs their sense. But what we're discovering now is that's not the case at all."

In fact the senses overlap in the brain to a degree we didn't realize.

"They all converge," says Gardy, "and activate your brain in this wonderfully complex way that can create these tremendous opportunities for trickery, like you see in the rubber hand illusion."

Below, you can watch another illusion, the disappearing ball, which again demonstrates how the brain falls for tricks. 

This overlap between the senses fools us every day — from colour affecting what we taste, to how much our hearing is influenced by what we see.

There's really tremendous everyday implications to how we experience our world as a result of these incredibly subtle cues that are coming in from all of our senses.- Jennifer Gardy

The study of sensory overlap can help design rehabilitation for people who are losing one of their senses.

But it also gives clues about deeper ways we understand the world — research, for example, is showing that we really can smell danger, by distinguishing regular from aggressive sweat.

"There's really tremendous everyday implications to how we experience our world as a result of these incredibly subtle cues that are coming in from all of our senses..." says Gardy adding that it points to the underlying sensory layer in what we perceive as the ordinary world. 

Listen to the full story at the top of this web post.

This segment was produced by The Current's Karin Marley.