4+
Gallery 7

Rototron

A teenage girl holds onto hand rails in a large cylinder lined with blue and white led lights. She is leaning to the right.
White and blue led lights line the inside of a large cylinder you can walk through. There is also hand railing in the photo.

A loss of balance can be created by fooling your sensory inputs.

How it works

This Rototron tunnel turns LEDs on and off to generate the visual illusion of movement.

Things to try or ask around the exhibit

How does your experience of the Rototron tunnel differ when your eyes are closed compared to when they are open?

Walk through the Rototron tunnel and notice whether you walk in a straight line.

If you feel dizzy inside the tunnel, look straight ahead. Why would this small trick help?

Background

You may lose your balance or feel dizzy inside the Rototron tunnel, because of contradictory sensory messages between your vision (the world is spinning) and your balance receptors (the ground is perfectly still).

Human sensory systems (including areas of the brain that interpret sensory information) can be easily confused. Your visual system (eyes and visual cortex) see the LEDs within the Rototron tunnel. They flash in unison to create the illusion of movement, so your brain thinks that the tunnel is spinning. At the same time, balance receptors inside your joints and within the ear, detect that the ground is stable and level. The brain interprets visual messages as ‘the world is spinning’, while interpreting the joint and inner ear messages as ‘the world is stationary’. These conflicting sensory messages generate a feeling of dizziness and may cause you to walk off balance inside the tunnel.

Humans have balance organs called the vestibular system that is designed to help us stay upright and balanced. Situated in each ear are three semi-circular canals that are part of this system. These detect rotational movement and are located at right angles to each other. They are filled with a fluid called endolymph that, when the head rotates, lags behind and exerts pressure against the canals’ sensory receptors. The receptors then send impulses to the brain about movement.

Specialised pressure receptors inside your joints, called proprioceptors, help your brain to map the position of your limbs and torso in your environment, so you stay upright and balanced. In the Rototron tunnel, the proprioceptors are detecting the ground to be relatively stable and level.

Finding the science in your world

The reason you feel dizzy when you stop spinning is because the fluid in your vestibular canals is still moving! As you spin, the fluid starts to spin too, but it lags behind slightly and exerts a pressure on the sensory receptors of the canal.  The movement of the fluid is similar to water in a bucket.  As you stir the water it starts to move, though lagging behind a little at the start.  When you stop stirring the water keeps moving for a while, depending on how fast and long you were stirring in the first place.  So even though you’ve stopped, the fluid keeps going, sending signals to the brain (through the sensory receptors) telling it that you are still spinning.  This is what makes you feel dizzy and possibly fall over.