Questacon > Kids > Exhibitions & Shows > The Archives > Illusions > Other Illusions Exhibits 28-33

Illusions

Non-visual Illusions

From the Illusions Exhibition at Questacon February 14 - August 29, 1999

28. Auditory Illusions

This computer exhibit allows visitors to listen to a number of auditory illusions through headphones. The illusions are explained graphically on the information panel and detail the cause of the illusions and where they can be heard in real life.

The inside story

Everyone receives sound waves in their ears. These usually come via the air, but sounds can and do travel differently through different materials. Normally we hear our own voice through our jaws and heads as well as through the air and our brains form on impression of how we sound based on that information. When we hear a recording of our voice, however, it travels only through air so the pattern does not match with our brain's previous experience of how we sound.

29. Can Fingers See?

This exhibit allows visitors to test if their sense of sight is better than their sense of touch. Visitors first touch two raised lines which they cannot see and decide which line is longer. They then can illuminate the lines they have touched and determine which line was in fact longer.

30. Hot and Cold

Visitors are presented with three metal bars and take hold of the left and right bars. The visitor will notice that one bar is warm and that the other is cold. They then move both hands simultaneously to the middle bar. This bar is at room temperature, however, a different sensation is felt in each hand.

The inside story

This exhibit illustrates how the temperature receptors in our hands function in response to sudden changes in temperature. A similar response occurs with all sensory systems and is known as the 'adaptation and rebound effects'. For more information refer to the Inside Story on Page 15.

31. The Cutaneous Rabbit

This exhibit demonstrates how easily movement can fool the touch receptors in the skin of the arm. Visitors place the "Cutaneous Rabbit" on their forearm and press the start button. Two prongs on the rabbit create the sensation of something crawling up the arm. In fact the prongs do not move along the arm but are timed to create this sensation.

32. The Rising Floor

Visitors stand on the rising floor, place their hands on a silver knob and close their eyes. They then press a foot pedal that activates the floor's movement. The floor rises while the knob lowers. Visitor's perceive a greater degree of movement when their eyes are closed than has actually occurred. When they open their eyes they realise that they have only risen a short distance.

33. Eyes Can Hear

We often take for granted how much our eyes assist us in understanding information obtained using other senses. In this exhibit a computer demonstrates how the eyes assist us in interpreting speech. Visitors start the program, whereupon a 'talking head' appears starts to speak. The sound that is produced does not match the movement of the talking head's mouth. Visitors attempt to interpret the sounds.

The inside story

Human language is thought to have developed 40 000 years ago, millions of years after scientists believe humans first appeared. Although we lived on earth successfully for millennia without even talking, never mind reading or writing, it makes it even more amazing that our lives are so totally dominated by language now. Humans evolved as visual creatures but our aptitude for communication is so strong that psychologists have shown we now think in words as well as images. Our brains are so accustomed to using language that they will: override other signals even when consciously trying not to; ignore words they don't expect to find; and convince themselves they can 'see' letters or words which aren't there!