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Sometimes it seems our eyes can be tricked. Because of this we must be very careful when making observations in science. What we think we see may not be an accurate observation. Scientists may have to use optical devices to overcome this problem.
How are our observations affected by various illusions?
A Stereoscope pictures
What to use
Flat mirror 15 cm tall, '3D illusion' sheet.
What to do
- Print the three-dimensional 3D illusion sheet. By viewing the drawings independently (one picture for each eye) a picture of the objects can be recreated in the mind of the viewer. It is an illusion. To view these pictures in 3D all you need is a flat mirror about 15 cm tall.
- Stand the mirror in the space between the two pictures, with the reflecting side facing your right. Place your nose near the mirror and look down and slightly to the left. When the two pictures fuse into one, you will see it in 3D.
- To see how these pictures produce a 3D image, check the positions of the frog and the butterfly. The butterfly in the left picture is slightly closer to the edge of the square, while the frog is slightly further from the same edge. You can make your own 3D pictures by using clip art in the computer as in 3D illusion sheet 2.
B Illusions
What to use
What to do
- In the diagram, which drawing of a cat seems the largest? In science your observations need to be more accurate than this.
- To check your answer, measure the cats. Which cat is largest?
- Suggest a reason why this illusion occurs.
- Make your own version of this illusion, or create an original illusion.
C Impossible figures
What to use
What to do
- Look at the drawing of the fork.
- Explain what appears to be happening.
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