Section 3: Eyes and cameras use light to capture images.ο»Ώ

Key Ideas     Unit Checklist

  Unit C: Section 3 – Introduction


Figure C.S.3.1 – ο»ΏWhat animal do you see in this image? A duck? A rabbit? Both?

Figure C.S.3.2 – Which orange circle is larger?


Figure C.S.3.3 – Could you travel up these stairs forever?
Optical Illusions

Vision depends on both the eyes and the brain. Light enters the eyes to form an image. Sensors and the optic nerve at the back of the eyes send a message about the image to the brain. The brain interprets the image into what a person sees.

Although images are transferred from the eye to the brain very quickly, the brain learns patterns and shortcuts to interpret images faster. Optical illusions are images that trick the brain into taking a shortcut based on patterns it has interpreted before. In an illusion, the brain’s interpretation does not correspond with the actual image produced in the eye.

Depending on what your brain perceives as most familiar, Figure C.S.3.1 can look like either a duck or a rabbit. Can you see the picture both ways?

In Figure C.S.3.2, both orange circles are the exact same size. Cover up the grey circles to confirm this. The brain takes shortcuts to classify the size of objects relative to the size of their surroundings. The orange circle on the left seems smaller because the surrounding grey circles are larger than it.

In Figure C.S.3.3, the stairs appear to form a never ending loop. In reality, this is a flat two-dimensional image with lines and shapes. Your brain is used to interpreting images in three dimensions, so it interprets the image as a loop of stairs. These stairs would be impossible to build in real life.

Share these optical illusions with a friend. Can you find some more interesting optical illusions?


Figure C.S.3.4 – Stare at these shapes. The picture should appear to move.

Figure C.S.3.5 – Count how many black dots you see in this image.

  Words to Think About:

Check out the word cloud below. It pictures the important words that you are going to learn in this section. Watch for these words, and combinations of these words, as you read. When you see them highlighted, you can click on them to learn more about what the word means. You can also visit the course glossary and read definitions for all of these words.


Lessons in This Section

Lesson C9:  Eyes and Cameras
Key Question – How are eyes and cameras similar?

Lesson C10: Vision-enhancing Technologies
Key Question – How do light technologies help people see better?

Lesson C11: Eyes of Other Animals
Key Question – How are eyes in other animals similar and different to human eyes?

Lesson C12: The Future of Light Technology
Key Question – How do we create digital images with light?
Reading and Materials for This Section

Science in Action 8
Reading: Pages 230–245

Materials Lists for Unit:
Master List of all materials
Materials organized by lesson and activity

 Watch More

When Light is Playing Tricks on You

Watch this video to learn more about different types of optical illusions.

 
 
 
 
In 2015, an optical illusion went viral on the internet. People debated whether a particular image of a dress was black and blue, or white and gold. How do you see the dress? Watch the video to find out what colour the dress actually is, and why people perceive its colours differently.