Optical illusion – hallucination

WARNING: If you suffer from photosensitive epilepsy, please do not view this video.

Look only at the letters in the center of the video.

If you follow the video’s instructions, when you look away you will continue to see wavy lines in your wall or on the floor. This happens due to an optical illusion that is the result of repeated psychological stimulation. When the video ends and you look away, your brain still expects to see the waves, and therefore it creates them for you. Saying the letters out loud doesn’t really play a role, it just ensures that you are focusing on the center of the screen, where you can best receive the stimulus.

For best results, view the video full screen on an HD display. The resultant hallucination is temporary and should wear off within a couple of minutes.

Read more at http://www.iflscience.com/brain/video-causes-natural-hallucinations#JZeeQghUFsw5LBcG.99

▶ ▶ Eye – Optical illusion – YouTube.

Optical illusions

There are many optical illusions, both natural and man-made, that can trick your brain… every time. The visual illusions are characterized by visually perceived images that differ from objective reality. The information your eyes gather doesn’t match the source in some way, causing a major (awesome) headache.

There are three main types of illusions: “literal optical illusions that create images that are different from the objects that make them, physiological ones that are the effects on the eyes and brain of excessive stimulation of a specific type (brightness, colour, size, position, tilt, movement), and cognitive illusions, the result of unconscious inferences.”

These 2 blocks are the same color. … … Cover the line with your finger to check.

optical-illusion-blocks-color

Stare at the cross for 10 seconds … … the purple dots disappear. 
optical-illusion-dots disappear
That’s not a bird. … … It’s a painted woman.
optical-illusions-woman parrot

When you are crying…

This photo series by Rose-Lynn Fisher captures tears of grief, joy, laughter and irritation under the microscope.

The tears from your eyes aren’t just water. They’re primarily made up of water, salts, antibodies and lysozymes, but the composition depends on the type of tear. There are three main types – basal tears, reflex tears, and weeping tears.

As you can see, they can look incredibly different when evaporated and placed under a microscope.

More info: http://bit.ly/RJqvK7

Images by Rose-Lynn Fisher, via the Smithsonian Magazine and ScienceAlert.

microscope-tears

Vocabulary :

tears : when you are sad and you cry, tears come out of your eyes.
grief : strong sadness