OPTICAL ILLUSIONS
Natural beauty
The eye says it’s a flower, the brain thinks it’s a face. Carefully positioned images can cause
discrepancies between the actual image and the perception created by the brain.
Credit: Tom Wigley/Flickr, CC BY-NC-SA 2.0.
When the world was flat
This garden in Paris is made up of grass at different heights and white lines. The area is oblong in
shape, but from one angle it looks like a sphere.
Credit: Jeff Hester/Flickr CC BY-NC-SA 2.0
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Going up?
Obscured horizons and the contrasting slopes of the landscape and trees often cause people to
lose their bearing on this downwards ‘gravity’ hill.
Credit: Ray/Flickr, CC BY-NC-ND 2.0
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I didn’t use Photoshop
A photo of the whole monitor is taken with a hand in front of the screen, and is then set as the
background on the monitor. The note is then opened over the top of the new background.
Credit: Evan/Flickr, CC BY-ND 2.0
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Spiralling snakes
This image appears to be moving; the brain detects movement, but this is actually triggered by
black-and-white edges, through the use of curvature, colour and shape.
Credit: Roman Soto/Flickr, CC BY 2.0
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Black or White?
Figure–ground perception is the tendency to simplify an image into its figure (i.e. its main subject)
and its background. Whether you perceive black or white as the figure determines what you see
(i.e. vase-like columns or men talking).
Credit: Sha Sha Chu/Flickr, CC BY-NC-SA 2.0
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Moving Triangles
The lines running from top to bottom appear tilted but are in fact vertical. Certain shapes and
colours cause the brain to perceive movement in some situations, a phenomenon called retinal slip.
Credit: ClintJCL/Flickr, CC BY-NC-SA 2.0
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Our house
Although this room appears to be cubic, it is actually a trapezoidal shape. The woman is actually
standing much closer to the camera than the man.
Credit: Ian Stannard/Flickr, CC BY-SA 2.0
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Could you live in this?
Two walls placed at very specific angles create what appears to be a complete building from a
particular viewpoint.
Credit: Thom Watson/Flickr, CC BY-NC-SA 2.0
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Reusing our images
Images and illustrations
• All images, unless otherwise indicated, are from Wellcome Images.
• Contemporary images are free to use for educational purposes (they have a Creative Commons
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done on the site; the format is ‘Creator’s name, Wellcome Images’.
• Historical images have a Creative Commons Attribution 4.0 licence: they’re free to use in any way as
long as they’re credited to ‘Wellcome Library, London’.
• Flickr images that we have used have a Creative Commons Attribution 4.0 licence, meaning we –
and you – are free to use in any way as long as the original owner is credited.
• Cartoon illustrations are © Glen McBeth. We commission Glen to produce these illustrations for
‘Big Picture’. He is happy for teachers and students to use his illustrations in a classroom setting, but
for other uses, permission must be sought.
• We source other images from photo libraries such as Science Photo Library, Corbis and iStock and
will acknowledge in an image’s credit if this is the case. We do not hold the rights to these images,
so if you would like to reproduce them, you will need to contact the photo library directly.
• If you’re unsure about whether you can use or republish a piece of content, just get in touch with
us at bigpicture@wellcome.ac.uk.