The human eye can be 'tricked' * -- something of which every decent artist and architect is aware.
an image of intersecting grey lines against a white background, with 12 black dots on the nodes where the grey lines meet.
All 12 dots are really on the image, but most people are unable to see them all at the same time, making the dots seem like they appear and disappear with every blink. This occurs because the eye’s stimulated light receptors can sometimes influence the ones next to them, creating illusions.
In this particular image, tweeted by game developer Will Kerslake on Sunday, the brain can see some black dots but guesses when it fills in the peripheral vision. Because mostly grey lines appear in the periphery, the black dots don’t appear…
How many dots can you see at once?
So because we perceive in a certain way, artists and architects use this in their work.
Based on understanding how we perceive colour and colour contrasts, artists use it to create real spatial depth in paintings.
Based on understanding how we perceive light (strong contrast between light and shadow needed to see real contrast), artists use it to create life and excitement on a canvas, and architects to create it in spaces.
Based on understanding howwe perceive colour in light and shade, architects use it to select darker colours on a window wall to relieve glom inside and better connect us with nature outside.
Yes, these are all visual tricks. But they work because they respond to the ways we perceive, and because they work they can and are used to create real meaning.
* This does not mean the eye is unreliable - it simply means that (in the case of refraction, for example) it often shows us more context than we know, so while our perception is automatic what what we perceive sometimes needs interpretation.
[Hat tip Kaila Geary Halling.]