The bodies on both sides of the door had to be moving with nearly identical momentum — otherwise, the illusion was shattered.
"That learning leads us to associate these two identical lines in this illusion as being at two different distances from us," Sinha explains.
For example, two successive stimuli may be identical but nevertheless give the illusion of being different.
With the exception of this latter small modification, the supernumerary illusion condition was identical to the synchronous condition used in experiments 1 4.
One model involves the illusion created when two identical objects moving towards each other on a two-dimensional visual display can be seen to either bounce off or stream through each other.
Most robots, for example, would not be fooled by the Adelson checkerboard illusion where we think two identical grey squares are different shades: "Humans looking at this illusion process the image and remove the effect of the shadow, which is why we end up seeing the squares as different shades of grey," explains McOwan.
In this illusion, the inside circles are identical in size, yet the surrounding information (i.e., surrounding circles) alters our perception.
Mr. Lang took a page from the Minimalists, giving the percussionists identical parts but allowing rhythmic displacement to create the illusion of variegated, contrapuntal textures.
This effect is highlighted by the classic size-weight illusion (SWI), where different-sized objects of identical mass feel different weights.
For example, an identical array of images of faces produced a greater illusion when observers were told that the faces represented fraternity or sorority members compared with when they were told that they represented men or women born in the month of May (Pickett, 2001).
