All lines on the image are parallel, but appear to tilt alternately.
by Johann Zolner
Even though the lines between the bricks appear to be sloped, they are actually parallel.
by Richard Gregory
"Twisted cords" are horizontally aligned but appear to tilt alternately. The apparent tilt is the same orientation as the tilt of each obliques.
by James Fraser
Waterways appear to tilt alternately, though they are parallel to each other. Moreover, "water" appears to swing in the horizontal directions.
by Akiyoshi Kitaoka
Even though the two lines seem to be curved, they are parallel to each other.
by Ewald Hering
"Rome to Paris"
The two poles look to be curved, but in reality they are parallel. This is a variation of the "Herring Illusion".
by Gianni A. Sarcone, co-founder of Archimedes-Lab
The floor appears to bulge out, though this image consists of only squares.
Even though the overlapping black arc segments appear to form a spiral, they are actually just a series of concentric circles.
Even though the arrow on top looks to be longer than the arrow on bottom, they actually have equal length.
The two yellow segments have equal length, even though the one on the bottom looks much shorter.
by Mario Ponzo
Even though the the vertical line looks much longer than the horizontal, the two have equal length.
Even though the shape on top looks smaller than the shape on bottom, they actually have the same size.
Even though the first table looks longer and thinner than the second table, they are actually identical.
by Roger Shepard
"Kanizsa Shrinkage Illusion"
After placing the rectangle over, it looks like the square on the right shrank.
by Gaetano Kanizsa
The right circle surrounded by smaller circles appears to be larger than the left circle surrounded by larger circles, though they are physically identical.
by Hermann Ebbinghaus
The two running men have the same size, even though the one behind looks much larger. This perspective illusion is a variation of the classic "Ponzo Illusion".
"Elder brother behind"
The two persons are the same, but the one who is in front appears to be smaller.
"Upside-down face overestimation illusion"
The lower face appears to be larger than the upper one, even though they are identical in size.
"Wollaston Illusion: Christmas Version"
The left face appears to gaze at the observer while the right one appears to look to the right, even though the two pairs of eyes are identical. This phenomenon was discovered by William Wollaston.
"Happy and Unhappy Masks"
The left face appears to be happy whereas the right one appears to be unhappy.
Even though it looks like the black line is a continuation of the blue line, actually it is a continuation of the red line.
"Leaning Tower Illusion"
Even though the two images of the Pisa Towers are identical, it looks like the right tower is leaning more to the right.
by Frederick Kingdom, Ali Yoonessi, Elena Gheorghiu
It looks like the grey stripes on the right are brighter than the grey stripes on the left, but they actually have the same color.
by M. White
The luminance of all cubes is the same, even though the last one appears to be much lighter than the first one. In addition, the farthest dice appears to be largest.
Which square is darker - A or B? They answer is none of them, they have the same color.
by Edward Adelson
The tops and the middle parts of the dynamites on the right appear darker than the ones on the left, but in reality they are the same.
"White's Dotted Lightness Illusion"
The left grey square appears to be lighter than the right one, even though they are identical in lightness.
"Koffka Ring Illusion"
When the image is split as shown on the right, the right half of the ring appears to be darker than the left half. Below the Adelson's Koffka Ring is illustrated.
In each rectangle, the right region appears to be darker than the left one, though they are of the same luminance.
Each ring is homogeneous in color but appears to be separated in color by a white thin circle. In each ring, the inner region appears to be lighter than the outer one.
"Eye color constancy"
The eyes in the left image appears to be yellow while those in the right one appears to be gray, though they are the same gray.
The image appears to scintillate. In addition, there appear to two types of stars of different luminance, but they are the same in luminance.
"Carpet of blue and green hearts"
There appear to be blue and green hearts, though they are identical in color.
The image appears to scintillate. In addition, it looks like there are two types of neurons (star shapes) of different colors, but they are actually the same.
"A Golden Star"
Although the radiations of diamonds are identical to each other, inner ones appear to be darker.
It appears as if there were a yellow horse and a red one, but they are identical in color actually.
"Hurry Border and the Goblet of Fire"
The left goblet is the same in color and texture as the right one, but the former appears to be reddish while the latter bluish.
The inside red appears to be purple-red.
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