par·al·lax An apparent change in the shape of an object, caused by a change in observational position that provides a new line of sight.
par·a·dox A seemingly contradictory statement that may nonetheless be true: the paradox that standing is more tiring than walking.

The drawing on the left, titled
"My wife & my mother-in-law,"
was published in 1915
by the cartoonist W.E. Hill.

It was "improved" recently by
adding a third face, as seen below.
Is this as successful?
Easy to draw;
impossible to build.
Starting from the top, there appear
to be two cubes with green tops,
followed by a row of one,
but starting from the
bottom, the green squares
are obviously the bottoms
of the cubes in a 2-3-2 stack.

The mind trains itself to add in what it
predicts to be appropriate information
 to match known patterns,
even if there is no physical evidence.
on the left is one called "rabbit/duck";
on the right is "rabbit/gull."
These don't bulge.

The purple lines are parallel.

Yes, they are.
The lines between the arrowheads
are the same length;
the middle dots in the two clusters
are the same cicumference.

The lines are all parallel.

Do they appear to be bending in the
middle or widening and narrowing at the
ends when you look at the other end?
That is because of the difficulty that the
human eye has with extreme contrast,
such as black and white, which can cause
headaches as the eye must continually
refocus to accommodate the difference
in amount of light that is reflected.

Someone once said, "Inside every
lie is a kernel of truth."

Another said, "You can always spot
a liar by looking into the eyes."

You can actually draw these two
quite easily by yourself .

How many colors are there?

Hint: 3

white, green, pink

The "two" pink shades are really
the same, but the eye's perception
of one is affected by its juxtaposition
to green versus the other pink
being next to white.

Ditto for the "two" greens,
which are really the same.
the famous five-footed elephant

A Japanese artist found
a lingering image of his profile
in a modern rendition of the
old silhouette scene at left.
Impossible Architecture

The Wrinkled Checkerboard

It's not, of course.

As you move your eye slowly
across it, does it apear to
shimmer in the wrinkle?
They colored the cube to make
the illusion more visible.

Is the blue the back wall
or the front?

Island on the left
and
giant bird on the right?

No.

Turn your monitor upside down
to see the real pictures:
a crater on the left
and a giant fish on the right.

This is my favorite.

Yep.

The men are all the same size.
There are no spirals in ether of these,
just concentric circles.

An added bonus to this one
is that, if you point your mouse
button at the scroll bar down
arrow and click rapidly, the one
above will seem to move in a spiral.

3 in 1--- very difficult to see

  1. a small cube floating in front
    of a large cube
  2. a large cube with a chunk
    chopped out of it
  3. a box sitting on the floor
    of a room
Stare at the flag for a minute,
and then look at a blank wall or
piece of paper, and you will
see the US flag.
It is important to note
that if you look at the
neckline of the dancer,
you will see that she is
wearing a blouse.

Eskimo or Indian?

Editor's Note: If you find the old
traditional name of this cartoon
to be offensive, then you may refer
to it by a more politically correct
modern substitution.

Inuit or Apache?
This beautiful painting depicts a very
disturbing construction site.

This is my favorite of the
"static motion" group.
Bonus points for anyone
who can name the term for this term.

Stare at it for a while and
the circles will begin to spin.
This one is amazing.
Stare at the light bulb for
53 seconds and then look
at a blank wall or
piece of paper and
you will see.
Supposedly, if you stare at the negative
image of the queen for a while
and then look at a blank white wall or
piece of paper you will see the "real"
queen. I can never get this one to work,
possibly because I find
the subject matter
to be too boring to stare at.
This one is easy because anyone can see
both pictures, but it is a failure because it
needs to cheat in order to show
the left eye of the girl.
What function does that black splotch
have in the sax player picture?
an engineer's nightmare, or
an engineer joke
Stare at the black dot.
The gray haze will diminish
and may even disappear.
Your mind will tire of processing the gray haze as it begins to perceive that it is superfluous to an understanding of the "picture" (the dot) as the primary input, so your mind will eliminate the haze until it is again "needed" to make sense of the input stream. This is the same phenomenon as when you drive a car and see only the outside world and not the rain or insects on the windshield. You still see them physically, but your subconscious mind removes them from your conscious focus, as it begins to determine that such information is not important to the primary task, i.e. driving.
The mind adjusts to what the eye sees to
make it make sense If the eye is reading
letters, the mind thinks the middle item is a
"B," but if it is reading numbers, it thinks
the middle item is a "13."

Read the ink color, not the word.

This one is very different.

It is not strictly speaking an optical illusion,
but instead reveals the battle between
the hemispheres of the brain.
The left side wants to call the
colors of the letters,
while the right wants to read the words.