Optical illusions are fun ways to improve kids’ cognitive abilities. An optical illusion image stimulates problem–solving skills and visual memory recall because the child will want to figure out how it works.
Optical illusions are caused when the brain interprets the object that the eyes see differently. The rods and cones are the optic receptors in the eyes. What the eyes see is transformed into the brain as electric impulses which the brain interprets. The brain tries to make sense of what the eyes see. Optical illusions present something unusual to the brain.
Illusions aren’t hallucinations. An optical illusion is seeing an object differently, whereas a hallucination is viewing an object that isn’t there.
The three types of optical illusions are literal, cognitive, and physiological. A literal illusion is seeing an image as something different than the image or images displayed. Although the images exist, what you see is based on your perception. A cognitive illusion is how the brain interprets something new that wasn’t explained. It reveals how the mind relates one object to another and what it’s subconsciously thinking. With a physiological illusion, the brain is confused by what the eye sees with light, color, size, movement, and dimension. The brain rectifies its confusion and then interprets what the eye saw, which isn’t physiologically possible.
The first known optical illusion created was about 2500 years ago on the island of Lesbos in Greece. The coin shows the two animals facing each other forms a wolf face facing forward.
How many different colored circles do you see?
The circles are all the same color. In July 2018, Dr. Novick, University of Texas professor, shared the Confetti illusion on Twitter. The optical illusion is an example of a Munker illusion where surrounding horizontal stripes in different colors influence the color perception of objects.
Hermann Grid Optical Illusion
Take a look at this illustration. How many black dots do you see?
No, this isn’t an animated GIF. There are no black dots. There are only black blocks and white space. The high contrast presents the eyes the illusion of grey or black dots at the intersections. Focus on the dot, and you’ll see the dots are white.
Animal Optical Illusion
Take a look at this sketch. How many animals do you see?
Two: a rabbit is looking to the right, and the duck is looking to the left. The duck’s beak is the rabbit’s ears.
The illusion appeared for the first time in a German magazine in 1892. According to American psychologist Joseph Jastrow, the quicker you switch between the two animals, the more creative you are.
Elephant Leg Illusion
How many legs does this unusual elephant have?
Kanizsa Triangle Optical Illusion
What patterns do you see? Do you see triangles? Discs?
Most people see a white triangle facing upwards and the outline of a black triangle downwards with three black discs. The symmetrical image is three black discs missing a triangular part and three pairs of lines. There is no large white triangle in the middle of the page – though I’m sure you see one!
Italian psychologist Gaetano Kanizsa described the illusion. It explains the law of closure where objects grouped seem to be part of a whole. The brain ignores the gaps and perceives the contour lines as a whole.
Color Gradient Optical Illusion
Which side of the inner rectangle is the darkest?
Muller-Lyer Optical Illusion
Observe the two lines with arrowheads on each end. Which line is the longest?
The lines are the same length. For most people, the line with the fins facing outward seems longer than the line with the spines facing inward. The illusion was created by a German psychologist F.C. Muller Lyar in 1889. Opinions differ on how the perceptual illusion works, whether it has to do with depth, size, or length
Wife or Mother-in-Law Illusion
Who do you see, the wife or the mother-in-law?
The mother-in-law’s nose is the wife’s jawline. The wife’s necklace is the mother-in-law’s mouth.
British cartoonist William Ely Hill created this brainteaser in 1915. It’s almost impossible to see the wife and the mother-in-law’s faces at the same time. According to Australian researchers, people tend to see the faces of people of similar ages. Therefore, younger people see the wife and older people see the face of the mother-in-law.
If you can’t see the mother-in-law, focus on the wife’s right ear. If you can’t see the wife, focus on the mother-in-laws left eyelash.
Impossible Trident Illusion
How many prongs are in the fork?
The impossible fork, also known as blivet, shows an object that can’t exist. At the one end, there are two rectangular prongs, and at the other end, it looks like three cylindrical prongs. It was discovered in 1964 when D. H. Shuster noticed an “ambiguous figure of a new kind” in the advertising section of an aviation journal.
Twelve Black Dots Illusion
How many dots do you see at the same time?
Most people can’t see all 12 dots simultaneously. The dots in the middle of their vision stay constant. Peripheral vision isn’t as clear. The brain guesses that the continuous pattern of white lines on a grey background continues peripherally and misses the black dots at certain intersections.
Although posted on Twitter and Facebook, the variation of the Hermann Grid was first published in 2000 in a scientific journal SAGE.
Pink or Grey Sneaker Illusion
What color is the sneaker?
The shoe is pink and white but many people see it as grey. The brain decides a color by considering the colors surrounding the object. Most people probably see the shoe as grey and teal because the brain takes into consideration the colors of the hand holding the shoe. Those who brains see a blue background depicts that the shoe is pink and white.
Zöllner Optical Illusion
Observe the diagonal lines in the image. Are the lines parallel?
German astrophysicist Johann K. F. Zöllner discovered this effect in 1760. The parallel diagonal lines intersect with short horizontal and vertical bars. It creates an image where the parallel lines seem to join and separate from each other. Scholars aren’t sure why this happens. It could be the way the brain adjusts angles, or it may be how it perceives depth. The illusion disappears when the colors in the image have equal values of red and green.
Lilac Chaser Illusion
Stare at the plus sign in the middle of the image for twenty seconds or so. What do you see happening in the circles around the +?
While staring at the + focal point, it seems as if the lilac dots move in a circle that changes to a space moving around the circle of lilac dots. After about 10-20 seconds a green dot appears that runs around the ring.
Vision expert Jeremy Hinton created the lilac disc in 2005. Apparent movement is when a person sees something in one spot and then in another place, and the brain perceives it as a movement. The green color is the afterimage. When a person stares at a color for a while and looks away, they may see the same color, which is the positive afterimage. Alternatively, they see the negative afterimage, which is the opposing color of the image.
Poggendorff optical Illusion
Observe the three lines on image. Which line does the black line connect to?
Although it seems as if the black line links with the blue line, it matches the red line. The image is distorted by the brain‘s perception of diagonal lines interacting with horizontal and vertical edges.
In 1860, German physicist Poggendorff received a letter from Johann Zöllner describing the illusion created by the fabric design. Poggendorff noticed the misalignment of the diagonal lines in the fabric design. The illusion is caused when a thin diagonal line is placed behind wider stripes at an angle.
Two Women Illusion
What do you notice about the women in the picture? Which one is shorter than the other?
The women are the same size – although they seem to be different sizes. The room appears square but distorts into a trapezoidal shape. The woman at the left is standing closer than the woman to the right, but it seems visually as if they are in the same depth of field. Hence, the one looks taller than the other.
Ponzo Optical Illusion
Which yellow horizontal line is the longest?
The two yellow lines are the same length. The upper line seems longer because of the parallel lines converging in the distance. The perspective hypothesis explains the illusion. In three dimensions an object in the distance needs to be larger to appear the same size as a closer object.
Ebbinghaus Optical Illusion
Which of the two orange discs is smaller – the left one or the right one?
The orange discs are the same size. The illusion was discovered by German psychologist Hermann Ebbinghaus but was popularized in 1901 when published in a textbook by Edward Titchener. It is a size contrast illusion. The surrounding blue disc sizes influence the perception of the orange disc sizes.
Hering Optical Illusion
Which way do the vertical lines bend?
The lines are straight. It seems as if the lines are bending outward due to the false impression of depth created by the radial background. German physiologist Ewald Hering discovered this geometric optical illusion in 1861.
Is the moon bigger when seen at the horizon than in the sky?
It seems as if the moon is more prominent, surrounded by scenery than high in the sky. The reason why the moon seems bigger closer to the horizon is due to depth perception. The trees, building, and surrounding images are the depth cues. In the sky, there aren’t any depth cues to relate to the moon. The color of the moon, atmospheric perspective, and visual factors influence how the moon’s size is perceived.
Stroop Effect Illusion
Which is faster to read the words or ignoring the words but reading the color of each word?
It’s faster to read the text. J. Ridley Stroop discovered this marvel in 1930. When reading the color instead of the word, the brain receives conflicting messages. The Speed of Processing theory explains the interference because the text reads faster than words. According to the Selective Attention Theory, naming the color requires more attention than reading the text.
What color are the strawberries?
The strawberries aren’t red. There are no red pixels in the image; only cyan pixels. Japanese Psychology professor Akiyoshi Kitaoka published the picture on Twitter. The National Eye Institute explains that the brain ‘corrects’ the color when it perceives it in a different color.
Troxler’s Fading Circle Illusion
What happens to the circle when you stare at the dot in center of the ring for about 20 seconds?
The circle fades and disappears. In 1804, Swiss physician and philosopher Ignaz Troxler used the illusion to demonstrate how efficient the brain functions. The brain filters out unimportant and non-threatening information to focus on what’s important. When staring at the dot, the brain doesn’t receive any new information, and the circle fades into the white background as the brain disposes of unimportant data.
Checkerboard Cylinder Shadow Optical Illusion
Take a look at the checkerboard pattern. What color is square A? Square B?
The two checker squares A and B are the same color. The illusion is created by the way the brain interprets contrasts and shadow. The brain perceives a light source from the right that casts a shadow on the board. Therefore, square A seems darker than square B, but both are light grey. The checker shadow illusion was published in 1995 by MIT professor of Vision Science, Edwards Adelson.
Question-Answer Optical Illusion
What word(s) do you see in the painting?
Question and Answer are the two words. John Langdon’s painting is an example of an intentional perceptional illusion. It is a type of steganography where words are hidden in larger scenes. A person tends to perceive the larger picture and often misses the smaller details.
Coffer Optical Illusion
How many circles do you see? How many rectangles?
There are 16 circles. Vision scientist Anthony Norcia form The Infant Laboratory at Smith-Kettlewell was one of the ten finalists in 2016 Best Illusion of the Year Contest with the Coffer Illusion. The brain identifies grouped objects to form edges and contours. Segmentation cues contradict the interpretation of a series of rectangular coffers with closed boundaries. The horizontal lines can represent a circle or the intersection of rectangles.