Illusions of contrast. Illusions of color vision

Illusions of color and contrast

First, check for color blindness

Normal vision

Colorblindness

How many color shades are there, not counting white?

Four? In fact, there are only two - pink and green. Several shades of green and red just seem.

There are only three colors: yellow, red and blue.

How many color shades are there?

Four? Wrong, only three. In this picture, pink and orange are replaced with black:

Goering grid

At the intersections of all white stripes, with the exception of the intersection where you are fixing your gaze at the moment, small gray spots are visible.

Another version of the Goering grid

Do you see small red spots at the intersection of black lines?

Goering grid effect in the shower

Defocused Goering grid

If the Hering grid is defocused, then the black dots at the intersections (which are actually absent and are the sick imagination of our brain) begin to randomly appear and disappear. Move your eyes over the drawing and the blinking will happen more often.

How many shades of red are there?

Only one.

Jumping colors

When viewed for a long time, the turquoise crosses begin to change color to yellow, and the black squares begin to turn red.

How many flowers?

The green border of the gray circles is your perception of strong contrast. She is not there. There are only 3 colors in the picture.

Eye Followers

Surprisingly, yellow dots appear only in the place where you look.

Purple dots

See the purple dots in the center of the flowers? If you look at only one of these points for some time, then all the others gradually disappear.

floating petals

The flower petals seem to float above the green substrate.

Offset squares

The blue squares where the red and green squares intersect appear offset, even though the side of the square is perfectly straight. By the way, not all people see this illusion of displacement. Colorblind people, for example, see straight sides of squares! The illusion is explained by the contrasting transition of colors.

Line shift

When viewing this picture, it creates the illusion of a horizontal displacement of each line in relation to the surrounding lines.

Blue mugs

If you look at the center of the image for some time, the blue circles will begin to change the color saturation.

Chromatism

If you look at the intersection of squares, then at some point in time the intersection will turn red.

Circles of flickers

Count the white and black dots on the circles.

Spiral

The spaces between the yellow in the spiral have a bluish tint (actually a shade of pure grey). At the same time, the density of the shade increases towards the center (in fact, the color density is the same everywhere).

Gray on color

Depending on the background, the gray squares appear brighter or darker in color, although, in fact, all the squares have the same color and shade, as in the square to the right of the picture.

Neon illusion

See the yellow color in the center of the squares? In fact, it is not there, everything there is pure white.

Net

Do you see the gray stripes along the diagonals? In fact, there are no stripes in the picture.

Bright dots

Look at one of the pictures for a while and you will see that intersections with missing points glow white (left picture) or, on the contrary, very dark (right picture).

pink dot

Do you think the dot in the middle is pink? It's actually grey!

Flashing dots

Move your gaze along the picture and you will see how the blue dots begin to blink like light bulbs. The illusion is based on the classical Hering grid.

How many ants?

Take a quick look at the picture excluding the ants. Which ants are there more? Red or white? Now count...

Achromatic contrast

The circles are the same shade of gray.

Chromatic contrast

When surrounded by green, gray appears lilac-pink, and when surrounded by red, it appears blue-greenish.

Mach bands (edge ​​contrast)

A smooth transition of color is perceived as stripes. At the border of white, an even whiter stripe is visible, and at the border of black, an even blacker one. The reason for this illusion is lateral inhibition in the retina.

Wertheimer-Koffka illusion

Part of the ring appears darker against a white background. If you remove the pencil, the illusion disappears.

Brightness comparison

The left and right inner squares have the same brightness, although the left square appears lighter.

T-merge illusion

Gray vertical rectangles of the same color and shade.

Snake

In Figure A, all the diamonds have a different shade, although in fact they are the same shade. This is clearly visible if you remove part of the background that misleads you - see Fig. B.

Do you see a chessboard with black and white cells?

Gray halves of black and white cells of the same shade.

Gray color is perceived either as black or as white.

Color constancy

Look carefully at the board. She is all right?

White cells in the shade and black cells in the light are the same color!

However, the eyes do not notice this. The brain sees black and white cells regardless of lighting!

Block-Gafter effect

On the left are rhombuses, on the right they were combined into a large rhombus, but the colors did not change.

Moron-Bur-Ross Illusion

In each rectangle, the right side (in the triangle) appears darker than the left, although in fact, the brightness is the same

Colored circles

All yellow circles are the same size.

Color distortion

Manker illusion. The red stripes on the top left and right of the picture are the same color. In the lower pictures there are green stripes of the same color.

Stars

The color of star A is equal to the color of the dark part of star B.

Karatekas

Take a look at the top picture. The shade of a karateka's shadow is different. In fact, the color of the shadow is the same, which is clearly visible in the bottom picture.

Red cubes

The red cubes at the top appear darker than the ones at the bottom. In fact, the color and shade are the same. The illusion is caused by the contrast of the cubes and the background.

The color of the figures seems brighter and more saturated if the figures are edged with black frames

The background color in the part of the picture where the hieroglyphs are not outlined in white appears more saturated

Is the center of the picture brighter?

The color along the edges and in the center of the picture is the same.

Which cell is brighter?

Cells A and B are the same color.

Distortion of colors

In the top picture, areas 1 and 2 have the same background. Let's put circles with gradients on top of the picture, and as you can see in the two bottom pictures, areas 1 and 2 began to have a different shade. In fact, areas 1 and 2 are the same color in all three pictures.

Knill and Kersten illusion

In Fig. 1, the squares appear identical. Let's move them together (Fig. 2) - it turns out they were different. To enhance the effect, we transform the squares into cubes, maintaining the shade of the front side (Fig. 3). And then, we transform the cubes into cylinders (Fig. 4), as you can see, the effect of “difference” has decreased.

Network

The color gradient creates the illusion of three-dimensionality in the image. The “braids” seemed to hang over the olive background.

Peacock

The colors of both peacocks are the same.

Same colors

Green, red and blue colors are the same throughout the whole picture, although they look different.

Day and night

The right girl looks darker than the left, although in fact they are the same.

Color change

Look at the square in the center whose background color is different from the rest of the background. After a while, you will see that the background color of adjacent squares has changed to a lighter color, although it is the same in relation to the peripheral squares.

Bright on dark

The gray background under the red dot looks lighter than under the blue one. In fact, the gray background underneath the blue dot is lighter!

Golden squares

The squares look different shades. Each square is filled with a gradient olive color. The left side is darker, the right side is lighter. One large square, in which there are small ones, is also filled with a gradient, only with a more expanded range of colors. But all the little squares are the same color.

Shades of red

There are four shades of red here.

And here there are three.

Dual green

The green background is the same everywhere, although it seems that the color is more saturated in the central square.

Depth perception

Look at the picture. Don't you think that the transition of gradients creates the illusion of volume (depth)?

Aliens

All diamonds consist of four small diamonds with the same gradient. But when you look at the picture, the illusion is created that some of the diamonds are orange, some are purple.

Horse color

It may seem strange to you, but the horses are completely identical in both color and shade. Feel free to check it out! And they look different because of the illusion that arises due to the contrast of the background.

Yellow and even yellower

Look at the animated picture. Squares appear once per second. Each new square looks more yellow than the previous one. In fact, the color of the squares is identical. They are exactly the same. But the transition of the gradient from yellow to red creates this effect.

Gray-green circles

All circles are the same color - gray. Although in the left area of ​​the picture they look greenish due to the contrasting background.

Grids

The black dots in the grids flicker in different colors.

Three colors

This picture uses only 3 colors: light green, purple and yellow.

Color perception

The frames around blue squares appear orange, those around yellow ones appear lilac-violet. In fact, the color of the frames is the same.

We take everything around us for granted: a ray of sunshine playing with reflections on the surface of the water, the play of colors in the autumn forest, the smile of a child... We have no doubt that the real world is exactly the way we see it. But is this really so? Why does our vision sometimes fail us? How does the human brain interpret perceived objects?

A person perceives most of the information about the world around him through vision, but few people think about how exactly this happens. Most often, the eye is considered to be similar to a camera or television camera, projecting external objects onto the retina, which is a light-sensitive surface. The brain “looks” at this picture and “sees” everything that surrounds us. However, not all so simple. First, the image on the retina is inverted. Secondly, due to imperfect optical properties of the eye, such as aberration, astigmatism and refraction, the image on the retina is defocused or blurred. Thirdly, the eye makes constant movements: jumps when viewing images and during visual search, small involuntary fluctuations when fixating on an object, relatively slow, smooth movements when tracking a moving object. Thus, the image is in constant dynamics. Fourthly, the eye blinks approximately 15 times per minute, which means that the image stops being projected onto the retina every 5-6 seconds. Since a person has binocular vision, he actually sees two blurry, twitching and periodically disappearing images, which means there is a problem of combining information coming through the right and left eyes.

Illusions are a distorted, inadequate reflection of the properties of a perceived object. Translated from Latin, the word “illusion” means “error, delusion.” This suggests that illusions have long been interpreted as some kind of malfunction in the visual system. Many researchers have been studying the causes of their occurrence. The main question of interest not only to psychologists, but also to artists is how the three-dimensional visible world is recreated on the basis of a two-dimensional image on the retina. Perhaps the visual system uses certain cues of depth and distance, for example, the principle of perspective, which assumes that all parallel lines converge at the horizon, and the size of an object proportionally decreases as it moves away from the observer. We are not aware of how much the projection of an object on the retina changes as it moves away.

One of the most famous optical-geometric illusions is (see Fig. 1).

Looking at this figure, most observers will say that the left segment with arrows pointing outward is longer than the right segment with arrows pointing inward. The impression is so strong that, according to experimental data, subjects claim that the length of the left segment is 25-30% greater than the length of the right.

Another example of optical-geometric illusions - (Fig. 2)

Also illustrates size perception distortions. Ponzo drew two identical segments against the background of two converging lines, like a railway track stretching into the distance. The top segment appears larger because the brain interprets converging lines as perspective (like two parallel lines converging in the distance). Therefore, we think that the upper segment is further away, and we believe that its size is larger. In addition to converging lines, the strength of the effect is added by the decreasing distance between intermediate horizontal segments.

The importance of perspective for the perception of the Müller-Lyer illusion is illustrated in Fig. 3. (The yellow lines in the corners of the wall are exactly the same size). In everyday life, we are surrounded by many rectangular objects: rooms, windows, houses. Therefore, a picture in which the lines diverge may be perceived as a corner of the building that is further away from the observer, while a picture in which the lines converge is perceived as a corner of the building that is closer. The Ponzo illusion can be explained in a similar way. Oblique lines converging at one point are associated either with a long highway or with a railroad track on which two objects lie. It is the visual patterns formed by such a “rectangular” environment that cause us to make mistakes.

Analysis of the proposed explanation of optical-geometric illusions shows that, firstly, all parameters of the visual image are interconnected, due to which a holistic perception arises and an adequate picture of the external world is recreated. Secondly, perception is influenced by stereotypes formed by everyday experience, for example, the idea that the world is three-dimensional, which begin to work as soon as signs indicating perspective are introduced into the picture.

An example of how a holistic image of an object can be destroyed are the so-called “”, contradictory figures, paintings with disturbed perspective.

If a person, sitting in a train carriage, fixes his gaze on the landscape outside the window, it seems to him that objects located closer to the point of fixation are moving towards him, and so quickly that he sometimes cannot distinguish the details. And objects located in the background, i.e. behind the fixation point, move along with the observer quite slowly. This phenomenon is called.

Fig.7. Motor
parallax

There are dynamic illusions that occur when using this phenomenon for flat images. In Fig. 7 we see an example of such an illusion. The circles in the foreground move quickly, and those in the background move slowly. It seems to the observer that the flat picture is turning into a three-dimensional one.

Another dynamic illusion is autokinetic movement. If you look at a luminous point in a dark room, you can observe an amazing phenomenon. The experiment is extremely simple: you need to light a cigarette and put it in an ashtray. The indispensable conditions for the appearance of an illusion are that the room must be so dark that, apart from this spot of light, nothing else can be seen. In this case, the gaze must be carefully fixed on the luminous point for several minutes. Knowing that the cigarette lies motionless in the ashtray, after a while you suddenly discover that its light is moving, making sweeping movements, sharp jumps, and describing circles around the room. The range of motion can be quite large. Moreover, the understanding that this is an illusion does not in any way affect the results of the observation. Hypotheses explaining this phenomenon by eye movements were refuted by experiments in which eye movements and the observer's report of the direction in which the light spot was moving were simultaneously recorded. A comparison of the data obtained showed that there is no correspondence between real eye movements and the apparent movement of the object.

But perhaps the greatest visual illusion is cinema and television. We can watch programs thanks to the stroboscopic effect, based on one of the most important properties of the visual system - inertia. The observer is presented with a static luminous dot in one place on the screen for several seconds, and after 60-80 ms it is shown in another place. A person does not see two different objects flashing in different places, but an object moving from one position to another. The visual system interprets successive and interconnected changes as movement. It is thanks to this effect that we see on the screens not a series of frames quickly replacing each other, but a single moving picture.

It is known that the first steps of cinema were accompanied by a curious episode: when the audience saw an approaching train on the screen, they jumped up and ran away screaming - it seemed to them that it was rushing right at them. This phenomenon is called looping. If a person is shown a spot of light that suddenly begins to expand in all directions, it will seem to him that it is moving directly towards him, and does not increase its size. Moreover, the illusion will be so strong that it will force you to involuntarily move away from the screen, as if from an object that poses a threat. Something similar can be seen when watching fans of computer games: someone leans to the side, trying to hide from bullets flying at him, someone recoils from a fireball rushing towards him. Obviously, in the case when there is no unambiguous information about a change in the shape of an object, the visual system prefers to interpret the increase in the retinal image as an approach of the object.

Some illusions arise in connection with the processing of incoming information. A person sometimes sees the world not as it really is, but as he would like to see it, succumbing to formed habits, secret dreams or passionate desires. He looks for the desired shape, color or other distinctive quality of an object among those presented in the outside world. This property of selectivity is called the phenomenon of perceptual readiness. Look at fig. 8.

Fig. 8 Illusions of information processing

Is the symbol in the center a letter or a number? If we consider a horizontal visual series consisting of letters, “B” will be in the center - the observer is prepared for this by the series of letters. If you look at the vertical row, it turns out that this is not a letter at all, but the number 13 - the numbers prompted this decision.

Such illusions are caused by a higher level of information processing, when the nature of the problem being solved determines what a person perceives in the world around him. The peculiarities of selectivity of perception are interesting. If you tell a person: your name is in this book, then he will be able to very quickly flip through the pages and find a mention of himself. Moreover, there is no talk of any reading of the text. Such skills are possessed by proofreaders who incomprehensibly identify errors in the text that are invisible to the average reader.

In this case we are talking about professional skills acquired in the process of activity.

Perception works very selectively when it comes to significant events that are too important for us. For example, the human face is perceived in a special way. The negative photograph of the face is practically unrecognizable and seems completely uninformative. If geometric objects, depending on how the shadows lie, can appear either convex or concave, then the human face is always convex (even a mask cannot be seen as concave). Paradoxical perception of an inverted image of a face (Fig. 9)

Fig.9. Illusions of information processing

If you look at two photographs of faces turned upside down, they seem to be no different: eyes, nose, lips, hair - everything is identical. But by turning these portraits over, you can see that they are completely different. On one - the calm and sweet smile of Gioconda, on the other - a terrible grimace. The point, apparently, is that the human face is too significant, it cannot be perceived from an unusual angle.

The most important property of our eye is its ability to distinguish colors. One of the properties related to color vision can be considered the phenomenon of a shift in the maximum relative visibility during the transition from daylight to twilight vision. With twilight vision (low light levels), not only does the sensitivity of the eye to the perception of colors in general decrease, but also under these conditions the eye has a decreased sensitivity to the colors of the long-wavelength part of the visible spectrum (red, orange) and increased sensitivity to the colors of the short-wavelength part of the spectrum (blue, violet) .

We can point to a number of cases where, when looking at colored objects, we also encounter visual errors or illusions.

Firstly, sometimes we mistakenly judge the color saturation of an object by the brightness of the background or by the color of other objects surrounding it. In this case, the patterns of brightness contrast also apply: the color brightens on a dark background and darkens on a light one (Fig. 10).

The great artist and scientist Leonardo da Vinci wrote: “Of colors of equal whiteness, the one that appears lighter will appear against a darker background, and black will appear gloomier against a background of greater whiteness. And red will appear more fiery against a darker background, and also all colors surrounded by their exact opposites."

Secondly, there is the concept of actual color or chromatic contrasts, when the color of the object we observe changes depending on the background against which we observe it. There are many examples of the effects of color contrasts on the eye. Goethe, for example, writes: “The grass growing in a courtyard paved with gray limestone appears to be an infinitely beautiful green color when the evening clouds cast a reddish, barely noticeable glow on the stones.” The additional color of dawn is green; This contrasting green color mixes with the green color of the grass and gives an “infinitely beautiful green color.”

Goethe also describes the phenomenon of so-called “colored shadows”. "One of the most beautiful cases of colored shadows can be observed during the full moon. Candlelight and moonlight can be completely equal in intensity. Both shadows can be made of the same strength and clarity, so that both colors will be completely balanced. Place the screen so that the light is full the moon fell directly on it, the candle is placed somewhat to the side at the appropriate distance, some transparent body is held in front of the screen. Then a double shadow appears, and the one cast by the moon and which at the same time is illuminated by the candle appears to be of a pronounced reddish-dark color. color, and, conversely, the one that is cast by a candle, but illuminated by the moon, is of the most beautiful blue color. Where both shadows meet and unite into one, a black shadow is obtained."

Blind spot. The presence of a blind spot on the retina of the eye was first discovered in 1668 by the famous French physicist E. Mariotte. Marriott describes his experience in verifying the presence of a blind spot as follows: “I attached a small circle of white paper on a dark background, approximately at eye level, and at the same time asked to hold another circle to the side of the first, to the right, at a distance of about two feet. ), but slightly lower so that its image fell on the optic nerve of my right eye, while I closed my left eye. I stood opposite the first circle and gradually moved away, keeping my right eye on it. When I was 9 feet away, the second circle , which was about 4 inches in size, completely disappeared from view. I could not attribute this to its lateral position, for I could distinguish other objects located even further to the side than it; I would have thought that it had been removed if I had not found it again when the slightest movement of the eyes."

It is known that Marriott amused the English king Charles II and his courtiers by teaching them to see each other without heads. The retina of the eye, where the optic nerve enters the eye, does not have the light-sensitive endings of nerve fibers (rods and cones). Consequently, images of objects falling on this place of the retina are not transmitted to the brain.

Here's another interesting example. In fact, the circle is perfectly smooth. We need to squint and we see it.

This effect includes illusions or optical phenomena caused by color and changing the appearance of objects. Considering the optical phenomena of color, all colors can be divided into two groups: red and blue, because Basically, colors in their optical properties will gravitate towards one of these groups. The exception is green. Light colors, such as white or yellow, create an irradiation effect, they seem to spread to the darker colors located next to them and reduce the surfaces painted in these colors. For example, if a ray of light penetrates through a crack in a plank wall, the crack appears wider than it actually is. When the sun shines through the branches of trees, the branches appear thinner than usual.

This phenomenon plays a significant role in the design of fonts. While the letters E and F, for example, retain their full height, the height of letters such as O and G are reduced somewhat, further reduced by the sharp ends of the letters A and V. These letters appear lower than the overall height of the line. So that they appear to be the same height as the rest of the letters of the line, when marking them, they are moved slightly up or down beyond the aisles of the line. This also explains the different impressions of surfaces covered with transverse or longitudinal stripes. A field with transverse stripes appears lower than a field with longitudinal stripes, since the white color surrounding the field penetrates at the top and bottom between the stripes and visually reduces the height of the field.

Main optical features of the red and blue color groups.

The yellow color visually lifts the surface. It also seems more extensive due to the irradiation effect. The red color is approaching us, blue, on the contrary, is moving away. The planes, painted in dark blue, purple and black, visually decrease in size and move downward.

Green is the calmest of all colors. It should also be noted that the centrifugal movement is yellow and the centripetal movement is blue.

The first color pricks the eyes, the second color drowns the eye. This effect increases if we add to it the difference in lightness and darkness, i.e. the effect of yellow will increase when white is added to it, blue - when it is darkened with black.

Academician S.I. Vavilov writes about the structure of the eye: “How simple is the optical part of the eye, so complex is its perceptive mechanism. Not only do we not know the physiological meaning of individual elements of the retina, but we are not able to say how appropriate the spatial distribution of light-sensitive cells is to what needs a blind spot, etc. What we have before us is not an artificial physical device, but a living organ in which advantages are mixed with disadvantages, but everything is inextricably linked into a living whole.”

A blind spot, it would seem, should prevent us from seeing the entire object, but under normal conditions we do not notice this.

Firstly, because the images of objects falling on the blind spot in one eye are not projected onto the blind spot in the other; secondly, because the falling out parts of objects are involuntarily filled with images of neighboring parts that are in the field of view. If, for example, when examining black horizontal lines, some areas of the image of these lines on the retina of one eye fall on a blind spot, then we will not see a break in these lines, since our other eye will compensate for the shortcomings of the first. Even when observing with one eye, our mind compensates for the deficiency of the retina and the disappearance of some details of objects from the field of vision does not reach our consciousness.
The blind spot is quite large (at a distance of two meters from the observer, even a person’s face can disappear from the field of view), however, under normal vision conditions, the mobility of our eyes eliminates this “disadvantage” of the retina.

Astigmatism of the eye is a defect of the eye, usually caused by the non-spherical (toric) shape of the cornea and sometimes the non-spherical shape of the surfaces of the lens. Astigmatism in the human eye was first discovered in 1801 by the English physicist T. Young. In the presence of this defect (by the way, not all people manifest it in a sharp form), there is no point focusing of rays falling parallel to the eye due to different refraction of light by the cornea in different sections. Severe astigmatism is corrected by glasses with cylindrical glasses, which refract light rays only in the direction perpendicular to the axis of the cylinder.

Eyes completely free from this defect are rare in people, as can be easily seen. To test the eyes for astigmatism, ophthalmologists often use a special table, where twelve circles have shading of equal thickness at equal intervals. An eye with astigmatism will see the lines of one or more circles blacker. The direction of these blacker lines allows us to draw a conclusion about the nature of the astigmatism of the eye.

If astigmatism is due to the non-spherical shape of the lens surface, then when moving from clear vision of horizontal objects to viewing vertical objects, a person must change the accommodation of the eyes. Most often, the distance of clear vision of vertical objects is less than horizontal ones.

An experimental study of the process of perception of real objects - two slats of equal size against the backdrop of railroad tracks - showed that the perceived size of the far slats was either smaller (in the vast majority of trials) or equal to the perceived size of the near slats, depending on the method of perception and observation distance. The “illusion” of perceiving a larger relative magnitude of the far staff occurred only in very rare cases.

This difference in the results of the process of perception of a real object and its abstract image on a plane is due to the difference in the content of the relationships formed in the process of reflecting the properties of both objects of perception. Thus, the processes of perception of a real object and its image, which differ in the objective content of the relationships formed in these processes, as well as in the conditions of perception, are not rightfully considered identical processes.

It is the variety of anisotropic relationships that is the direct sensory basis of the semi-functionality of the perception process, which provides the ability for a person to reflect various properties and relationships of objects under different conditions and tasks of acting with them.

Illusion of color and contrast

Look at the center of the picture.
At the intersection of all the white stripes, small black circles are visible. At the same time, if you concentrate your gaze on any of these intersections, the circle disappears. The illusion is known as the Goering Grid.

Do you see a chessboard with white and black squares?
Gray halves of black and white cells of the same shade. Gray color is perceived either as black or as white.

Pay attention to the shades of the circles.
When surrounded by green, gray appears lilac-pink, and when surrounded by red, it appears blue-greenish.

How many colors were used to paint this picture?
Three: white, green and pink. The presence of different shades of green and red in the picture is just an illusion. Its occurrence depends on whether the green and pink squares are adjacent to each other, or whether there is also a white one between them.

Which circle is lighter?
Here the circles are exactly the same shade of gray. But when compared to the background saturation, they appear to be a lighter or darker shade.

Look at these two squares. Which square is brighter?
The color of the figures appears brighter and more saturated if the figures are edged with black frames. In fact, in both one and the other square the colors are exactly the same.

Fix your gaze in the center of the picture.
Goering grid. At the intersections of all white stripes, with the exception of the intersection where you are fixing your gaze at the moment, small gray spots are visible. As you can imagine, they don't actually exist.

Which half is more saturated in color?
The tone of the lower half seems more saturated, despite the absolute sameness of the colors of both halves. The illusion occurs due to the presence of a white outline at the top of the design.

An effect well known to physicists and doctors.
Mach bands. A smooth transition of color is perceived as stripes. At the border of white, an even whiter stripe is visible, and at the border of black, an even blacker one. The reason for this illusion is lateral inhibition in the retina, in other words, the peculiarities of the processes and structure of our eyes.

Look at the picture and pay attention to the red spots that appear at the intersection of the black lines.
The reason for this illusion is, among other things, the structural features of the retina.

Which part of the ring is darker?
Part of the ring appears darker against a white background. If you remove the pencil, the illusion disappears. Try this experiment with real paper and pencil.

Pay attention to the board.
It's hard to believe, but white cells in the shadow and black cells in the light are the same color. At the same time, our brain does not perceive this. Our perception, due to a centuries-old habit, makes allowances for the shadow that the timber supposedly creates, and automatically sends signals to the brain to “highlight” the squares in the shadow in our consciousness in order to compare them with the colors in the rest of the space.

We are accustomed to taking the world around us for granted, so we do not notice how our brain deceives its own masters.

The imperfection of our binocular vision, unconscious false judgments, psychological stereotypes and other distortions of worldview give rise to optical illusions. There are a huge number of them, but we tried to collect the most interesting, crazy and incredible of them for you.

Impossible figures

Impossible trident

Classical blivet is perhaps the most striking representative of optical patterns from the “impossible figures” category. No matter how you try, you will not be able to determine where the middle prong originates.

Another striking example is the impossible Penrose triangle.

It is in the form of a so-called “endless staircase”.

And also “The Impossible Elephant” by Roger Shepard.

Ames room

How does the Ames room work?

Movement Illusions

floating star

There are quite a few similar illusions of movement, that is, static images that appear to be moving. For example, the famous rotating circle.

Or yellow arrows on a pink background: when you look closely, they seem to sway back and forth.

Caution: This image may cause eye pain or dizziness in people with weak vestibular systems.

Honestly, this is a regular picture, not a GIF! Psychedelic spirals seem to drag you somewhere into a universe full of strangeness and wonder.

Changeling illusions

Two classic illusions-shifters: nurse/old woman and beauty/ugly.

A more highly artistic picture with a trick - when turned 90 degrees, the frog turns into a horse.

Other “double illusions” are more subtle.

Girl/old woman

Old people/Mexicans

Lovers/dolphins

The list of such dual pictures can be continued endlessly:

In the picture above, most people see the Indian's face first, and only then look to the left and see the silhouette in the fur coat. The image below is usually interpreted by everyone as a black cat, and only then does a mouse appear in its outline.

A very simple upside-down picture - something like this can be easily done with your own hands.

Illusions of color and contrast

Gray squares

This trick is possible due to the way our brain works. A shadow without sharp boundaries falls on square B. Thanks to the darker "surrounding" and the smooth shadow gradient, it appears to be significantly lighter than Square A.

Green spiral

Is the dress white and gold or blue and black?

The explanation of the dress phenomenon is very simple: as in the case of gray squares, everything depends on the imperfect chromatic adaptation of our visual organs. As you know, the human retina consists of two types of receptors: rods and cones. Rods capture light better, while cones capture color better. Each person has a different ratio of cones to rods, so the determination of the color and shape of an object is slightly different depending on the dominance of one or another type of receptor.

Those who saw the dress as white and gold noticed the brightly lit background and decided that the dress was in the shadows, which means the white color should be darker than usual. If the dress seemed blue-black to you, it means that your eye first of all paid attention to the main color of the dress, which in this photo actually has a blue tint. Then your brain judged that the golden hue was black, lightened due to the sun's rays directed at the dress and the poor quality of the photo.

In reality the dress was blue with black lace.

Here's another photo that baffled millions of users who couldn't decide whether it was a wall in front of them or a lake.

Contrast illusions are distortions in the perception of stimuli that result from the opposing, or contrasting, influence of the surrounding, or contextual, stimuli in which they are embedded. Contrast illusions are of particular interest because they highlight the role of visual context in the perception of area, length, shape, and spatial orientation.

The illusion described at the end of Chapter 2 as the Baldwin illusion (see Fig. 2.12) and the Ebbinghaus illusion, shown in Fig. 10.29 are the most important examples of persistent perceptual distortions caused by contrast.

horizontal lines are equal in size

The two inner circles at A and B (Fig. 10.29) are physically equal to each other. However, the area of ​​circle A appears larger due to the fact that it is surrounded by smaller circles, and the area of ​​circle B appears smaller because it is adjacent to larger circles. (A version of this illusion is described in Stapel & Koomen, 1977.) Shown in Fig. 10.30 Jastrow's illusion also illustrates the effect of contrast on the perception of magnitude.

The central circle in A, thanks to the small circles surrounding it, appears larger than it actually is. The central circle on B, identical in size, appears to the observer smaller than it actually is, since it is surrounded by larger circles

Although both figures are identical, it appears to the observer that 5 is longer than /1. The shorter side of A contrasts with the longer side of B, causing A to be perceived as shorter and B as longer.

The lower curved figure B appears to the viewer to be longer than the upper figure L, although they are identical. In Fig. Figure 10.31 is an example of an illusion created by tilt contrast, in which vertical lines appear to tilt in the opposite direction to the tilt of the surrounding background lines.

10.32. A - illusion of W. Wundt (1896). It seems horizontal

the parallel lines in the middle are curved. B - Hering's illusion. The horizontal parallel lines in the middle seem to bend - the top one “bends” up and the bottom “bends” down

The effect of contrast, leading to a distorted perception of shape, is illustrated by the illusions of Wundt and Hering (Fig. 10.32).

In the central circles, surrounded by slanted lines, there are vertical straight lines, which, due to the background, seem inclined in the direction opposite to the slope of the lines forming the background

Both pairs of horizontal lines are straight lines parallel to each other, but in Wundt’s illusion they seem to “bend” inward, and in Goering’s illusion they seem to “bend” outward. A similar distortion of perception as a result of the contrast between two adjacent areas (of the picture) is also characteristic of the Fraser illusion (Fig. 10.33).

The obvious influence of the contrast between white and black rectangles adjacent to each other distorts the perception of figures physically parallel to each other in the Münsterberg illusion, shown in Fig. 10.34.

Only a ruler applied to the base of the horizontal rectangles can.

33. The “twisted rope” illusion, or the J. Fraser illusion (1908)

Against the background of a pattern formed by intersecting diagonals, straight lines appear curved. This illusion gets its name because it can be experienced by looking at a twisted rope against a checkered background.

formed by alternating white and black rectangles, appear non-parallel