Presentation of light and color illusion. Optical illusions. I. Organizational moment of the lesson

  • 07.03.2020

optical illusions 8th grade

Borisova Irina Dmitrievna,

Physics teacher,

Public Educational Institution of Omsk "Secondary School No. 101"




“Through the eye, not the eye the mind knows how to look at the world "William Blake.

Light, refracted in the optical system of the eye, which is formed by the cornea, lens and vitreous body, gives real, reduced and inverse images of the objects in question on the retina. Hitting the endings of the optic nerve. of which the retina consists, light irritates these endings.

These stimuli are transmitted along the nerve fibers to the brain, and a person has a visual sensation: he sees objects.

The image of an object that appears on the retina is inverted (I. Kepler).

? Why, then, do we see all objects as they are?


  • visual distortion
  • size illusions
  • Color and contrast
  • Apparent figures
  • Depth perception
  • Changelings
  • Pattern recognition
  • Figure and background

In fact, all impossible figures can exist in the real world.

So, all objects drawn on paper are projections of three-dimensional objects, therefore, it is possible to create such a three-dimensional object that, when projected onto a plane, will look impossible.

When looking at such an object from a certain point, it will also look impossible, but when viewed from any other point, the effect of impossibility will be lost.

The most famous impossible figures are the impossible triangle, the endless staircase and the impossible trident.


Impossible figures gained wide popularity thanks to the lithographs of the Dutch artist M.K. Escher.

The direction in the visual arts, aimed at depicting impossible figures, is called imp art.

Escher cube


How many dinosaurs are there?

Impossible transformer

How many legs does an elephant have?

Amazing seating

Impossible Wheel


Illusion of perception

Our brain builds distorted images of reality. He is able to create the appearance of something that does not exist in reality and at the same time not notice the obvious.

We can observe some phenomenon, even knowing that it is impossible.

In psychology, this is called the illusion of perception.


AT There are two types of illusions - those that are based on certain physical conditions, and those that are psychologically conditioned.

Examples of illusions of the first type are mirages or distortion of objects when they are perceived in water or through a prism. The explanation for such illusions lies outside of psychology. More physics here.

Illusions of the second type are associated with the peculiarities of perception, for example, geometric shapes when their proportions, colors, etc. are distorted in visual images.

It's more physiology and psychology.


More examples of well-known illusions.

Rails on railway are parallel and at some distance from each other. However, if we look into the distance, we see that they supposedly converge towards the horizon.

Electric or telegraph poles of the same height. But those that are far away seem small in comparison with those that are near.

In general, we are used to the fact that all objects receding to the horizon decrease on the retina in their linear dimensions: people, trains, clouds, airplanes.


size illusions

They are due to the fact that the same lengths in a horizontal and vertical position or in the presence of additional elements seem different.

BUT). Muller-Lyer illusion. Which of the horizontal lines is longer? It seems to be the top one. In fact, they are equal.

B). Kinescope illusion. Which red line is longer? Seems to be right. No, they are the same length.


Illusion by Nick Williams (Nik Williams, 1996)

The top picture is just a mask of an Egyptian mummy (2-2.5 thousand years BC). On the middle - the same mask, but from the inside.

On the bottom - an enlarged part of the back of the mask. Note how difficult it is to perceive this image as concave.

The brain unconsciously sees this face as normal.


AT). Ebbinghaus illusion.

Which circle is bigger?

The one that is surrounded by small circles or the one that is surrounded by large ones? It seems that the one that is small.

No, they are the same.


Changelings

A shifter is a type of optical illusion in which the nature of the perceived object depends on the direction of the gaze. One of these illusions is the "duck hare": the image can be interpreted both as an image of a duck and as an image of a hare.



This is without a doubt the best illusion.

Be sure to try:

1) Relax and watch non-stop for 30 seconds. into 4 small dots in the center.

2) Then slowly look at the wall (or something large and of the same color) near you.

3) You will see how a light circle is formed.

4) Blink a couple of times and you will see how a figure is formed in this circle.

5) What or who do you see?



The effect is enhanced by tilting, rotating, approaching/removing the head

A still image appears to be moving.

When considering the same moving balls, you can see that they different sizes.

The same animated image can depict a rotating object clockwise, counterclockwise or alternately (make oscillatory movements).



rubber pencil illusion








Well, lastly...

Follow the instructions carefully.

This is amazing!

1. Put your hand on the mouse.

2. Hover your mouse over the symbol below (it's free of viruses).

3. Concentrate on the dot in the middle of the screen.

4. Look at it for at least 30 seconds, but no more than 45 seconds.

5. Now look at your hand on the mouse.

6. No need to shout - everything is in order with your hand.

Class: 8

Presentation for the lesson





























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Attention! The slide preview is for informational purposes only and may not represent the full extent of the presentation. If you are interested this work please download the full version.

Educational objectives of the lesson:

  • Formation of interest and cognitive motivation in teaching physics;
  • Development of theoretical thinking skills;
  • Creative search;
  • Formation of the concept of "illusion", types of illusions and identification of the causes of their occurrence;
  • Development of communication skills.

Main goals:

  • Expansion and deepening of knowledge in physics.
  • Development of figurative thinking.
  • Development of the ability to model and think creatively.
  • Development of communication skills and individual personality traits of students.
  • The development of students' emotions by creating a state of surprise, amusement, paradox during the lesson.

Equipment: a computer; multi-video projector; presentation.

Lesson type: learning new material.

During the classes

The visible does not always correspond to the real.
N. Copernicus

I. Organizing time lesson

- Hello, dear guys! The epigraph of our lesson is the words “The visible does not always correspond to the real”, said by N. Copernicus. Today in the lesson we will try to understand some of the mysteries of nature. The topic of our lesson is "Optical Illusions"

We know that our eyesight is imperfect. Sometimes what we see is not what is actually happening. But this is a fact. Let's try to understand the features of our observations.

II. Learning new material using presentation.

The concept of optical illusion. (slides 2-3)

What is an optical illusion? An optical illusion is a representation of a visible phenomenon or object that does not correspond to reality due to the structural features of our visual apparatus, simply speaking, this is an incorrect representation of reality. Optical illusions are not associated with individual visual impairments, such as color blindness.

Causes of an optical illusion? The human visual apparatus is a complex system with a well-defined limit functionality. It includes: the eyes, the nerve cells through which the signal is transmitted from the eye to the brain, and the part of the brain responsible for visual perception. (picture 1).

Picture 1

In this regard, there are three illusion reasons:

  1. Our eyes perceive the light coming from the object in such a way that erroneous information comes to the brain;
  2. If the transmission of information signals through the nerves is disrupted, failures occur, which again leads to erroneous perception;
  3. The brain does not always respond correctly to signals coming from the eyes. (picture 2)

Figure 2

Regarding the causes of visual illusions (errors, deceptions), it should be noted, firstly, that sometimes they appear as a result of specially created, special conditions of observation, for example: observation with one eye, observation with fixed axes of the eyes, observation through a slit, etc.

Secondly, most visual illusions do not arise from the optical perfection of the eye.

Illusions of vision do not include optical tricks and mysterious ghosts created with the help of mirrors, projectors and other technical devices, as well as interesting optical phenomena, sometimes observed in nature (mirages, northern lights). The appearance of the latter is due to the optical properties of the earth's atmosphere.

Consider some types of illusions:

1. The illusion of depth perception . (slides 5, 6)

Visual illusions arise under the conditions of the relief or depth of the pattern that we see. The emergence of these illusions is associated with the ability of the eye to see objects at different distances, with the ability to perceive space by the brightness of objects, by their shadows and by the number of intermediate objects. On the other hand, these illusions also arise in the process of comprehending the visible. The brain, perceiving an object, distorts the relief image that we see. The following figure serves as an example of this: the cube seems to be visible from above, then from the side. (picture 3)

Figure 3

2. Size illusion.(slides 7, 8)

In general, we are used to the fact that all objects receding to the horizon decrease in their linear dimensions on the retina: people, trains, clouds, planes... (picture 4)

Figure 4

3. Illusion of perception of movement. (slides 9-11)

I think this illusion is the most interesting because nothing is actually moving. If we make drawings of these pictures, the illusion still arises.

There is an illusion that can be called the Plateau spiral, or, to put it more simply, the spinning top effect. If a disk with a spiral (top) is rotated clockwise, then after a long fixation of it with the eye, we get the impression that all the branches of the spiral are being pulled towards the center; when the spiral rotates in the opposite direction, we see the divergence of the spirals in the opposite direction from the center to the periphery. So, for example, if, after a long observation of the terrain from the window of a moving train or of water from the window of a moving steamer, we shift our gaze to stationary objects inside the train or steamer, then it will seem to us that they are also moving, but in the opposite direction. These illusions are associated with successive moving images. (picture 5)

Figure 5

4. Impossible figures.(Figure 6) (slides 12-13)

Figure 6

5. Upside down paintings (Figure 7) (slide 14)

Figure 7

These are illusions associated with a change in orientation. Human visual mechanisms provide the ability to recognize objects viewed in different orientations, but a person gets used to certain conditions of observation that prevail in everyday life. As a result of this habit, different orientations of objects become unequal for a person. This is especially true for human faces and printed text.

6. The ratio of the figure and the background.(Figure 8) (slides 15-17)

Figure 8

Here we will consider a number of visual illusions due to the influence of the contrast of brightness, i.e. the ratio of the difference between the brightness of the object and the background to the brightness of the background. First, on a darker background, we see the figures as lighter and, conversely, on a light background, as darker. Secondly, when perceiving the figure and the background, we tend to see, first of all, spots of a smaller area, as well as brighter “protruding” spots, and most often the background seems to us to lie farther from us, behind the figure. The greater the brightness contrast, the better the object is visible and the more clearly its outline and shape are visible.

7. Dual images. (Figure 9) (slide 18)

Figure 9

What do you see in the picture? Why is there such an illusion? Consider carefully, how many people are there?

8. Illusion of Goering.(Figure 10) (slides 19–21)

Figure 10

Many illusions are explained by the ability of our vision to exaggerate the sharp corners that we see on flat figures. Perhaps this kind of illusion appears due to the phenomenon of irradiation, as the light space we see expands around the dark lines that limit the acute angle. Of great importance in these illusions is the direction of eye movement and their mobility in general. If there is a break in the lines, then our eye first of all “grabs” an acute angle, since the axis of the field of view first moves along the shortest direction and only then examines the sides of obtuse angles.

Sharp corners always seem to be larger than they actually are, and therefore certain distortions appear in the true ratio of the parts of the visible figure. In the figure, parallel straight lines, due to the influence of the background, appear non-parallel and curved.

Sometimes a change in the direction of the lines and a distortion of the shape of the figure also occurs due to the fact that the eye follows the directions of other lines in the field of view. In the above figure, the straight sides of the square appear to be curved, and the entire square appears to be deformed.

9. Apparent figures.(Figure 11) (slides 22-23)

Figure 11

10. Pattern recognition.(Figure 12) (slides 24–26)

Figure 12

11. Follow-up pictures.(Figure 13) (slide 27)

Figure 13

Many have seen the so-called mysterious, as if alive, portraits that are always looking at us, following our movements and turning their eyes to where we are moving. This is due to the fact that the pupils of the eyes in the portrait are placed in the middle of the section of the eyes. This is how we see the eyes looking at us, but when the eyes look to the side, past us, the pupil and the entire iris seem to us to be not in the middle of the eye, but shifted to the side. When we move away from the portrait, the pupils, of course, do not change their position - they remain in the middle of the eyes, and since we continue to see the whole face in the same position in relation to us, it seems to us that the portrait has turned its head and is following us

12. Colors and contrasts.(Figure 14) (slide 28)

Figure 14

III. Conclusion.

If our eyes were not capable of succumbing to any deceptions, there would be no painting, architecture, sculpture, and we would be deprived of all pleasures. fine arts. We would not be able to understand optical illusions in the world around us and apply them in our lives.

Bibliography:

  1. ME AND. Perelman. Entertaining physics. Book 2. - M .: Triada-Litera, 1994, p. 222–242.
  2. Keith Kay. Optical illusions. Smolensk, "Rusich", 1999.

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Then calmly look at the following pictures... Well, do you want to deceive your eyes??? Click Next

How many people can be found in this picture? Click Next

Red, horizontal lines - are they parallel or not? Click Next

Black or white dots, what do you see? Click Next

You can see black and white dots, but there is only white. Click Next

What do you see? A spiral, or is it still rather circles? Click Next

Are there gray dots between the squares, or not? Click Next

In the next picture, you need to focus on the black dot. After a while, the gray aura will disappear...

In the next picture, you need to fix the center point and move your head forward and backward.

This is without a doubt the best PC illusion. Try it for sure: 1) Relax and watch non-stop for 30 seconds. into 4 small dots in the center. 2) Then slowly look at the wall (or something large and of the same color) near you. 3) You will see how a light circle is formed. 4) Blink a couple of times and you will see how a figure is formed in this circle. 5) What or who do you see? Click Next

Follow the instructions carefully. This is amazing! What to do: 1. Place your hand on the mouse. 2. Hover your mouse over the symbol below (it's free of viruses). 3. Concentrate on the dot in the middle of the screen. 4. Look at it for at least 30 seconds, but no more than 45 seconds. 5. Now look at your hand on the mouse. 6. No need to shout - everything is in order with your hand.

Preview:

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Every day, from morning to earlier, a productive and cheerful ANT came to work

He had a good performance and he was cheerful.

And the company was successful but. ..

BUMBLEBEE, CEO of the firm where ANT worked, decided that ANT could not work on his own, so the position of overseer was created and he hired dung beetle.

The main concern of the BEETLE-DUNGERY was to organize the work of the ANT. And he forced the ANT to make reports on the daily work done.

Soon a secretary position was needed to help the beetle in reading and filing ANT's reports.

Therefore, a SPIDER was hired to classify documents and answer phone calls.

Meanwhile, the happy ANT worked, worked, worked...

Bumblebee, was very pleased with the dung beetle reports, so he requested additional reports, forecasts and calculation of various indicators.

In such a case, it was necessary to hire a ROCKET as an assistant to the dung beetle.

And also buy a computer and a color printer.

Soon, a productive and happy ANT, began to complain about all the disassembly and reports that he was supposed to provide, and he became less and less cheerful

SHMEL, CEO, understands that action must be taken.

So, at the place where the productive and still cheerful ANT worked, a department was created

KUZNECHIK was appointed to the post of chief. He built himself a modern office and equipped accordingly.

The new head of the department needed an assistant who would help him in preparing the strategic plans and budget for the department in which the productive and cheerful ANT worked.

But the ANT no longer sang as before and became more and more irritable...

One day, the CEO, looking at the numbers, realized that the department where ANT works is no longer as profitable as before.

After thinking, SHMEL decided to hire OWL as a consultant to carry out diagnostics.

SOVA spent 3 months at the firm, and after studying the case, she concluded: “There are too many staff in the department ..”

... following the advice of a specialist, they carried out a reduction in the number. ANT was the first in the list, because. I was dissatisfied all the time...

Moral: Don't even think about being a happy and productive ant. Better to be incompetent and useless. The incompetent don't need overseers... everyone understands why. And, if, despite your “efforts”, you still continue to be productive, do not show for anything in the world that you are happy and cheerful. You will never be forgiven for this. But if, contrary to what has been said above, you stubbornly continue to be a HAPPY AND PRODUCTIVE ANT, work for yourself so that you do not carry bumblebees, dung beetles, cockroaches, spiders, grasshoppers and owls on your back.

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We convince ourselves that life will get better when we get married, have a child, then another. Then we get frustrated that our kids are still young and expect things to get better as they get older. Then we worry that they have become teenagers, and we need to somehow cope with them. Undoubtedly, we will be happier when they grow out of their "... eleven" years. We tell ourselves that our lives will get better when our spouse gets away with it, when we have a nicer car, when we take a vacation, when we finally retire. The truth is that there is no better time to be happy than now. If not now, then when? Your life will always be full of challenges. It is better to accept everything as it is and decide to be happy no matter what.

For a very long time, it seemed that life was about to begin. Real life. But there was always some obstacle in the way, a severe test to be passed; work to be completed; the time to be dedicated; invoice to be paid. And then we'll live. Finally I came to understand that these obstacles were life itself. This understanding helped me see that there is no path to happiness. Happiness is THAT is the way. Therefore, enjoy every moment. Stop waiting for graduation, start school, wait until you lose $10, make $10, when you get a job, until you get married, until Friday night, until Sunday morning, wait for a new car, until your mortgages are paid in full, until spring, until summer , until autumn, until winter, until the first or fifteenth, when your song is played on the radio, when you die, when you are born again ... before you decide to be happy / oh.

Happiness is a WAY, not a destination. There is no other time to be happy except... NOW! Live and enjoy this moment. - Author unknown- Now, think and answer these questions: 1 - Name 5 the richest people on the planet. 2 - Name the last 5 Miss World winners. 3 - Name the last 5 Nobel Prize winners. 4 - Name the last 5 Oscar winners for best performance.

Didn't quite work out? It's hard, isn't it? Don't worry, no one remembers this. The applause subsides! Prizes covered in dust! Winners are soon forgotten. Now answer these questions: 1 - Name 3 teachers who contributed to your education. 2 - Name 3 friends who helped you in difficult times. 3 - Think of a few people who made you feel special. 4 - Name 5 people you enjoy spending time with. Feasible? It's easier, isn't it? The people who mean something in your life are not in the "best" ranking, do not have the most money, have not won the greatest prizes ... These are the ones who care about you, value you, those who, no matter what, remain beside. Think about it for a moment. Life is very short! What list are you on? You do not know?

Let me shake your hand. You are not among the most "famous", but among those whom I remembered sending this message ... Some time ago, at the Seattle Olympics, nine athletes stood at the start of the 100-meter running track. They were all physically or mentally handicapped. A shot was fired and the run began. Not everyone ran, but everyone wanted to take part and win. They ran a third of the distance when the boy stumbled, did a few somersaults and fell. He began to cry. The other eight members heard him cry. They slowed down and looked back. They stopped and came back ... That's it ... A girl with Down syndrome sat down next to him, hugged him and asked: “Are you feeling better now?” Then, all nine of us went shoulder to shoulder to the finish line. The entire crowd stood up and applauded. The applause went on for a very long time...

Those who saw it are still talking about it. Why? Because deep inside ourselves, we all know that the most important thing in life means much more than winning for ourselves. The most important thing in this life is to help others win. Even if it means slowing down or changing your own race. If you send this letter, perhaps we will be able to change our hearts, perhaps the hearts of someone else ... "A candle loses nothing if another candle is lit by its flame" So, what is your decision? Delete this letter or send it to someone?


Slide 3. Definition of illusion.

    distorted perception or representation of reality.

    errors in visual perception caused by inaccuracy or inadequacy of the processes of unconscious correction of the visual image.

Slide 4. Types of illusions.

    Impossible

    Color perception

    visual distortion

    pattern recognition

    dual image

    Illusion of movement

    Changelings

    Stereo illusions

Slide 5. Impossible illusion.

When considering such drawings, each individual detail seems quite plausible, however, when trying to trace the line, it turns out that this line is no longer, for example, the outer corner of the wall, but the inner one.

Slide 6. Illusion of color perception.

When an image appears on the retina of the eye, consisting of light and dark areas, we observe mysterious effects. For example, lines of the same color may appear different colors.

Slide 7. Visual distortion.

Illusions often lead to completely wrong quantitative estimates real geometric quantities. According to the theory of relative size, the perceived size depends not only on the size on the retina, but also on the sizes of other objects in the field of view that we observe simultaneously.

Slide 8. Pattern recognition.

If you do not know what is depicted in these drawings, then it is almost impossible to see the drawing. Typically, such pictures depict faces, animals, people, etc., which cannot be seen with the naked eye.

Slide 9. Dual image.

In the picture, one person can see a hare, another a duck. There is no secret, but still interesting.

Slide 10. The illusion of movement.

Look at still images and they will start to move. Look at the same moving balls and you will see that they are of different sizes. The same rotating image can rotate in different directions or even oscillate.

Slide 11. Changeling.

A shifter is a type of optical illusion in which the nature of the perceived object depends on the direction of the gaze. One of these illusions is the "duck hare": the image can be interpreted both as an image of a duck and as an image of a hare. The shifter is one of the most beautiful and fun optical illusions.

Slide 12. Stereo illusions.

The main and, perhaps, the only secret is the unique combination of dots and strokes that unexpectedly creates the illusion of a three-dimensional image. Stereo pairs superimposed on a periodic structure make it possible to observe a stereo image in the same way as a conventional stereo pair.

Slide 13. Irradiation.

The phenomenon of irradiation consists in the fact that light objects on a dark background seem to be larger than their real sizes and, as it were, capture part of the dark background. When we consider a light surface against a dark background, due to the imperfection of the lens, the boundaries of this surface seem to move apart, and this surface seems to us larger than its true geometric dimensions.

It is curious to note that, knowing about this property of black color to conceal dimensions, duelists in the 19th century preferred to shoot in black suits in the hope that the enemy would miss when shooting.

Slide 15. Ames' room.

A room designed by Adelbert Ames Jr. in 1946, is an example of a three-dimensional optical illusion. The room is designed in such a way that when viewed from the front it seems ordinary, with perpendicular walls and a ceiling. In fact, the shape of the room is a trapezoid, where the far wall is located at a very acute angle to one wall and, accordingly, at an obtuse angle to the other. The right corner is thus much closer to the observer than the left.

Slide 17. History of discovery.

The first study in the field of optical illusions was made by the physicist Oppel. Then there were more than 200 scientific works. Each scientist has been looking for his own theory on this subject for a long time, however, apparently, no one has guessed that these illusions are the rule rather than the exception.

Slide 18. Causes of illusions.

    Our eyes perceive the light coming from the object in such a way that erroneous information comes to the brain;

    If the transmission of information signals through the nerves is disrupted, failures occur, which again leads to erroneous perception;

    The brain does not always respond correctly to signals coming from the eyes.

Slide 19-21. Types of atmospheric mirages.

    Natural, or created by nature (for example, a mirage)

2. Artificial, or invented by man (for example, the “levitation” trick or, as the people say, “flying lady”).

3. Mixed, that is, natural illusions recreated by man (for example, well-known illusion pictures, a mirage model).

Slide 22. Mirage.

A mirage is an optical phenomenon in the atmosphere: the reflection of light by a boundary between layers of air of different density, due to which images of objects appear in the visibility zone, which under normal conditions are hidden from observation.

Slide 23. Types of mirages.

    "lake" mirages, also called inferior mirages;

    superior mirages;

    double and triple mirages;

    a more complex type of mirage is called "Fata Morgana".

Slide 24. Lake mirages.

The so-called "lake", or lower, mirages are the simplest. Inferior mirages arise over a strongly heated surface, in deserts and sultry steppes. When the surface of the earth is strongly heated by the Sun and is just beginning to cool before dusk.

Slide 25. Mirages of distant vision.

This type of mirage in its origin is not more complicated than "lake", but more diverse. They are called "mirages of distant vision."

The air is heated by the Earth's surface, and its temperature drops with height. Then there is a "raising of the horizon", or an upper mirage.

Slide 26. Double and triple mirages.

Let us assume that the refractive index of air decreases with height, first rapidly and then slowly. In this case, the light rays in the first region will be bent more than in the second. The result is two images.

Slide 27. Mirage Fata Morgana.

Constantly changing mirages, called Fata Morgana, they owe their appearance to air layers of different densities moving one above the other.

Slide 28. Blind spot.

Natural illusions appear due to peculiarities in the structure of our visual apparatus. On the surface of the retina, at the base of the optic nerve, there is an area devoid of light-sensitive cells. Rays coming into this zone are not perceived by us. We can "lose" elements of the picture around us if they coincide with the blind spot.

Slide 29. Disease Astegmatism

Astigmatism is a phenomenon caused by uneven bulge of the cornea of ​​the eye. The illusion provides a way to detect astigmatism in the eye. Bringing it closer to the examined eye (closing the other), at a fairly close distance, focus on the white square, you will notice in about half a minute that one band will disappear (due to retinal fatigue).

So, an illusion is an impression about a visible object or phenomenon that does not correspond to reality, i.e. optical illusion. Translated from Latin, the word "illusion" means "mistake, delusion." This suggests that illusions have long been interpreted as some kind of malfunction in the visual system. Illusions often accompany us through life, introducing into it a certain secret...