If you want to have fun without much time and other resources, then you need such a phenomenon as the illusion of perception: its manifestations in a person can boggle the imagination of even skeptical characters.
However, familiar laws are often transformed into something unusual. A person sees what, it would seem, he should not see.
However, one should not think that this is a consequence of some misunderstandings and possibly deviations or even diseases. Of course, this is possible, but still, you should not be immediately scared if you see some unusual things for yourself.
Quite often, this effect is due to the peculiarities of a particular image, to which the senses and the human brain react in a certain way. And although in this case the perception seems atypical, it should not be considered as some kind of deviation from the norm.
The same psychology and physiology explains such things quite well. And what is more, these are not mere assumptions, but sound scientific data and theories.
In scientific terms, one of the most famous phenomena was Mueller-Lyer illusion a. What is she like?
We see two horizontal lines. They are the same length when measured with a ruler or any other available measurement tool.
However, the human eye for some reason sees them as objects of different lengths. How does this happen?
The fact is that one of the lines is equipped with a bifurcated tip, while the other is not. And the first of them, the senses are presented to our brain as longer.
This variant of the Muller-Lyer phenomenon is possible, when the lines are considered as arrows. It is not for nothing that both lines have a tip, only they are multidirectional: in one case, this element is directed inward, and in the other - outward.
If we talk about the scientific explanation of this focus, then for these purposes the theory of displacement is used. It is also known as the theory of misalignment.
According to research, the main effect is believed to be due to the arrowhead with the diverging wedges. Because of it, the main line is lengthened.
The significance of the converging wedges, which, as one can logically assume, contribute to the shortening of the line drawn next to them, is considered by scientists to be not so significant.
Phenomenon in psychology
How does psychology explain this phenomenon? Let's start by defining what is meant by the concept of "illusion".
So, an illusion is nothing more than a false or distorted perception of familiar reality. On the one hand, it is not dangerous at all and only delights, especially among children.
However, on the other hand, everything is not as simple as it might seem at first glance. With an illusion, you perceive the world in a completely different way from what it really is.
What is it fraught with? First of all, false conclusions about the world around. Your senses tell you about the presence of something that is not really there.
However, if this is not a disease, then why are your senses deceiving yours? And is this a deception or is it something else?
To clarify this, let's find out that two main sciences are involved in the phenomenon of human perception: psychology and physiology. And each of them has its own explanation for the oddities taking place.
All the reasons due to which there are illusions can also be divided into physical and psychological.
Let's try to give a conditional classification of such phenomena. So, there are effects that differ in the sense organs, due to which they arise:
- visual;
- flavoring;
- auditory.
Probably, most often we meet with the so-called visual or optical illusions. Pictures with geometric shapes that imitate movement or distort the size and shape of familiar objects have become very popular on the Internet and on social networks.
In psychology, such a direction as Gestalt psychology is especially concerned with the problems of perception. Such a representative of psychological science as I. Rock recommends contacting her.
In Gestalt psychology, it is believed that it is a mistake to have an idea of the world as a kind of constant. Thus, any phenomenon can be questioned. In such a coordinate system, it is easy to accept the possibility that nothing is true, and the effects on pictures on the Internet only confirm such a theory.
Perception of space
Optical illusions relate to changes in the perception of space. How can this be manifested?
Distortion can relate to the following parameters:
- size;
- depths;
- length;
- curvature;
- directions.
The Necker cube and the Schroeder ladder are examples of the breakdown of habitual depth judgments.
Looking at the picture of the Schroeder ladder, we can see completely different things. Someone will really notice the stairs in the picture, while others will think that this is a niche in the wall. Such options are also possible when the viewer will not see anything in the drawing except a piece of paper folded like an accordion.
The Necker cube is an ordinary cube. However, it is painted in two colors: yellow and blue. At the same time, there is much more yellow in the figure. And blue is used to paint only one face.
The viewer's task is to determine if the blue face of the cube is in front of or behind the image. And either one or the other answer may be correct.
The phenomena of Ebbinghaus, Baldwin, Yastrov, Zander are known as distortions in judgments about the size of objects. As we can see, there are both foreign and domestic specialists among the scientists dealing with this issue.
It is interesting that humanity has been dealing with such problems for a long time. For example, the Yastrov phenomenon was discovered back in 1891, Ebbinghaus in 1902, and Zander's parallelogram in 1926.
And at present, this problem is being actively studied at the psychological faculty of Moscow State University. On the official website of this educational institution, you will find detailed descriptions of many of these artifacts.
Pareidolic illusions
There are various types of optical distortions of the senses. And here such a complex, at first glance, term is known as pareidolia. 
However, this term essentially does not hide anything complicated behind itself. In fact, it is just an illusory perception of a real object.
In this case, this does not in any way apply to the distortions in the work of the senses discussed above, which change the usual perception of the size and depth of objects created on special pictures invented by the human mind and made by hand.
Here we are talking about real objects that are present in the surrounding world. And in this the main difference between pareidolia from all the other phenomena discussed above.
Of course, the judgment of the whole object depends on the small details of which it is composed. And here the principle of operation of our senses and the brain, which processes the signals coming from them, is essentially the same as what happens when we look at drawings on the Internet.
And it should be borne in mind that we are talking here not only about natural objects. They can be considered as pareidolia and: the main thing is that they exist in the real world.
Distortions in photographs can also be considered pareidolias. For example, when it comes to space images, many people see signs of the presence of extraterrestrial civilizations there.
For example, we can talk about a fancy wallpaper pattern. If we talk about objects of living nature, then here we can mention unusual animals or even humans.
The phenomenon of pareidolia was discovered and described by those people who have a recognized value in official science. Their names are: Karl Jaspers and Karl Kalbaum.
The pioneer was Kalbaum, who described the phenomenon back in 1866. Jaspers worked on this issue a little later and presented the results of his activities only at the beginning of the next century, or rather in 1913.
What are illusions of perception?
Illusions of perception are not true versions of how we see, hear and feel the world around us. Although is it possible to speak with confidence about what reality really is, because we see it exactly to the extent that our vision allows us, we hear only those sounds that human ears are able to perceive. The aroma of flowers and the taste of food are individual for everyone. The properties of objects will differ depending on who is touching them. In fact, our idea of the external world is just a set of electro-biochemical signals coming from the senses through the nervous system to the brain. There they are processed by neurons and become what we call feelings, thoughts, sensations.
In such a science as psychology, the process of conscious perception of a previously known sensory impression is described, the result of which is clarity and distinctness in the understanding of individual elements. It is called apperception and is characterized by the transition from forced perception to cognition of reality. In other words, different people, seeing or feeling the same thing, can perceive it in completely different ways. Apperception is influenced by the way of thinking, goals, motives, the current activity of the subject, extreme experience, creativity, in addition, it is due to other personal characteristics. Thus, we can conclude that a child and an adult will perceive almost everything in a different way. This also explains the difference in the vision of the surrounding world between men and women. The perceived flow of information will be more equally understood by different individuals if their individual characteristics are similar to each other.
Optical illusions
Distortion of space perception occurs in various modalities, but most often illusions of visual perception occur. The conditioning factor for the first type of such illusions is certain physical conditions, the distortion of objects occurs when they are perceived, for example, through water or through a prism. Twilight often distorts perception. This is due to the fact that with a decrease in the level of illumination, vision is rebuilt from cone to rod, that is, it is more tuned to sensitive light, rather than color perception. At the moment of transition, vision is most vulnerable, this becomes the cause of the so-called car accidents due to inattention, most often recorded precisely at twilight.
Another factor that forms the second type of optical illusion is psychological. So the moon, which is low above the horizon, will seem much larger than when it is located high in the sky. A similar impression is created due to the filling of the space between the horizon and the observer, in contrast to the immense emptiness between the beholder and the moon at its zenith. You can make sure of equal size with a coin at your outstretched hand. Comparing with one eye, you will be convinced of the illusory nature of this phenomenon. It will also disappear if you look at the moon without surrounding objects by means of a sheet of paper rolled into a tube.
Types of visual illusions
Illusions of visual perception surround us everywhere and every day in everyday life. All objects that move away to the horizon will decrease on the retina of the eye by their linear dimensions. Telegraph poles located far away of the same height are smaller than those that are close by. The parallel rails of the railroad converge visually in the distance. The list can be continued endlessly. At the moment in psychology there is no single classification of illusions of perception. The existing division is conditional.
Illusions of false perception of physical parameters
Illusions in which any element changes its parameters, but the distortion can be easily eliminated using measuring instruments:
- The illusion of size perception. They are connected with the fact that the same lengths in the horizontal and vertical position or in the presence of additional elements seem to be different. Examples are the Müller-Lyer illusion with horizontal lines or Ebbinghaus circles, one of which is among the smaller circles, the second among the larger circles. Because of this, they appear to be different in diameter, but in reality they are not. There is a space designed by Adelbert Ames in 1946 and is trapezoidal in shape. One wall is located at an acute angle in the farthest part of the room from the observer, forming an obtuse angle near. The room seems ordinary due to the initially distorted checkerboard cells that decorate its space and visually make the walls with the ceiling perpendicular. The presence of identical objects in an acute and obtuse corner of the room creates a deception that the near object is many times larger than the distant one.
- Visual illusions with distortion or distortion effect. The most famous example is the so-called "Cafe Wall illusion", first spotted by James Fraser in 1908 on the walls of a Bristol cafe. Blocks of contrasting color are displaced relative to each other, which gives the impression of narrowing and widening of parallel lines, which, as you know, never intersect. This effect has been applied to the facade of the huge Digital Harbor Port building in Melbourne.
- Illusion of color perception. Different backgrounds and contrasts affect perception, distorting the correctness of the color. There is a well-known picture in which a cylinder, located on a chessboard, casts a shadow. When compared, it seems that a cell in the shade is lighter than another in the light. This is actually because the brain automatically tries to compensate for the shadow by detecting the original color. Another sensational photograph depicts a dress, for some people one blue and black, for others - white and gold. Serious disputes unfolded on the network about where the truth is. They ended when a store selling the dress confirmed that it was made from dark fabrics. Although for some it still looks white and gold. Another experiment consists in setting up lighting in a special way, at a distance of about 20 cm. An object placed vertically between the lamps will show its shadow on a white screen. After that, special light filters of different bright shades are put on the lamps, they will also be reflected on the screen, but removing one color filter, the observer will still see its color on the screen.
- Illusions of depth perception. Surfaces can be convex and concave at the same time, depending on the focus of the gaze, the properties of objects change. There are whole presentations of such illusions of perception, squares and streets of large cities around the world are decorated with similar 3d-drawings, in which errors in the perception of depth play a key role.
Figurative illusions
Often they combine various images, which can be discerned with certain parameters. The following groups can be distinguished:
- Upside-down pictures. The image depends on how you position it in space. Most often it is necessary to turn the drawing upside down to see something completely different, sometimes a 90º rotation is enough. Examples: the image of a French soldier, after turning over, turns into a horse, a huge crow - into a floating fisherman. This effect is often played up humorously with the help of funny inscriptions, while in the drawings a student transforms into a teacher, a young girl into an old woman, and sometimes even a man.
- False motion effect. Most often it is represented by drawings with circles that move like a clockwork. Perceptual properties in some patterns convey the sensation of pulsation, shaking, or a wave running through the image. You can feel that you are moving inside the picture, as if along a corridor, but it is worth concentrating your attention in the center of the image, and the static returns again.
- Illusions of seeming, non-existent figures. The arrangement of the lines is made in such a way that the brain itself draws on non-existent elements. At first glance, the drawing can be seen as the most ordinary, but detailed examination creates two contradictory perceptions, in which it is almost impossible to grasp the sign that allows you to determine where the background is, and where is the figure itself. The famous elephant with an incomprehensible number of legs or the player who disappears after changing the upper halves of the images of the football team is perplexing to many people.
- Watching gaze. From any angle of view, it will seem that the person from the image is looking directly into the eyes. Artists often had to use this effect when creating inviting and motivating posters in Soviet times.
Observer Dependent Illusions
Individual characteristics play a key role in some cases. While one person sees an illusion, the other may not understand at all what is at stake. Or two subjects looking at an object can see completely different things. The following groups are usually denoted:
- Dual images. Depending on the thought process and concentration, you can see this or that image. A very popular example is the Jastrow illusion, which depicts a hare and a duck at the same time.
- Illusions of the relationship between figure and background, in which the background itself can also act as an object. The most famous examples are the various incarnations of the Rubin vase. And just in one black and white portrait of Abraham Lincoln, you can see many objects at once: a wolf, a horse, a snail, a mouse, a bird, a praying man, a clown and a fish.
- Stereo pictures. For many, they remain inaccessible for perception, someone begins to see them after long training and endless attempts, and there are those for whom such visualizations are very easy. They are different in levels, the simplest are stereo pairs. There are also SIRDS images from single image random dot stereograms, striking in their scale and fantasy. They are created using special computer programs. Viewing such images is useful for both training the eye muscles and developing the imagination.
- Pareidolia, characterized by the formation of an illusory image from separate elements of the real. Every person at least once in his life looked at the clouds and guessed in them the images of bizarre animals. Pareidolia can be seen on wallpaper, carpet, table, and can be formed from cracks in the ceiling or stains on fabric. The photograph of the fire in the building of the World Trade Center in 2001 became widely known. On it, many journalists and newspaper readers saw the face of the devil, although the photographer captured the clouds of smoke.
- Illusions of image recognition are manifested in a situation when a person, looking at an image, sees only one general picture, but if he is prompted what to look for, then the imagination immediately begins to work differently. After seeing the landscape, you can enjoy the rivers, forests and animals, but when you learn that the branches of the trees form faces, you will surely find them too. Practice shows that dual images also work: the beholder only sees the duck, but as soon as he is prompted about the simultaneous image of a hare, the picture immediately becomes fuller.
- Rotation illusion. While one part of the people sees the rotation of the object to the right, the other observes the same effect, but in the opposite direction. Units see both directions at once and can even consciously change it in the other direction. The silhouette of a girl spinning in different ways for a long time haunted the Internet space.
Many optical illusions are difficult to classify, since they belong to several groups at once: depth with the effect of inward movement or color changes simultaneously with size. Perhaps when we can study them better, there will be a clear division based on an explanation of why this or that distortion occurs.
Optical effects
The illusions of perception are not conditioned by the perceiver's temperament, character, or age. There are also little-studied effects of scientists. One of these is irradiation. This is a phenomenon in which three-dimensional objects or flat figures against a contrasting background are seen by a person in a different size. Otherwise, they simply say that this is an optical illusion. So, for example, a black square on a white background will appear smaller than a white square on black, although if you calculate their area using measuring instruments, then equality in size will become obvious. Irradiation has been proven only practically on numerous concrete experiments, but the level of modern medical devices and methods of study do not allow it to be explained from the physiological point of view.
The illusions of perception depend on such components as the structural features of the eye, the specifics of the process of encoding and decoding information, but why the effect on the brain occurs in one way or another is still a mystery. When one object is imprinted on the retina and its properties are transferred to another, an optical aftereffect occurs. After looking at McKay's illusion, an aftereffect occurs, described by the subjects as the movement of rice grains. Concentration of attention on black and white pictures when transferring your gaze to a pure white space (wall, ceiling, sheet of paper) helps to form easily recognizable images of the one who was depicted, like a negative.
There is a perceptual readiness effect. Most people are able to read texts fluently without hesitation, even if the order of letters is changed in all words, except for the first and last. This is because it is difficult for the brain to see what it does not expect. It is important to note, though, that this effect works to a lesser extent for children. When a child is just learning to read, he pays attention to each letter separately, over time the brain memorizes whole words, and while reading, an adult person recognizes them as a whole image, quickly glancing from the first to the last letter. Almost everyone finds it difficult to name the font color of a word that denotes any shade if the meaning does not match. By regularly performing this exercise, you can train your thinking well, although soon the task will become very easy, because the brain very quickly adapts to certain tasks.
Other illusions of perception
On the one hand, errors in visual perception are characteristic of most people, which means that the mechanism of perception works the same for everyone, moreover, it is equally erroneous. On the other hand, the degree of error is different for everyone, this indicates the subjectivity and relativity of visual sensations. Optical illusion is associated with the special properties of various analyzers (retina, nerve reflexes), but nevertheless, the main reason for the appearance of illusions lies not in the optical imperfection of the eye, but in the brain's false rethinking of the information received. It is worth taking the simplest comparative measurements, and optical illusion becomes obvious.
The brain is wrong not only visually. Sitting in a stopped train, it is difficult to immediately understand which of the trains began to move: the one in which the observer himself sits, or the neighboring one. The brain needs additional data in the form of surrounding objects on the ground. After a long voyage on a ship, people are shaking for a long time on a solid surface, as if they were in a roll. An object of less volume with equal weight with another will be perceived by the brain as heavier. After salty, the sour taste intensifies, and after sweet, salty.
Even the ranges of perception of reality that are sensitive for a person transmit information to the brain in a form in which it cannot always understand it correctly. What can we say about data that lie outside of our physical abilities for perception. Everything that we know about the world around us as a fact is only what nature, creating man, allowed him to know. Objective reality is only in our head, but in order to comprehend it, we still have to study a lot in the complex process of the work of the most unique mechanism - the human brain.
In the perception of the size of an object, the size of its image on the retina plays an essential role. The larger the image of an object on the retina, the larger the object seems to us. It is likely that the magnitude of the image of the perceived object on the retina of the eye depends on the magnitude of the visual angle. The larger the visual angle, the larger the image on the retina. It is believed that the law of the visual angle as the law of perception of size was discovered by Euclid. It follows from this law that the perceived size of an object changes in direct proportion to the size of its retinal image. It is quite logical that this pattern persists at the same distance from objects. For example, if a long pole is twice as far from us as a pole, which is two times shorter than a pole, then the angle of view from which we see these objects is the same and their images on the retina are equal to each other. In this case, one could assume that we will perceive the stick and the pole as objects of equal size. However, in practice this does not happen. We can clearly see that the pole is much longer than the stick. The perception of the size of an object is preserved even if we move further and further from the object, although the image of the object on the retina of the eye will decrease. This phenomenon is called the constancy of perception of the size of an object.
The perception of the size of an object is determined not only by the size of the image of the object on the retina, but also by the perception of the distance at which we are from the object. This pattern can be expressed as follows:
Perceived size = Angle x Distance.
Accounting for the removal of objects is mainly carried out due to our experience of perceiving objects with a changing distance to them. Knowledge of the approximate size of objects serves as an essential support for the perception of the size of objects. As soon as we recognize an object, we immediately perceive its magnitude as it really is. In general, it should be noted that the constancy of the value increases significantly when we see familiar objects.
The environment in which the object perceived by us is located has a noticeable effect on its perception. For example, a person of average height, surrounded by tall people, seems much smaller than his real height. Another example is the perception of geometric shapes. A circle among large circles appears to be much smaller than a circle of the same diameter found among circles of much smaller size. Such a distortion of perception caused by the conditions of perception is usually called an illusion. The perception of the size of an object can be influenced by the whole in which the object is located. So, for example, two perfectly equal diagonals of two parallelepipeds are perceived to be different in length if one of them is in the smaller one, and the other is in the larger parallelepiped. Here there is an illusion caused by the transfer of the property of the whole to its separate parts. Other factors also affect the perception of an object in space. For example, the tops of a shape appear larger than the bottom, just as vertical lines appear longer than horizontal ones. In addition, the perception of the size of an object is influenced by the color of the object. Light objects appear somewhat larger than dark objects. Volumetric shapes, such as a ball or cylinder, appear smaller than the corresponding planar images.
Course work
Work performed by: S.I. Karpov
Military Medical Academy named after S.M. Kirov
Saint Petersburg, 2007
Introduction
Man is an open biological system that actively interacts with the environment. Any open system is characterized by three flows of exchange with the environment: the exchange of energy, the exchange of substances, and, finally, the exchange of information. For the latter, sensory systems - analyzers are fundamental. They provide perception, analysis, transformation of information coming from the surrounding and internal environments in the form of energies of various modalities. For humans, the main source of sensory information (up to 90%) is the perception of electromagnetic radiation in the range from 400 to 700 nm, based on the functioning of the visual system, a complex multilevel structure. The latter consists of a peripheral section (eyes), a pathway and a central link. The physiology of this system has not yet been studied in many respects, since in addition to the transmission of impulses, they are transformed and corrected, compared with images stored in a person's memory, analyzed and converted into an image. Such an organization of perceptual processes and certain features of constancy that we establish in the world during our life, provide us with a consistent and plastic perception of the environment. However, there are cases when perception is distorted - when, for example, conflicting signals come from the objects themselves, or when we incorrectly perceive / interpret monocular signals received from objects. In the first case, we are talking mainly about ambiguous images that can cause two conflicting perceptions. In the second case, we meet with some signs of perspective, depth, shape or size, which, in contradiction with each other, give rise to visual illusions. At the same time, it is important to emphasize that optical illusions are not based on any special properties of an object, but on its incorrect, subjective recognition by our senses. It is also important to distinguish illusions from hallucinations, since the latter are dysfunctions of our brain - images of non-existent objects, and illusions are distorted images of reality that arise in the process of visual perception.
From the above, we can conclude that visual perception, despite all its versatility, does not fully and objectively give an idea of the world around us.
The study of visual illusions is important both in theoretical (clarification of the physiology of sensory mechanisms, scientific foundations for the design of technical analogs of the visual system) and in practical terms (for example, the creation of measures to eliminate parallax distortions when registering fast processes, various errors in studying the movement of an object that scatters light in different ways). in various directions, etc.). Taking into account the laws of illusory perception is necessary for various kinds of direct observations and assessments, as well as in the practice of architecture and the external design of products, art.
3. Visual Illusions Definition of Illusion
(Latin illusio, from illudo - I deceive, mock, play), an inadequate idea of the perceived object, which goes beyond the boundaries of ordinary errors of perception. I. are primarily an unconscious phenomenon that does not lend itself to arbitrary correction.
Classification
In principle, there is no universal classification of illusions, since the mechanisms and reasons for their appearance are quite diverse and largely unexplored. However, conventionally optical illusions can be divided according to the following criteria:
By the nature of occurrence:
Physical nature.
These are illusions arising from errors of perception associated with deceptive manifestations of the properties of objects or actions, associated mainly with optical phenomena (for example, a “broken” spoon in a glass of tea).
Physiological nature
a) distortion by the optical system of the eye
The same illusions of physical nature, but within the eyeball.
b) distortions of the sensory and conductive systems of the eye
These are illusions arising from comparison and comparison errors caused by the physiological characteristics of normally functioning sensory systems.
Psychological nature
In psychiatric practice, there are:
Affective illusions - arise under the influence of affect - fear, anxiety, depression.
Verbal illusions - contain separate words or phrases.
Organic illusions - dysmorphopsias, metamorphopsias.
Peak Illusions - Enter Pica Syndrome
Illusions of awareness - a patient's feeling, indicating that someone is supposedly nearby. According to the author, these illusions are a sign of the formation of hallucinations and delusions.
Installation illusions [Uznadze DN, 1930] are a form of physiological illusions. One of the types of illusion of perception of mass, volume, size. It arises from multiple comparisons of pairs of objects, while in the preliminary series of experiments, the prerequisites for the emergence of an illusion are created, revealed in the main (control) series of experiments. For example, if several times to raise simultaneously with both hands a pair of objects of different mass, and then another pair of the same mass, then the object in the hand, in which it was lighter before, will seem heavier than in the other hand (contrasting illusion) ... The mechanisms of illusion are explained from the standpoint of the theory of installation by D.N. Uznadze by the formation of a person's internal unconscious states (attitudes), which prepare him for the perception of further events and are a factor guiding conscious activity. illusion. are used as one of the methodological techniques for the study of the installation.
Functional illusions - pareidolia.
Epileptic illusions are disturbances of perception, which are significant, sometimes the only clinical manifestations of some focal epileptic seizures that occur when an epileptogenic focus is localized in the temporal lobe cortex adjacent to the sensory region. Distinguish between epileptic perceptual illusions, when the observed object is perceived distorted and not recognized, and apperceptive, in which the object is recognized, but perversely compared with previous experience (the phenomena of "already seen", "already heard", "already experienced" or, conversely, "never not seen "," never heard "," never experienced "). This group includes the illusion of epileptic incoherence, unreality observed in epileptic sleep-like states.
Generally:
Visual distortion
Dual images
Size perception illusions
Shape to background ratio
Illusions of color and contrast
Apparent figures
Stereo illusions
Aftereffect
Depth perception illusions
Illusions of movement
Impossible figures
The perceptual readiness effect
Inverted pictures
Pattern recognition
Pareidolic illusions
Illusions of the face (tracking pictures, intertwined portraits)
Drawings that cause discomfort
The Physiology of Distortion Illusions
Visual distortion
We see some simple drawings distorted. These distortions can be quite large. Part of the picture may appear 20% longer or shorter; a straight line can be so curved that it is difficult to believe that it is really straight. In essence, we all see these distortions, and in the same direction in each such drawing. It was found that the same phenomenon is observed in animals. This has been shown in experiments in which animals were trained to choose, say, the longer of two lines. Then, under the influence of the illusion, the animals will choose a line that seems longer to us, although in fact it is the same length as the line being compared to it. This result was obtained in pigeons and fish. All of this suggests that there is some common factor underlying these illusions.
Many theories have been put forward to explain this phenomenon, but most of them can be easily refuted experimentally or rejected as poorly thought out and therefore useless. First of all, we will briefly dwell on various theories that can be safely discarded, after which we will try to present more adequate theories. But first, we need to experience some illusion. Figures 9.4-9.6 illustrate many of the more well-known illusions. They bear the names of the researchers who discovered them, mainly psychologists who worked in Germany in the last century, but it would be more convenient to give descriptive names to some of them. The most famous of these drawings are the Müller-Lyer arrows shown in Fig. 9.4. It is just a pair of arrows, the shafts of which are the same length, but one arrow has diverging points, and the other with points converging towards the shaft. The diverging arrow appears to be longer, although in fact both arrows are the same length.
The second example is also well known, and experts call it the Poizo figure. It consists of only four lines: two of the same length, running side by side, but converging, and between them two others, equal in length and parallel (see Fig. 9.5). One of the lines, located in a narrow part of the space enclosed between two converging lines, appears to be longer, although in fact both parallel lines are the same length.
Rice. 9.6 shows two variants of Goering's drawing.
Finally, we have drawings in which a square and a circle are curved against a background of circular or intersecting lines (Fig. 9.7).
Illusions can be divided into two groups: some are distortions caused by a certain kind of background (for example, the illusion of a fan), others are distortions of the figure itself (for example, the illusion of an arrow), without a background. These independent distortions are most clearly shown in Fig. 9.8, which shows arrowheads without shafts: the arrowheads move on their own, although there are no other lines in the drawing. On the other hand, with the fan illusion, the diverging rays are perceived by themselves without distortion, however, any figure superimposed on them is distorted in a certain way. These drawings cause distortion, but are not distorted themselves.
Over the past hundred years, psychologists have tried to explain these illusions, but only now are we coming to understand why such drawings disrupt the functioning of the visual system.
Rice. 9.5. The Ponzo illusion, or the railway track illusion Fig. 9.5. The Mueller-Lyer illusion, or the arrow illusion
Rice. 9.6. Hering's drawing, or fan illusion Fig. 9.7. Background effect causing shape distortion
Rice. 9,8- Müller-Layer arrowheads without shafts.
Illusions often lead to completely incorrect quantitative estimates of real geometric quantities. It turns out that you can be mistaken by 25% or more if the eye estimates are not checked with a ruler.
Eye-measurement estimates of geometric real values very strongly depend on the nature of the background of the image. This applies to lengths (Ponzo illusion), areas, radii of curvature. It can also be shown that what has been said is also true for angles, shapes, and so on.
Ponzo illusion- an optical illusion, first demonstrated by the Italian psychologist Mario Ponzo (1882-1960) in 1913. He suggested that the human brain determines the size of an object from its background. 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 the converging lines as perspective (as two parallel lines converging at a distance). Therefore, we think that the top segment is located further, and assume that its size is larger. In addition to converging lines, the effect is enhanced by the decreasing distance between the intermediate horizontal lines.
Some researchers [ who?] believe that the lunar illusion is an example of the Ponzo illusion, in which trees, houses and other landscape details act as converging lines. Foreground objects make our brains think the moon is bigger than it really is.
This type of visual illusion also occurs when using a sensory substitution device. However, for its perception, it is necessary to have such a visual experience, since people with congenital blindness are not sensitive to it.
A shape-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.
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Based on the modern literature on psychology, several approaches to the classification of perception can be distinguished. One of the classifications of perception, as well as sensations, is based on differences in analyzers. In accordance with which analyzer (or which modality) plays a predominant role in perception, visual, auditory, tactile (tactile), kinesthetic (perception of movement), olfactory and gustatory perception are distinguished.
Different types of perception are rarely found in their pure form. They usually combine to create complex perceptions. So, the student's perception of the text in the lesson includes visual, auditory and kinesthetic perception.
The basis of another classifier of types of perception is the forms of existence of matter: space, time and motion. In accordance with this classification, the perception of space, the perception of time, and the perception of movement are distinguished.
The perception of a person by a person is highlighted separately. Let us give in detail the mechanisms of perception according to the second of the above classifiers.
Perception of the size and shape of objects
In the perception of the size and shape of objects, their image on the retina is of great importance. However, observations of the activity of people born blind, who recovered their sight after a successful operation, indicate that correct perception depends not only on vision. People who have cleared up do not immediately learn to determine the size and shape of an object only with the help of visual perception. At first, they find it difficult to distinguish a ball from a circle, a quadrangular object from a triangle, and cannot determine the distance to an object. Only after a certain practice in a complex combination of vision, feeling of objects and motor reactions, those who have received their sight acquire a free orientation in space.
The peculiarity of the structure of the human eye is such that the image of a distant object will be smaller than the image of an equal object located close.
It is likely that the magnitude of the image on the retina depends on the magnitude of the visual angle. It is believed that the law of the visual angle as the law of perception of size was discovered by Euclid. It follows from this law that the perceived size of an object changes in direct proportion to the size of its retinal image.
It is quite logical that this pattern persists at the same distance from objects. For example, if a long pole is twice as far from us as a pole, which is two times shorter than a pole, then the angle of view from which we see these objects is the same and their images on the retina are equal to each other. However, in practice this does not happen. We clearly see that the pole is still longer than the stick. The perception of the size of the object is preserved if you move further and further. This phenomenon is called the constancy of visual perception. We wrote about it above.
The perception of the size of an object is determined not only by the size of the image of the object on the retina, but also by the perception of the distance at which we are removed from the object. This pattern can be expressed as follows:
Perceived size = Sight angle x distance.
Accounting for the removal of objects is mainly carried out due to our experience of perceiving an object with a changing distance to them. Knowledge of the approximate size of objects is an essential support for the perception of size. As soon as we recognize an object, we immediately perceive its magnitude as it really is. It should be noted that the constancy of the value increases significantly if we recognize familiar objects, and decreases significantly in the case of abstract geometric figures. Another feature of the perception of an object in space is the contrast of objects. The environment in which the object perceived by us is located has a noticeable effect on its perception. A man among tall people is much smaller than his real height. This distortion of space is called an illusion.
The perception of the size of an object can also be influenced by the environment in which the object is located. So, for example, two perfectly equal diagonals of a parallelogram seem to be different in length if one is in a small parallelogram and the other in a large parallelogram. Here the transfer of the properties of the whole to its separate parts takes place. Other factors, such as color, also affect the perception of objects in space. Light objects appear somewhat larger than dark objects. Therefore, it seems that white clothes make you look fat. Volumetric shapes (ball, cylinder) seem to be smaller than their flat projections.
If an object is too far from us, then its perception of form may change. So, the small details of the contour disappear as the object is removed, and its shape takes on a more simplified form. Rectangular objects appear rounded from a distance. This is because we see the distance between the sides of the rectangle near its vertices at such a small angle that we stop perceiving it, and the vertices seem to be drawn inward, that is, the corners are rounded.
According to the laws of optics, our eye gives an inverted image, and the brain has nothing to do but correct it. Therefore, we perceive objects as they are. The same image correction occurs when the angle of view is changed. For example, we always see a cube as a cube, no matter from what angle we looked at it.
The perception of the size and shape of objects is carried out, therefore, with a complex combination of visual, tactile and muscular-motor sensations.
