Perception of the size of an object. Perception of size (size) Types of visual illusions

Illusions often lead to completely incorrect quantitative estimates of real geometric quantities. It turns out that one can be wrong by 25% or more if the eye estimates are not checked with a ruler.

Eye estimates of geometric real quantities depend very strongly 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 true of angles, shapes, and so on.

Illusion Ponzo is 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 railroad track receding into the distance. The top segment appears larger because the brain interprets converging lines as perspective (as two parallel lines converging at a distance). Therefore, we think that the upper segment is located further, and we believe that its size is larger. In addition to converging lines, the decreasing distance between intermediate horizontal segments adds strength to the effect.

Some researchers [ Who?] believe that the moon illusion is an example of the Ponzo illusion, in which trees, houses, and other landscape features play the role of converging lines. Foreground objects make our brain think the Moon is bigger than it really is.

This type of visual illusion also occurs when using a sensory substitution device. However, to perceive it, it is necessary to have such a visual experience, since people with congenital blindness are not sensitive to it.

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.

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Based on modern literature on psychology, there are several approaches to the classification of perception. 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 the predominant role in perception, there are visual, auditory, tactile (tactile), kinesthetic (motion perception), olfactory and gustatory perception.

Different types of perception are rarely found in their pure form. Usually they are combined, and as a result, complex types of perception arise. Thus, 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, space perception, time perception, and motion perception are distinguished.

Separately stands out the perception of man by man. 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

When perceiving the size and shape of objects, their image on the retina is of great importance. However, observations of the activities of blind-born people who regained their sight after a successful operation show that correct perception depends not only on vision. People who have seen the light 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, they cannot determine the distance to the object. Only after a certain practice in a complex combination of vision, palpation of objects and motor reactions, those who have seen the light 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 object equal to it, which is close.

It is likely that the size of the image on the retina depends on the size of the visual angle. It is generally accepted 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 is preserved at the same distance from us objects. For example, if a long pole is twice as far from us as a stick, which is half as long as 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, this does not happen in practice. 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 farther and farther away. This phenomenon is called 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 rule can be expressed as follows:

Perceived size = visual 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. An essential support for the perception of size is the knowledge of the approximate size of objects. 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 significantly decreases 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 we perceive is located has a noticeable effect on its perception. A man among tall people is much smaller than his real height. Such a distortion of space is called an illusion.

The environment in which the object is located can also influence the perception of the size of an object. So, for example, two completely equal diagonals of a parallelogram seem to be different in length if one is in a small and the other is in a large parallelogram. Here there is a transfer of the properties of the whole to its individual parts. Other factors, such as color, also affect the perception of objects in space. Light objects appear somewhat larger than dark ones. Therefore, it seems that white clothes make you fat. Volumetric forms (ball, cylinder) seem smaller than their flat projections.

If an object is too far away from us, then its perception of shape may change. So, the small details of the contour disappear as the object is removed, and its shape takes on a more simplified look. Rectangular objects from a distance appear rounded. This is explained by the fact that 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 no choice but to correct it. Therefore, we perceive objects as they are. The same image adjustment occurs when changing the angle of view. For example, we always see a cube as a cube, regardless of the angle from which 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 musculoskeletal sensations.

1. Introduction

2. General characteristics of perception

3. General characteristics of visual illusions

4. size illusions

5. Illusions of distortion

6. Illusions arising from changing terrain and depending on perspective

7. Illusions arising from the background on which the figure

8. Portrait illusions

9. Illusions when an object moves

10. Illusions and the influence of knowledge about the object on perception

11. Illusions and the influence of previous experience on perception

12. Other types of illusions

13. Bibliography

Introduction:

The theme of my work is the illusion of perception. According to the definition of the "Psychological Dictionary", illusions of perception (from Latin illusere - to deceive) of particular signs of certain objects.

The most numerous group of perceptual illusions are spatial visual illusions.

There is no unity on the classification of illusions in the psychological literature.

In my work, I have classified illusions as follows:

1. Visual illusions:

a) size illusions;

b) distortion illusions

c) illusions arising from changing terrain and depending on perspective

d) illusions arising from the background on which the figure is located

e) portrait illusions

f) illusions when an object moves

g) color perception illusions

2. Other illusions:

a) auditory illusions;

c) other illusions

General characteristics of perception:

Perception - a very complex, but at the same time, a single process aimed at understanding what is currently affecting us. This is a reflection of objects and phenomena in the totality of their properties and parts. It includes the past experience of a person in the form of ideas and knowledge. Everything that a person perceives, invariably appears before him in the form of integral images.

Suppose we observe a child playing. It occupies a certain place in space, is located at a certain distance from us and in a certain direction; we see it either moving or stationary, we know that we can touch it, unlike, for example, the sky. He wears clothes of certain colors. If it collides with a small object, we get the impression that the child is causing it to move. All this is perceived by us with the help of vision. But we also hear his laughter, and this sound has a certain pitch, volume and timbre and comes from a certain part of the space. We perceive it in the totality of properties, and from our past experience we know that before us is a child.

The process of perception proceeds in connection with other psychological processes of the individual: thinking (we are aware of what is in front of us), speech (we can realize that we have in front of us only when we can call the perceived image: a child), feelings (we relate in a certain way to what we perceive), will (we arbitrarily organize the process of perception in one form or another).

Perception may not be entirely adequate; for various reasons, the object may be perceived distorted or ambivalent.

General characteristics of visual illusions:

Distortions of the visual image are otherwise called visual illusions. This is an incorrect or distorted perception of the size, shape and distance of objects. The nature of illusions is determined not only by subjective reasons, such as attitude, orientation, emotional attitude, etc., but also by physical factors and phenomena: illumination, position in space, etc.

The fact that the vast majority of people sometimes receive the same erroneous visual impressions speaks of the sufficient objectivity of our vision. The vast majority of illusions of vision arise not because of the optical imperfection of the eye, but because of a false judgment about the visible, so we can assume that deception here arises when comprehending the visual image. Such illusions disappear when certain factors that interfere with correct perception are excluded.

Sometimes illusions of vision appear due to special conditions of observation, for example: observation with one eye, observation with fixed axes of the eyes, observation through a slit, etc. Such illusions disappear when the unusual conditions of observation are eliminated.

Finally, a number of illusions are known that are also caused by the optical imperfection of the eye, by certain special properties of various analyzers involved in the visual process (retina, nerve reflexes).

Close your left eye and look at the figure on the left with your right eye, holding the drawing at a distance of 15-20 cm. At a certain position of the drawing relative to the eye, the image of the right figure ceases to be visible.

In 1668, the famous French physicist E. Mariotte discovered the phenomenon of the "blind spot". In the place where the optic nerve enters the eye, the retina of the eye does not have light-sensitive endings of nerve fibers. Therefore, images of objects that fall on this place of the retina are not transmitted to the brain and, therefore, are not perceived. A blind spot, it would seem, should prevent us from seeing the whole object, but under normal conditions we do not notice this. First, 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 missing parts of the object are involuntarily replaced by images of neighboring parts or the background surrounding this object.

Illusions of size perception:

In the figure, a white square on black appears larger than a black square on a white background. In fact, the figures are the same. This illusion is explained by the phenomenon irradiation (in Latin - incorrect radiation): light objects on a dark background seem larger than their real sizes and, as it were, capture part of the dark background. This is due to the imperfection of the lens. Knowing about this property of black color to hide the size, duelists in the 19th century preferred to shoot in black suits in the hope that the enemy would miss when shooting.

We perceive objects as a whole, together with other objects surrounding them, the background or setting. And this explains the largest number of visual illusions encountered in practice.

Often illusions are explained by the fact that we mistakenly transfer the properties of a figure to its parts.

The segments in the figure are equal, although the upper one seems to be larger (Muller-Lyer illusion).

Another example of this kind of illusion is Sander's parallelogram (1926).

In fact, segments AB and BC are equal.

Visual illusions can arise as a result of the so-called general psychological law of contrast, that is, due to the relationship of figures with other figures.

In the figure, the circle closest to the sides of the acute angle appears larger than the other, while their dimensions are the same.

In the figure, the inner circle on the left appears larger than the right inner circle.

Another example of contextual illusion: the man next to the giant appears to be smaller than the figure in the background, although it is the same figure placed on the drawing without changing the size.

The reason for some illusions of size perception lies in the insufficient ability of the visual apparatus to distinguish a part from the whole - in view of the complexity of the situation. For example, in a mess of lines of the same color, brightness and thickness, it is not immediately possible to single out (recognize) any particular figure.

A special type of illusion of size perception is the overestimation of vertical lines compared to horizontal ones, which is common to most people.

If you ask a number of people to draw vertical and horizontal lines of the same length, then in most cases the drawn vertical lines will be shorter than the horizontal ones.

Here are two examples of vertical line overvaluation illusions:

The vertical line is perceived as longer.
If you look at the picture with one eye, then the effect is somewhat reduced.

Look at the numbers "3" and "8". It seems to you that the top half of each number is equal to the bottom.

Let's flip those numbers.

The difference in size between the top and bottom halves becomes apparent.

In addition, vertical parallel lines, with their considerable length, usually appear slightly divergent in the upper part, while horizontal ones converge.

The group of illusions under consideration also includes illusions of filled space. The filled space, over which the eye slides horizontally, lengthens. Thus, for example, on the sea, all distances seem smaller, since the boundless expanse of the sea is an undivided space. Buildings decorated with figures and ornaments seem to us larger than their actual size.

Even in antiquity, people were confused by the fact that the moon and sun appear larger on the horizon than when they are high in the sky. This optical illusion is called moon illusion . The effect is that the presence of the earth gives the impression that the moon at the horizon is further away than the moon at its zenith, since the filled space between the observer and the horizon gives the impression of a greater extent than the unoccupied space between the observer and the sky above. Therefore, it seems to us that the moon on the horizon looks larger than the rising moon.

In the perception of the size of an object, the size of its image on the retina plays an important role. The larger the image of an object on the retina, the larger the object appears to us. It is likely that the magnitude of the image of a perceived object on the retina depends on the magnitude of the visual angle. The larger the visual angle, the larger the image on the retina. It is generally accepted 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 is preserved at the same distance from us objects. For example, if a long pole is twice as far from us as a stick, which is half as long as 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 might assume that we would perceive a stick and a pole as objects of equal size. However, this does not happen in practice. We clearly see that the pole is much longer than the stick. The perception of the size of the object is preserved even if we move farther and farther away from the object, although the image of the object on the retina will decrease in this case. This phenomenon is called the constancy of perception of the size of the 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 rule can be expressed as follows:

Perceived size = visual 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. An essential support for the perception of the size of objects is the knowledge of the approximate 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 magnitude increases significantly when we see familiar objects.

The environment in which the object we perceive 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 larger circles appears much smaller than a circle of the same diameter among much smaller circles. Such a distortion of perception, caused by the conditions of perception, is commonly called an illusion. The perception of the size of an object can also be influenced by the whole in which the object is located. So, for example, two completely equal diagonals of two parallelepipeds are perceived as different in length if one of them is in a smaller and the other in a larger parallelepiped. Here there is an illusion caused by the transfer of the property of the whole to its separate parts. Other factors also influence the perception of an object in space. For example, the tops of a figure appear larger than the bottoms, 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 ones. Volumetric forms, such as a sphere or a cylinder, appear smaller than the corresponding flat images.

Course work

The work was completed by: Karpov S.I.

Military Medical Academy named after S.M. Kirov

St. Petersburg, 2007

Introduction

Man is an open biological system actively interacting 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 environment and internal environment 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 multi-level structure. The latter consists of a peripheral section (eyes), pathways 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 the human memory, analyzed and converted into an image. Such an organization of perceptual processes and certain features of constancy, which we establish in the world during our life, provide us with a consistent and plastic perception of the environment. However, there are cases when the perception is distorted - when, for example, conflicting signals come from the objects themselves, or when we incorrectly perceive / interpret the monocular signals received from the 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, form or size, which, coming into conflict 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 the 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 foregoing, we can conclude that visual perception, despite all its universality, does not sufficiently 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 designing technical analogues of the visual system) and practical (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 differently 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, and 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 perception errors. I. are predominantly an unconscious phenomenon that is not amenable to arbitrary correction.

Classification

In principle, there is no universal classification of illusions, since the mechanisms and causes of their appearance are quite diverse and largely unexplored. However, conditionally optical illusions can be divided according to the following criteria:

By the nature of occurrence:

physical nature.

These are illusions that arise as a result of perceptual errors 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 a physical nature, but already within the limits of the eyeball.

b) distortions of the sensory and conductive systems of the eye

These are illusions that arise as a result of comparison and comparison errors due to the physiological characteristics of normally functioning sensory systems.

psychological nature

In psychiatric practice, there are:

Illusions affective - arise under the influence of affect - fear, anxiety, depression.

Verbal illusions - contain separate words or phrases.

Organic illusions - dysmorphopsia, metamorphopsia.

Illusions of the peak - part of the peak syndrome

Illusions of awareness - a feeling of the patient, indicating that someone is allegedly nearby. According to the author, these illusions are a sign of the formation of hallucinations and delusions.

Installation illusions [Uznadze D.N., 1930] are a form of physiological illusions. One of the types of illusions of perception of mass, volume, size. It occurs when pairs of objects are repeatedly compared, while in a preliminary series of experiments, prerequisites are created for the appearance of an illusion, which is revealed in the main (control) series of experiments. For example, if you lift a pair of objects of different mass with both hands several times at the same time, and then another pair of the same mass, then the object in the hand, in which it was previously lighter, will seem heavier than in the other hand (contrast illusion) . The mechanisms of illusion are explained from the point of view of D.N. Uznadze by the formation of internal unconscious states (settings) in a person, 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 studying the installation.

Illusions functional - pareidolia.

Illusions epileptic - disturbances of perception, which are significant, sometimes the only clinical manifestations of some focal epileptic seizures that occur when the epileptogenic focus is localized in the cortex of the temporal lobe adjacent to the sensory area. There are epileptic perceptual illusions, when the observed object is perceived distortedly and is 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 never seen", "never heard", "never experienced"). This group includes illusions, epileptic incoherence, unreality observed in epileptic dream-like states.

According to general characteristics:

visual distortion

Dual images

size illusions

Figure-to-Ground Relationship

Illusions of color and contrast

Apparent figures

Stereo illusions

Aftereffect

Illusions of depth perception

Illusions of movement

Impossible figures

Perceptual readiness effect

upside down pictures

Pattern recognition

Pareidolic illusions

Illusions of the face (following pictures, reversed portraits)

Drawings that cause discomfort

Physiology of distortion illusions

visual distortion

We see some simple drawings distorted. These distortions can be quite large. Part of the pattern may appear 20% longer or shorter; a straight line can be so curved that it's hard to believe it's really straight. In fact, we all see these distortions, and in the same direction in each such drawing. The same phenomenon was found to be 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 illusion, the animals will choose a line that appears longer to us, although in fact it is the same length as the line being compared with it. This result has been obtained in pigeons and in fish. All 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 dismissed as ill-conceived 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 must experience some illusions. Figures 9.4-9.6 show many of the most famous 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 some of them descriptive names. The most famous of the drawings of this kind are the Muller-Lyer arrows shown in fig. 9.4. This is just a pair of arrows, the shafts of which are the same length, but one arrow has tips with divergent ends, and the other with ends converging towards the shaft. A divergent arrow appears to be longer, even though both arrows are actually 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 the narrow part of the space enclosed between two converging lines, seems to be longer, although in fact both parallel lines are of the same length.

Rice. 9.6 shows two versions of Goering's drawing.

Finally, we have drawings in which a square and a circle are bent against a background of circular or crossing lines (Fig. 9.7).

Illusions can be divided into two groups: some are distortions caused by a certain kind of background (for example, the fan illusion), others are distortions of the figure itself (for example, the arrow illusion), without a background. These independent distortions are most clearly shown in Fig. 9.8, which shows arrowheads without shafts: the arrowheads are displaced by themselves, although there are no other lines in the figure. On the other hand, in the fan illusion, the diverging rays themselves are perceived without distortion, but any figure superimposed on them is distorted in a certain way. These drawings cause distortion, but do not distort themselves.

For the past hundred years, psychologists have tried to explain these illusions, but only now are we coming to understand why such drawings disrupt the visual system.