Topic 2. Illusions of perception

Lecture



Constructive nature of perception. Functional limitations of the visual analyzer and their compensation at the subjective level.

Perception phenomena. Physiological and cognitive mechanisms of illusions in the light of the main phenomena of the perceptual image.

Sensory quality, perceptual image configuration and illusions associated with them. Mach stripes and illusions of contrast. Optical and geometric illusions. Induced movement.

The constancy of perception and the frame of reference and the illusions associated with them. Illusion Adelson. The illusion of the moon. Illusion Ebbingauza. Cognitive interpretation of optical-geometric illusions. Illusions and effects based on the manipulation of signs of distance and depth. Ames room and other demonstrations.

Subject and installation perception and illusions associated with them. Understanding and interpretation of multi-valued images. Impossible images. The perception of human faces and the "illusion of Margaret Thatcher." The role of context and motivation in the occurrence of perceptual errors and distortions. The phenomenon of perceptual protection.

Applications of perceptual illusions. Visual arts. Illusion graphics: anamorphic images (art "Madonnari"). Three-dimensional technology.

Literature

Primary:

  1. Gregory R. Knowledge and illusions of perception. // Cognitive psychology. History and modernity. Reader / M.V. Falikman, V.F. Spiridonov (ed.). M .: Lomonosov, 2011. P. 177-194.

Additional:

  1. Gregory R. Reasonable Eye. M .: Editorial URSS, 2010. p. 32-48.

Depth perception illusions

Visual Illusions / Illusions of Perception of Depth


How many cubes are there?
  Topic 2. Illusions of perception

Six or seven?


The Necker Cube (1832).

  Topic 2. Illusions of perception
Is the blue face in front or behind?

The illusion is named after the Swiss crystallographer Louis Albert Necker (Necker),
who in the middle of the XIX century discovered this illusion.


The staircase Schroeder (1858).

  Topic 2. Illusions of perception

Is it a staircase, a niche, or just a gray strip of paper folded in accordion?


How is this cylinder?
  Topic 2. Illusions of perception

Right to left or left to right?


  Topic 2. Illusions of perception

What is the front part of the ring?


How is the magazine located?
  Topic 2. Illusions of perception

Cover to you or vice versa?


  Topic 2. Illusions of perception

Is it a small cube in the room or a big cube with a piece of sawn-off?


Cheese illusion.
  Topic 2. Illusions of perception
How much cheese is there?


Amazing chessboard.
  Topic 2. Illusions of perception


Strange workers.

  Topic 2. Illusions of perception


Motor parallax

  Topic 2. Illusions of perception

Due to the fact that the circles move at different speeds, an illusion of depth arises.
Compare with a still picture.

  Topic 2. Illusions of perception


Due to the motor parallax arises a very strong illusion of depth.

  Topic 2. Illusions of perception   Topic 2. Illusions of perception

Which of the pictures seems voluminous?


Due to the fact that the "near" elements of the picture are shifted to a greater distance than the "far" there is the effect of depth

  Topic 2. Illusions of perception


Another example of this effect. There was a feeling that the picture is three-dimensional?

  Topic 2. Illusions of perception


Illusion of Nick Williams (Nik Williams, 1996)

  Topic 2. Illusions of perception
This is just a mask of the Egyptian mummy (2-2.5 thousand years BC)

  Topic 2. Illusions of perception
This is the same mask, but from the inside.

  Topic 2. Illusions of perception
Pay attention to how difficult it is to perceive this image as concave.
The brain unconsciously sees this face as normal.


See the hole in hell?

  Topic 2. Illusions of perception

It is simply painted on asphalt.


Painted pit

  Topic 2. Illusions of perception


Which artist is real and which one is drawn?

  Topic 2. Illusions of perception

More asphalt illusions from Kurt Weimer: http://www.kurtwenner.com


What is it?
Square groove or pyramid?

  Topic 2. Illusions of perception

Illusions of visual perception

Content:

Introduction

Optical and geometric illusions.

Illusions of perception of movement.

Illusions of processing information.

Illusions of color vision.

Illusions associated with the features of the structure of the eye.

Optical effect of color.

Irradiation.

Astigmatism of the eye.

Conclusion




Introduction

We perceive the environment around us as a given: a sunbeam playing highlights on the surface of the water, a play of colors in the autumn forest, a child's smile ... We have no doubt that the real world is exactly as we see it. But is it really? Why sometimes vision fails us? How does the human brain interpret perceived objects?

A person perceives most of the information about the world through vision, but few people think about exactly how this happens. Most often, the eye is considered to resemble a camera or a television camera, projecting external objects onto the retina, which is a photosensitive surface. The brain "looks" at this picture and "sees" everything that surrounds us. However, not all so simple. First, the image on the retina is inverted. Secondly, due to the imperfect optical properties of the eye, such as aberration, astigmatism and refraction, the picture on the retina is defocused or smeared. Thirdly, the eye makes constant movements: jumps when viewing images and during visual search, small involuntary oscillations when fixing on an object, relatively slow, smooth movements while tracking a moving object. Thus, the image is in constant dynamics. Fourth, the eye blinks about 15 times per minute, which means that the image ceases to be projected onto the retina every 5-6 seconds. Since a person has binocular vision, in fact he sees two blurry, jerking and periodically disappearing images, which means that the problem of combining information coming through the right and left eye arises.




Optical-geometric illusions

Illusions are a distorted, inadequate reflection of the properties of the perceived object. Translated from Latin, the word "illusion" means "mistake, delusion." This suggests that illusions have long been interpreted as some kind of malfunction of the visual system. Many researchers have been studying the causes of their occurrence. The main question that interests not only psychologists, but also artists, is how a three-dimensional visible world is recreated on the basis of a two-dimensional image on the retina. It is possible that the visual system uses certain signs of depth and distance, for example, the principle of perspective, implying that all parallel lines converge at the level of the horizon, and the size of the object as it moves away from the observer is proportionally reduced. We do not realize how much the projection of an object on the retina changes as it is removed.

One of the most famous optical-geometric illusions is the Muller-Lyer illusion (see fig. 1).

  Topic 2. Illusions of perception
Fig.1. Illusion of Muller-Lyer

Looking at this picture, most observers will say that the left segment with the arrows outwards is longer than the right segment with the arrows directed inward. The impression is so strong that, according to experimental data, the subjects assert that the length of the left segment is 25-30% higher than the length of the right one.

Another example of optical-geometric illusions is the Ponzo illusion (Fig. 2).

  Topic 2. Illusions of perception

Fig.2. Illusion Ponzo

- also illustrates the perception of size perception. Ponzo drew two identical segments on the background of two converging lines, like a railroad track stretching into the distance. The upper 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 upper segment is located further, and we assume that its size is larger. In addition to converging lines, the effect is added by the decreasing distance between intermediate horizontal lines.

The importance of perspective for the perception of the Muller-Lyer illusion is illustrated in Fig. 3. (The yellow lines at the corners of the wall are exactly the same size). In everyday life we ​​are surrounded by many rectangular objects: rooms, windows, houses. Therefore, the image on which the lines diverge can be perceived as a corner of a building located farther from the observer, while a drawing on which the lines converge is perceived as a corner of a building located closer. Similarly, the Ponzo illusion can be explained. Oblique lines, converging at one point, are associated either with a long highway or with a railroad track on which two objects lie. Visual patterns formed by such a "rectangular" environment, and make us make mistakes.

  Topic 2. Illusions of perception
Fig.3. Distortion of real dimensions due to perspective

Analysis of the proposed explanation of optical-geometric illusions shows that, firstly, all the parameters of the visual image are interconnected, which creates a holistic perception, recreates an adequate picture of the external world. Secondly, perceptions are influenced by stereotypes formed by everyday experience, for example, the notion that the world is three-dimensional, which begin to work as soon as signs are added to the picture that indicate perspective.

  Topic 2. Illusions of perception

Fig.4. Two balls in a niche have the same size

An example of how to destroy the holistic image of an object is the so-called "impossible", contradictory figures, pictures with a broken perspective.

  Topic 2. Illusions of perception
Fig.5. Impossible stairs

Penrose’s “impossible” staircase (Fig. 5) and its interpretation in Aspen and Descent lithography by Maurits Cornelius Escher (Fig. 6) illustrates this well. Look at Figure 5 and answer the question: is the person moving up? Each individual flight of the stairs tells us that it rises, however, after passing four flights, it turns out to be in the same place from which it began its journey. "Impossible" ladder is not perceived as a whole, because there is no consistency between its individual fragments. Time after time we follow the gaze on the steps leading upwards, trying to find a way to solve this problem, and we don’t find it.

  Topic 2. Illusions of perception

Fig.6. Climbing and descending




Illusions of motion perception

If a person, sitting in a train carriage, fixes his gaze on the landscape outside the window, it seems to him that objects that are closer to the fixation point move on him, and so quickly that he sometimes fails to discern details. And the objects in the background, i.e. after the fixation point, they move along with the observer rather slowly. This phenomenon is called motor parallax.

  Topic 2. Illusions of perception
Fig.7. Motor parallax

There are dynamic illusions arising from the use of this phenomenon for flat images. In fig. 7 we see the famous painting by Russian artist Shishkin "Morning in a pine forest". The trees in the foreground move quickly, and in the background slowly. It seems to the observer that the flat picture turns into a volumetric one.

Another dynamic illusion is the autokinetic movement. If you look at a luminous point in a dark room, you can observe an amazing phenomenon. The experiment is extremely simple: you need to light a cigarette and put it in an ashtray. The indispensable conditions for the appearance of an illusion - the room must be so dark that, in addition to this spot of light, nothing could be seen. In this view, you need to carefully fix the glowing point for a few minutes. You, knowing that a cigarette is lying motionless in an ashtray, after a while you suddenly find that its light is moving, making sweeping movements, sudden leaps, describes circles around the room. The range of motion can be quite large. Moreover, the understanding that this is an illusion does not affect the results of observation. The hypotheses explaining this phenomenon by eye movements were refuted by experiments in which eye movements and an observer's report on the direction in which the light spot was moving were simultaneously recorded. A comparison of the data obtained showed that there is no correspondence between real eye movements and the apparent movement of an object.

But perhaps the greatest visual illusion is film and television. We can watch the transmission due to the stroboscopic effect, based on one of the most important properties of the visual system - inertia. Within a few seconds, the observer is shown a static luminous point in one place on the screen, and after 60-80 ms it is shown in another place. A person sees not two different objects that have flashed in different places, but a movement of an object from one position to another. The visual system interprets sequential and related changes as movement. It is due to this effect that we see on the screens not a series of quickly replacing frames, but a single moving picture.

It is known that the first steps of the cinema were accompanied by a curious episode: when the audience saw the approaching train on the screen, they jumped up and ran away screaming - it seemed to him that he was rushing straight at them. This phenomenon is called luping. If a person demonstrates a light spot, which suddenly begins to expand in all directions, it will seem to him that it is moving directly towards him, and does not increase his size. And the illusion will be so strong that it will force us to unwittingly move away from the screen, as if from an object representing a threat. Something similar can be seen by watching computer game lovers: someone leans to the side, trying to hide from the bullets flying at him, someone recoils from the fireball rushing into him. It is obvious that in the case when there is no unambiguous information about the change in the shape of an object, the visual system prefers to increase the retinal image as an object approximation.




Illusions of information processing

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

  Topic 2. Illusions of perception
Fig.8. Illusions of processing information

Symbol in the center - a letter or number? If we consider a horizontal visual row consisting of letters, in the center there will be a "B" - the observer is prepared for this by an alphabetic row. If you look at the vertical row, it turns out that this is not a letter at all, but the number 13 - the figures pushed this decision.

Such illusions are due to a higher level of information processing, when the nature of the problem being solved determines what a person perceives in the surrounding world. Interesting features of selectivity perception. If you say to a person: in this book there is your last name - then he will be able, very quickly scrolling through the pages, to find a mention of himself. And about any reading of the text of the speech does not go. Such skills are possessed by proofreaders who incomprehensibly isolate errors in the text that are inconspicuous to the ordinary reader.

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

Perception works very selectively when it comes to significant, too important events for us. For example, the human face is perceived in a special way. The negative image of the face is almost not recognized, it seems completely uninformative. If geometrical objects, depending on how the shadows fall, can seem both convex and concave, then the human face is always convex (even the mask cannot be seen concave). Paradoxically, the perception of an inverted image of the face (Fig. 9)

  Topic 2. Illusions of perception   Topic 2. Illusions of perception
Fig.9. Illusions of information processing

If you look at two photos of people turned upside down, it seems that they do not differ: eyes, nose, lips, hair - everything is identical. But, turning these portraits, you can make sure that they are completely different. On one is Joekonda's calm and sweet smile, on the other is a terrible grimace. The point, apparently, is that the human face is too significant, it can not be perceived in an unusual perspective.




Illusions of color vision

The most important feature of our eyes is its ability to distinguish colors. One of the properties related to color vision can be considered the phenomenon of the shift of the maximum relative visibility during the transition from daylight vision to twilight. При сумеречном зрении (низких освещенностях) не только понижается чувствительность глаза к восприятию цветов вообще, но и в этих условиях глаз обладает пониженной чувствительностью к цветам длинноволнового участка видимого спектра (красный, оранжевый) и повышенной чувствительностью к цветам коротковолновой части спектра (синий, фиолетовый).

Можно указать на ряд случаев, когда мы при рассматривании цветных объектов также встречаемся с ошибками зрения или иллюзиями.

Во-первых, иногда о насыщенности цвета объекта мы ошибочно судим по яркости фона или по цвету других, окружающих его предметов. В этом случае действуют также закономерности контраста яркостей: цвет светлеет на темном фоне и темнеет на светлом (рис. 10).

  Topic 2. Illusions of perception

Fig.10. Клетки A и B одного цвета

Великий художник и ученый Леонардо да Винчи писал: "Из цветов равной белизны тот кажется более светлым, который будет находится на более темном фоне, а черное будет казаться более мрачным на фоне большей белизны. И красное покажется более огненным на более темном фоне, а также все цвета, окруженные своими прямыми противоположностями."

Во-вторых существует понятие собственно цветовых или хроматических контрастов, когда цвет наблюдаемого нами объекта изменяется в зависимости от того, на каком фоне мы его наблюдаем. Можно привести множество примеров воздействия на глаз цветовых контрастов. Гете, например, пишет: "Трава, растущая во дворе, вымощенном серым известняком, кажется бесконечно прекрасного зеленого цвета, когда вечерние облака бросают красноватый, едва заметный отсвет на камни." Дополнительный цвет зари - зеленый; этот контрастный зеленый цвет, смешиваясь с зеленым цветом травы и дает "бесконечно прекрасный зеленый цвет".

Гете описывает также явление так называемых "цветных теней". "Один из самых красивых случаев цветных теней можно наблюдать в полнолуние. Свет свечи и лунное сияние можно вполне уравнять по интенсивности. Обе тени могут быть сделаны одинаковой силы и ясности, так, что оба цвета будут вполне уравновешиваться. Ставят экран так, чтобы свет полной луны падал прямо на него, свечу же помещают несколько сбоку на надлежащем расстоянии; перед экраном держат какое-нибудь прозрачное тело. Тогда возникает двойная тень, причем та, которую отбрасывает луна и которую в то же время освещает свеча, кажется резко выраженного красновато-темного цвета, и, наоборот, та, которую отбрасывает свеча, но освещает луна - прекраснейшего голубого цвета. Там, где обе тени встречаются и соединяются в одну, получается тень черного цвета."




Illusions associated with the features of the structure of the eye

Слепое пятно. Наличие слепого пятна на сетчатой оболочке глаза впервые открыл в 1668 г. известный французский физик Э. Мариотт. Свой опыт, позволяющий убедиться в наличии слепого пятна, Мариотт описывает следующим образом: "Я прикрепил на темном фоне, приблизительно на уровне глаз, маленький кружочек белой бумаги и в то же время просил другой кружочек удерживать сбоку от первого, вправо на расстоянии около двух футов), но несколько пониже так, чтобы изображение его упало на оптический нерв моего правого глаза, тогда как левый я зажмурю. Я стал против первого кружка и постепенно удалялся, не спуская с него правого глаза. Когда я был в расстоянии 9 футов, второй кружок, имевший величину около 4 дюймов, совсем исчез из поля зрения. Я не мог приписать это его боковому положению, ибо различал другие предметы, находящиеся еще более сбоку, чем он; я подумал бы, что его сняли, если бы не находил его вновь при малейшем передвижении глаз".

Известно, что Мариотт забавлял английского короля Карла II и его придворных тем, что учил их видеть друг друга без головы. Сетчатая оболочка глаза в том месте, где в глаз входит зрительный нерв, не имеет светочувствительных окончаний нервных волокон (палочек и колбочек). Следовательно, изображения предметов, приходящиеся на это место сетчатки, не передаются мозгу.

Вот еще интересный пример. На самом деле круг идеально ровный. Стоит прищуриться и мы это видим.

  Topic 2. Illusions of perception

Рис.11. Искаженная окружность




Оптическое воздействие цвета

К этому воздействию относятся иллюзии или оптические явления, вызываемые цветом и изменяющие внешний вид предметов. Рассматривая оптические явления цвета, все цвета можно условно разделить на две группы: красные и синий, т.к. в основном цвета по своим оптическим свойствам будут тяготеть к какой-нибудь из этих групп. Исключение составляет зеленый цвет. Светлые цвета, например белый или желтый создают эффект иррадиации, они как бы распространяются на расположенные рядом с ними более темные цвета и уменьшают окрашенные в эти цвета поверхности. Для примера, если через щель дощатой стены проникает луч света, то щель кажется шире, чем в действительности. Когда солнце светит сквозь ветви деревьев, ветви эти кажутся более тонкими, чем обычно.

Это явление играет существенную роль при конструировании шрифтов. В то время, как, например, буквы E и F сохраняют свою полную высоту, высота таких букв как O и G, несколько уменьшаются, еще больше уменьшаются из-за острых окончаний буквы A и V. Эти буквы кажутся ниже общей высоты строки. Чтобы они казались одинаковой высоты с остальными буквами строки, их уже при разметке выносят несколько вверх или вниз за приделы строки.Эффектом иррадиации объясняется и различное впечатление от поверхностей, покрытых поперечными или продольными полосками. Поле с поперечными полосками кажется более низким, чем поле с продольными, так как белый цвет окружающий поля проникает наверху и внизу между полосками и визуально уменьшает высоту поля.

Основные оптические особенности групп красных и синих цветов.

Красный, желтый, оранжевый Фиолетовый, синий, голубой
теплые, тяжелые,
материальные, прочные, плоские



фактурные, шероховатые, матовые



расширение распространяемое по горизонтали



подчинены дуге



глухие, шумные и низкие
легкость, не
материальность, проницаемость, пространство



безфактурные, гладкие и блестящие



сжатие, распространение по вертикали



подчинены углу,

холодные, острые и колючие,



тихие, звонкие, высокие

Желтый цвет зрительно как бы приподнимает поверхность. Она кажется к тому же более обширной из за эффекта иррадиации. Красный цвет приближается к нам, голубой, наоборот удаляется. Плоскости, окрашенные в темно-синий, фиолетовый и черный цвета, зрительно уменьшаются и устремляются книзу.

Зеленый цвет - наиболее спокойный из всех цветов. Так же нужно отметить центробежное движение желтого цвета и центростремительное синего.

Первый цвет колет глаза, во втором глаз утопает. Это воздействие увеличивается, если к нему добавить различие в светлоте и темноте, т.е. воздействие желтого увеличится при добавлении к нему белого цвета, синего - при утемнении его черным.

Academician S.I. Vavilov writes about the structure of the eye: "How simple is the optical part of the eye, how complex is its perceiving mechanism. We not only do not know the physiological meaning of individual elements of the retina, but are not able to tell how appropriate the spatial distribution of photosensitive cells is, what a blind spot is needed, and so on. Before us is not an artificial physical device, but a living organ in which virtues are mixed with flaws, but everything is inseparably connected into a living whole. "

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

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




Irradiation

The phenomenon of irradiation lies in the fact that light objects on a dark background seem to be enlarged against their actual size and capture a part of the dark background. This phenomenon has been known since very ancient times. Even Vitruvius (1st century BC), an architect and engineer of ancient Rome, pointed out in his writings that when a combination of dark and light "light consumes darkness." On our retina, light partly captures the place occupied by the shadow. The initial explanation of the phenomenon of irradiation was given by R. Descartes, who argued that the increase in the size of bright objects is due to the spread of physiological arousal to the places adjacent to the directly irritated retinal space.

However, this explanation is currently being replaced by a new, more stringent, formulated by Helmholtz, according to which the following causes are the root cause of irradiation. Each luminous point is depicted on the retina in the form of a small scattering circle due to the imperfection of the lens (aberration, deviation from Latin), inaccurate accommodation, etc. When we look at the bright surface on a dark background, the boundaries of this surface move apart due to aberration scattering , and the surface seems to us more than its true geometric dimensions; it extends, as it were, through the edges of the surrounding dark background (Fig. 12).

  Topic 2. Illusions of perception

Fig.12. Irradiation

The effect of irradiation affects the sharper, the worse the eyes are accommodated. Due to the presence of light scattering circles on the retina, under certain conditions (for example, very thin black threads) dark objects on a light background may also be exposed to illusory exaggeration - this is the so-called negative irradiation. There are many examples when we can observe the phenomenon of irradiation, there is no possibility to bring them completely.

The great Italian artist, scientist and engineer Leonardo da Vinci, in his notes, talks about the phenomenon of irradiation as follows: "When the Sun is visible behind leafless trees, all their branches opposite the solar body are so reduced that they become invisible, the same will happen with a pole placed between the eye and the sun body. I saw a woman dressed in black with a white bandage on her head, and the latter seemed twice as large as the width of the woman’s shoulders who were wearing black. five teeth fortresses, separated by intervals equal to the width of the teeth, the spaces appear much larger than the teeth ... ".

The great German poet Goethe points out in a treatise on the whole series of observations of the phenomenon of irradiation in nature in his treatise The Teaching of Flowers. He writes about this phenomenon as follows: “A dark object appears to be less than a light one of the same size. If we consider simultaneously a white circle on a black background and a black circle of the same diameter on a white background, then the latter seems to be about 1/5 less than the first. If black the circle should be made larger accordingly, they will seem equal. The young sickle of the moon seems to belong to a circle of larger diameter than the rest of the dark part of the moon, which is sometimes discernible. "

The phenomenon of irradiation during astronomical observations makes it difficult to observe thin black lines on objects of observation; in such cases it is necessary to diaphragm the lens of the telescope. Physicists due to the phenomenon of irradiation do not see thin peripheral rings of the diffraction pattern. In a dark dress, people seem thinner than in a light one. Sources of light, visible from the edge, produce an apparent cut in it. The ruler, due to which a candle flame appears, appears with a notch in this place. The rising and setting sun makes it like a hollow in the horizon. Some more examples.

A black thread, if held in front of a bright flame, seems to be interrupted in this place; The glowing filament filament seems thicker than it really is; light wire on a dark background seems to be thicker than on a light one. The bindings in the window frames seem smaller than they really are. A bronze cast statue looks smaller than a cast made of plaster or white marble.

The architects of ancient Greece made the corner columns of their buildings thicker than others, given that these columns would be visible from many points of view against the bright sky and, due to the phenomenon of irradiation, would seem thinner. We are subjected to a kind of illusion with respect to the apparent magnitude of the sun. Artists, as a rule, paint the sun too large in comparison with other depicted objects. On the other hand, in photographic landscape photographs in which the Sun is also depicted, it seems to us unnaturally small, although the lens gives the correct image of it.

Note that the phenomenon of negative irradiation can be observed in such cases when a black thread or a slightly shiny metal wire on a white background appears thicker than on black or gray. If, for example, a lace maker wants to show her art, then it is better for her to make lace of black threads and spread it on a white lining. If we observe wires against a background of parallel dark lines, for example, against a tiled roof or brickwork, then the wires appear thickened and broken where they intersect each of the dark lines.

These effects are also observed when the wires overlap in the field of view on the clear outline of the structure. Probably, the phenomenon of irradiation is associated not only with the aberration properties of the lens, but also with the scattering and refraction of light in the medium of the eye (the fluid layer between the eyelid and the cornea, the medium filling the anterior chamber and the entire interior of the eye). Therefore, the irradiation properties of the eye are obviously related to its resolving power and the radiant perception of “point” light sources. The ability of the eye to overestimate acute angles is connected with the aberrational properties, and therefore, partly with the phenomenon of irradiation.




Astigmatism of the eye

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

Eyes completely free from this deficiency are rarely seen in humans, as can be easily seen. For an astigmatism eye test, oculist physicians often use a special table, where twelve circles have a hatching of equal thickness at regular intervals. An eye with astigmatism will see the lines of one or several circles more black. The direction of these more black lines allows us to conclude about the nature of the astigmatism of the eye.

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

Conclusion

An experimental study of the perception of real objects — two equal-sized rails against the background of rail track rails — showed that the perceived value of a distant rail was either smaller (in the vast majority of samples) or equal to the perceived value of the near-rail, depending on the mode of perception and the distance of observation. The “illusion” of the perception of a larger relative value of the far Reiki took place only in very rare cases.

This difference in the results of the process of perception of a real object and its abstract image on a plane is due to the difference in the content of the resulting relationships in the process of reflecting the properties of one and the other object of perception. Thus, the processes of perception of a real object and its images, which differ in the objective content of the relations formed in these processes, as well as the conditions of perception, are wrongfully considered to be identical processes.

It is the diversity of anisotropic relations that is the directly sensual basis of the semi-functionality of the perception process, which provides the possibility for a person to reflect various properties and relations of objects under various conditions and tasks of action with them.


Comments


To leave a comment
If you have any suggestion, idea, thanks or comment, feel free to write. We really value feedback and are glad to hear your opinion.
To reply

Psychology of errors and illusions

Terms: Psychology of errors and illusions