Recognition and Perception of Images. Группа авторов
viewing slides with a stereoscope, that is, when presenting each eye with slightly different planar images of the same scene, called stereograms, the illusion of volume.
Stereograms can also be created with a random set of black and white elements. Meaningful perception of the depth of these stereograms is possible only after the two images are combined in a certain central visual zone. When viewed with a monocular, these images lose depth and are perceived as uniformly arranged random elements. A special form of a stereogram containing two combined patterns for both eyes is called an autostereogram. An autostereogram is an unusual and difficult task for the visual system, since it is necessary to focus the eyes at a distance different from the one on which the drawing itself is located. But if you look with two eyes and do not suffer from stereo-blindness, then with a certain training session (and patience) you can see the stereoscopic image.
1.5 Visual Illusions
Illusion is a false or distorted perception of a phenomenon. Visual (optical) illusions arise when the visual perception does not correspond to the physical, real properties of an external stimulus. Illusions can be considered distorted perception of the surrounding reality, and thus differ from hallucinations, which are a false perception that occurs in the absence of external conditionality. According to the mechanism of occurrence, visual illusions can be divided into the following types:
– arising from the imperfection of the optical properties of the eye;
– resulting from the action of the entire visual system, including the brain;
– dynamic illusions arising from a change in the position of the stimulus in space or in time.
The survey of [King et al., 2017] is dedicated to the analysis of distortions of perceiving the visual illusions in case of confusional insanity. People suffering from confusional insanity may experience the anomalies at the different stages of processing of visual information. Generally, such people are unperceptive to the illusions of high level. Moreover, they may be influenced by some illusions of initial stage.
Let’s consider the illusion of “Hollow mask” [Website youtube.com, 2020] taken as an example. The mask is turned both clockwise and counterclockwise upon view (the successive steps are shown in Figure 1.5.1). In fact, the mask is turned one way. However, for the majority of observers the mask changes the direction of movement at some point of time. At the start of movement the convex front side of the mask doesn’t make a difficulty for the visual system and consciousness. When the mask begins to move toward the back side (the backing may be observed through the hollow eye pits) our brain turns it out because the convex side is more familiar for us. We didn’t use to see people with concave faces. In the course of further turning the brain turns out and restores the usual convex form of the mask at the crossing line once again. However, the brain of scizophrene cannot be deceived; that’s why the mask is still hollow for it after turning.
Figure 1.5.1 Sequenced frames of illusion of ‘Hollow mask’ [Website youtube.com, 2020].
It is necessary to admit that visual illusion doesn’t have the same effect on some people who are under the influence of alcohol and narcotics. The initially given illusion was found out in the case of hollow mask of famous actor Charlie Chaplin. The inversion of reality and processing of visual information belong to the functioning properties of the brain of a healthy man. The study of principles of brain activity is a quite difficult field. There are no definitive explanations even to this date. What is more real – the perception of real-world view by the brain of scizophrene (without processing) or the visual information processed by the brain of a healthy man?
1.5.1 Constancy Perception
As a result of evolution, our sensory system has adapted to an adequate perception of objects and phenomena of the surrounding world [Arnheim, 1974], [Shiffman, 2008], [Abbasov, 2019]. In the process of perception, surrounding objects are characterized by some relatively stable physical properties. Perceptual stability when changing parameters of physical stimulation is called perception constancy.
Constant Perception of Lightness
The brightness of the surface of objects is characterized by the intensity of the light reflected by it, or luminosity. When the light intensity changes, the degree of lightness of a sheet of white paper practically does not change, despite the change in luminosity. It will also be perceived as white paper, but with less brightness.
Constancy Perception of Size
The tendency to perceive the size of objects unchanged relative to the observer (the size of the projection on the retina) is a consequence of the constancy of the perception of size. As follows from Figure 1.5.2, a person sitting at the end of the corridor is perceived to be the same size as the one sitting in the foreground, although the size of the retinal image on the retina is several times smaller [Website istockphoto, 2020]. If you place the images next to each other, you can visually detect the resizing of seated human figures.
Figure 1.5.2 Constancy perception of size.
Constancy of Perception of the Form
The shape of the object can also be perceived stably, regardless of the angle of view. This feature of the visual system is called the constancy of perception of the form. Familiar to us doors are perceived as rectangular shapes, despite the angle at which we look at them. However, their projection on the retina has a rectangular shape only if they are directly in front of the observer.
1.5.2 The Development of the Process of Perception
To analyze the perceptual abilities of a person, some studies of abilities in infants can be noted. At the age of one month, babies cannot distinguish small details; their vision can only be distinguished by relatively large objects. Visual acuity is weak, facial expressions are difficult to distinguish, they see mostly the external contours of the face. Infants find some forms more interesting than others; they are more inclined to look at forms similar to human faces. By three months, the sharpness improves; the baby can already decipher facial expressions, and he has much more social reactions. He recognizes something in the face of the mother; when viewing he prefers to look at the photo of the mother, and not at the photo of an unfamiliar woman.
The perception of depth begins to appear at about three months of age, but is finally formed only by six months. At the age of four months, the infant begins to reach for the nearest of the two objects, determining which one is located closer to it, thanks to the binocular disparity. Constancy of perception also begins to develop from the first months of life.
1.5.3 Perception after Surgery Insight
From medical practice it is known that a person born blind, after an operation to restore vision in adulthood, faces many problems due to the lack of spatial impressions about the outside world. The mature people were unable to distinguish even simple objects or forms [Gregory, 1970]. After a long workout, they learned to recognize the simplest of the visible objects. But many have not been able to learn this,