What Are Visual Hallucinations?

Illusion refers to people's incorrect feelings or perceptions of external things. The most common is optical illusion. The cause of the illusion, in addition to the effects of the characteristics of the objective stimulus, is also the physical and psychological reasons of the observer. Its mechanism is not fully understood.

Optical illusion

In addition to being widely used in the military field, visual illusions are also used by many companies and designers in the field of daily life. The principle of visual illusion can effectively change people's reception of spatial information, and can change the interaction between people and space. For example, the direction and size of the "eye" can be changed through the principle of optical illusion, and even beautiful and delicate pictures can be presented.

Many designers use the principle of optical illusion when doing indoor or outdoor advertising design. Using visual illusions and perspective principles (the following figure is a perspective schematic of spatial elements), you can design works with a sense of space.

Staring at the picture

You can easily be deceived by your own visual system. We usually think we can see anything in the field of vision with the same clarity, but if our eyes remain motionless for a short period of time, we will find it wrong. Only when you are close to the center of the gaze, you can see the details of the object. The more you deviate from the center of vision, the worse the resolution of the details is. At the outer periphery of the field of vision, it is even difficult to identify the object.

The reason why this is not obvious in daily life is because we can easily move our eyes constantly, so that we have the illusion that objects everywhere are equally clear. In addition, there are many patterns that can make the eyes illusion, such as the Canissa triangle that makes the eyes have "illusion contours". The effect that occurs on the retina and the cerebral cortex during the processing of simple graphics. This spiral effect may be caused by orientation-sensitive cells in these areas. For example, the continuous visual effect is between "similar" cells in the visual cortex of V1 The pattern of cross-connection between paired cells is not completely fixed and changes slightly with changes in the environment. The interaction between cells makes the simple continuous lines formed on the retina due to directional cells. Tilt creates the illusion. Vision is a function of the brain,

There are different reasons for the illusion: the paralytic nerve is paralyzed or disturbed; the sudden attack of external adverse stimuli; eye fatigue, long working hours; when the brain is confused; the brain sensory analysis is wrong; Pictures (quite interesting); then there are some special reasons that are probably not used. Illusion is a distorted perception, that is, the actual existence of the thing is distorted and perceived as something completely incompatible with the actual thing.

Common illusions include:

(1) Misunderstanding: For example, a coat hanging on a hanger is regarded as a person hiding behind a door; a ceiling lamp installed on the ceiling is regarded as a person hanging on the ceiling. These are all examples of illusion. In addition, there is a special illusion, which is the illusion of fantasy, meaning that the patient wrongly perceives what actually exists through the patient's own subjective imagination as an image completely different from the original thing. For example, the patient treats the colorful clouds in the sky. Perceived as a flying fairy image through imagination; some patients perceive cracks on the wall as imaginary misperceptions as some beautiful patterns or crooked monsters.

(2) In addition to false vision, there are also wrong taste, wrong touch, wrong smell, wrong hearing, and inner perceptual illusion. Illusions are common in hysteria, schizophrenia, mental illness caused by various substance poisoning, cerebral organic mental illness, and patients with mild disturbance of consciousness. At the same time, illusions can also be seen in normal people. For example, fantasy illusions can be found in healthy people with rich imagination, but also in hysteria and schizophrenia. Illusions can also occur in people under excessive tension and weakness. For example, the cups, snakes, and soldiers are illusions; the sound of wind and cranes is wrong; for a patient who is bedridden for a long time, the infusion set is regarded as a long snake trying to crawl to the patient. This is also an example of misunderstanding. The definition of illusion in psychology is: "incorrect perception of objective things". The illusion usually refers to the wrong vision. False vision is incorrect visual perception of objective things. Most psychology textbooks need to mention illusion, but there is no scientific and unified explanation for the mechanism of its occurrence.

There are several types of false vision:

1. Geometry Illusion Geometry illusion is a combination of geometry and line shape that creates a special environment that causes vision errors. Some are "caused by the relative size of the contrast to the surroundings" ([US] E.R.Hilgard and others, "Introduction to Psychology", Vol. 1). The normal straight line has an unrealistic bending. This rule Although it can be used in design, more often it is managed to avoid such situations. The "visual correction method" used in ancient Greek architecture avoids large buildings from bending due to misunderstanding. Vessel shapes sometimes need to be corrected, and the shoulders and abdomen are slightly convex to avoid rectilinear depressions. The other case is the "multiple space" of "assuming that the graphic is projected in a three-dimensional space", and the visual judgment of the graphic will flicker. The famous "Neckel cube" was designed by Swiss naturalist Neckel in 1832. It is intended to illustrate that the perspective relationship of transparent cubes can be understood differently by the visual. The oblique surface can be at the front or the front. Available at the back. There are also "tuning fork misunderstanding" graphics that seem to be three-dimensional, but they are unrealistic. When we look at the right end of the tuning fork, it is a box; when we look at the left end, it becomes three cylinders. These principles have been applied and developed in modern graphic design.

2. Color illusion Color illusion is mainly caused by the contrast of colors and the spatial mixing of colors. The so-called color contrast affects the accuracy of vision due to the juxtaposition of colors of different properties. Such as the expansion of bright colors and the contraction of dark colors, the colors of the same area will not look the same. Because of this, the three colors of the French flag must be made in different sizes. When the same color is placed in different environments, the sense of brightness will be different. Others, such as complementary color contrast, warm and cold color contrast, can also cause misunderstanding. The color space mixing misunderstanding is the juxtaposition of dots and lines of different colors, which will be regarded as the third color from a certain distance. For example, the color of a television is composed of three light points: red, blue, and green. The colors are black. Blue, red and yellow are mixed. This spatial mix has long been used by pointillism painting.

3 Using perceptual constancy, illusion Perceptual constancy means that we have a lasting and stable consciousness of some familiar and common things, and are often not affected by environmental changes. For example, the photographic paper under the red light in the dark room will not be mistaken for white. It enables graphic design to pursue diversity and interest in form while guaranteeing correctness. For example, the change of text is sometimes large, and it is easy to misunderstand when looking at a single word, but when context words are connected, it is not difficult to read using the perceptual normality.