Our nervous system can't directly deal with the physical energy and chemical energy input from the outside, and these energies can only be converted into nerve energy or nerve impulse acceptable to the nervous system through the energy exchange of the senses. This process is what we call sensory coding. There is more knowledge about feeling below. Let's have a look with me!
1. Feeling and the meaning of feeling
Feeling? Human brain's understanding of individual attributes of things.
Feeling is of great significance in our life and work:
(1) Sensation provides information about the internal and external environment.
(2) Feeling ensures the information balance between the body and the environment.
(3) Feeling is the basis of all advanced complex psychological phenomena, and it is also the basis of all human psychological phenomena.
Feeling is the response of the nervous system to external stimuli. Like all psychological phenomena, it has the nature of reflection. Feeling includes not only the activities of the receptor, but also the activities of the effector.
At the beginning of the 20th century, German-American psychologist Kaufka divided stimulation into near stimulation and far stimulation. Proximity stimulation refers to the stimulation that directly acts on the sensory organs, such as the projection of objects on the omentum. Telestimulation refers to the stimulation from the object itself, such as light with a certain wavelength and air vibration with a certain frequency. Far stimulation belongs to the object itself, so it won't change much; Proximity stimulus is the stimulus directly received by sensory organs, which is constantly changing.
2. The coding of feelings
[Coding] To convert one kind of energy into another, or to convert one symbol system into another.
(1) sensory coding? Our nervous system can't directly deal with the physical energy and chemical energy input from the outside, and these energies can only be converted into nerve energy or nerve impulse acceptable to the nervous system through the energy exchange of the senses. This process is what we call sensory coding.
② Miao Lei, a German physiologist, put forward the theory of special nerve energy in19th century. It is believed that all kinds of sensory nerves have their own special energy, and they are different in nature. Each sensory nerve can only produce one kind of feeling, but not the other. Different properties of the senses, different energy of sensory nerves, produce different feelings. In his view, feeling does not depend on the nature of stimulation, but on the nature of sensory nerves. It denies that feeling is an understanding of the objective world, which is wrong in epistemology.
(3) There are two representative theories about sensory coding: specialization theory and pattern theory.
A. specialization theory: different senses have different neurons to transmit information.
B pattern theory: coding is caused by the activation pattern of a whole group of neurons, but some neurons are activated to a greater extent, while others are activated to a lesser extent.
3. Sensitivity and sensory threshold
(1) Absolute sensitivity and absolute sensory threshold
A. absolute sensory threshold-the minimum amount of stimulus that can cause this feeling.
B. absolute sensitivity-the ability of human sensory organs to detect this weak stimulus.
Absolute sensory threshold is inversely proportional to absolute sensitivity!
(2) Differential sensitivity and perceptible difference.
A. perceptible difference: the smallest difference between stimuli that can cause different senses.
B. difference sensitivity: the ability to feel the smallest difference.
The differential sensitivity and the just-perceptible difference are also inversely proportional in value!
Weber's law: K=△I/I(I is the intensity of standard stimulus or original stimulus; △I is the stimulation increment that causes differential sensation, namely JND；; K is a constant. According to Weber's score, we can judge the sensitivity of a certain feeling. The smaller the Weber score, the sharper the feeling. However, Weber's law only applies to moderate intensity stimuli.
4. The relationship between stimulus intensity and sensory size
There are two relationships between sensory intensity and sensory size: Fechner's law of logarithm and Stevens' law of power.
(1) Logarithmic law P=KlogI(P is the sensory quantity, that is, the sensory intensity; K is a constant in Weber's law; I refers to the amount of stimulation)
The formula shows that when the stimulus intensity increases geometrically, the sensory intensity only increases arithmetically. When the physical quantity rises rapidly, the sensory quantity changes gradually. Note: Fechner's Logarithmic Law is based on Weber's Law, so this law is only applicable to moderate intensity stimuli.
(2) power law P=KIn(P is the size of feeling; I refers to the physical quantity of stimulus; K and n are constant characteristics of a certain type of experiment being evaluated)
This formula shows that the magnitude of perception is directly proportional to the intensity of stimulus.
5. The physiological mechanism of vision:
Vision: produced by the stimulation of light to the human eye.
The physiological mechanism of vision includes refractive mechanism, sensory mechanism, conduction mechanism and central mechanism.
The eyeball includes the eyeball wall and eyeball contents. The eye wall is divided into three layers: the outer layer is sclera and cornea (refraction); The middle layer is iris, ciliary muscle and choroid; The inner layer is the inner segment of retina and optic nerve. The contents of eyeball include lens, aqueous humor and vitreous body. Both are refractive media. There are three pairs of eye muscles outside the eyeball, which are innervated by oculomotor nerve, trochlear nerve and abducens nerve respectively.
The retina is the photosensitive layer of the eyeball. The outer layer consists of pyramidal cells and rod cells; Bipolar cells in the middle; Ganglion cells in the inner layer.
The difference between rod-shaped cells and cone-shaped cells;
(1) has obvious differences in morphology. One is a rod and the other is a cone.
(2) The distribution on the omentum is also different. There are only pyramidal cells in the central fossa of the most sensitive area of omentum, and there are no rod cells. The number of somatic cells leaving the central fossa gradually increased, reaching the maximum at 16o-20o. There are only a few pyramidal cells at the edge of the omentum. Near the central fossa, there is an area insensitive to light, called blind spot, where nerve fibers from retinal ganglion cells gather into optic nerve.
(3) Different functions. Rod cells are night vision organs, which work under dim light conditions and mainly feel the light and shade of objects; Pyramidal cells are visual organs in the daytime, which work under medium and strong light conditions and mainly feel the details and colors of objects.
6. The basic phenomenon of vision:
The basic phenomena of vision are lightness, color, spatial factors and time factors in vision.
Color vision theory:
(1) trichromatic theory: British scientist Thomas? Yang, suppose there are three different receptors in the retina, and each receptor is only sensitive to a specific component in the spectrum. When they are stimulated by different wavelengths of light, they will have different color experiences. But this theory can't explain red-green color blindness.
(2) Theory of opposing process: Heilin put forward the four-color theory, which is the predecessor of the theory of opposing process. Hailin believes that there are three kinds of retinas: black and white retina, red-green retina and yellow-blue retina. Stimulated by light, they show a process of confrontation, namely assimilation and alienation. Hellwich and jamison confirmed Hailin's theory of opposing process with psychophysical methods. Three kinds of antagonistic cells were found: black and white, red and green, yellow and blue. Among them, black and white cells are related to lightness, and red, green, yellow and blue cells are related to color coding. According to these findings, we think that there are three kinds of pyramidal cells in the retina, which are sensitive to different wavelengths of light. At the retina level, color vision is produced according to the principle provided by trichromatic theory; On the other hand, at the higher level of the visual system, there are cells with opposite functions, and the color information processing presents the opposite process.
7. Some visual phenomena:
(1) dark adaptation: the time process of improving visual perception when light stops or turns from bright to dark.
(2) light adaptation: the time process of visual sensitivity decreasing when lighting starts or when a dark place turns into a bright place.
(3) Purkinje phenomenon: When people change from cone vision to rod vision, the maximum sensitivity of human eyes to the spectrum will move to the short wave direction, so different brightness changes will occur, which is called Purkinje phenomenon.
(4) Maher band: refers to people who often see a bright band in the bright area and a darker line in the dark area on the dividing line of light and dark changes. This is the phenomenon of Mach band, not because of the distribution of stimulus energy, but because of the processing of visual information by neural network.
(5) After-image: After the stimulus stops acting on the receptor, the sensory phenomenon does not disappear immediately, but it can last for a short time. This phenomenon is called afterimage.
(6) Flash fusion: With the increase of intermittent flash frequency, people will get the feeling of fusion. This phenomenon is called flash fusion.
(7) Visual masking: Under certain time conditions, when a flash appears after another flash, this flash can affect the perception of the previous flash, and this effect is called visual masking.
(8) Visual acuity: refers to the ability of the visual system to distinguish the smallest object or object details.
8. Basic auditory phenomena:
(1) Relationship between tone and frequency: Tone is a psychological quantity, which does not completely correspond to the physical characteristics and frequency changes of sound waves. Above 1000 Hz, the frequency and tone are almost linear, and the rising amplitude of tone is lower than that of frequency; But below 1000 Hz, the relationship between frequency and tone is not linear, and the change of tone is faster than that of frequency.
(2) Relationship between sound and frequency: Under the same sound pressure level, the loudness of different frequencies is different. But different sound pressure levels can produce the same sound.
(3) The range of human auditory frequency is 16 Hz -20000 Hz, in which 1000 Hz -4000 Hz is the most sensitive area of human ear.
(4) Sound masking: A sound is interfered by other sounds at the same time, which leads to an increase in hearing threshold.
9. Auditory theory
(1) frequency theory: also called telephone theory. 1886, physicist? Phil suggested it. It is considered that the basement membrane and stapes of the inner ear move at the same frequency, and the vibration is adapted to the original frequency of sound. Frequency theory is difficult to explain the analysis of sound frequency by human ear, and the basement membrane of human ear cannot make more than 1000 movements per second.
(2)*** Ming theory: also called position theory. It was put forward by Helmholtz. Because the transverse fibers of the basement membrane are different in length, they can produce * * * sounds with different frequencies. Later, it was found that the length of transverse fibers in the basement membrane did not correspond to the frequency.
(3) Traveling wave theory: physiologist Feng? Beksey developed the * * * theory and put forward a new position theory-traveling wave theory. It is considered that when sound waves reach human ears, the whole basement membrane will vibrate. The vibration starts from the bottom of the cochlea and gradually advances to the top of the cochlea, and the amplitude of the vibration gradually increases, thus realizing the analysis of different frequencies. However, traveling wave theory is difficult to explain the influence of sound below 500 Hz on basement membrane (but it can be explained by frequency theory).
(4) Neural salvo theory: put forward by Wavell. It is considered that when the sound frequency is lower than 400 Hz, the frequency of individual fibers of auditory nerve corresponds to the sound frequency. When the sound frequency increases, a single nerve fiber cannot respond to it alone. In this case, the nerve fibers will act according to the principle of volley. But for frequencies above 5000 Hz, neural salvo theory can't explain it.
10. Other feelings
(1) Skin sensation: touch, cold sensation, warm sensation and pain sensation.
(2) Smell and taste
(3) Internal sensation: kinesthetic sensation, sense of balance and visceral sensation.
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