أنواع الاحساس - ١ - الإحسَاس .. كتاب علم النَّفس جميل صَليبا

Types of sensation - 1 - Sensation

Types of sensation

Let us now mention the types of sensation by way of classification, and explain the status of each of them. The ancients knew of only five senses, namely touch, taste, smell, hearing, and sight, but the later people discovered new sensory nerves and divided touch into different senses. They found a new sense in the ear, which they called the sense of balance, and thus the number of senses among the later people became at least ten. Let us now examine each of these feelings separately.

1 - Common sense (2):
- It is also called internal sense. The internal sense is generated by changes in the body’s conditions, especially changes in the muscles, nerves, digestive system, and respiratory system. And circulatory organs. Through it, we become aware of the fatigue of the organs, the degeneration of the nerves, hunger, thirst, chest tightness, suffocation, the contraction of the heart and viscera, and other sensations. It has also been called general internal sensitivity and cénésthenic fever because it is common to all organs. It is closer to emotion than perception. Therefore, it was difficult to rely on him to truly know the inner organs.

Developing this sense is not necessary, because it generates many illusions. Yes, the development of the internal sense allows a person to accurately describe the changes in his internal organs, but we do not need this description, because the patient can know on his own much of what is going on inside him, and then he gives that to the doctor in a precise description. Some neurological diseases are even accompanied by a condition called autoscopic delirium.

If a person pays too much attention to his inner feelings, his delusions increase, he thinks himself sick, and he poisons his life with the fear of an imaginary illness.

3- Touch:
Touch is the first of the senses, and it is essential for every animal. The things that are touched are: heat, cold, humidity, dryness, roughness, smoothness, pressure, heaviness, lightness, hardness, softness, viscosity, and fragility. But scientists removed matters of heat and cold from tangible objects, and established a special sense for them. Touch is therefore a complex sense that includes different elements. As we said, it is the first of the senses, because its machinery is nerves spread throughout all parts of the body, and we can consider each of the senses as a kind of transformation of the nerves. Sight is a state of touch, because its nerves are affected by contact with sound waves. Therefore, scientists said that touch is a basin from which all senses are generated, and perhaps evolution has not yet generated all the senses latent in the body.

The power of touch results from the large number of nerves spread throughout the body. The more nerve-connected an organ is, the stronger the power of touch. For example, the fingertips are more sensitive than the forearm. The forearm has more sensation than the back. Scientists measure the strength of the sense of touch with a Picard (Weber) or a telemeter (Figure 32).

The development of a sense of roughness and smoothness is not necessary for every human being. Rather, it is necessary for cloth and paper merchants. Printing house owners differentiate between rough paper and smooth paper, just as merchants differentiate between woolen fabrics and cotton fabrics.

It may be said that everything that is touched has movement in itself. This combination of movement and touch makes the separation of touch from the motor muscular elements very difficult. However, the feeling of roughness and smoothness does not necessarily require movement, and the best way to cultivate touch is to combine it with muscular sensation, and developing this latter sense is the best means for mastering handicrafts.

(Figure - 32)
1 - A machine to measure the threshold of sensation and its capacity is 2 stereo meters with a pin


3- The sense of heat and cold:
- The ancients used to say that the sense of touch perceives matters of heat and cold, but today’s scientists have proven that matters of heat and cold have a special sense independent of the sense of touch. This is because if you stimulate some parts of the body with subtle stimuli, you will find that sensitivity is not spread across all parts of it equally, and that there are individual points that feel heat and cold, heaviness, pressure, and pain, and that hot points are different from cold points and pressure points. If you want to determine the points of coldness, touch some bare points of hair (such as the back of the hand between the index finger and the thumb), and you will first feel touch, then after a while you will feel coldness.

Charles Riche proved the independence of the sense of heat and cold from the sense of touch with his well-known experiment. This is because he injected a frog with a little strychnine, which doubled its sense of touch and made it lose its sense of the contrast between hot and cold (1). This indicates that these two senses have two different mechanisms.

(Figure - 33)
Pressure, heat and cold points
(Pressure points are black, cold points are white, and the other points are heat points).

The sense of heat and cold does not inform us of the heat and cold of external bodies except by way of addition, because the temperature of bodies is dependent on the temperature of the body. A thing may be hot or cold, but its temperature is additional and we cannot know it except through the body.
A person must therefore doubt this sense because the body is not a measure of temperature.

4- The sense of pain:
When examining the conditions of pleasure and pain (p. 205), we said that some scholars state the existence of a special sense that they call the sense of pain. We can summarize their evidence as follows:
1 - The sensation of pain is later than the sensation of touch and the sensation of heat and cold. This indicates the independence of the feeling of pain from these two sensations.

2- The sensation of pain can be separated from the sensation of touch by injecting some substances into the skin. Either the feeling of pain disappears and the feeling of touch remains, or the feeling of touch disappears and the feeling of pain remains. Both of these examples indicate the independence of the feeling of pain from other sensations.

3 - The sensory nerves in the dermis are independent limbs that perceive pain. The physiologist von Frey proved in 1894 that there are points on the surface of the skin that sense pain, just as there are points that sense heat and cold.

4- Sense of movement:
- It is the sense with which we know the movements and conditions of our organs. Movement is the sister of touch, or as some say it is the sister of all senses, and it is either the movement of moving one place to another, or it is the movement of contraction and relaxation in the organs. An example of this is hand and leg movements. And the fingers, you see them with the sense of movement. Whether the movement is voluntary or involuntary, we perceive it without touching, so we feel the expansion and contraction of our fingers through the joints. Or through the nerves spread throughout the muscles, and it appears that the muscles are the center of the feeling of fatigue, contraction, contraction, and spasm, because they include some sensory nerves, but they are not unique to the feeling of movement. There are sensory nerves in the joints and their coverings that also make us feel passive movements that do not require voluntary effort. Therefore, muscular sensation is important in voluntary movements, because they require muscular effort, while movements that arise from an external cause are caused by the nerves of the joints and tendons of the muscles. In short, scientists call these sensations, whether muscular or joint, the sense of movement (Sens Kinesthesique). The sense of movement is therefore an instrument for detecting effort, fatigue, spasms, and resistance. They distinguished between the feeling of resistance and the feeling of pressure. They said that the first is subordinate to the sense of movement, while the second is subordinate to the sense of touch.

Movements vary according to the different organs and the number of moving muscles, their strength, and their fatigue. They also differ according to the direction, duration, and intensity of the movement.

If I folded my forearms, I felt movement in the elbow, and if I clenched my index fingers as if Ziad was trying to press a gun, I felt fatigue caused by the joints being affected.

The sense of movement has a great influence on generating the perception of place, and there is no room to mention this influence here, because we will return to it in the perception chapter. Let us now confine ourselves to explaining the seriousness of this sense from a practical point of view. This sense has an impact on mastering sports and handicrafts. Look at the sword player how he moves his hand while hitting his opponent. He knows the degree to which his forearm is bent without looking at it. Then look at the skater on the ice, how he pushes his leg forward. He knows the position and direction of his soles, and he knows how to bring his feet closer, how to spread them apart, and how to apply pressure to them with his action. The center of all these sensations is the heel joint above the foot.

If the sense of movement is incomplete in a person, then its possessor is qualified to be a blacksmith or a woodcutter, not a surgeon or dentist.