MUSCLE-JOINT SENSITIVITY

The subject sits down at the kinematometer and closes his eyes. The researcher alternately sets the angle that the subject must subsequently reproduce on the large and small scales of the device. AT

during the performance of this exercise, the following data were obtained (given and performed by the test subject) 48, 52, 45 with a given value of 50 (large scale) 25, 27, 27 with a given value of 25 (small scale) for the first subject and 55, 51 , 54 for a given value of 50 (large scale) 30, 28, 29 for a given value of 30 (small scale) for the second subject.

Based on this, we can say that fine articular-muscular sensitivity is higher, in addition, one of the subjects showed better results, which indicates that his joint-muscular sensitivity is better developed.

TACTILE SENSITIVITY

The subject stretches his arms forward and closes his eyes, opens his palms up, and the researcher simultaneously, without pressure, lowers a weight of 1 to 5 g on the palms of both hands.

By changing the ratio of the weight of the load in the palm of the hand, the researcher determines the minimum difference in the weight of the load that the researcher is able to distinguish. In the course of this exercise, the following data were obtained (the minimum difference in the weight of the load that the subject is able to distinguish) 1 gr. for both test subjects. This is explained by the difference threshold of tactile sensitivity, i.e. the minimum difference in the strength of two stimuli of the same type (weight of cargo on different palms) necessary to change the intensity of sensation.

The difference threshold is measured by a relative value, which shows what part of the initial strength of the stimulus must be added (or reduced) in order to get a barely noticeable sensation of a change in the strength of these stimuli. To feel a minimal increase in the pressure of the load on the hand, an increase in the initial strength of irritation by 1/17 of its initial value is necessary, regardless of the units in which this pressure intensity is expressed.

The subject closes his eyes, and the researcher at the same time, without pressure, lowers the needles of the legs of the compass onto his skin. Consistently reducing the distance between the needles of the legs of the compass, the researcher determines the minimum distance between them, which is perceived by the researcher when touched as the impact of two stimuli.

In the course of this exercise, the following data were obtained (the minimum distance between the needles of the legs of the compass, perceived when touched as the impact of two stimuli) 1 mm for both subjects. This is explained by the phenomenon of the spatial threshold of tactile sensitivity, i.e. the minimum distance between two different, but adjacent points, the simultaneous stimulation of which causes two independent, distinct tactile sensations.

Touch sensations occur when a mechanical stimulus causes deformation of the skin surface. When pressure is applied to a small area of skin (less than 1 mm), the greatest deformation occurs precisely at the site of direct application of the stimulus. If pressure is exerted on a large surface (more than 1 mm), then it is distributed unevenly, its least intensity is felt in the depressed parts of the surface, and the greatest along the edges of the depressed area.

ARISTOTLE’S EXPERIENCE

The subject rolls a small ball between the index and middle fingers, while he makes sure that he perceives it as one object. If the subject rolls the same ball between the crossed fingers so that it is between the medial (inner) surface of the index finger and the lateral (outer) surface of the middle finger, he can verify that the perception of the presence of two balls is created. This is due to the phenomenon of the illusion of touch, which can arise under the influence of immediately preceding perceptions. In this case, the fact that the medial surface of the index and the lateral surface of the middle finger under normal conditions can be simultaneously irritated by only two objects. There is an illusion of irritation with two objects, because. in the brain there are two centers of excitation.

PUPIL REACTION

The subject becomes facing daylight, and the researcher measures the width of his pupil. Then one eye of the subject is covered with a hand and the width of the pupil of the open eye is measured. Then the closed eye is opened and the width of its pupil is again measured.

During this exercise, the following data were obtained (pupil width) 5 – 7 – 5 mm and 6 – 8 – 6 mm for the first and second subjects, respectively. Thus, the pupil width changed by an average of 2 mm, and the pupillary reaction time did not exceed 1 sec for both subjects. When both eyes were closed for 30 sec, the pupil width was 5–9–5 mm and 6–10–6 mm, respectively, while the pupillary reaction time did not exceed 1 sec.

The subject fixes his gaze on a distant object, and the researcher measures the width of his pupil, then the subject fixes his gaze on an object 15 cm distant, and the researcher again measures the width of his pupil. During this exercise, the following data were obtained (pupil width) 5 – 3 mm and 6 – 4 mm for the first and second subjects, respectively. Thus, the pupil width changed by an average of 2 mm, and the pupillary reaction time did not exceed 1 sec for both subjects.

From the foregoing, it follows that the reaction of the pupil to light in both subjects is at the same level, and the difference in indicators is due to individual differences (in this case, pupil width at rest).

SPHERICAL ABERATION

The subject closes one eye, and brings a pencil close to the other, to such a distance that the image is blurry, then a sheet of paper with a hole 1 mm in diameter is placed between the pencil and the eye, and the object becomes clearly distinguishable. This is explained by the fact that spherical aberration is better expressed for the central beams. In the course of this exercise, the following data were obtained (the distance from the eye to the pencil at the moment when it becomes less clearly distinguishable) 10 cm and 11 cm for the first and second subject, respectively.

Looking at a pattern of vertical and horizontal lines, the subject fixes his gaze on the vertical and then on the horizontal lines and makes sure that he cannot see the horizontal and vertical lines equally clearly.

The subject looks through a thin grid at the printed text from a distance of 50 cm from the eye, if you fix the letters with your eyes, then the threads of the grid are less visible, and if you fix the grid with your eyes, then the letters.

From the foregoing, it follows that the subject cannot simultaneously clearly see two objects at different distances due to the fact that the optical system of the eye has spherical aberration, i.e. the focus of the peripheral rays is closer than the focus of the central ones.

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