The concept of the strength of the nervous system was advanced by I. P. Pavlov in 1922. In the study of conditioned reflex activity of the brain of animals it was found that the greater the intensity of the stimulus or the more often it the more the conditioned reflex response is applied. However, at reaching a certain high intensity or frequency of stimulus conditioned reflex response begins to decline.
In animals with weak the nervous system this decline begins with less intensity and frequency of the stimulus than in animals with a strong nervous system. It gave reason to diagnose the strength of the nervous system in two ways: by maximum intensity of a single stimulus and by quantity irritations of medium strength.
The first method is called «measurement of force over the upper threshold», the second — «the measurement of force through its endurance» In the laboratory of B. M. Teplova, a greater sensitivity of the weak nervous system was detected in comparison with a strong one. From here came another way to measure strength — through the speed of human response to signals of varying intensity, subjects with a weak nervous system react to weak and medium-intensity signals faster than subjects with a strong nervous system. In this case, the strength of the nervous system is determined by «Lower threshold».
Physiological rationale. Repeated submission an equally strong stimulus at relatively short intervals of time causes the phenomenon of summation, i.e., an increase in reflex responses over growth expense background activation (arousal) of increased excitability in those neurons that respond to the stimulus since each previous excitement leaves a trail and therefore each subsequent excitation begins at a higher functional level (activation rest) than the former.
Since the initial level of activation in subjects with weak nervous system is higher, then the phenomenon of excitation summation and the associated increase in response (despite constant physical parameters force of the stimulus) will quickly reach its limit, beyond which comes inhibitory effect, it is in the «weak». The «strong» because of the lower activation of the rest there is a greater «margin of safety» and therefore the summation they may last longer without reaching the response limit.
Since the amount of summation is determined by the duration of stimulus (time or number of repetitions of the stimulus), strong the nervous system is more resilient than the weak. It means that with repeated presentation of the same strength of the stimulus reduction response effect (magnitude or reaction rate) of the «weak» will happen faster than the «strong». Various methods are based on this.
Determine the strength of the nervous system through its endurance. Two significant points should be noted. First, you can not determine the strength of the nervous system through endurance when using weak intensity stimuli, as in this case occurs the reverse of the required: weak stimuli reduce rather than increase activation of the nervous system. As a result, more hardy to monotonous.
Subjects with a weak nervous system turn out to be an irritant, and not with strong. Secondly, not every measure of endurance can serve the criterion of the strength of the nervous system. Physical work related to aerobic endurance, i.e. with efficiency of functioning of the cardiovascular and respiratory systems, cannot be considered as a model to measure the strength of the nervous system. The latter is determined by endurance nerve cells, integrative systems of the brain, so the samples should be focused on the ease of transition of nerve formations in the beyond braking by I. P. Pavlov.
«Tapping test» is a method for diagnosing health and development of overwork. The method is based on measuring the speed drop reactions with continuous dynamic load. It allows you to identify adverse states of the central nervous system indicating on the development of fatigue, including in the process of learning activities, and also allows you to identify a predisposition to rapid fatigue. Test not requires additional equipment for its use.
The test duration is 30 seconds. After diagnostic test subject receives a negative or positive result indicating the absence or presence of negative states of the central nervous system of the subject. Positive the test result indicates the development of a state of fatigue and how consequence of a decrease in reaction rate and performance below normal.
Of particular note is the use of dough for individual diagnostics. The state of overwork, determined by the test, may have significant negative health effects. At the same time test due to its simplicity and efficiency, it can be very useful for people who care about their health. For the test, you need a stopwatch, a pencil and a sheet of paper.
A square of 20 X 20 cm is put on the paper and divided by two lines into four equal parts. The subject for 10 seconds at the maximum rate puts the points in the first square, after 20 s — in the second, and so on. So that the points do not lay down against each other, it is recommended to move the hand in a circle. For rate results count the number of points in each square, connecting all the points between themselves. A sharp decrease in the frequency of movements, i.e. a decrease in the number of points from square to square, indicates a lack of mobility of the nervous processes, and she, in turn, is about slowing down the process of workability.
This test is used to control speed, agility and development of fatigue.
Technique «Taping-test». The test is based on the time change of the maximum rate of movement of the brush. Test subjects in. For 30 seconds they try to keep the maximum tempo for themselves. Indicators tempos are fixed every 5 seconds and six points received builds the performance curve of the subject.
Equipment required for research. To register the frequency movements can use simple equipment: a key telegraph, dimming button with little or little resistance contact area; the power source can be a battery or electric network, the number of movements is recorded by an electric meter pulses (if it is one, then it’s better with a dial indicator, it’s easier to visually set the position of the arrow at the time of the signal about the expiration of the next 5 seconds; you can use two digital counters that switch automatically every 5 seconds; in row laboratories use instruments with six electronic digital indicators that allow you to flash all points of the curve at once health). For practical purposes it is more convenient (in the sense of transportability) equipment with one or two meters; with six indicators devices are very bulky and difficult to transport, they are convenient for stationary conditions.
In the absence of recording equipment, you can use graphic way to record the maximum pace of movement. For this a sheet of paper is divided into six squares arranged in two rows.
The subject should be a pencil or pen put in each square for time allotted to him (5 seconds each) as many points as possible. Transition from one squares in the other should be made in a clockwise direction, not interrupting work. Unfortunately, a slight loss of time with all do occur, so with this method of recording the frequency of movements there are fewer cases with a convex curve type, since at first the square of time for the transfer of the pencil is not lost, and the loss concerns the second square compared to the first, and to avoid this, we must put the pencil before starting work is not in the first square, but in front of it. Then share seconds will be lost when moving the pencil to each square and the inequality of the time spent by the pencil first and subsequent squares disappears.
The study procedure. After preliminary testing instrumentation and determine the maximum for 5 seconds pace of movements the subject proceed to the experiment. The subject is given a task work with a maximum frequency for 30 seconds. In the instructions emphasizes that the subject should work all the time at the maximum volitional effort, even if he notices that his pace of movement will decrease. He is warned that the greater the numbers of movements he will have time in the allotted time, the stronger his nervous system.
Actually, another criterion is used for diagnosis. If there is a device for recording the frequency of movements with six automatically switching every 5 seconds with counters, there are no problems in reading the indicators. If I eat indicators of the frequency of movements produced from one counter (digital or dial gauge), then an assistant is needed who monitors stopwatch, giving a signal (“Start!”) to the patient and every 5 seconds the experimenter (the signal is better to give a sharp pressure with his hand on his shoulder the experimenter).
With small samples in order to establish any patterns It is advisable to combine in one group of persons with large (strong) and medium strength of the nervous system, and in another group of people with medium-weak and weak nervous system, although it has been experimentally proved that each of the four groups reflects differences in the strength of the nervous system, i.e. that degree the severity of force in subjects with a convex curve type is higher than with even type, and in the latter — higher than in subjects with an intermediate type etc.
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