RU2233115C1 - Method for detecting lability of human vision system - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: the present innovation enables to detect lability of human vision system by the following technique: a patient is suggested a sequence of paired light impulses of preset duration being 110, 90, 70, 50, 30, 10, 5 1 msec, correspondingly, divided with interimpulse interval being equal to 150 msec repeated every constant time interval of 1 sec. At every preset duration of light impulses the duration of interimpulse interval between light impulses in the pair should be decreased till patient could determine the moment of subjective blending of two light impulses in the pair into a single one. Duration of interimpulse interval between light impulses in the pair at present moment is considered to be a threshold duration of interimpulse interval. One should calculate the time for perception of visual information

where

- duration of light impulse,

- threshold duration of interimpulse interval between light impulses in the pair. One should plot the function

to find minimum function. Lability of human vision system should be stated to be equal to frequency value in Hz in point of minimum function

Hz. The innovation enables to detect true value for lability of human vision system.

EFFECT: higher efficiency of detection.

4 dwg, 1 ex, 1 tbl

Description

The invention relates to medicine and is intended to determine the lability of the human visual system.

A known method for determining the lability of the visual system of a person using the critical frequency of fusion of light flickers (CFSM). The maximum frequency of rhythmic stimuli, at which the subject ceases to distinguish between the pulsation of light signals or begins to distinguish them with a gradual decrease in the frequency of flickering from maximum to minimum, serves as a measure of lability [1].

A known method of studying the lability of the human visual system using a neurochronometer. According to this method, the subject is presented with light flicker with a frequency of from 7 to 60 Hz. The moment when individual flickers merge into continuous light, the subject marks the word “together”. The moment of occurrence of individual flickers - the word "separately." A measure of lability is the arithmetic mean between the merger frequency and the frequency of occurrence of individual flickers. The upper and lower boundaries are determined repeatedly, at least five times each [2].

A known method for determining the time of perception of visual information. In this method, the test subject is presented with two light pulses of a given duration equal to 50 ms, separated by a pause, repeated through a constant time interval of 1.5 s. The duration of the pause between light pulses is reduced until the subject determines the moment of subjective merging of two light pulses into one. The time of perception of visual information by a person is taken equal to the value of the sum of the duration of the light pulse and the duration of the pause between two light pulses at the moment of subjective merging of two light pulses into one [3].

A disadvantage of the known methods is an unreliable determination of the true value of lability.

None of the known methods can be adopted as a prototype to the proposed method for determining the lability of the human visual system.

It is known that a measure of lability is the maximum frequency of reactions that an organ can reproduce in exact accordance with the rhythm of the applied stimuli [4].

The lability of the human visual system is limited by its inertia, that is, by the time the visual sensation of time exists between the moment of light exposure on the retina and the moment the corresponding visual sensation occurs, and the time of restoration of time between the moment the light stops acting on the retina and the moment the corresponding visual sensation disappears [4, 5] .

In FIG. 1 shows time diagrams of two light pulses of duration τ _imp , separated by the interpulse interval t of the _mission , and the visual sensations caused by them, where:

- FIG. 1a is a timing diagram of two light pulses separated by an interpulse interval t of a _mission , causing a visual sensation of impulse separation;

- FIG. 1b is a timing diagram of the visual sensation of two light pulses shown in FIG. 1a;

- FIG. 1c is a timing diagram of two light pulses separated by a threshold interpulse interval t _pop , at which a subjective sensation of fusion of two light pulses in a pair into one is achieved;

- FIG. 1d is a timing diagram of the visual sensation of two light pulses shown in FIG.

- τ ₁ is the time of visual sensation;

- τ ₂ is the recovery time;

- t _take - time perception of visual information.

When a subject presents two light pulses with a duration of τ _imp > τ ₁ separated by an interpulse interval t _mission > t _pop (Fig. 1a), he experiences a subjective sensation of separation of two light pulses (Fig. 1b). With a decrease in the duration of the interimpulse interval t of the _mission between two light pulses to a value of t _mission = t _pop (Fig. 1c), the subject experiences a sensation of subjective merging of two light pulses into one (Fig. 1d).

The time of perception of visual information is _taken as the time interval from the beginning of the first light pulse to the beginning of the second light pulse when the light pulses in a pair merge into one.

The proposed method allows to determine the true value of the lability of the human visual system.

The proposed method for determining the lability of the human visual system is that the subject is presented with a sequence of paired light pulses of a given duration equal to 110, 90, 70, 50, 30, 10, 5, 1 ms, respectively, separated by an interpulse interval of 150 ms, repeated through a constant time interval of 1 s, in which for each given duration of light pulses in the first measurement stage, the duration of the inter-pulse interval is reduced discretely with a given constant step of 0.4 ms, until the subject it limits the moment of subjective merging of two light pulses in a pair into one; at the second stage of measurements, the duration of the interpulse interval is increased discretely with a given constant step of 0.2 ms, until the subject determines the moment of subjective sensation of the separation of two light pulses in a pair, at the third stage of measurements, the duration of the interpulse the interval is reduced discretely with a given constant step of 0.1 ms, until the subject determines the moment of subjective fusion of two light pulses in a pair into one, while the inter-pulse interval between the light pulses in the pair at a given time is taken as the threshold duration of the inter-pulse interval, the time of perception of visual information is calculated

T _take = τ _imp + t _then

where τ _imp - the duration of the light pulse;

t _pop - threshold duration of the interpulse interval between light pulses in a pair, plot the function

t _take = f (τ _imp ),

find the minimum of the function, the lability of the human visual system is taken equal to the frequency value in Hz at the minimum point of the function

In FIG. 2 presents a timing diagram of a sequence of paired light pulses presented to determine the lability of the human visual system, where:

t _NMI - the initial duration of the interpulse interval;

T is a constant time interval for the repetition of pairs of light pulses;

τ _imp - the duration of the light pulse.

In FIG. Figure 3 presents a time diagram of the change in the duration of the inter-pulse interval between light pulses in a pair when determining the lability of the human visual system.

The proposed method for determining the lability of the human visual system is as follows.

The test subject is presented with a sequence of paired light pulses of a given duration τ _imp equal to 110 ms, separated by an interpulse interval of the initial duration t _nm , equal to 150 ms, repeated through a constant time interval T equal to 1 s (Fig. 2; Fig. 3, time interval T ₀ -T ₁ ).

The duration of the inter-pulse interval between light pulses in a pair is reduced until the subject determines the moment of subjective fusion of two light pulses in a pair into one.

At the first stage of the measurements, the initial duration of the _inter -pulse interval τ of the _signal between the light pulses in a pair is reduced discretely with a given constant step of 0.4 ms (Fig. 3, the time interval T ₁ -T ₃ ) until the subject determines the moment of subjective fusion of two light pulses in pair in one (Fig. 3, point in time T ₃ ).

At the second measurement stage, the duration of the inter-pulse interval t of the _mission between the light pulses in a pair is increased discretely with a given constant step of 0.2 ms (Fig. 3, the time interval T ₄ -T ₆ ), until the subject determines the moment of subjective sensation of the separation of two light pulses in a pair (Fig. 3, point in time T ₆ ).

At the third stage of measurements, the duration of the interpulse interval t of the _mission between the light pulses in a pair is reduced discretely with a given constant step of 0.1 ms (Fig. 3, the time interval T ₇ -T ₈ ) until the subject determines the moment of subjective fusion of two light pulses in a pair in one (Fig. 3, point in time T ₈ ). The duration of the interpulse interval t of the _mission between the light pulses in the pair at time T _{8 is} taken as the threshold duration t _{pop of the} interpulse interval.

The time of perception of visual information is calculated:

t _take = τ _imp + t _then

where τ _imp - the duration of the light pulse;

t _{p the} threshold duration of the interpulse interval between light pulses in a pair.

Similarly, the measurement process is carried out at light pulse durations of 90, 70, 50, 30, 10, 5, and 1 ms.

_{Using the} measured values of the threshold duration of the interpulse interval t _pop obtained at various light pulse durations T _imp , a function graph is constructed

t _take = f (τ _imp ),

which determine the minimum.

The lability of the human visual system is taken equal to the frequency value in Hz at the minimum point of the function

It is known that with rhythmic stimulation, the response of the human visual system in exact accordance with the frequency of light pulses is observed only at frequencies of no more than 13-15 Hz [6]. At higher repetition rates of light pulses, sequential visual masking is observed [7], which consists in the fact that part of the light pulses are not perceived.

The value of visual information perception time t _CTB obtained in function of the minimum point F, at which the subjective feeling of merging two light pulses in a pair in one determines a threshold period beyond which the visual system can perceive light pulses in exact accordance with their frequency.

Therefore, for the lability of the human visual system, the repetition rate of light pulses in Hz at the minimum point of the function F can be taken

The initial duration of the _inter -pulse interval t _{NMI was} chosen equal to 150 ms from the analysis of the temporal parameters of the development of the receptive field (RP). In well-known studies, upon presentation of test flashes, the dynamics of RP developed as follows [8]. In the tested section of the field of view, at first an RP of a small size appeared. Then the responses intensified, and the recorded RP field expanded, after which it weakened, fragmented, and disappeared. The dynamics of RP during the development of the on- and off-response turned out to be similar. A statistical evaluation showed that for different neurons, the appearance of a registered RP field falls mainly on 20-80 ms after the stimulus is turned on, the maximum expansion of RP falls on 60-100 ms, and its disappearance in a period from 100 to 200 ms.

Since the disappearance of RP occurs in the period of 100-200 ms after the presentation of the test flash, two light pulses will appear separate if the second light pulse is presented 100-200 ms after the start of the presentation of the first light pulse. Therefore, the initial duration of the _inter -pulse interval t _{NMI is} chosen equal to 150 ms.

It is known that the perception of a visual stimulus is hampered under the conditions of reverse masking, which consists in the deterioration of the perception of the first time stimulus due to the presentation of the second stimulus in the immediate spatio-temporal proximity to the first. It was shown that there is not only a reverse effect, but also direct masking, in which the first stimulus affects the quality of perception of the second [9]. With an interstimulus interval of 500 ms, masking effects are absent or weakly expressed [10]. To eliminate the masking effect, the sequence of paired light pulses is repeated at a constant time interval of 1 s.

Thus, the inventive method for determining the lability of the visual system has new properties that determine the receipt of a positive effect.

Example. Subject N., 20 years old, using a personal computer compatible with IBM PC that _{outputs light flickers} through the LPT port to the indicator of the subject's remote control, showed a sequence of paired light pulses of duration τ _imp equal to 110 ms separated by an interpulse interval of initial duration t _nm equal to 150 ms repeating through a constant time interval T of 1 s (FIG. 2; FIG. 3, time interval T ₀ -T ₁ ).

During measurements, signals from the buttons “Decrease 0.4 ms”, “Increase 0.2 ms”, “Decrease 0.1 ms” and “Measurement” were sent to the personal computer from the remote control of the test person via the LPT port.

When a signal from the “Decrease 0.4 ms” button arrives, the computer discretely decreases the duration of the inter-pulse interval between light pulses paired with a predetermined constant step of 0.4 ms, when a signal arrives from the “Increase 0.2 ms” button, it discretely increases with a predetermined constant increments of 0.2 ms, upon receipt of a signal from the button, "Decrease 0.1 ms" - discretely reduced with a given constant increment of 0.1 ms.

At the first stage, the test subject, giving a signal from the "Decrease 0.4 ms" button (Fig. 3, time interval T ₁ -T ₃ ), determined the moment of subjective merging of two light pulses in a pair into one (Fig. 3, time moment T ₃ )

At the second stage, the test subject, giving a signal from the “Increase 0.2 ms” button (Fig. 3, time interval T ₄ -T ₆ ), determined the moment of subjective sensation of the separation of two light pulses in a pair (Fig. 3, time moment T ₆ ) .

At the third stage, the test subject, giving a signal from the “Decrease 0.1 ms” button (Fig. 3, time interval T ₇ -T ₈ ), determined the moment of subjective merging of two light pulses in a pair into one (Fig. 3, time point T ₈ ), then gave a signal from the "Measurement" button (Fig. 3, time point T ₉ ).

The computer recorded the duration of the threshold interpulse interval between light pulses in a pair, calculated the value of the time of perception of visual information using the formula

t _take = (τ _imp + t _pop ) = (110 + 10.9) = 120.9 ms,

where τ _imp - the duration of the light pulse;

t _pop is the threshold duration of the interpulse interval between light pulses in a pair, determined at the third stage of measurements at time T ₈ (Fig. 3).

Then the computer displayed the value of the time of perception of visual information on the monitor screen, entered the measurement result in the archive and presented the initial sequence of paired light pulses.

In accordance with the recommendations of physiologists, the subject performed a series of 10 measurements. As a result of the measurements, the following values of the time of perception of the subject’s visual information in ms were obtained: 120.9; 121.3; 121.2; 120.3; 120.5; 121.1; 120.5; 121.2; 121.0; 121.7. The arithmetic average of the measured values of the time of perception of visual information is 120.97 ms, the standard deviation is 0.09 ms, the confidence limits of the random component of the error of the measurement result with a confidence probability of 0.95, taking into account the student coefficient of 0.20 ms.

Similarly, the subject performed measurements of the time of perception of visual information with durations of light pulses equal to 90, 70, 50, 30, 10, 5, and 1 ms.

The results of processing the measurement results are shown in the table.

_{Using the} measured values of the threshold duration of the interpulse interval t _pop obtained at different light pulse durations τ _imp , we plotted the function t _take = f (τ _imp ), shown in Fig. 4, which defines the minimum of the function t _take = 47.95 ms at τ _imp = 10 ms.

The lability of the human visual system is taken equal to the frequency value in Hz at the minimum point of the function

Thus, the proposed method allows to determine the true value of the lability of the human visual system.

Sources of information

1. Makarenko N.V. The critical frequency of light flickering and alteration of motor skills // Human Physiology. - 1995. - T. 21. - No. 3. - S.13-17.

2. Peysakhov N.M. Patterns of dynamics of mental phenomena. - Kazan: Publishing house Kazan. University, 1984. - 235 p.

3. Patent No. 2209030 of the Russian Federation. A method for determining the time of perception of visual information / V.V. Rozhentsov, I.V. Petukhov (RF). - 16 p.

4. Semenovskaya E.N. Electrophysiological studies in ophthalmology. - M .: Medgiz, 1963 .-- 279 p.

5. Kravkov S.V. Eye and his work. Psychophysiology of vision, lighting hygiene. - 4th ed., Revised. and add. - M.-L.: Publishing House of the Academy of Sciences of the USSR, 1950 .-- 531 p.

6. Anokhin P.K. Nodal questions of the theory of a functional system. - M .: Nauka, 1980 .-- 196 p.

7. Supin A.Ya. Neural mechanisms of visual analysis. - M .: Nauka, 1974. - 192 p.

8. Shevelev I.A. Temporary signal processing in the visual cortex // Human Physiology. - 1997. T. 23. - No. 2. - S.68-79.

9. Kropotov Yu.D., Ponomarev V.A. The reaction of neurons and evoked potentials in the subcortical structures of the brain during visual recognition. Message IV. The effect of masking visual stimuli // Human physiology. - 1987. - T.13. - No. 4. - S. 561.

10. Taroyan N.A., Myamlin V.V., Genkina O.A. Interhemispheric functional relations in the process of solving a visual-spatial problem by a person // Human Physiology. - 1992. - T.18. - No. 2. - C.5.

Claims (1)

A method for determining the lability of the human visual system, which consists in the fact that the test subject is presented with a sequence of light pulses of a given duration, characterized in that the light pulses are paired light pulses with a duration of 110, 90, 70, 50, 30, 10, 5 and 1 ms, the interpulse interval is equal to 150 ms, the pulses are repeated through a constant time interval equal to 1 s, in which for each given duration of light pulses in the first stage of measurements, the duration of the interpulse interval is reduced discretely at a given constant step of 0.4 ms, until the subject determines the moment of subjective fusion of two light pulses in a pair into one, at the second measurement stage, the duration of the interpulse interval is increased discretely with a given constant step of 0.2 ms, until the subject determines the moment of subjective sensation of separation of the two light pulses in a pair, at the third stage of measurements, the duration of the inter-pulse interval is reduced discretely with a given constant step of 0.1 ms, until the subject determines the moment of subjective merging of two light pulses in a pair in one, while the duration of the interpulse interval between light pulses in a pair at a given time is taken as the threshold duration of the interpulse interval, calculate the time of perception of visual information t _take = τ _imp + t _then where t _take - the time of perception of visual information, ms; τ _imp - the duration of the light pulse, ms; t _pore is the threshold duration of the inter-pulse interval between light pulses in a pair, ms, build a graph of the dependence of the time of perception of visual information on the duration of the light pulse, find the minimum of the function, and take the lability of the human visual system equal to the frequency at the minimum point of the function, defined as

where F is the frequency at the minimum point of the function, Hz.

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