Method for determining human vision system persistence time

FIELD: medicine.

SUBSTANCE: method involves showing sequence of two luminous pulses of 10 ms duration separated by 150 ms long pause. The pulses are repeated in constant 1.5 s long interval. Pause duration between two luminous pulses is reduced at the first measurement stage at constant speed of 20ms/s until a testee fixes fusion of two luminous pulses into single one in subjective assessment mode. Pause duration between two luminous pulses is increased at the second measurement stage with given constant step of 0.4 ms until the testee identifies the moment of subjective perception of two luminous pulses separation. Pause duration is reduced in discrete mode with given constant 0.1 ms long step at the third measurement stage until the testee identifies the moment of subjective perception of two luminous pulses fusion into single one. Human vision system persistence time is determined to be equal to pause duration between two luminous pulses when subjective fusion into single pulse takes place at the third measurement stage.

EFFECT: high accuracy in determining human vision system persistence time.

3 dwg

 

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

A known method for determining the time of inertia of view using a pendulum and contrast filters [1]. In this way measured threshold contrast ε for a given object at a stationary observation, then at different contrasts Topcreated set of filters, bring an effective contrast Toeto the threshold of visibility of the selection of the exposure time τ set the amplitude of swing of the pendulum. During the inertia is made effective time saving visual impressions, which, when the exposure time τ <0,01 s is determined by the formula

θ =Kpτ/ε .

The disadvantage of this method is the use of mechanical principle job exposure time, which reduces the accuracy of the time of inertia.

Known method of tachistoscope for measuring the threshold time required for recognition of presented images [2]. The threshold time of recognition of the image depends on the parameters of the inertia of the visual system [3]. In this way in the centre of the pre-exposure field projecting a fixation point, which is used as a signal of readiness. The fronts field exposure-1.5-2.0 MS. Time expose the tion varies with the electronic device with a minimum step of 1.5 MS.

The disadvantage of this method is its complexity and low measurement accuracy threshold time of recognition of the image resulting from prolonged fronts field exposure, components and duration of stimuli presentation order of 10 MS at least 3-4 MS.

Known studies inertia of the human visual system using electroretinography and visual evoked cortical potentials [4, 5].

The common disadvantage of the methods is a long preparatory period before the research, the need to use special equipment, the complexity of behavior research.

The closest to the technical nature of the proposed method is a method for determining the time the inertia of the human visual system by presenting the subject light pulses, namely, that the subject produces a sequence of two light pulses of a given duration that is equal to, for example, 50 MS, separated by a pause equal to, for example, 150 MS, repeated at a constant time interval of the order of 1.5 s pause time between the light pulses is reduced, until the subject will determine the point of subjective fusion of two light pulses in one, and the first step measurements reduce the duration of a pause between two light pulses with a given the permanent speed order 20 MS/s, until the subject will determine the estimated subjective fusion of two light pulses in one, at the second stage of measurements increase the duration of a pause between two light pulses with a given constant speed of the order of 5 MS/s, until the subject will determine the point of subjective feelings of separateness of the two light pulses, in the third phase measurements reduce the duration of a pause between two light pulses with a given constant speed of 2 MS/s, until the subject will determine the point of subjective fusion of two light pulses at one time the inertia of the human visual system is equal to the value of the pause time between two light pulses at the moment of subjective fusion of two light pulses in one defined in the third phase measurements [6].

The disadvantage of this method is:

- the impossibility of determining the time of persistence in the absence of a signal generated by the off-system about the end of the light pulse. It is known that at all levels of the visual system there are two different ways of signal transmission: direct path and the path of the transmission signal on the horizontal relations. On the straight path is transmitted excitation from level to level, and horizontal communication occurs tormoznoy-stimulatory interaction between neurons at each level sees the school system. When this braking process occurs in 15-20 MS later excitative, therefore, when the pulse duration, less 15-20 MS, off-the response of neurons does not occur [7, 8]. For this reason, time, inertia when the pulse duration smaller, 15-20 MS, is determined when no signal is generated off-system about the end of the light pulse, while the duration of the light pulses of 50 MS, time, inertia is determined in the presence of off-response;

- low accuracy of the time inertia, because the definition of subjective moment of the fusion of two light pulses in one occurs when a continuous change of the length of time that is in continuous adaptation of the visual system to continuously changing parameter.

The proposed method for determining the time the inertia of the human visual system allows you to:

- to determine the time the inertia of the human visual system in the absence of off-answer about the end of the light pulse.

to increase the accuracy of the time of persistence of the visual system.

The proposed method for determining the time the inertia of the human visual system, namely, that the subject produces a sequence of two light pulses of a given duration, separated by a pause equal to 150 MS, duplicate h the rez constant time interval of 1.5 s, and the first step measurements reduce the duration of a pause between two light pulses with a given constant speed of 20 MS/s, until the subject will determine the estimated subjective fusion of two light pulses in one, at the second stage of measurements increase the duration of a pause between two light pulses, until the subject will determine the point of subjective feelings of separateness of the two light pulses, in the third phase measurements reduce the duration of a pause between two light pulses, until the subject will determine the point of subjective fusion of two light pulses at one time the inertia of the human visual system is equal to the value of the pause time between two light pulses at the moment of subjective the merger of the two light pulses in one defined in the third phase measurements, wherein the duration of the light pulses is equal to 10 MS, the second stage of measurements increase the duration of a pause between the two light signals discretely with a given constant pitch of 0.4 MS, the third phase measurements reduce the duration of a pause between the two light signals discretely with a given constant step size of 0.1 MS.

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

On Phi is .1 presents the timing diagram shown light pulses to determine the time the inertia of the human visual system, where:

τ - the duration of the light pulse;

tPNACthe initial duration of a pause between the two light signals;

T is a constant time interval between repeated two light pulses.

Figure 2 presents a time chart of the changes in the time duration tpbetween two light pulses in figure 3 - timing diagram of two light pulses of duration τ separated by a pause and the resulting visual sensations, where:

- figa - time diagram of two light pulses, separated by a pause in tpcausing a visual sensation of separateness pulses;

- PIGB - temporal diagram of the visual sensations of the two light pulses presented on figa;

- FIGU - time diagram of two light pulses, separated by a threshold pause tpor, which guarantees the subjective feeling of the merger of two light pulses in one;

- high - temporal diagram of the visual sensations of the two light pulses presented on FIGU;

- τ1- time visual experience - the time between the moment the effects of light on the retina and the moment of occurrence of the corresponding visual experience [9, 10] (figh);

- τ2- recovery time - the time between the date of termination of the light exposure on the retina and mo is entom disappearance of the corresponding visual experience [9, 10] (figb).

The subject produces a sequence of two light pulses of desired duration τ equal to 10 MS, divided by the initial pause in tPNACequal to 150 MS, repeated at a constant time interval T, is equal to 1.5 (figure 1, figure 2, the time interval T0-T1).

At the first stage of measurement, the duration of the initial pause tPNACbetween the two light pulses is reduced with a given constant speed of 20 MS/s (figure 2, the time interval T1-T2), until the subject will determine the estimated subjective fusion of two light pulses in one (figure 2, point in time T2).

In the second stage of the measurement pause time tpbetween two light pulses increase discretely with a given constant pitch of 0.4 MS (figure 2, a time interval T2-T3), until the subject will determine the point of subjective feelings of separateness of the two light pulses (figure 2, point in time T3).

In the third stage of the measurement pause time tnbetween two light pulses reduce discretely with a given constant 0.1 MS (figure 2, a time interval T3-T4), until the subject will determine the point of subjective fusion of two light pulses in one (figure 2, point in time T4).

The pause time tporbetween the two svetosimunska, defined in the third phase measurements is equal to the time the inertia of the human visual system.

Under the inertia of view understand elongation visual experience after turning off the stimulus [11]. During the duration of the stimulus picture passing the excitatory and inhibitory processes in the receptive fields of neurons known [7]. As a result of these processes receptive fields of neurons undergo 3 phases of restructuring. During the first phase duration of about 10 MS is spatio-temporal accumulation of signals and the formation of a zone of excitation receptive fields. During the second phase, lasting from 50 to 60 MS, depending on the parameters of the stimulus, the process of narrowing zone summation receptive fields. During the third phase of restructuring is expanding zones of combining receptive fields and functional disorganization. Neural patterns come in its original state and ready for a new cycle of perception.

As the first phase of the formation of receptive fields of neurons, i.e. the emergence of the SOS response that ends after a time of about 10 MS after the presentation of the light stimulus, the duration of the light pulses has been taken equal to 10 MS. When such a pulse duration off-the response of neurons does not occur, the time of persistence of the visual system is determined by the PR is the lack of off-response.

Upon presentation of the subject of two light pulses of duration τ >τ1separated by a pause in tp>tpor(figa), the processes of excitation and inhibition in the receptive fields of neurons caused by the first pulse ends, the neural patterns come in its original state and be ready to perception the second pulse, so the test occurs subjective sense of separateness of the two light pulses (figb).

When reducing the length of time tnbetween two light pulses to a value of tp=tpor(pigv) the processes of excitation and inhibition in the receptive fields of neurons caused by the first pulse, do not have time to finish, neural structures do not come in original condition and not ready to perception the second pulse, so the test there is a feeling of subjective fusion of two light pulses in one (high).

Thus, the inventive method of determining the time of the inertia of the human visual system has new properties that govern the receipt of a positive effect.

Example. The subject P., 21, using a personal computer compatible with the IBM PC, issuing through the LPT port on the indicator panel of the test light pulses were presented with a sequence of two light pulses glutelin the STI τ equal to 10 MS, divided by the initial pause in tPNACequal to 150 MS, repeated at a constant time interval T, is equal to 1.5 (figure 1, figure 2, the time interval T0-T1).

In the measurement process via the LPT port on a personal computer with remote control of the test was applied signals from the buttons "continuous Decrease", "Increase of 0.4 MS", "Decrease by 0.1 MS" and "Measurement". When the presence of a signal from the button "Reducing a continuous computer continuously reduced the duration of a pause between two light pulses with a speed of 20 MS/s, upon receipt of the signal from the button "Increase of 0.4 MS" increased discretely 0.4 MS, upon receipt of the signal from the button "Decrease of 0.1 MS was reduced discretely 0.1 MS, upon receipt of the signal from the button “Measurement” fixed pause time tporbetween two light pulses, took the time value of persistence at the screen, put it in the archive and made the initial sequence of two light pulses.

At the first stage of the measurement subject, feeding the signal from the button "rapid Decrease" (figure 2, the time interval T1-T2), has determined the estimated subjective fusion of two light pulses in one (figure 2, point in time T2).

In the second stage of the measurement subject, feeding the signal from the buttons "Zoom 0.4 MS (figure 2, the interval in which the time T 2-T3), determined the point of subjective feelings of separateness of the two light pulses (figure 2, point in time T3).

In the third stage of the measurement subject, feeding the signal from the button "Decrease of 0.1 MS (figure 2, the time interval T3-T4), determined the point of subjective fusion of two light pulses in one (figure 2, point in time T4), then gave the signal from the button “Measurement” (figure 2, point in time T5).

The computer has determined the length of time tpor=56,2 MS between two light pulses recorded test at time T5(figure 2), took the time value of persistence at the screen, put it in the archive and presented initial sequence of two light pulses.

In accordance with the recommendations of psychologists, the subject performed a series of 10 measurements. In the measurement result obtained the following values of time the inertia of the visual system of the subject, MS: 56,2; 56,4; 56,8; 56,7; 56,9; 57,2; 57,3; 57,8; 57,6; 58,2. The arithmetic mean of the measured time values of the inertia of the visual system is 57,11 msec, root mean square deviation of 0.13 MS, confidence limits of the random component of the error measured at a confidence level of 0.95 with the same coefficient student's t - 0,29 milliseconds.

Measurement time inertia the activity of the visual system using pulse duration τ =10 MS, performed by a known method [6]obtained the following values of time the inertia of the visual system of the subject, MS: 58,9; 59,5; 59,4; 59,9; 59,7; 59,3; 60,2; 60,6; 61,2; 61,9. The arithmetic mean of the measured time values of the inertia of the visual system is 60,06 MS, standard deviation - 0,19 MS, confidence limits of the random component of the error measured at a confidence level of 0.95 with the same coefficient student's t - 0,43 milliseconds.

The reduction in the average standard deviations describing the measurement error and which is the criterion of accuracy when performing measurements on the proposed method compared with measurements performed by a known method, was 32,27%.

To assess the validity of reducing the error of the measurements carried out a time dimension to the inertia of the visual system on the proposed and known methods in a group of 10 subjects, each of which performed a series of 10 measurements for each method. Reducing measurement errors when performing measurements on the proposed method compared with measurements performed by a known method, ranged from 24,82 to 42,85%.

Thus, the proposed method allows to determine the time the inertia of the human visual system when no signal is detected, formiruet the CSOs off-system about the end of the light pulse, to reduce error and increase the accuracy of the measurements.

Sources of information

1. Loizou AV Eye and the light. - L.: Energy, 1983. - 140 C.

2. Kroll V.M., Tenenholz LI the Time of recognition, the threshold time of presentation and duration of mask images // human Physiology. - 1976. - Vol.2. No. 4. - S-570.

3. Ivanitsky A.M. Brain potentials during mental operations of different complexity // human Physiology. - 1989. - T.15. No. 3. - Page 11-18.

4. Samsonova A. M., Volkov V.V. Functional methods of research in ophthalmology. - M.: Medicine, 1999. - 416 S.

5. Nechaev V.B. have been, Klyucharev, VA, Kropotov UD, Ponomarev V.A. evoked potentials of the cerebral cortex when compared to visual stimuli // human Physiology. - 2000. - T. No. 2. - P.17-23.

6. Patent 2195174 RF, MCI And 61 5/16 In. The method for determining the time the inertia of the human visual system / ROE, Ivithout (RF). - Publ. 27.12.2002, bull. No. 36.

7. Podvigina NF Dynamic properties of the neural structures of the visual system. - L.: Nauka, 1979. - 158 S.

8. William Seiple, Karen Holopigian. The OFF response of the human electroretinogram does not contribute to the brief flash b-wave // Visual. Neurosci. - 1994. No. 11. - P.667-673.

9. Kravkov SV Eyes and his work. Psychophysiology of vision, hygiene lighting. - 4th ed., revised and enlarged extra - M. - L.: Izd-vo an SSSR, 1950. - 531 S.

10. Semenovskaya E.N. Electrophysiological studies in ophthalmology. - M.: Medgiz, 1963.- 279 C.

11. Lollo Vincent Di, John H. Hogben Supression of visible persistence // J. Exp. Psychol.: Hum. percept, and Perform. - 1985. - V.11. No. 3. - P.304-316.

The method for determining the time the inertia of the human visual system, namely, that the subject produces a sequence of two light pulses of a given duration, separated by a pause equal to 150 MS, repeated at a constant time interval of 1.5 s, and the first step measurements reduce the duration of a pause between two light pulses with a given constant speed of 20 MS/s, until the subject will determine the estimated subjective fusion of two light pulses in one, characterized in that the duration of light pulses is equal to 10 MS, the second stage of measurements increase the duration of a pause between the two light signals discretely with a given constant pitch of 0.4 MS while the subject will determine the point of subjective feelings of separateness of the two light pulses, in the third phase measurements reduce the duration of a pause between the two light signals discretely with a given constant 0.1 MS, until the subject will determine the point of subjective fusion of two light pulses at one time the inertia of the human visual system is equal to the value of the pause time between two light pulses at the moment of subjective merger of two Svetova the pulses in one, defined in the third phase measurements.



 

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