[Bandwidth measurement technique for spatial frequency channels in human visual system]. / Metodika izmereniya polosy propuskaniya prostranstvenno-chastotnykh kanalov zritel'noi sistemy.

AIM: to determine the number of measurements required to obtain stable bandwidth values for spatial frequency channels (SFCs) in the human visual system. MATERIAL AND METHODS: Ten untrained, normal vision subjects 18-22 years old were presented with light pulses (flickers) with initial frequency of 10 Hz and then with a higher-than-initial and lower-than-initial frequency alternately at 1-sec intervals. The difference between flickers frequencies was gradually increased until the test subject determined his/her discrimination threshold. This threshold was assumed to represent the SFC bandwidth. Measured values were plotted on a coordinate system «SFC bandwidth - the number of measurement¼. The described procedure was repeated and a graph resulted showing SFC bandwidth as a function of Ni, where Ni is the number of i-th measurement and i = 1, 2, ..., k (k - the sequence number of measurement at which the transition process was completed and a quasi-stationary state achieved): ΔF=f(Ni). The number of measurements required to obtain stable SFC bandwidth values was determined from the number of measurements made during the transition process. RESULTS: It has been found that to obtain stable bandwidth values for SFCs of the human visual system, 2 to 8 measurements are required (point estimate of the median for the given sample equaled 5). CONCLUSION: The duration of a transition process to stable SFC bandwidth values is individual and this should be taken into account when assessing the visual system.

Study of the time of the visual system recovery.

The time of the visual system recovery was studied. The experimental method is presented. The results confirm a relationship between the duration of the threshold interval between pulses and the duration of light pulses. The type of this relationship is identified; the distribution of results of observations for groups is statistically evaluated.

[Study of the accuracy of measure the critical flicker frequency].

The possible accuracy of determining the critical flicker frequency (CFF) was assessed. According to the results of experimental studies, the individual accuracy of CFF determination was 0.7 to 1.3 Hz in a group of 30 examinees; the median distribution was 1.0 Hz; confidence interval for the median at 95% significance was 0.9 and 1.0 Hz. From the data of the experimental studies, it is recommended that a change step for a flicker frequency should be 0.5 Hz at mass CFF measurements.

[Assurance of accuracy in measurement of the flicker fusion frequency].

The instrumental errors of the devices for measuring the flicker frequency and period are calculated. The errors in the measurement of the period are shown to be several times lower than the errors in the frequency. It is suggested to determine the flicker fusion frequency as the inverse of the measured period.

On the accuracy of evaluations of temporal characteristics of visual perception.

We studied the accuracy of evaluations of the temporal characteristics of visual perception: critical frequency of light flickers, time of perception, and time of visual analyzer recovery. Results of comparison of the accuracy of evaluations are presented.

[Differential sensitivity of vision to flicker rate].

A method is suggested for measurement of the differential sensitivity of vision to the light flicker rate. The best accuracy of the method with subsequent presentation of the increment and decrement flicker rates was experimentally established.

[Measurement method and determination accuracy of the critical frequency of light flashing]. / Metodika izmerenii i tochnost' opredeleniia kriticheskoi chastoty sliianiia svetovykh mel'kanii.

The influence of a measurement method on an accuracy of determining the critical frequency of light flashing was investigated. The least incidental contributing error of measurements was found for the method based to be on progressive approximation with discrete changes of the frequency of light flashing made at the final measurement stage.

Study of the relationship between pulse duration and the accuracy of evaluation of the critical frequency of light flashing.

The relationship between pulse duration and accuracy of evaluation of the critical frequency of light flashing was studied. The accuracy of measurement of this parameter increased if the duration of light pulses decreased. Our results indicate that the optimal duration of light pulses for determining critical frequency of light flashes is 3-5 msec.