Sains Ma1aysiana 25(2): 59-69 (1996)                                                                                                          Sains Hayat/

                                                                                                                                                                                Life Sciences

 

Components in Flicker Detection

 

Sharanjeet-Kaur

Jabatan Optometri

Fakulti Sains Kesihatan Bersekutu

Universiti Kebangsaan Malaysia 50300 Kuala Lumpur Malaysia

 

J.J. Kulikowski

Department of Optometry and Visual Sciences UMIST

P.O. Box 88 Manchester M60 IQD

United Kingdom

 

 

ABSTRACT

 

This study was conducted to see if slow test presentations of 1 Hz was detected by the chromatic system and higher rates of flicker of 25 Hz, 33 Hz and 40 Hz were detected by the pure flicker system at lower and higher background luminances. Spectral sensitivity measurements were carried out using a 1.2 degree test spot presented at a rate of 1 Hz, 25 Hz, 33 Hz and 40 Hz on a white background. The background luminance used were 100 td, 250 td, 500 td, 750 td, 1000 td, 2500 td and 4000 td. The study showed that the detection of a 1 Hz test is possible by 2 mechanisms, the chromatic system at high background luminance and the achromatic and chromatic systems at low background luminance. In the case 25 Hz, it is not entirely detected by the 'pure flicker system' and the transient achromatic system might contribute in its detection. Flicker rates of 33 Hz and higher are detected by the pure flicker system.

 

ABSTRAK

 

Kajian ini dilakukan untuk melihat sama ada presentasi ujian secara perlahan iaitu 1 Hz dikesan oleh sistem kromatik dan ketipan pada kadar yang tinggi, iaitu 25 Hz, 33 Hz dan 40 Hz dikesan oleh sistem ketipan yang tutin pada luminans latar belakang rendah dan tinggi. Pengukuran sensitiviti spektral telah dijalankan dengan menggunakan satu cahaya ujian bulat berukuran 1.2 darjah yang dipersembahkan pada kadar 1 Hz, 25 Hz, 33 Hz dan 40 Hz pada latar belakang putih. Luminans latar belakang yang telah digunakan adalah 100 td, 250 td, 500 td, 750 td, 1000 td dan 4000 td. Kajian ini menunjukkan yang pengesanan ujian 1 Hz adalah melalui 2 mekanisma, mungkin sistem kromatik pada luminans latar belakang yang tinggi dan sistem akromatik dan kromatik pada luminans latar belakang yang rendah. Bagi 25 Hz pula, ia tidak secara keseluruhannya dikesan oleh sistem kelipan yang tutin dan mungkin sistem akromatik transien yang terlibat dalam pengesanannya. kadar ketipan 33 Hz dan lebih darinya adalah dikesan oleh sistem ketipan yang tulin.

 

RUJUKAN/REFERENCES

 

Burbeck C.A. 1981. Criterion-free pattern and flicker thresholds. J. Opt. Soc. Am. 71: 1343-1350.

Crook J.M., Lee B.B., Tigwell D.A. & Valberg A. 1987. Thresholds of chromatic spots of cells in the macaque lateral geniculate nucleus as compared to detection sensitivity in man. J. Physiol. 392: 193-211.

de Lange H. 1958. Research into the dynamic nature of the human fovea cortex systems with intermittent and modulated light. II. Phase shift in brightness and delay in colour perception. J. Opt. Soc. Am. 48: 784-789.

Eisner A. & MacLeod D.I.A. 1980. Blue sensitive cones do not contribute to luminance. JOSA 70: 121.

Hess R.F., Mullen K.T. & Zrenner E. 1989. Human photopic vision with only short wavelength cones: post-receptoral properties J. Physiol. 417: 151-172.

Kelly D.H. 1961. Visual response to time dependent stimuli-I: Amplitude sensitivity measurements. J. Opt. Soc. Am. 51: 422-429.

Kelly D.H. & Burbeck 1987. Further evidence for a broadband isotropic mechanism sensitive to high velocity stimuli. Vis Res. 27: 1527-1537.

King-Smith P.E. 1975. Visual detection analysed in terms of luminance and chromatic signals. Nature 255: 69-70.

King-Smith P.E. & Carden D. 1976. Luminance and opponent colour contributions to visual detection and adaptation and to temporal and spatial integration. J. Opt. Soc. Am. 66: 709-717.

King-Smith P.E. & Kulikowski J.J. 1975. Pattern and flicker detection analysed by subthreshold summation. J. Physiol. 249: 519-548.

Kulikowski J.J. 1975. Apparent fineness and briefly presented gratings: balance between movement and pattern channels. Vis. Res. 15:673-680.

Kulikowski J.J. 1988. Sensory analysis of vision, A comment on Laming's ‘Sensory Analysis'. Behav. Brain Sci. 11: 300-301.

Kulikowski J.J. & Tolhurst D.J. 1973. Psychophysical evidence for sustained and transient mechanisms in human vision. J. Physiol. 149-163.

Lee B.B. 1990. Spectral sensitivity in primate vision. In Vision and visual dysfunction, vol. 5, eds. Kulikowski J.J., Walsh V. and Murray I.J.M. MacMillan.

Mitchell D.E. & Rushton W.A.H. 1971a. Visual pigments in dichromats. Vision Res. 13: 2017-2031.

Nacer A. 1990. The interactions between chromatic and achromatic mechanisms of human colour vision: limits of selectivity. Ph.D. Thesis, University of Manchester.

Rouf J.A.J. 1972. Dynamic properties of vision-I. Experimental relationships between flicker and flash thresholds. Vis. Res. 12: 261-278.

Tolhurst D.J. 1973. Separate channels for the analysis of the shape and movement of a moving visual stimulus. J. Physiol. 231: 385-402.

Tolhurst DJ. 1975. Sustained and transient channels in human vision. Vis. Res. 15: 1151-1155.

 

 

 

sebelumnya