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OSCILLATORY MOVEMENT DISPLACEMENT THRESHOLDS: RESISTANCE TO OPTICAL IMAGE DEGRADATION
Author(s) -
Whitaker David,
Buckingham Terry
Publication year - 1987
Publication title -
ophthalmic and physiological optics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.147
H-Index - 66
eISSN - 1475-1313
pISSN - 0275-5408
DOI - 10.1111/j.1475-1313.1987.tb01006.x
Subject(s) - degradation (telecommunications) , displacement (psychology) , resistance (ecology) , movement (music) , computer science , computer vision , optics , geology , environmental science , physics , psychology , acoustics , telecommunications , biology , psychotherapist , ecology
Vernier acuity, under optimal conditions, appears remarkably resistant to image degradation. This characteristic has been used to assess neural function in cataract patients who exhibit poor spatial resolution. Conventional resolution tests fail to differentiate between neural and optical causes of visual loss. The oscillatory movement displacement threshold—the smallest amplitude of oscillation which gives rise to the perception of movement—provides an alternative hyperacuity test. This may offer advantages over vernier acuity. The effect of image defocus upon displacement thresholds for a sinusoidal contrast grating of spatial frequency 2 c deg ‐1 was investigated for high (15 Hz) and low (2 Hz) oscillation frequencies. With visible stationary references, subjects were more sensitive to oscillation frequencies of 2 Hz than to 15 Hz (F 1,9 = 33.34, p < 0.005) whilst blur of up to 2 dioptres had no significant effect (F 3,27 = 1.73, p > 0.1). Simulating media opacities by spatial degradation affected both grating acuity and contrast sensitivity functions, whilst displacement thresholds remained largely unaffected. Results suggest that oscillatory movement displacement thresholds may be of value in assessing ocular neural dysfunction in the presence of media opacities.