Effects of contrast and spatial frequency on vernier acuity.
نویسندگان
چکیده
We have examined vernier acuity using sinusoidal luminance gratings. Vernier thresholds were affected by both grating contrast and spatial frequency. With fixed (50%) contrast gratings, vernier thresholds reached minimum values of approximately 10 sec of arc at spatial frequencies between 6 and 16 c/deg. Vernier thresholds for all spatial frequencies are related to contrast by a power law with exponents of approximately -0.8. Thresholds approach half a grating period (180 deg phase shift) as grating contrast approaches detection thresholds. We discuss our results in relation to three models for vernier detection. Most of our data are consistent with the predictions of Wilson's [(1986) Vision Res. 26, 453-469] model. Detection of vernier off-sets at low spatial frequencies may depend on detection of the horizontal border formed between the two halves of the grating.
منابع مشابه
Pattern perception at high velocities
BACKGROUND When objects are stationary, human pattern vision is exquisitely acute. A number of studies show, however, that Vernier acuity for lines is greatly impaired when the target velocity exceeds about 5 deg sec-1. The degradation of line Vernier acuity under image motion appears to be a consequence of a shift in the spatial scale of analysis to low spatial frequencies. If correct, this im...
متن کاملVernier step acuity and bisection acuity for texture-defined form
Using as the stimulus a texture pattern of short lines, we compared positional acuity thresholds for an orientation-texture-defined (OTD) boundary and a luminance-defined (LD) boundary. Texture lines had different orientations but the same luminance on either side of the OTD boundary, and different luminances but the same orientation on either side of the LD boundary. For the LD boundary, both ...
متن کاملDiscrimination of position and contrast in amblyopic and peripheral vision.
Many computational models of normal vernier acuity make predictions based on the just-noticeable contrast difference. Recently, Hu, Klein and Carney [(1993) Vision Research, 33, 1241-1258] compared vernier acuity and contrast discrimination (jnd) in normal foveal viewing using cosine gratings. In the jnd stimulus the test grating was added in-phase to the (sinusoidal) pedestal, whereas in the v...
متن کاملDifferences in vernier discrimination for grating between strabismic and anisometropic amblyopes.
Two gratings composed of lines were displayed one above the other, and the vernier threshold was measured as a function of spatial frequency and vertical separation between gratings for 12 strabismic and/or anisometropic amblyopes. The vernier acuity of the anisometropic amblyopes was similar to that of nonamblyopic eyes when scaled proportionally to their reduced grating acuity. Strabismic amb...
متن کاملVelocity dependence of Vernier and letter acuity for band-pass filtered moving stimuli
The ability to see fine detail diminishes when the target of interest moves at a speed greater than a few deg/s. The purpose of this study was to identify fundamental limitations on spatial acuity that result from image motion. Discrimination of Vernier offset was measured for a pair of vertical abutting lines and letter resolution was measured using a four-orientation letter 'T'. These stimuli...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Vision research
دوره 27 10 شماره
صفحات -
تاریخ انتشار 1987