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Description
Paper
Link: https://pubmed.ncbi.nlm.nih.gov/26889822/
Year: 2016
Summary
- evaluate peripheral resolution and detection for different orientations in different visual field meridians
Learnings
- for accurate visual evaluation, 3 factors should be taken into considerations:
- acuity (resolution or detection)
- field loci (enncentricity and meridian)
- stimulus properties (orientation of stimulus)
- peripheral resolution acuity is dependent on the orientation of visual stimuli (the meridional effect)
- stimuli oriented radially along a meridian are better resolved
- high contract resolution is relatively unaffected by optical errors because it is neurally limited, whereas detection is affected by optical errors
- stimulus with spatial frequency above neural sampling limit cannot be resolved
- undersampled stimulus undergoes aliasing and can be perceived through moire patterns with a low spatial frequency, lower contrast, and different orientation
- meridional preference for detection tasks may be a combination of optical and neural orientation sensitivities
- sinusoidal gratings are common stimulus choice for research on peripheral vision, suitable for evaluating detection and resolution acuity and contrast sensitivity
Methods
- sinusoidal grating stimuli presented for 500 ms
Results
- acuity is better for gratings oriented along the meridian
- sinusoidal gratings's Gaussian window reduce the contrast of the stimuli, at radius of 1 standard deviation, the Gaussian window reduces the contrast, this means that the contrast in the center of the stimulus has been reduced to about 55% at 1 standard deviation away from the center
- studies that uses sinusoidal gratings in circular window have reported better detections, caused by well known edge effect
- grating parallel to visual field meridian will produce better acuity than perpendicular grating