What is the spatial frequency hypothesis?
The spatial frequency hypothesis contends that performance differences between the hemispheres on various visuospatial tasks are attributable to lateralized processing of the spatial frequency content of visual stimuli.
When viewing a sine-wave grating its spatial frequency is?
If you viewed the above grating at an appropriate distance so that its image exactly covered 1° of visual angle, then the grating would have a spatial frequency of three — there are three oscillations of the darker and lighter bars in the figure.
What is sine-wave gratings?
A sine-wave grating is a repeated number of fuzzy dark and light bars, or cycles. The number of grating cycles over a specified visual angle determines its spatial frequency. A small number of cycles over a specified visual angle are defined as having a low spatial frequency.
What is the difference between square wave and sine-wave gratings?
Sine-wave gratings are patterns of bars where the light intensity varies along a line in a sinusoidal manner (fig. 1). Fourier analysis shows that a square wave grating contains another frequency three times higher than the fundamental, at one third of the contrast.
How do you calculate spatial frequency?
For the spatial variation where L is measured in distance units, the spatial frequency of the variation is 1/L. Generally, a sinusoidal curve f(x) = A sin(ωx + θ) is similar to the above pure sine but may differ in phase θ, period L = 2π/ω (i.e. angular frequency ω), or / and amplitude A.
What is the relationship between spatial frequency and spatial resolution?
Spatial resolution is the ability to image small objects that have high subject contrast. Resolution is an imaging system’s ability to distinguish object detail. Define and discuss spatial frequency. Spatial frequency is the measure of resolution.
Why do we lose the ability to see gratings at large distances?
Because spatial frequency is defined in terms of visual angle, a grating’s spatial frequency changes with viewing distance. As this distance decreases, each bar casts a larger image; as a result, the grating’s spatial frequency decreases as the distance decreases.
What is spatial frequency vision?
“Spatial frequency” refers to the number of pairs of bars imaged within a given distance on the retina. One-third of a millimeter is a convenient unit of retinal distance because an image this size is said to subtend one degree of visual angle on the retina.
What phenomenon in hearing is analogous to spatial frequency channels in vision?
sine wave grating
The analogous stimulus for vision is the sine wave grating. Such gratings can vary in spatial frequency (measured in cycles/degree, for a retinal image), orientation, phase and contrast.
What is contrast sensitivity function?
The contrast sensitivity function (CSF) relates the visibility of a spatial pattern to both its size and contrast, and is therefore a more comprehensive assessment of visual function than acuity, which only determines the smallest resolvable pattern size.
How does spatial frequency affect grating response?
When you adapt to a lower spatial frequency grating, you see the opposite shift in the response (upper-right graph). Similar shifts happen with orientation and direction of motion, indicating that there are channels tuned for various orientaitions and directions of motion.
What is the difference between high and low spatial frequency?
A grating of high spatial frequency — many cycles within each degree of visual angle — contains narrow bars. A grating of low spatial frequency — few cycles within each degree of visual angle — contains wide bars. Because spatial frequency is defined in terms of visual angle, a grating’s spatial frequency changes with viewing distance.
What is the relationship between grating contrast and frequency?
As this distance decreases, each bar casts a larger image; as a result, the grating’s spatial frequency decreases as the distance decreases. “Contrast” is related to the intensity difference between the light and dark bars of the grating. If this difference is great, the grating’s contrast is high; a small difference means the contrast is low.
What is spatial frequency in visual perception?
Visual perception. In these stimuli, spatial frequency is expressed as the number of cycles per degree of visual angle. Sine-wave gratings also differ from one another in amplitude (the magnitude of difference in intensity between light and dark stripes), and angle.