PURPOSE To determine whether the spatial structure of the frequency doubling technology (FDT) perimetry stimulus is visible at detection-contrast threshold in normal observers and those with glaucoma and to assess its perceived spatial frequency at threshold and suprathreshold contrast. METHODS Three subject groups were assessed: 10 young normal observers (aged <40 years), 10 older normal obs...

Spatial data mining focuses on searching rules of the geographical statement, the structures of distribution and the spatial patterns of phenomena. However, many methods ignore the temporal information, thus, limited results describing the statement of spatial phenomena. This paper focuses on developing a mining method which directly detects spatial-temporal association rules hidden in the geog...

It is well known that inspecting a cyclopean grating causes threshold for detecting a subsequently presented test cyclopean grating to be elevated, and that the threshold elevation is greatest at the adapting frequency. We report here that spatial frequency discrimination threshold is also elevated, but the elevation is greatest at frequencies offset from the adapting frequency, and the elevati...

Spatial localization was investigated for each eye of amblyopic observers using a bisection paradigm. The stimuli were comprised of a grating composed of bright lines, and a test line. The test line was either placed above the grating (bisection-no overlap) or within the row of lines comprising the grating (bisection-with overlap) and thresholds for each bisection task were measured as a functi...

Density-independent and density-dependent variables both affect the spatial distributions of species. However, their effects are often separately addressed using different analytical techniques. We apply a spatially explicit regression framework that incorporates localized, interactive and threshold effects of both density-independent (water temperature) and density-dependent (population abunda...

We report two experiments with stimuli composed of dynamic noise stereograms in which binocular disparity was modulated sinusoidally with chan_res in vertical spatial position. The experiments demonstrated that the human visual system contains independent stereoscopic mechanisms selectively tuned for different spatial frequencies of disparity modulation. The first experiment showed that observe...

Previous work (Verrillo, 1963, 1968) has shown that when measured as a change in absolute threshold, spatial summation occurs only at vibration frequencies above 40 Hz. The present study measured vibrotactile spatial summation at suprathreshold amplitudes. A matchingtask was used to investig-ate the effect of varying contactor size on sensory magnitude at three different vibration frequencies. ...

We used Gaussian blurred stimuli to explore the effect of blur on three tasks: (i) 2-line resolution; (ii) line detection; and (iii) spatial interval discrimination, in observers with amblyopia due to anisometropia, strabismus, or both. The results of our experiments can be summarized as follows. (i) 2-Line resolution: in normal foveal vision, thresholds for unblurred stimuli are approx. 0.5 mi...

A new lateral inhibitory phenomenon is suggested between spatially neighboring channels that detect similar spatial frequencies. This mechanism tends to enhance the apparent contrast of gratings at their boundaries, and Mach-band-type effects are demonstrated at the edge of a suprathreshold half-field grating. We studied the dependence of this effect on the grating parameters of spatial frequen...

This thesis is concerned with a number of novel uses of spatial coupling, applied to a class of probabilistic graphical models. These models include error correcting codes, random constraint satisfaction problems (CSPs) and statistical physics models called diluted spin systems. Spatial coupling is a technique initially developed for channel coding, which provides a recipe to transform a class ...