Contrast thresholds for 75% correct depth identification in narrow-band filtered random dot stereograms were determined for different center spatial frequencies and binocular disparities. Rigorous control over vergence was maintained during testing, and a forced-choice procedure was used. The resulting contrast sensitivity function for stereopsis revealed sensitivity over a greater range of dis...

To investigate the spatial and temporal frequency tunings for stereopsis, we measured the contrast sensitivity for depth discrimination with variable spatiotemporal frequencies and disparities using drifting sinusoidal gratings. The results showed that the contrast sensitivity changed with the stimulus disparity and the disparity tuning function varied with the spatial frequency. The disparity ...

Letter-by-letter (LBL) dyslexia is an acquired reading disorder characterized by very slow reading and a large linear word length effect. This suggests the use of a sequential LBL strategy, in sharp contrast with the parallel letter processing used by normal subjects. Recently, we have proposed that the reading difficulty of LBL dyslexics is due to a deficit in discriminating visually similar l...

Single neurons in primate V2 and cat A18 exhibit identical orientation tuning for sinewave grating and illusory contour stimuli. This cue invariance is also manifested in similar orientation maps to these stimuli, but in V1/A17 the illusory contour maps appear reversed. We hypothesized that this map reversal depends upon the spatial frequencies of the inducers in the illusory contours, relative...

impulsive and convective frequencies are one of the most important subjects for evaluation of the seismic behavior of tanks. these two frequencies are defined by housner and used for obtaining rayleigh damping in time history analysis. aci 350 and nzsee standards have suggested some analytical solutions for finding convective and impulsive frequencies. these frequencies can also extract from mo...

We recorded from single units in the medial and lateral banks of the posterolateral suprasylvian visual cortex (PMLS/PLLS) of the cat. The responses to drifting high-contrast gratings of optimum orientation and direction of motion, but varying in spatial and temporal frequency, were examined quantitatively for a sample of cells, whose receptive fields covered a wide range of eccentricities. The...

There is considerable controversy over the existence of orientation and direction sensitivity in lateral geniculate nucleus (LGN) neurons. Claims for the existence of these properties often were based upon data from cells tested well beyond their peak spatial frequencies. The goals of the present study were to examine the degree of orientation and direction sensitivity of LGN cells when tested ...

The purpose of the study was to find out what spatial frequency information human observers use in the recognition of face images. Signal-to-noise ratio thresholds for the recognition of facial images were measured as a function of the centre spatial frequency of narrow-band additive spatial noise. The relative sensitivity of recognition to different spatial frequencies was derived from these r...

Illusory bands at a luminance transition in space (ie an edge) are well known. Here we demonstrate illusory bands of enhanced orientations or spatial frequencies at transitions between higher-contrast and lower-contrast image content along the orientation and spatial-frequency dimensions--the dimensions of cortical spatial coding. We conclude that this illusion is a consequence of cortical-leve...