The effect of spatial frequency adaptation on detection response time was studied using 2-D Gabor functions as stimuli. On the basis of pilot studies, it was expected that reaction time to a given spatial frequency at a low contrast would increase following adaptation to that spatial frequency at a high contrast. Subjects were tested using 2-D Gabor functions that ranged in frequency from 25 to...

understanding the spatial distribution of weeds would provide good results for the commercial applications of future research programs, development forecast desirable of yield loss and understanding the processes that cause changes in spatial and temporal distribution weeds. in this order an experiment was conducted in 1388 to find the effects of biological interactions, climate and agricultura...

The capability of Degree Heating Weeks index (DHWs) was examined for prediction of bleaching events in the coral reef communities of the Kish Island located in the north of the Persian Gulf. In doing so, weekly Sea Surface Temperature (SST) values (in 1°×1° spatial resolution) prepared by National Oceanic and Atmospheric Administration (NOAA), coupled with documented bleaching events, such...

Spatial localization of flashed stimuli across saccades shows transient distortions of perceived position: Stimuli appear shifted in saccade direction and compressed towards the saccade target. The strength and spatial pattern of this mislocalization is influenced by contrast, duration, and spatial and temporal arrangement of stimuli and background. Because mislocalization of stimuli on a backg...

To investigate the effect of exposure duration on stereopsis and its spatial frequency dependency, we measured disparity threshold for the depth discrimination varying stimulus exposure duration between 0.05 and 2 s for three spatial frequencies (0.23, 0.94 and 3.75 c/deg). The results showed that disparity threshold decreased with increase in exposure duration up to a certain duration, beyond ...

Threshold elevations were measured as a function of the spatial frequency of high contrast cosine masks using spatially localized test stimuli with a 1.0 octave bandwidth. The cosine masks were oriented at 14.5 degrees relative to the vertical test patterns in order to average out spatial phase effects. The experiment was repeated for each of 14 test frequencies spanning the range 0.25-22.0 c/d...

We compared the number of spatial frequency and orientation mechanisms underlying first- versus second-order processing by measuring discrimination at detection threshold for first- and second-order Gabors to determine the smallest difference in spatial frequency and orientation that permits accurate discrimination at threshold. For second-order gratings, the number of channels is the same as f...

This paper presents a spatial-correlation thresholding scheme for noise reduction by wavelet transform. Observing that edge structures are of high magnitude across wavelet scales but noise decays rapidly, we multiply two adjacent wavelet scales to form a spatial-correlation function to enhance significant structures and dilute noise. Dissimilar to the traditional thresholding schemes that apply...

We examined whether data demonstrating contrast sensitivity losses in dyslexia that have been interpreted as evidence for loss of magnocellular visual function could be explained by inattention. Computer simulations of observers with poor concentration yielded inflated estimates of threshold that were a constant proportion of the true threshold across spatial frequencies. Data from many, but no...

Contrast matching was performed with isoluminant red-green and s-cone gratings at spatial frequencies ranging from 0.5 to 8 c/deg. Contrast threshold curves were low-pass in shape, in agreement with previous findings. Contrast matching functions resembled threshold curves at low contrast levels, but became flat and independent of spatial frequency at high contrasts. Thus, isoluminant chromatic ...