With luminance gratings, psychophysical thresholds for detecting a small increase in the contrast of a weak 'pedestal' grating are 2-3 times lower than for detection of a grating when the pedestal is absent. This is the 'dipper effect'--a reliable improvement whose interpretation remains controversial. Analogies between luminance and depth (disparity) processing have attracted interest in the e...

Recent studies have reported that flanking stimuli broaden the psychometric function and lower detection thresholds. In the present study, we measured psychometric functions for detection and discrimination with and without flankers to investigate whether these effects occur throughout the contrast continuum. Our results confirm that lower detection thresholds with flankers are accompanied by b...

and insecticides are incorporated during acid delinting and just before seed is bagged. An additional dipper can be added to commercial chemical treaters to meter 30 cc of AMP in water solution at the same time PCMB, Captan, and insecticide treatments are added to each eight pound "dump" of cottonseed. Alternatively, concentration of AMP can be increased, and it can be used as the aqueous porti...

We compare luminance-contrast-masking thresholds for fully and poorly attended stimuli, controlling attention with a demanding concurrent task. We use dynamic displays composed of discrete spatiotemporal wavelets, comparing three conditions ("single," "parallel," and "random"). In contrast to static displays, we do not find that attention modulates the "dipper" regime for masks of low luminance...

BackgroundThe month of Ramadan is the ninth lunar month of the Islamic calendar, during which every year millions of Muslims fast from sunrise to sunset. These fasting episodes are associated with changes in sleeping pattern, medication timing, extra prayers at night, etc. The goal of this work was to evaluate the safety of Ramadan fast with respect to blood pressure for treated hypertensive pa...

To investigate amblyopic contrast vision at threshold and above we performed pedestal-masking (contrast discrimination) experiments with a group of eight strabismic amblyopes using horizontal sinusoidal gratings (mainly 3c/deg) in monocular, binocular and dichoptic configurations balanced across eye (i.e. five conditions). With some exceptions in some observers, the four main results were as fo...

The aim of this study was to identify the relationship of QT dispersion on 12-lead electrocardiograms and left ventricular mass index on echocardiograms associated with the circadian rhythm of blood pressure (BP). Heart rate and BP were monitored every 30 min for 48 h in 62 patients with essential hypertension using an ambulatory BP monitoring device. The patients were divided into four groups ...