How do humans perceive the passage of time and the duration of events without a dedicated sensory system for timing? Previous studies have demonstrated that when a stimulus changes over time, its duration is subjectively dilated, indicating that duration judgments are based on the number of changes within an interval. In this study, we tested predictions derived from three different accounts de...

AIM Flicker deficits have been reported in various maculopathies, including age-related macular degeneration. We test whether flicker losses exist in patients with central serous chorioretinopathy (CSC) and whether the size and flicker frequency of the target is important in detecting such losses. METHODS We examined four CSC patients with temporal modulation (flicker perception) perimetry us...

THE critical flicker frequency (cff) may be defined as the fastest rate at which a flickering source of light appears to be flickering as opposed to being steady. It has a number of determinants including the luminance, wave-length, wave-form, and light-dark ratio of the stimulating light, the area, position, and light-adapted state of the retina illuminated, the duration of exposure, and the s...

Flickering lights that are detected by the blue cones of the human visual system fuse to yield a steady sensation at much lower rates of flicker than do lights that are detected by the red or green cones. Yet, although blue-cone-detected lights flickering at 30-40 Hz appear to be steady, they are still able to interact with red- or green-cone-detected flickering lights to produce clearly detect...

A polarimetric method for the measurement of linear retardance in the presence of phase fluctuations is presented. This can be applied to electro-optic devices behaving as variable linear retarders. The method is based on an extended Mueller matrix model for the linear retarder containing the time-averaged effects of the instabilities. As a result, an averaged Stokes polarimetry technique is pr...

The final stage of the Adelson-Bergen model [J. Opt. Soc. Am. A 2 (1985) 284] computes net motion as the difference between directionally opposite energies E(L) and E(R). However, Georgeson and Scott-Samuel [Vis. Res. 39 (1999) 4393] found that human direction discrimination is better described by motion contrast (C(m))--a metric where opponent energy (E(L)-E(R)) is divided by flicker energy (E...

Attention biases sensory processing toward neurons containing information about behaviorally relevant events. These attentional biases apparently reflect the combined influence of feature enhancement and suppression. We examined the separate influence of enhancement and suppression in visual processing by determining whether responses to an unattended flicker were modulated when the flicker fea...