Given the great range of visual systems, tasks and habitats, there is surprisingly little experimental evidence of how visual limitations affect behavioural strategies under natural conditions. Analysing this relationship will require an experimental system that allows for the synchronous measurement of visual cues and visually guided behaviour. The first step in quantifying visual cues from an...

We have examined the visual potential evoked by two motion stimuli. In the first stimulus (termed coherent motion) a random-dot pattern oscillated between phases of coherent and incoherent ("snowstorm") motion, and in the second a random-dot pattern alternated in direction of motion (termed direction change). We found that the response to the coherent motion stimulus is low-pass with respect to...

We measured saccadic latencies in a large sample (total n = 459) of individuals with amblyopia or risk factors for amblyopia, e.g., strabismus or anisometropia, and normal control subjects. We presented an easily visible target randomly to the left or right, 3.5° from fixation. The interocular difference in saccadic latency is highly correlated with the interocular difference in LogMAR (Snellen...

Attention and adaptation are both mechanisms that optimize visual performance. Attention optimizes performance by increasing contrast sensitivity for and neural response to attended stimuli while decreasing them for unattended stimuli; adaptation optimizes performance by increasing contrast sensitivity for and neural response to changing stimuli while decreasing them for unchanging stimuli. We ...

Behavioral measures of the development of spatial vision, such as contrast sensitivity and acuity, do not distinguish between optical and neural contributions to the emergence of adult visual sensitivity in primates. The optical contribution to visual development in monkeys was estimated by measuring retinal image quality in the eyes of seven infant monkeys ranging in age from 2 days to 9 month...

Contrast sensitivity for orientation discrimination is limited to spatial frequencies below 50-60 cycles per degree by neural spatial integration, and we find that contrast sensitivity, measured using an orientation-discrimination criterion, declines sharply with increasing spatial frequencies in that range. Yet interference fringe patterns pulsed at constant mean luminance can be detected at s...

PURPOSE To determine whether face perception can be equalized across the visual field by scaling size and contrast simultaneously. METHODS Contrast sensitivities were measured for detection (N = 1) and identification (N = 2-8) of a target face as a function of size (0.4 degrees-10 degrees) across eccentricities (E = 0 degrees-10 degrees). RESULTS In all conditions contrast sensitivity first...

This study examined the extent to which letter optotypes and grating stimuli provide equivalent measures of contrast sensitivity under conditions designed to favor the magnocellular (MC) and parvocellular (PC) pathways. The contrast sensitivity functions (CSFs) of three visually normal observers were measured for Sloan letters and Gabor patches, using steady- and pulsed-pedestal paradigms to bi...

Like all saccades, microsaccades cause both spatial and temporal changes in the input to the retina. In space, recent studies have shown that these small shifts precisely relocate a narrow (smaller than the foveola) high-acuity retinal locus on the stimulus. However, it has long been questioned whether the temporal modulations resulting from microsaccades are also beneficial for vision. To addr...

For five anisometropic amblyopes and five normal controls, contrast sensitivities in both grating motion direction discrimination and moving grating detection were measured with the same moving sine-wave stimuli over a wide range of spatial and temporal frequencies. We found that the apparent local motion deficits in anisometropic amblyopia can be almost completely accounted for by deficits in ...