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Human observers fixated the center of a search array and were required to discriminate the color of an odd target if it was present. The array consisted of horizontal or vertical black or white bars. In the simple case, only orientation was necessary to define the odd target, whereas in the conjunctive case, both orientation and color were necessary. A cue(More)
"Express" saccades, named for their extremely short latencies, occur more frequently in a paradigm with a "gap" in time between the disappearance of the fixation mark and the appearance of the target to be fixated. To explain this result, it has been hypothesized that movements of the eyes are preceded by movements of attention [Posner (1980) Quarterly(More)
We show that transient attention summoned by an exogenous cue shows rapid learning of the relationship between the cue and a subsequent target in a discrimination task. In experiment 1, performance was unaffected when a target always appeared in the same position on a large cue, but was degraded when the target could appear anywhere within the extent of the(More)
Macaque monkeys were trained to fixate a small spot while we recorded epidural steady state visual evoked potentials (SSVEP) in response to counterphase modulated sinusoidal gratings. This led to the following results: (1) the SSVEP can show either broad or narrow spatial frequency tuning, depending on electrode location, temporal frequency, contrast and(More)
PURPOSE To measure eccentric fixation characteristics in visual fields of patients with Stargardt's disease. METHODS The positions of fixation loci (FL) in the visual field were determined by Tübingen perimetry (TP), using the position of the blind spots in 173 patients. Altogether, 669 visual fields were measured at baseline and during follow-up. Twenty(More)
PURPOSE To introduce a novel approach to topographic function assessment in visual impairment that requires neither fixation nor reading. METHODS One hundred thirty-five consecutive low vision patients with varying diagnoses and 30 control subjects of comparable median age participated. Performance was measured in a search task that required finding and(More)
We investigated whether dyslexics make instantaneous automatic adjustments of reading saccades depending on word length. We used a single-word reading paradigm on 10 dyslexic and 12 normally reading children aged 11-15 years. Eye movements were recorded by scanning laser ophthalmoscope (SLO) while subjects read single words of different length aloud. All(More)
We measured pictogram naming (PN) and text reading in dyslexic and normally reading young teenagers. Eye movements were monitored by scanning laser ophthalmoscope, revealing positions of fovea, stimuli on the retina, and speech simultaneously. While text reading speed showed the expected difference between groups, PN speeds overlapped widely. PN was mainly(More)