Foveal

About: Foveal is a research topic. Over the lifetime, 2652 publications have been published within this topic receiving 94120 citations.

Stable individual differences across images in human saccadic eye movements.

Abstract: Individual differences in eye movements during picture viewing were examined across image format, content, and foveal quality in 3 experiments. Experiment 1 demonstrated that an individual's fixation durations were strongly related across 3 types of scene formats and that saccade amplitudes followed the same pattern. In Experiment 2, a similar relationship was observed for fixation durations across faces and scenes, although the amplitude relationship did not hold as strongly. In Experiment 3, the duration and amplitude relationships were observed when foveal information was degraded and even removed. Eye movement characteristics differ across individuals, but there is a great deal of consistency within individuals when viewing different types of images.

A cognitive-anatomical approach to attention in lexical access

Abstract: Recent PET studies have suggested a specific anatomy for feature identification, visual word forms and semantic associations. Our studies seek to explore the time course of access to these systems by use of reaction time and scalp electrical recording. Target detection times suggest that different forms of representation are involved in the detection of letter features, feature conjunctions (letters), and words. Feature search is fastest at the fovea and slows symmetrically with greater foveal eccentricity. It is not influenced by lexicality. Detecting a letter case (conjunction) shows a left to right search which differs between words and consonant strings. Analysis of scalp electrical distribution suggest an occipito-temporal distribution for the analysis of visual features (right sided) and for the visual word form discrimination (left sided). These fit with the PET results, and suggest that the feature related analysis begins within the first 100 millisec and the visual word form discriminates words from strings by about 200 msec. Lexical decision instructions can modify the computations found in both frontal and posterior areas.

Microsaccadic Efficacy and Contribution to Foveal and Peripheral Vision

Abstract: Our eyes move constantly, even when we try to fixate our gaze. Fixational eye movements prevent and restore visual loss during fixation, yet the relative impact of each type of fixational eye movement remains controversial. For over five decades, the debate has focused on microsaccades, the fastest and largest fixational eye movements. Some recent studies have concluded that microsaccades counteract visual fading during fixation. Other studies have disputed this idea, contending that microsaccades play no significant role in vision. The disagreement stems from the lack of methods to determine the precise effects of microsaccades on vision versus those of other eye movements, as well as a lack of evidence that microsaccades are relevant to foveal vision. Here we developed a novel generalized method to determine the precise quantified contribution and efficacy of human microsaccades to restoring visibility compared with other eye movements. Our results indicate that microsaccades are the greatest eye movement contributor to the restoration of both foveal and peripheral vision during fixation. Our method to calculate the efficacy and contribution of microsaccades to perception can determine the strength of connection between any two physiological and/or perceptual events, providing a novel and powerful estimate of causal influence; thus, we anticipate wide-ranging applications in neuroscience and beyond.

Post-saccadic location judgments reveal remapping of saccade targets to non-foveal locations

Abstract: The present study addresses the question of how objects are localized across saccades. In a task requiring participants to compare the location of a post-saccadic probe with the pre-saccadic target, we investigated the roles of saccade landing site and post-saccadic probe location. Saccade landing sites vary from trial to trial because of oculomotor error but can also be shifted by saccadic adaptation. Visual targets were extinguished during the saccade and reappeared after a short blank to counteract saccadic suppression of displacement. Performance in localizing targets after unadapted saccades was nearly veridical and independent of actual landing site, showing that trial-to-trial oculomotor error did not contribute to post-saccadic localization. This result suggests that much of the oculomotor error of saccades is included in the efference copy vector and this allows the recovery of a remapped target location that is often not foveal, but stable and accurate across trials. Displacement judgments relative to this remapped location will be independent of trial-to-trial variability in landing site. After adapted saccades, post-saccadic localization shifted in the direction opposite to adaptation but again, trial-by-trial landing site variability did not correlate with performance. This result suggests that the efference copy matches the planned upcoming saccade, be it adapted or not.