Biology subjects

Kreichman, O.

Publications and source records attributed to Kreichman, O..

3 recordsLinked to original sources

bioRxiv2023

Parafoveal vision reveals qualitative differences between FFA and PPA

The center-periphery visual field axis guides early visual system organization with enhanced resources devoted to central vision leading to reduced peripheral performance relative to that of central vision (i.e., behavioral eccentricity effect) for most visual functions. The center-periphery organization extends to high-order visual cortex where for example the well-studied face-sensitive fusiform face area (FFA) shows sensitivity to central vision and place-sensitive parahippocampal place area (PPA) shows sensitivity to peripheral vision. As we have recently found that face perception is more sensitive to eccentricity than place perception, here we examined whether these behavioral findings reflect differences in FFA and PPAs sensitivities to eccentricity. We assumed FFA would show higher sensitivity to eccentricity than PPA would, but that both regions modulation by eccentricity would be invariant to the viewed category. We parametrically investigated (fMRI, n=32) how FFAs and PPAs activations are modulated by eccentricity ([≤]8{degrees}) and category (upright/inverted faces/houses) while keeping stimulus size constant. As expected, FFA showed an overall higher sensitivity to eccentricity than PPA. However, both regions activation modulations by eccentricity were dependent on the viewed category. In FFA a reduction of activation with growing eccentricity ("BOLD eccentricity effect") was found (with different amplitudes) for all categories. In PPA however, there were qualitative modulations of the BOLD eccentricity effect with mild BOLD eccentricity effect for houses but a reverse BOLD eccentricity effect for faces and no modulation for inverted faces. Our results emphasize that peripheral vision investigations are critical to further our understanding of visual processing both quantitatively and qualitatively. Significance statementVisual perception significantly deteriorates with growing distance from central vision (behavioral eccentricity effect) with varying degrees according to visual function. For some functions (but not others) deterioration follows the reduction of resources devoted to peripheral vision at early visual processing stages. While early stages of visual processing reflect retinal spatial arrangement, here we found that activations in high-order visual areas that are less sensitive to visual field location show a BOLD fMRI activation eccentricity effect that mirrors the behavioral eccentricity effect. Importantly, the BOLD eccentricity effects we found varied across regions and were modulated quantitatively and qualitatively by the viewed visual categories. Our results emphasize that peripheral vision investigations are critical to further our understanding of visual processing.

neuroscience↗

bioRxiv2020

Size matters - larger images are better remembered

We are constantly exposed to multiple visual scenes, and while freely viewing them without an intentional effort to memorize or encode them, only some are remembered. It has been suggested that image memorability is influenced by multiple factors as depth of processing (1-3), familiarity (4), and visual category (5-7). However, this is typically investigated with intentional (8, 9) or unintentional (10, 11) encoding tasks. Furthermore, since visual memory relies on size-invariant visual perception (12-14), image size is not considered a contributing factor. Here we reasoned that during naturalistic free viewing of images without an encoding task, bigger images would be better remembered due to multiple factors (as vaster expanse of activated visual cortex (15, 16), deeper processing). In an extensive set of experiments participants (n=117) freely viewed small to large images (3{degrees}-24{degrees}) without any encoding task. Subsequently, they were presented with mid-sized images (50% already seen) and were asked to report if they recall seeing them or not. Larger images were better remembered (~23% more than smaller images), image memorability was proportional to image size, faces were better remembered, and outdoors the least. These were independent of image set, presentation order, or screen resolution. While multiple factors affect image memorability (1-7), here we show that during free viewing with no encoding task, a basic physical image dimension influences its memorability.

neuroscience↗

bioRxiv2019

Face discrimination does not outperform house discrimination at foveal to parafoveal locations

Since perceptual and neural face sensitivity is associated with a foveal bias, and neural place sensitivity is associated with a peripheral bias (integration over space), we hypothesized that face perception ability will decline more with eccentricity than place perception ability. We also hypothesized that face perception ability may show an upper visual field (UVF) bias due to the proximity of face-related regions to UVF retinotopic representations, and a left visual field (LeVF) bias due to earlier reports suggesting right hemisphere dominance for faces. Participants performed foveal and parafoveal face and house discrimination tasks for upright or inverted stimuli ([≤] 4{degrees}) while their eye movements were monitored. Low-level visual tasks were also measured. The eccentricity-related accuracy reductions were evident for all categories. Through detailed analyses we found (i) a robust face inversion effect across the parafovea, while for houses an opposite effect was found, (ii) higher eccentricity-related sensitivity for face performance than for house performance (via inverted vs. upright within-category eccentricity-driven reductions), (iii) within-category but not across-category performance associations across eccentricities, and (iv) no hemifield biases. Our central to parafoveal investigations suggest that high-level vision processing may be reflected in behavioural performance.

neuroscience↗