Parafoveal Locations Research Articles

Eye-movement methodology reveals a shift in attention from threat to neutral stimuli with self-reported symptoms of social anxiety across children, adolescents and adults

ABSTRACT The current study used an eye-movement remote distractor paradigm (RDP) to examine the relationship between self-reported symptoms of social anxiety in children (9–11-year-olds), young adolescents (12–14-year-olds) and adults (18–43-year-olds) on saccade latencies to identify a target and saccadic errors to task irrelevant distractor (angry, neutral and happy faces). Distractors were presented simultaneously, either at the centre of the display, or at a contralateral parafoveal or peripheral location to the target. Symptoms of social anxiety in children were associated with increased saccade latencies in the presence of angry and neutral faces suggesting avoidance of these emotion expressions in this age group. Symptoms of social anxiety in adolescents and adults were respectively linked with longer latencies for neutral faces, indicating that neutral faces represent ambiguous and potentially negative stimuli for individuals with elevated social anxiety, and fit with research that has questioned the role of neutral faces as non-emotional control stimuli in attention research and anxiety.

Sustained attention operates via dissociable neural mechanisms across different eccentric locations.

In primates, foveal and peripheral vision have distinct neural architectures and functions. However, it has been debated if selective attention operates via the same or different neural mechanisms across eccentricities. We tested these alternative accounts by examining the effects of selective attention on the steady-state visually evoked potential (SSVEP) and the fronto-parietal signal measured via EEG from human subjects performing a sustained visuospatial attention task. With a negligible level of eye movements, both SSVEP and SND exhibited the heterogeneous patterns of attentional modulations across eccentricities. Specifically, the attentional modulations of these signals peaked at the parafoveal locations and such modulations wore off as visual stimuli appeared closer to the fovea or further away towards the periphery. However, with a relatively higher level of eye movements, the heterogeneous patterns of attentional modulations of these neural signals were less robust. These data demonstrate that the top-down influence of covert visuospatial attention on early sensory processing in human cortex depends on eccentricity and the level of saccadic responses. Taken together, the results suggest that sustained visuospatial attention operates differently across different eccentric locations, providing new understanding of how attention augments sensory representations regardless of where the attended stimulus appears.

The use of colour and rapid flicker sensitivity tests for early detection and monitoring of vision changes in diabetes

Aims/Purpose: There is increasing evidence of impaired visual function prior to the presence of diabetic retinopathy (DR), yet current diagnostic criteria and treatment onset rely mostly on retinal vascular changes. In this study we measured changes in chromatic and rapid flicker sensitivity in subjects with prediabetes and diabetes to establish the value of such tests as a potential biomarker in the detecting early diabetes.Methods: Three groups of subjects were recruited: 1) normal controls, 2) subjects with prediabetes (HbA1c between 42‐47 mmol/mol), and 3) diabetics (with or without DR). Monocular cone‐ and rod‐enhanced flicker modulation thresholds (FMTs) were measured at the point of regard and in four parafoveal (5°) locations using the Flicker‐Plus test. Monocular red/green (RG) and yellow/blue (YB) colour thresholds were also measured at the fovea using the Colour Assessment and Diagnosis (CAD) test.Results: Both the RG and YB thresholds, as well as rod‐ and cone‐mediated flicker thresholds were significantly higher in both diabetic and prediabetic groups (when compared with healthy controls). When examined individually, ~50% and ~ 63% of the prediabetics and ~ 58% and ~ 70% of the diabetics revealed abnormal RG and YB thresholds, respectively (when compared with the upper normal limits for the corresponding age). HBA1c levels also revealed a positive trend with increasing RG and YB thresholds in the prediabetic group.Conclusions: In agreement with previous findings, both colour and FMTs are affected in patients diagnosed with diabetes. Unexpectedly, those deemed prediabetic that do not meet the clinical criteria for diabetes exhibit considerable loss of both colour and flicker sensitivity. The results suggest that colour and rapid flicker tests can provide useful information when screening for diabetes.

The value of assessing progressive loss of red/green and yellow/blue chromatic sensitivity in glaucoma

*Correspondence: franziska.rauscher@medizin.uni-leipzig.deThe value of assessing progressive loss of red/green and yellow/blue chromatic sensitivity in glaucoma.The study employed visual stimuli designed to isolate and reveal how spatial, temporal and chromatic aspects of visual processing change from normal sensitivity to extreme loss in glaucoma. The experiments carried out examined the fovea and each of four paracentral retinal regions, arranged diagonally away from fixation at an eccentricity of 6°. Spatial vision was investigated by measuring both absolute detection thresholds and functional contrast sensitivity using Landolt ring stimuli (Ophthalmic Physiol Opt 2022;42:1363–1378). These psychophysical tests based on Landolt C optotypes measure both detection thresholds and gap orientation discrimination thresholds in the same experiments using randomly interleaved test locations. First‐order motion perception was examined by using moving stimuli embedded in static luminance contrast noise. Red/green (RG) and yellow/blue (YB) colour thresholds were measured with the Colour Assessment and Diagnosis (CAD) test, which makes use of random, dynamic luminance contrast noise (±45%) to isolate the use of RG and YB colour signals. Subjects were normal controls (n = 65) and glaucoma patients with binocular visual field defects (n = 15) classified based on their Humphrey Field Analyser mean deviation (MD) scores. The impairment of visual function varied depending on the stimulus attribute and location tested. The severity of loss increased monotonically with disease progression. For subjects with mild glaucoma (MD −0.01 to −6.00 dB), significantly more data points exceeded the upper normal threshold limits for the corresponding age for RG colour thresholds than for any other visual test (Br Med Bull 2017;122:51–77), followed by motion thresholds. This was particularly the case for the parafoveal locations when compared with the equivalent thresholds measured at the fovea. The results suggest that a multifaceted measure of binocular visual performance based on foveal and parafoveal tests of RG colour vision and first‐order motion, can best inform on the progression of glaucoma and the overall loss of visual performance for comparison with other measures of changes in the quality of life in patients with glaucoma.Keywords: Glaucoma, Visual function, Colour vision, Motion detection, Contrast, Acuity, Colour Assessment and Diagnosis, CAD.

Early visual experience refines the retinotopic organization within and across visual cortical regions

Early visual areas are retinotopically organized in human and non-human primates. Population receptive field (pRF) size increases with eccentricity and from lower- to higher-level visual areas. Furthermore, the cortical magnification factor (CMF), a measure of how much cortical space is devoted to each degree of visual angle, is typically larger for foveal as opposed to peripheral regions of the visual field. Whether this fine-scale organization within and across visual areas depends on early visual experience has yet been unknown. Here, we employed 7T functional magnetic resonance imaging pRF mapping to assess the retinotopic organization of early visual regions (i.e., V1, V2, and V3) in eight sight recovery individuals with a history of congenital blindness until a maximum of 4 years of age. Compared with sighted controls, foveal pRF sizes in these individuals were larger, and pRF sizes did not show the typical increase with eccentricity and down the visual cortical processing stream (V1-V2-V3). Cortical magnification was overall diminished and decreased less from foveal to parafoveal visual field locations. Furthermore, cortical magnification correlated with visual acuity in sight recovery individuals. The results of this study suggest that early visual experience is essential for refining a presumably innate prototypical retinotopic organization in humans within and across visual areas, which seems to be crucial for acquiring full visual capabilities.

Relationship between ganglion cell complex thickness and brief presentation stimuli ‐ visual acuity across foveal and parafoveal locations in healthy eyes

AbstractPurpose: Knowledge of the retinal structure ‐ visual function relationship of healthy eyes would be important to the early detection of neuropathies of the retina. This study investigated the association between brief presentation stimuli ‐ visual acuity (BPS‐VA) and the thicknesses of the retina in healthy young eyes.Methods: Photopic and high‐mesopic BPS‐VA was measured in 35 healthy eyes of 35 young subjects (24.3 ± 3.1 years) with the Acuity‐Plus test in the fovea and the parafovea (5° eccentricity) using an optotype presentation of duration 160 ms. The macular thicknesses of the central fovea, parafovea, and macular ganglion cell complex (mGCC), and the thickness of the peripapillary retinal nerve fibre layer (pRNFL) were measured by spectral‐domain optical coherence tomography (SD‐OCT). Relationships between foveal and parafoveal BPS‐VA and the retinal thickness in the corresponding region were examined after adjusting for confounding variables.Results: In photopic luminance conditions, the inferior mGCC thickness was the only structural significant predictor to the foveal BPS‐VA (p = 0.007). Under high‐mesopic level, retinal illuminance and inferior mGCC thickness were contributing factors to the foveal BPS‐VA (p = 0.001). Retinal thicknesses were not predictors of parafoveal BPS‐VA at any of the light levels.Conclusions: The inferior mGCC thickness predicts foveal BPS‐VA measured at both photopic and high‐mesopic light levels in healthy eyes of young subjects.

An image-computable model of how endogenous and exogenous attention differentially alter visual perception

Attention alters perception across the visual field. Typically, endogenous (voluntary) and exogenous (involuntary) attention similarly improve performance in many visual tasks, but they have differential effects in some tasks. Extant models of visual attention assume that the effects of these two types of attention are identical and consequently do not explain differences between them. Here, we develop a model of spatial resolution and attention that distinguishes between endogenous and exogenous attention. We focus on texture-based segmentation as a model system because it has revealed a clear dissociation between both attention types. For a texture for which performance peaks at parafoveal locations, endogenous attention improves performance across eccentricity, whereas exogenous attention improves performance where the resolution is low (peripheral locations) but impairs it where the resolution is high (foveal locations) for the scale of the texture. Our model emulates sensory encoding to segment figures from their background and predict behavioral performance. To explain attentional effects, endogenous and exogenous attention require separate operating regimes across visual detail (spatial frequency). Our model reproduces behavioral performance across several experiments and simultaneously resolves three unexplained phenomena: 1) the parafoveal advantage in segmentation, 2) the uniform improvements across eccentricity by endogenous attention, and 3) the peripheral improvements and foveal impairments by exogenous attention. Overall, we unveil a computational dissociation between each attention type and provide a generalizable framework for predicting their effects on perception across the visual field.

Glaucoma diagnostic capabilities of macular vessel density on optical coherence tomography angiography: superficial versus deep layers

Background/aimsTo compare glaucoma diagnostic capabilities of superficial and deep macular vessel density (mVD) parameters in a series of healthy and open-angle glaucoma (OAG) eyes with central visual field (CVF) loss.MethodsWe...

Age-related change in flicker thresholds with rod- and cone-enhanced stimuli.

PurposeRod and cone photoreceptor-specific tests can be time-consuming. A new non-invasive test is described. The test is based on the measurement of flicker modulation thresholds with rod- and cone-enhanced visual stimuli, which requires only minimum adaptation time. Here, we investigated how the rod-and cone-mediated flicker thresholds vary with age.MethodsMonocular thresholds with rod and cone–enhanced stimuli were measured in 140 healthy adults, (age range: 18–75 years), foveally (0°) and at four parafoveal locations, at an eccentricity of 5° in each of the four quadrants using five, adaptive, interleaved staircases. Temporal frequencies, stimulus sizes, background luminance and spectral composition, were adjusted appropriately to achieve approximately 1 log unit separation in sensitivity between the rod- and cone-enhanced stimuli. Spectrally calibrated, ‘neutral density’ filters were used to enable adequate control of display luminance for rod enhanced stimuli.ResultsThe magnitude of central and parafoveal rod thresholds was significantly higher than the central and parafoveal cone thresholds, respectively (p < 0.001) in both the age groups. However, the rate of increase in central rod thresholds (y = 0.45x—12.79; linear regression equation) was not significantly steeper than the rate of increase in central (y = 0.29x—8.53) cone thresholds (p = 0.15). Centrally, cone thresholds showed a better correlation with rod central thresholds for the age > 45 years (Spearman correlation, ρ = 0.74, p < 0.001) compared to age ≤ 45 years (ρ = 0.41, p < 0.001).ConclusionsThresholds with rod- and cone-enhanced stimuli are largely invariant below 45 years of age and increase rapidly above this age. This age-wise normative database can be used as an effective functional-marker to assess photoreceptor sensitivities in retinal diseases.

Testing a goal-driven account of involuntary attentional capture by threat.

Attention has long been characterized within prominent models as reflecting a competition between goal-driven and stimulus-driven processes. It remains unclear, however, how involuntary attentional capture by affective stimuli, such as threat-laden content, fits into such models. Although such effects were traditionally thought to reflect stimulus-driven processes, recent research has increasingly implicated a critical role of goal-driven processes. Here we test an alternative goal-driven account of involuntary attentional capture by threat using an experimental manipulation of goal-driven attention. To this end we combined the classic contingent capture and emotion-induced blink paradigms in an RSVP task with both positive or threatening target search goals. Across 6 experiments, positive and threat distractors were presented in peripheral, parafoveal, and central locations. Across all distractor locations we found that involuntary attentional capture by irrelevant threat distractors could be induced via the adoption of a search goal for a threatening category; adopting a goal for a positive category conversely led to capture only by positive stimuli. Our findings provide direct experimental evidence for a causal role of voluntary goals in involuntary capture by irrelevant threat stimuli, and hence demonstrate the plausibility of a top-down account of this phenomenon. We discuss the implications of these findings in relation to current cognitive models of attention and clinical disorders. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Investigating face and house discrimination at foveal to parafoveal locations reveals category-specific characteristics

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 wanted to examine whether face perception ability would show a left visual field (LeVF) bias due to earlier reports suggesting right hemisphere dominance for faces, or would show an upper or lower visual field bias. Participants performed foveal and parafoveal face and house discrimination tasks for upright or inverted stimuli (≤4°) 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.

Neural Activation During Visual Attention Differs in Individuals with High versus Low Macular Pigment Density.

The neural efficiency hypothesis for lutein (L) and zeaxanthin (Z) suggests that higher levels of L+Z in the central nervous system (CNS) are predictive of stronger stimulus-specific brain responses. Past research suggests that supplementing L+Z can improve neural processing speed and cognitive function across multiple domains, which supports this hypothesis. The purpose of this study is to determine the extent to which CNS L+Z levels predict brain responses using an attentionally taxing task. Macular pigment optical density (MPOD) is measured at baseline in 85 participants ranging in age from 18-92 years. Brain activation is measured using dense array electroencephalography. Stimuli evoking the signal include a grating array of vertical bars, oscillating at four driving frequencies. Significant stimulus-specific interactions are detected between attend condition, location, and age (p < .002) for unattended image locations, and between age and location (p < .008) for attended locations. Although no differences are found across age by MPOD, this measure is found to be predictive of neural power at parafoveal bar locations (R2 .080). CNS L+Z status is related to differences in brain activation in conditions designed to stress visual attention. These differences are strongest for older subjects.

Temporal attention improves perception similarly at foveal and parafoveal locations.

Temporal attention, the prioritization of information at a specific point in time, improves visual performance, but it is unknown whether it does so to the same extent across the visual field. This knowledge is necessary to establish whether temporal attention compensates for heterogeneities in discriminability and speed of processing across the visual field. Discriminability and rate of information accrual depend on eccentricity as well as on polar angle, a characteristic known as performance fields. Spatial attention improves speed of processing more at locations at which discriminability is lower and information accrual is slower, but it improves discriminability to the same extent across isoeccentric locations. Here we asked whether temporal attention benefits discriminability in a similar or differential way across the visual field. Observers were asked to report the orientation of one of two targets presented at different points in time at the same spatial location (fovea, right horizontal meridian, or upper vertical meridian, blocked). Temporal attention improved discriminability and shortened reaction times at the foveal and each parafoveal location similarly. These results provide evidence that temporal attention is similarly effective at multiple locations in the visual field. Consequently, at the tested locations, performance fields are preserved with temporal orienting of attention.

The optimal use of non-optimal letter information in foveal and parafoveal word recognition

Letters and words across the visual field can be difficult to identify due to limiting visual factors such as acuity, crowding and position uncertainty. Here, we show that when human readers identify words presented at foveal and para-foveal locations, they act like theoretical observers making optimal use of letter identity and letter position information independently extracted from each letter after an unavoidable and non-optimal letter recognition guess. The novelty of our approach is that we carefully considered foveal and parafoveal letter identity and position uncertainties by measuring crowded letter recognition performance in five subjects without any word context influence. Based on these behavioral measures, lexical access was simulated for each subject by an observer making optimal use of each subject's uncertainties. This free-parameter model was able to predict individual behavioral recognition rates of words presented at different positions across the visual field. Importantly, the model was also able to predict individual mislocation and identity letter errors made during behavioral word recognition. These results reinforce the view that human readers recognize foveal and parafoveal words by parts (the word letters) in a first stage, independently of word context. They also suggest a second step where letter identity and position uncertainties are generated based on letter first guesses and positions. During the third lexical access stage, identity and position uncertainties from each letter look remarkably combined together through an optimal word recognition decision process.

Temporal attention improves perception at foveal and parafoveal locations equally

Temporal attention improves perception at foveal and parafoveal locations equally

Does a Flatter General Gradient of Visual Attention Explain Peripheral Advantages and Central Deficits in Deaf Adults?

Individuals deaf from early age often outperform hearing individuals in the visual periphery on attention-dependent dorsal stream tasks (e.g., spatial localization or movement detection), but sometimes show central visual attention deficits, usually on ventral stream object identification tasks. It has been proposed that early deafness adaptively redirects attentional resources from central to peripheral vision to monitor extrapersonal space in the absence of auditory cues, producing a more evenly distributed attention gradient across visual space. However, little direct evidence exists that peripheral advantages are functionally tied to central deficits, rather than determined by independent mechanisms, and previous studies using several attention tasks typically report peripheral advantages or central deficits, not both. To test the general altered attentional gradient proposal, we employed a novel divided attention paradigm that measured target localization performance along a gradient from parafoveal to peripheral locations, independent of concurrent central object identification performance in prelingually deaf and hearing groups who differed in access to auditory input. Deaf participants without cochlear implants (No-CI), with cochlear implants (CI), and hearing participants identified vehicles presented centrally, and concurrently reported the location of parafoveal (1.4°) and peripheral (13.3°) targets among distractors. No-CI participants but not CI participants showed a central identification accuracy deficit. However, all groups displayed equivalent target localization accuracy at peripheral and parafoveal locations and nearly parallel parafoveal-peripheral gradients. Furthermore, the No-CI group’s central identification deficit remained after statistically controlling peripheral performance; conversely, the parafoveal and peripheral group performance equivalencies remained after controlling central identification accuracy. These results suggest that, in the absence of auditory input, reduced central attentional capacity is not necessarily associated with enhanced peripheral attentional capacity or with flattening of a general attention gradient. Our findings converge with earlier studies suggesting that a general graded trade-off of attentional resources across the visual field does not adequately explain the complex task-dependent spatial distribution of deaf-hearing performance differences reported in the literature. Rather, growing evidence suggests that the spatial distribution of attention-mediated performance in deaf people is determined by sophisticated cross-modal plasticity mechanisms that recruit specific sensory and polymodal cortex to achieve specific compensatory processing goals.

Spatial Scaling of the Profile of Selective Attention in the Visual Field.

Neural mechanisms of selective attention must be capable of adapting to variation in the absolute size of an attended stimulus in the ever-changing visual environment. To date, little is known regarding how attentional selection interacts with fluctuations in the spatial expanse of an attended object. Here, we use event-related potentials (ERPs) to investigate the scaling of attentional enhancement and suppression across the visual field. We measured ERPs while participants performed a task at fixation that varied in its attentional demands (attentional load) and visual angle (1.0° or 2.5°). Observers were presented with a stream of task-relevant stimuli while foveal, parafoveal, and peripheral visual locations were probed by irrelevant distractor stimuli. We found two important effects in the N1 component of visual ERPs. First, N1 modulations to task-relevant stimuli indexed attentional selection of stimuli during the load task and further correlated with task performance. Second, with increased task size, attentional modulation of the N1 to distractor stimuli showed a differential pattern that was consistent with a scaling of attentional selection. Together, these results demonstrate that the size of an attended stimulus scales the profile of attentional selection across the visual field and provides insights into the attentional mechanisms associated with such spatial scaling.

Modulating foveal representation can influence visual discrimination in the periphery.

A previous study by Williams et al. (2008) provided evidence for a novel form of feedback in the visual system, whereby peripheral information is contained in foveal retinotopic cortex. Beyond its possible implication for peripheral object recognition, few studies have examined the effect of a direct behavioral manipulation of the foveal feedback representation. To address this question, we measured participants' peripheral visual discrimination performance while modulating their foveal representation in a series of psychophysical experiments. On each trial, participants discriminated the identities of briefly presented novel, three-dimensional objects or the orientations of gratings in a peripheral location while fixating at the center. Besides the peripheral target, another stimulus (foil) was also presented and masked at the fovea. Our results showed that for objects, when the foveal foil that was identical to the peripheral target was presented 150 ms after the onset of the peripheral target, visual discrimination of the peripheral target was improved. This congruency effect occurred even though participants did not consciously perceive the foveal stimulus. No such effect was observed when the foveal foil was presented simultaneously with the peripheral target, or when the foil was presented in a parafoveal location. The foil effect in gratings was different from that in objects in terms of its effective timing and foveal specificity, suggesting that foveal feedback may be specific to high-level objects. These results indicate that modulating foveal information can affect individuals' ability to discriminate peripheral objects, suggesting a functional role of foveal representations in peripheral visual perception.

Macular structure–function relationship at various spatial locations in glaucoma

Background/aimsTo study whether the structure–function (S-F) relationship in glaucoma differs according to macular location using spectral-domain optical coherence tomography (SD-OCT) and standard automated perimetry 10-2 and 24-2 visual fields (VFs).MethodsWe...

Dome-Shaped Macular Configuration: Longitudinal Changes in the Sclera and Choroid by Swept-Source Optical Coherence Tomography Over Two Years

To study longitudinal changes in the posterior pole in eyes with dome-shaped macular configuration within the staphyloma. Prospective, longitudinal study. We prospectively examined the macular area in 35 eyes (26 patients) with dome-shaped macular configuration and high myopia (mean spherical equivalent, -14.83 ± 4.50 diopters) using swept-source optical coherence tomography. Scleral and choroidal thicknesses were measured at the fovea and at 4 parafoveal locations 2000 μm from the foveal center. Height of the macular bulge was measured as well. During the mean follow-up of 24.8 ± 2.5 months, the scleral thickness significantly decreased at the fovea from 496.1 ± 95.7 μm to 484.7 ± 96.2 μm (P < .001) and at all 4 parafoveal locations (P < .001, respectively). The scleral thinning was asymmetric, with an estimated decrease per year of 5.6 μm at the foveal center, 11.1 μm superiorly, 12.1 μm inferiorly, 10.4 μm temporally, and 5.8 μm nasally. The ocular concavities deepened over time, and mean macular bulge height increased from 136.5 ± 60.9 μm to 157.6 ± 67.0 μm (P < .001). The choroid within the staphyloma showed generalized thinning during follow-up. Mean choroidal thickness decreased significantly at the fovea from 28.3 ± 17.2 μm at baseline to 22.9 ± 17.2 μm (P < .001). Progressive asymmetric scleral thinning occurred in the macular region of eyes with dome-shaped macular configuration. The scleral thinning was more pronounced in the parafoveal area than at the foveal center, resulting in an increase of the macular bulge height.