Poster Session: Spatial-frequency-selective enhancement of visual sensitivity from saccade dynamics.

ABSTRACTCurrent models of visual perception suggest that, during scene categorization, low spatial frequencies (LSF) are rapidly processed and activate plausible interpretations of visual input. This coarse analysis would be used to guide subsequent processing of high spatial frequencies (HSF). The present study aimed to further examine how information from LSF and HSF interact and influence each other during scene categorization. In a first experimental session, participants had to categorize LSF and HSF filtered scenes belonging to two different semantic categories (artificial vs. natural). In a second experimental session, we used hybrid scenes as stimuli made by combining LSF and HSF from two different scenes which were semantically similar or dissimilar. Half of the participants categorized LSF scenes in hybrids, and the other half categorized HSF scenes in hybrids. Stimuli were presented for 30 or 100 ms. Session 1 results showed better performance for LSF than HSF scene categorization. Session 2 scene categorization was faster when participants attended and categorized LSF than HSF scene in hybrids. The semantic interference of a semantically dissimilar HSF scene on LSF scene categorization was greater than the semantic interference of a semantically dissimilar LSF scene on HSF scene categorization, irrespective of exposure duration. These results suggest a LSF advantage for scene categorization, and highlight the prominent role of HSF information when there is uncertainty about the visual stimulus, in order to disentangle between alternative interpretations.

Glare visual acuity and contrast sensitivity are important indicators of visual quality. Studies have shown that the glare visual acuity and contrast sensitivity in dry eye patients tend to degenerate, further affecting their quality of life. The objective of this study was to investigate the effect of notch filters on glare VA and contrast sensitivity in patients with dry eye or with dry eye syndrome. 36 subjects in the 20‒65 age group were diagnosed as having dry eye disease or perceived dry eye syndromes themselves who were included after the initial screening with the OSDI questionnaire, and one was subsequently excluded as they had undergone retinal detachment surgery. Finally, 35 subjects (14 male and 21 female) with a mean age of 40.66 ± 15.62years participated in this study. All subjects wore their habitual prescriptions and four different filter lenses (namely 480, 620, dual 480 & 620 notch filter, and FL-41 tinted lens), and measured the parameters of glare visual acuity and contrast sensitivity using CSV-1000 and sine wave contrast test (SWCT), respectively. Student t-test and Repeated measurement analysis (R-ANOVA) were utilized by using SPSS 26.0 software. A dual-wavelength 480 & 620nm optical notch filter had a significant anti-glare effect decreasing glare disabilities or discomfort, and leading to better visual quality, the same effect was also shown on a 480nm notch filter lens. All participants showed a significant difference among the baseline, three notch filters (480nm, 620nm, dual-wavelength 480 & 620nm), and FL-41 tinted lens were used on SWCT_A (1.5cpd, F = 3.054, p = 0.019) and SWCT_E (18cpd, F = 2.840, p = 0.049); but did not show statistical different on SWCT_B (3cpd, F = 0.333, p = 0.771), SWCT_C (6cpd, F = 1.779, p = 0.159), and SWCT_D (12cpd, F = 1.447, p = 0.228). The baseline showed the best visual performance on CS at a low spatial frequency (SWCT_A, 1.5cpd), any filter might reduce the contrast sensitivity at low spatial frequencies in the clinical trial, whereas 480nm notch filter showed the best effectiveness on CS at a high spatial frequency (SWCT_E, 18cpd), the FL-41 lens that also filters out the 480nm band does not achieve the same effect. Moreover, patients with dry eye or those older than 40years old preferred optical multilayer notch filters to FL-41 tinted lenses. The 480- & 620-nm dual-wavelength and 480-nm single-wavelength notch filters have the best effect on the glare visual acuity and contrast sensitivity (CS) at high spatial frequencies in dry eye patients. The 620-nm notch filter performs better in CS at low and mid-low spatial frequencies; the FL-41 tinted lens performs poorly for glare VA and CS spatial frequencies examination. Patients with glare disabilities or CS disturbance at high spatial frequencies may choose a 480-nm notch filter lens, and patients who have CS disturbance at low spatial frequencies may consider a 620-nm notch filter for the prescription.

The red-green axis of colour vision evolved recently in primate evolutionary history. Signals serving red-green colour vision travel together with signals serving spatial vision, in the parvocellular (PC) division of the subcortical visual pathway. However, the question of whether receptive fields of PC pathway cells are specialized to transmit red-green colour signals remains unresolved. We addressed this question in single-cell recordings from the lateral geniculate nucleus of anaesthetized marmosets. Marmosets show a high proportion of dichromatic (red-green colour-blind) individuals, allowing spatial and colour tuning properties of PC cells to be directly compared in dichromatic and trichromatic visual systems. We measured spatial frequency tuning for sine gratings that provided selective stimulation of individual photoreceptor types. We found that in trichromatic marmosets, the foveal visual field representation is dominated by red-green colour-selective PC cells. Colour selectivity of PC cells is reduced at greater eccentricities, but cone inputs to centre and surround are biased to create more selectivity than predicted by a purely 'random wiring' model. Thus, one-to-one connections in the fovea are sufficient, but not necessary, to create colour-selective responses. The distribution of spatial tuning properties for achromatic stimuli shows almost complete overlap between PC cells recorded in dichromatic and trichromatic marmosets. These data indicate that transmission of red-green colour signals has been enabled by centre-surround receptive fields of PC cells, and has not altered the capacity of PC cells to serve high-acuity vision at high stimulus contrast.

Cerebral regions and hemispheric specialization for processing spatial frequencies during natural scene recognition. An event-related fMRI study

Motion detection and the coincidence of structure at high and low spatial frequencies

Interocular suppressive interactions in amblyopia depend on spatial frequency

The subcortical visual pathway to the amygdala has long been considered a rapid and crude stream for processing emotionally salient information that is reliant on low spatial frequency (LSF) information. Recently, research has called this LSF dependency into question. To resolve this debate, we take advantage of an anatomical hemiretinal asymmetry, whereby the nasal hemiretina sends a higher proportion of information through the subcortical pathway than the temporal hemiretina. We recorded brain activity using electroencephalography (EEG) in human participants (N = 40) while they completed a monocular viewing paradigm. Pairs of faces (one fearful and one neutral, or both neutral) were projected simultaneously to the nasal and temporal hemiretina in three contrast-equated blocks; faces filtered to display only (i) LSF, (ii) high spatial frequency (HSF), or (iii) unfiltered information (broadband spatial frequency; BSF). BSF fearful faces were found to produce a greater naso-temporal asymmetry, with greater N170 amplitudes evoked by BSF faces in the nasal field, compared to HSF faces. Conversely, the naso-temporal asymmetry for LSF fearful faces did not differ between BSF and HSF. Collectively, these findings provide crucial evidence that the subcortical pathway carries combined spatial frequency visual signals, with a potential bias against HSF content.

Face perception in adults depends on skilled processing of interattribute distances ('configural' processing), which is disrupted for faces presented in inverted orientation (face inversion effect or FIE). Children are not proficient in configural processing, and this might relate to an underlying immaturity to use facial information in low spatial frequency (SF) ranges, which capture the coarse information needed for configural processing. We hypothesized that during adolescence a shift from use of high to low SF information takes place. Therefore, we studied the influence of SF content on neural face processing in groups of children (9-10years), adolescents (14-15years) and young adults (21-29years) by measuring event-related potentials (ERPs) to upright and inverted faces which varied in SF content. Results revealed that children show a neural FIE in early processing stages (i.e. P1; generated in early visual areas), suggesting a superficial, global facial analysis. In contrast, ERPs of adults revealed an FIE at later processing stages (i.e. N170; generated in face-selective, higher visual areas). Interestingly, adolescents showed FIEs in both processing stages, suggesting a hybrid developmental stage. Furthermore, adolescents and adults showed FIEs for stimuli containing low SF information, whereas such effects were driven by both low and high SF information in children. These results indicate that face processing has a protracted maturational course into adolescence, and is dependent on changes in SF processing. During adolescence, sensitivity to configural cues is developed, which aids the fast and holistic processing that is so special for faces.

In the present paper, we report two experiments out of series of studies designed to examine various aspects of visual search for icons of differing spatial frequencies. Specifically, the present experiments explore whether there exists a search asymmetry between high and low spatial frequency icons (A amongst B > B amongst A), and whether observers can limit their search to the relevant set of items in a display containing both types of icons. Our results show that a classic search asymmetry does not exist for spatial frequency; that, rather, both types of targets ‘pop out’; that search for a high spatial frequency target amongst high spatial frequency distractors is less efficient than search for a low spatial frequency target amongst low spatial frequency distractors; and that observers are partially able to limit their search to the relevant subset in mixed displays. Implications for the design of touch screen user interfaces are discussed.

Text contains a range of different spatial frequencies but the effectiveness of spatial frequencies for normal variations in skilled adult reading ability is unknown. Accordingly, young skilled adult readers showing fast or slow reading ability read sentences displayed as normal or filtered to contain only very low, low, medium, high, or very high spatial frequencies. Reading times and eye movement measures of fixations and saccades assessed the effectiveness of these displays for reading. Reading times showed that, for each reading ability, medium, high, and very high spatial frequencies were all more effective than lower spatial frequencies. Indeed, for each reading ability, reading times for normal text were maintained when text contained only medium, high, or very high spatial frequencies. However, reading times for normal text and for each spatial frequency were all substantially shorter for fast readers than for slow readers, and this advantage for fast readers was similar for normal, medium, high, and very high spatial frequencies but much larger for low and very low spatial frequencies. In addition, fast readers made fewer and shorter fixations, fewer and shorter regressions, and longer forward saccades, than slow readers, and these differences were generally similar in size for normal, medium, high, and very high spatial frequencies, but larger when spatial frequencies were lower. These findings suggest that fast and slow adult readers can each use a range of different spatial frequencies for reading but fast readers make more effective use of these spatial frequencies and especially those that are lower. (PsycINFO Database Record

Temporal studies with flashed gratings: Inferences about human transient and sustained channels

Temporal and spatial frequency tuning of the flicker motion aftereffect.

Low spatial frequency filtering modulates early brain processing of affective complex pictures

A method is presented that permits the extraction and visualization of topological domain structure information contained in small-angle scattering (SAS) patterns without complex pretreatment. Multi-dimensional noisy raw data can be processed. Such data are, for instance, accumulated in the field of materials research from short-exposure-timein situsmall-angle X-ray scattering (SAXS) experiments with synchrotron radiation. The result is a multi-dimensional intersect or chord distribution, which is defined as the Laplacian of the correlation function. Moreover, it is equivalent to the autocorrelation of the gradient of the electron density. The procedure is, in particular, adapted to the analysis of the nanoscale structure of samples with fibre symmetry, such as polymer fibres or strained elastomers. Multi-dimensional relations among morphological components become apparent in real space and help to elucidate the nature of the processes governing formation and change of structure on the nanometre scale. Utilizing digital signal processing tools, the algorithm is based on spatial frequency filtering of the raw data. The background to be subtracted from the small-angle scattering pattern is formed from its own low spatial frequencies. Noise may be removed by suppressing high spatial frequencies. In the frequency band between these low and high spatial frequencies, the domain structure information of the studied nanocomposite appears.

Coarse-to-fine information integration in human vision