Effects Of Spatial Frequency Research Articles

The early visual processing of faces in a basic classification task: An ERP study of spatial frequency, other-race and other species effect

ABSTRACT This study investigates the neural processing of other-race and other-species faces, using spatial frequencies (SFs) to probe into early visual processing mechanisms. We conducted a basic classification task to reveal fundamental aspects of facial processing without the complexity of higher-order recognition tasks. This approach utilized SFs set at low (LSF, 0.53 cycles per degree [cpd]), broadband (BB), and high (HSF, 2.1 cpd) SFs to examine their impact on the both P100 and N170 components of event-related potentials. Our findings revealed a significant latency difference in the N170 component under HSF conditions, indicating race-specific efficiency in processing fine details between Asian and Caucasian faces. Furthermore, N170 amplitudes were consistently larger for human than monkey faces, with this difference more pronounced in LSF and BB conditions. This finding indicates that the other-species effect in early visual processing is more pronounced in holistic processing (LSF and BB conditions) rather than in fine-detail processing.

Comparison of Foraging Interactive D-prime and Angular Indication Measurement Stereo with different methods to assess stereopsis

Purpose Stereopsis is a critical visual function, however clinical stereotests are time-consuming, coarse in resolution, suffer memorization artifacts, poor repeatability, and low agreement with other tests. Foraging Interactive D-prime (FInD) Stereo and Angular Indication Measurement (AIM) Stereo were designed to address these problems. Here, their performance was compared with 2-Alternative-Forced-Choice (2-AFC) paradigms (FInD Stereo only) and clinical tests (Titmus and Randot) in 40 normally-sighted and 5 binocularly impaired participants (FInD Stereo only). Methods During FInD tasks, participants indicated which cells in three 4*4 charts of bandpass-filtered targets (1,2,4,8c/° conditions) contained depth, compared with 2-AFC and clinical tests. During the AIM task, participants reported the orientation of depth-defined bars in three 4*4 charts. Stereoscopic disparity was adaptively changed after each chart. Inter-test agreement, repeatability and duration were compared. Results Test duration was significantly longer for 2-AFC (mean = 317s;79s per condition) than FInD (216s,18s per chart), AIM (179s, 60s per chart), Titmus (66s) or RanDot (97s). Estimates of stereoacuity differed across tests and were higher by a factor of 1.1 for AIM and 1.3 for FInD. No effect of stimulus spatial frequency was found. Agreement among tests was generally low (R2 = 0.001 to 0.24) and was highest between FInD and 2-AFC (R2 = 0.24;p<0.01). Stereoacuity deficits were detected by all tests in binocularly impaired participants. Conclusions Agreement among all tests was low. FInD and AIM inter-test agreement was comparable with other methods. FInD Stereo detected stereo deficits and may only require one condition to identify these deficits. AIM and FInD are response-adaptive, self-administrable methods that can estimate stereoacuity reliably within one minute.

Impaired stationarity perception is associated with increased virtual reality sickness.

Stationarity perception refers to the ability to accurately perceive the surrounding visual environment as world-fixed during self-motion. Perception of stationarity depends on mechanisms that evaluate the congruence between retinal/oculomotor signals and head movement signals. In a series of psychophysical experiments, we systematically varied the congruence between retinal/oculomotor and head movement signals to find the range of visual gains that is compatible with perception of a stationary environment. On each trial, human subjects wearing a head-mounted display execute a yaw head movement and report whether the visual gain was perceived to be too slow or fast. A psychometric fit to the data across trials reveals the visual gain most compatible with stationarity (a measure of accuracy) and the sensitivity to visual gain manipulation (a measure of precision). Across experiments, we varied 1) the spatial frequency of the visual stimulus, 2) the retinal location of the visual stimulus (central vs. peripheral), and 3) fixation behavior (scene-fixed vs. head-fixed). Stationarity perception is most precise and accurate during scene-fixed fixation. Effects of spatial frequency and retinal stimulus location become evident during head-fixed fixation, when retinal image motion is increased. Virtual Reality sickness assessed using the Simulator Sickness Questionnaire covaries with perceptual performance. Decreased accuracy is associated with an increase in the nausea subscore, while decreased precision is associated with an increase in the oculomotor and disorientation subscores.

The effects of spatial frequency on the decoding of emotional facial expressions.

The accurate identification of emotion is critical to effectively navigating our social lives. However, it is not clear how distinct types of visual information afford the accurate perception of others' emotion states. Here, we sought to examine the influence of different spatial frequency visual information on emotion categorization, and whether distinctive emotional dimensions (valence and arousal) are differentially influenced by specific spatial frequency content. Across one pilot and two experiments (N = 603), we tested whether emotional facial expressions that vary in valence, arousal, and functional significance differ in accuracy of categorization as a function of low, intact, and high spatial frequency band information. Overall, we found a general decrease in the breadth of emotional expressions for filtered images but did not see a decrease in accuracy of categorization for the positive emotion, joy. Together, these results suggest that spatial frequency information influences perception of emotional expressions that differ in valence and arousal. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Neural Correlates of Natural Scenes: Effects of Scene Category and Spatial Frequency on Preference and Brain Activation Responses

過去研究證實人們偏好自然景觀更甚於都市景觀，然而這類環境尚不清楚是否有關鍵的視覺特徵造成這樣的影響。本研究以景觀分類加上影像低階視覺特徵的觀點，探討不同景觀類型與空間頻率構成的環境影像偏好，並深入討論景觀影像刺激對人體大腦反應之影響。研究方法為將環境影像分為三種景觀類型與兩種空間頻率類別共六種景觀類型，利用持續注意力測驗、偏好問卷與功能性磁振造影儀器進行實驗。研究結果顯示景觀類型對偏好具有顯著差異(F=19.42, p<0.001)，以海岸類型偏好平均數(3.39)為最高；空間頻率對偏好之影響雖無顯著，但當景觀類型與空間頻率共同作用時，對偏好亦有影響；在景觀影像刺激對大腦反應之結果，主要具有顯著活化的腦區為枕葉中之舌回(lingual gyrus)與楔葉(cuneus)；而觀看都市類型影像相較於海岸類型，海馬旁回(parahippocampal gyrus)會具有顯著活化的現象。藉由本研究結果能夠提供景觀影像低階視覺特徵對人們感知之影響的研究觀點，並瞭解人們與自然環境間互動的關係。Previous researches have shown that human have a preference for images of natural scenes over built environments, and being in or viewing natural scenes can improve attention and psychological benefits. However, what are the features in the landscapes that produce these benefits? The purpose of this study is to explore the responses of brain activation to natural scenes. We focused on the relationship between individuals’perceptions and the environmental features. In this study, we used functional magnetic resonance imaging (fMRI) to monitor brain activity responses. Participants were asked to perform the Sustained Attention to Response Test (SART), answer the preference question scales, while viewing a mixture of photographs of scene category (coast, forest, and urban) and different spatial frequency (low and high frequency). The result shows that there is interaction effect of scene category and spatial frequency on preference. People prefer coast and forest than urban. The result shows that there were different patterns of brain activation associated with different landscapes, activation responses were commonly found in lingual gyrus and cuneus. In viewing urban minus coast images condition, the parahippocampal gyrus were found activated. The findings of this study provide a viewpoint to the influence of landscape features on human perceptions, and how individuals interact with nature and environment.

Association between retinal and cortical visual electrophysiological impairments in schizophrenia.

Electrophysiological impairments in the magnocellular visual system have been reported among patients with schizophrenia, but previous theories proposed that these deficits may begin in the retina. We therefore sought to evaluate the potential contribution of the retina by comparing retinal and cortical visual electrophysiological impairments between patients with schizophrenia and healthy controls. We recruited patients with schizophrenia and age- and sex-matched healthy controls. We recorded the P100 amplitude and latency using electroencephalography (EEG) while projecting low (0.5 cycles/degree) or high (15 cycles/degree) spatial frequency gratings at a temporal frequency of 0 Hz or 8 Hz. We compared the P100 results with previous results for retinal ganglion cell activity (N95) in these participants. We analyzed data using repeated-measures analysis of variance and correlation analyses. We recruited 21 patients with schizophrenia and 29 age- and sex-matched healthy controls. Results showed decreased P100 amplitude and increased P100 latency among patients with schizophrenia compared with healthy controls (p < 0.05). Analyses reported the main effects of spatial and temporal frequency but no interaction effects of spatial or temporal frequency by group. Moreover, correlation analysis indicated a positive association between P100 latency and previous retinal results for N95 latency in the schizophrenia group (p < 0.05). Alterations in the P100 wave among patients with schizophrenia are consistent with the deficits in early visual cortical processing shown in the literature. These deficits do not seem to correspond to an isolated magnocellular deficit but appear to be associated with previous retinal measurements. Such an association emphasizes the role of the retina in the occurrence of visual cortical abnormalities in schizophrenia. Studies with coupled electroretinography-EEG measurements are now required to further explore these findings. https://clinicaltrials.gov/ct2/show/NCT02864680.

Exploring the Distinctiveness of Early Visual Processing in Human and Illusory Faces: An ERP Study of Spatial Frequency Effects

Exploring the Distinctiveness of Early Visual Processing in Human and Illusory Faces: An ERP Study of Spatial Frequency Effects

Pupil size is sensitive to stimulus features independent of effects of arousal

Aside from luminance, pupil size is modulated by stimulus properties such as contrast and spatial frequency. Additionally, pupil size is affected by cognitive processes, including attention and arousal. However, it's unclear how these factors interact with each other. We hypothesized that stimulus properties interact, independent from arousal effects on pupil size. We measured pupil responses to equiluminant stimuli and tested how response amplitude depends on contrast, spatial frequency, and reward. Pupil size was recorded in 65 subjects (20,723 trials total) performing a demanding RSVP task at fixation, while attention and mean luminance were kept constant. High and low levels of reward modulated arousal. On 75% of trials, task-irrelevant stimuli appeared in the periphery. These stimuli consisted of sinusoidal gratings at two different contrast levels and five different spatial frequencies. On the remaining trials (null) no gratings appeared. Modulation in pupil response on null trials was hence attributable solely to the cognitive aspects of the task. To estimate task-related pupil responses, we modeled responses on stimulus trials as a combination of task-related and stimulus-evoked components and then regressed against the mean response to obtain trial-wise amplitude estimates. On null trials, the pupil size increased following trial onsets. These task-related responses were larger on high reward trials, indicating that reward modulated arousal, as expected. Stimulus-evoked responses, however, were unaffected by reward level. Stimulus-evoked response amplitude increased with contrast and with spatial frequency. We further uncovered an interaction between contrast and spatial frequency; the effect of spatial frequency was larger for high than for low contrast. Our results shed light on interactions between pupillary response pathways. Specifically, under constant luminance, unattended stimuli evoke responses that are distinct from general arousal or attentional effects. Finally, future studies should account for effects of stimulus properties in order to correctly identify impact of higher cognitive processes.

The Effect of Spatial Frequency on Visual Evoked Potentials Components in Visual Acuity Assessment

The Effect of Spatial Frequency on Visual Evoked Potentials Components in Visual Acuity Assessment

Parameters of Optokinetic Nystagmus Are Influenced by the Nature of a Visual Stimulus

Studies on contrast sensitivity (CS) testing using optokinetic nystagmus (OKN) proposed adjusting the stimulus presentation duration based on its contrast, to increase the time efficiency of such measurement. Furthermore, stimulus-specific limits of the least OKN gain might reduce false negatives in OKN detection procedures. Therefore, we aimed to test the effects of various stimulus characteristics on OKN and to propose the stimulus-specific limits for the OKN gain and stimulus presentation duration. We tested the effect of contrast (C), spatial frequency (SF), and color on selected parameters of robust OKN response, namely its onset and offset time, amplitude, and gain. The right eyes of fifteen emmetropes were tracked with an infrared eye tracker during monocular observations of sinusoidal gratings moving over the horizontal plane with a velocity of (21∘/s). The available contrast levels were C: 0.5%, 2.0%, 8.2%, 16.5%, 33.0%, and 55.5% presented in a random order for ten times in all measurements of SF: 0.12, 0.25, 0.5, and 1.00 cycles per degree and grating type: luminance, red-green, and blue-yellow. This study showed a significant effect of the stimulus characteristics on the OKN onset, offset and gain. The effect of SF was insignificant in OKN amplitude; however, it indicated significance for the C and grating type. Furthermore, the OKN gain and offset limits were proposed as functions of contrast for the luminance and chromatic gratings. This study concludes the characteristics of a visual stimulus have an effect on the OKN gain and onset and offset time, yet do not affect the eye-movement amplitude considerably. Moreover, the proposed limits are expected to improve the time efficiency and eye-movement detection in OKN-based contrast sensitivity measurements.

Supplemental Material for The Effects of Spatial Frequency on the Decoding of Emotional Facial Expressions

Supplemental Material for The Effects of Spatial Frequency on the Decoding of Emotional Facial Expressions

Contrast discrimination in images of natural scenes.

Contrast discrimination determines the threshold contrast required to distinguish between two suprathreshold visual stimuli. It is typically measured using sine-wave gratings. We first present a modification to Barten's semi-mechanistic contrast discrimination model to account for spatial frequency effects and demonstrate how the model can successfully predict visual thresholds obtained from published classical contrast discrimination studies. Contrast discrimination functions are then measured from images of natural scenes, using a psychophysical paradigm based on that employed in our previous study of contrast detection sensitivity. The proposed discrimination model modification is shown to successfully predict discrimination thresholds for structurally very different types of natural image stimuli. A comparison of results shows that, for normal contrast levels in natural scene viewing, contextual contrast detection and discrimination are approximately the same and almost independent of spatial frequency within the range of 1-20 c/deg. At higher frequencies, both sensitivities decrease in magnitude due to optical limitations of the eye. The results are discussed in relation to current image quality models.

Visual Sensitivity in Complex Regional Pain Syndrome and Fibromyalgia: An Online Study.

Perceptual anomalies can provide insights into underlying pathologies even when they are not the main symptom of many clinical conditions. Complex regional pain syndrome (CRPS) and fibromyalgia are chronic pain conditions associated with changes in the central nervous system, possibly leading to enhanced visual sensitivity. It is unclear whether this occurs more than for people with other types of pain. We examined visual sensitivity elicited by different stimuli and in daily life, through an online study of people with CRPS (n = 57), fibromyalgia (n = 74), other pain (n = 50), and no pain (n = 89). Respondents rated changes in pain, discomfort, or distress from viewing patterns with different spatial frequencies (lower-order visual processing), and reversible figures (bistable images; higher-order visual processing). We assessed visual sensitivity in daily life using the Leiden Visual Sensitivity Scale and Visual Discomfort Scale. Respondents with CRPS or fibromyalgia reported more visual discomfort than pain-related and pain-free controls while viewing striped patterns and a circle, with no effect of spatial frequency. They reported more pain while viewing a nonreversible square, but not reversible figures (Necker Cube, Duck/Rabbit). Finally, they reported more daily visual sensitivity than pain-related and pain-free controls. Suppressing visual cortical activity might benefit people with CRPS or fibromyalgia.

Eye Tracking Research on the Influence of Spatial Frequency and Inversion Effect on Facial Expression Processing in Children with Autism Spectrum Disorder.

Facial expression processing mainly depends on whether the facial features related to expressions can be fully acquired, and whether the appropriate processing strategies can be adopted according to different conditions. Children with autism spectrum disorder (ASD) have difficulty accurately recognizing facial expressions and responding appropriately, which is regarded as an important cause of their social disorders. This study used eye tracking technology to explore the internal processing mechanism of facial expressions in children with ASD under the influence of spatial frequency and inversion effects for improving their social disorders. The facial expression recognition rate and eye tracking characteristics of children with ASD and typical developing (TD) children on the facial area of interest were recorded and analyzed. The multi-factor mixed experiment results showed that the facial expression recognition rate of children with ASD under various conditions was significantly lower than that of TD children. TD children had more visual attention to the eyes area. However, children with ASD preferred the features of the mouth area, and lacked visual attention and processing of the eyes area. When the face was inverted, TD children had the inversion effect under all three spatial frequency conditions, which was manifested as a significant decrease in expression recognition rate. However, children with ASD only had the inversion effect under the LSF condition, indicating that they mainly used a featural processing method and had the capacity of configural processing under the LSF condition. The eye tracking results showed that when the face was inverted or facial feature information was weakened, both children with ASD and TD children would adjust their facial expression processing strategies accordingly, to increase the visual attention and information processing of their preferred areas. The fixation counts and fixation duration of TD children on the eyes area increased significantly, while the fixation duration of children with ASD on the mouth area increased significantly. The results of this study provided theoretical and practical support for facial expression intervention in children with ASD.

Spatial frequency impacts perceptual and attentional ERP components across cultures

Culture impacts visual perception in several ways.To identify stages of perceptual processing that differ between cultures, we usedelectroencephalography measures of perceptual and attentional responses to simple visual stimuli.Gabor patches of higher or lower spatialfrequencywere presented at high contrast to 25 American and 31 East Asian participants while they were watching for the onset of aninfrequent, oddball stimulus. Region of interest and mass univariate analyses assessed how cultural background and stimuli spatial frequency affected the visual evoked response potentials. Across both groups, the Gabor of lower spatial frequency produced stronger evoked response potentials in the anterior N1 and P3 than did the higher frequency Gabor. The mass univariate analyses also revealed effects of spatial frequency, including a frontal negativity around 150 ms and a widespread posterior positivity around 300 ms. The effects of spatial frequency generally differed little across cultures; although there was some evidence for cultural differences in the P3 response to different frequencies at the Pz electrode, this effect did not emerge in the mass univariate analyses. We discuss these results in relation to those from previous studies, and explore the potential advantages of mass univariate analyses for cultural neuroscience.

The effect of spatial frequency on visual-vestibular conflict detection

The effect of spatial frequency on visual-vestibular conflict detection

The effect of spatial frequency on perceiving the gist of abnormality in mammograms

The effect of spatial frequency on perceiving the gist of abnormality in mammograms

Scalp-recorded N40 visual evoked potential: Sensory and attentional properties.

N40 is a well‐known component of evoked potentials with respect to the auditory and somatosensory modality but not much recognized with regard to the visual modality. To be detected with event‐related potentials (ERPs), it requires an optimal signal‐to‐noise ratio. To investigate the nature of visual N40, we recorded EEG/ERP signals from 20 participants. Each of them was presented with 1800 spatial frequency gratings of 0.75, 1.5, 3 and 6 c/deg. Data were collected from 128 sites while participants were engaged in both passive viewing and attention conditions. N40 (30–55 ms) was modulated by alertness and selective attention; in fact, it was larger to targets than irrelevant and passively viewed spatial frequency gratings. Its strongest intracranial sources were the bilateral thalamic nuclei of pulvinar, according to swLORETA. The active network included precuneus, insula and inferior parietal lobule. An N80 component (60–90 ms) was also identified, which was larger to targets than irrelevant/passive stimuli and more negative to high than low spatial frequencies. In contrast, N40 was not sensitive to spatial frequency per se, nor did it show a polarity inversion as a function of spatial frequency. Attention, alertness and spatial frequency effects were also found for the later components P1, N2 and P300. The attentional effects increased in magnitude over time. The data showed that ERPs can pick up the earliest synchronized activity, deriving in part from thalamic nuclei, before the visual information has actually reached the occipital cortex.

Effects of luminance contrast, averaged luminance and spatial frequency on vection

Changing the speed, size and material properties of optic flow can significantly alter the experience of vection (i.e. visually induced illusions of self-motion). Until now, there has not been a systematic investigation of the effects of luminance contrast, averaged luminance and stimulus spatial frequency on vection. This study examined the vection induced by horizontally oriented gratings that continuously drifted downwards at either 20° or 60°/s. Each of the visual motion stimuli tested had one of: (a) six different levels of luminance contrast; (b) four different levels of averaged luminance; and (c) four different spatial frequencies. Our experiments showed that vection could be significantly altered by manipulating each of these visual properties. Vection strength increased with the grating's luminance contrast (in Experiment 1), its averaged luminance (in Experiment 2), and its spatial frequency (in Experiment 3). Importantly, interactions between these three factors were also found for the vection induced in Experiment 4. While simulations showed that these vection results could have been caused by effects on stimulus motion energy, differences in perceived grating visibility, brightness or speed may have also contributed to our findings.

Preliminary Result on the Direct Assessment of Perceptible Simultaneous Luminance Dynamic Range

The human visual system is capable of adapting across a very wide dynamic range of luminance levels; values up to 14 log units have been reported. However, when the bright and dark areas of a scene are presented simultaneously to an observer, the bright stimulus produces significant glare in the visual system and prevents full adaptation to the dark areas, impairing the visual capability to discriminate details in the dark areas and limiting simultaneous dynamic range. Therefore, this simultaneous dynamic range will be much smaller, due to such impairment, than the successive dynamic range measurement across various levels of steady-state adaptation. Previous indirect derivations of simultaneous dynamic range have suggested between 2 and 3.5 log units. Most recently, Kunkel and Reinhard reported a value of 3.7 log units as an estimation of simultaneous dynamic range, but it was not measured directly. In this study, simultaneous dynamic range was measured directly through a psychophysical experiment. It was found that the simultaneous dynamic range is a bright-stimulus-luminance dependent value. A maximum simultaneous dynamic range was found to be approximately 3.3 log units. Based on the experimental data, a descriptive log-linear model and a nonlinear model were proposed to predict the simultaneous dynamic range as a function of stimulus size with bright-stimulus luminance-level dependent parameters. Furthermore, the effect of spatial frequency in the adapting pattern on the simultaneous dynamic range was explored. A log parabola function, representing a traditional Contrast Sensitivity Function (CSF), fitted the simultaneous dynamic range data well.