Perception Of Visual Stimuli Research Articles

Early cognitive processes in OCD: An ERP study.

Obsessive-compulsive disorder (OCD) is characterized by persistent, intrusive, and distressing obsessions and/or compulsions and is associated with marked impairments in quality of life. The goal of the present study was to examine initial stages of information processing, specifically, perceptual and attention orientation phases that precede response preparation in OCD. The P3 event-related potential (ERP) component was used as a measure of early cognitive processes of visual stimulus perception. ERPs were recorded while 38 participants diagnosed with OCD and 38 healthy controls performed a passive visual oddball task with neutral and angry schematic faces. OCD participants demonstrated significantly enhanced P3 amplitude over bilateral parietal areas in response to neutral stimuli that activate basic primary perceptual processes. Emotional valence reduced this effect such that OCD patients did not differ from healthy controls in P3 amplitude under the angry stimuli condition. Patients in this study were noncomorbid and unmedicated partially limiting the generalizability of the results. Our hypothesis of altered early perceptual processes in OCD was supported. These alterations, specific to OCD and not anxiety and depression symptoms, may represent distracted primary cognitive processes in OCD, possibly serving as a basic source for compulsion initiation.

Effect of visual working memory contents on visual function and fluid intelligence

Objective To explore the influence of visual working memory contents on visual function and fluid intelligence. Methods 42 subjects were randomly divided into three groups: controll group including 17 people who had no training, working memory based on Gabor vision group including 13 people and standard working memory group including 12 people who received the N-back working memory training for 15 days, and lasted half an hour in every day.The contrast sensitivity was recorded and measured using OPTEC6500, and the fluid intelligence was measured with the Raven's advanced progressive matrices before and after training. Results In the Gabor working memory group, there were salient gains in contrast sensitivity(respectively(1.48±0.26)log, (1.87±0.13)log, P 0.05), the fluid intelligence increased significantly(respectively(11.25±1.91), (13.00±1.86), P 0.05)and in fluid intelligence(respectively(11.41±1.87), (11.58±1.94), P>0.05) between pre- and post-test. Conclusion Working memory training based on Gabor vision can enhance the subjective perception of visual stimuli and improve the behavioral effect of visual contrast sensitivity, but the visual working memory contents do not affect the migration effect of working memory training on fluid intelligence. Key words: Visual working memory contents; Visual function; Fluid intelligence; Visual contrast sensitivity

Multiscale neural connectivity during human sensory processing in the brain.

Stimulus-related brain activity is considered using wavelet-based analysis of neural interactions between occipital and parietal brain areas in alpha (8-12 Hz) and beta (15-30 Hz) frequency bands. We show that human sensory processing related to the visual stimuli perception induces brain response resulted in different ways of parieto-occipital interactions in these bands. In the alpha frequency band the parieto-occipital neuronal network is characterized by homogeneous increase of the interaction between all interconnected areas both within occipital and parietal lobes and between them. In the beta frequency band the occipital lobe starts to play a leading role in the dynamics of the occipital-parietal network: The perception of visual stimuli excites the visual center in the occipital area and then, due to the increase of parieto-occipital interactions, such excitation is transferred to the parietal area, where the attentional center takes place. In the case when stimuli are characterized by a high degree of ambiguity, we find greater increase of the interaction between interconnected areas in the parietal lobe due to the increase of human attention. Based on revealed mechanisms, we describe the complex response of the parieto-occipital brain neuronal network during the perception and primary processing of the visual stimuli. The results can serve as an essential complement to the existing theory of neural aspects of visual stimuli processing.

Diagnostics of the Brain Neural-Ensemble States Using MEG Records and Artificial Neural-Network Concepts

We propose a method for the diagnostics of human brain states using MEG records and an artificial neural-network apparatus. It is shown that this approach allows various states of the human brain to be classified in the case of making decisions related to the perception of visual stimuli.

Диагностика состояний нейронного ансамбля головного мозга по записям магнитоэнцефалограмм с привлечением искусственных нейронных сетей

AbstractWe propose a method for the diagnostics of human brain states using MEG records and an artificial neural-network apparatus. It is shown that this approach allows various states of the human brain to be classified in the case of making decisions related to the perception of visual stimuli.

Neuroanatomy of the Visual Pathway

Precise knowledge of the neuroanatomy of the visual system including the perception of visual stimuli in the retina, the transmission of visual information to other areas of the central nervous system and the processing of visual information, are most important for diagnostics of diseases, which are affecting this system. Such knowledge allows, even after just a clinical examination, already a quite precise localisation of potential lesions. The aim of this article is to illustrate the neuroanatomy of the visual system with the focus on the visual pathway and the processing of visual information. Next to the main visual pathway, also other retinofugal projections are discussed. Domains, which are important for the oculomotor system, are discussed in another article in this edition of the journal.

Unconscious perception of visual stimuli reveals an early neural signature of memorability

Unconscious perception of visual stimuli reveals an early neural signature of memorability

Biased visuospatial perception in complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a chronic pain condition associating sensory, motor, trophic and autonomic symptoms in one limb. Cognitive difficulties have also been reported, affecting the patients’ ability to mentally represent, perceive and use their affected limb. However, the nature of these deficits is still a matter of debate. Recent studies suggest that cognitive deficits are limited to body-related information and body perception, while not extending to external space. Here we challenge that statement, by using temporal order judgment (TOJ) tasks with tactile (i.e. body) or visual (i.e. extra-body) stimuli in patients with upper-limb CRPS. TOJ tasks allow characterizing cognitive biases to the advantage of one of the two sides of space. While the tactile TOJ tasks did not show any significant results, significant cognitive biases were observed in the visual TOJ tasks, affecting mostly the perception of visual stimuli occurring in the immediate vicinity of the affected limb. Our results clearly demonstrate the presence of visuospatial deficits in CRPS, corroborating the cortical contribution to the CRPS pathophysiology, and supporting the utility of developing rehabilitation techniques modifying visuospatial abilities to treat chronic pain.

Shaping visual space perception through bodily sensations: Testing the impact of nociceptive stimuli on visual perception in peripersonal space with temporal order judgments.

Coordinating spatial perception between body space and its external surrounding space is essential to adapt behaviors to objects, especially when they are noxious. Such coherent multisensory representation of the body extended into external space is conceptualized by the notion of peripersonal reference frame, mapping the portion of space in which somatic and extra-somatic inputs interact closely. Studies on crossmodal interactions between nociception and vision have been scarce. Here we investigated how the perception of visual stimuli, especially those surrounding the body, can be impacted by a nociceptive and potentially harmful stimulus inflicted on a particular body part. In two temporal order judgment tasks, participants judged which of two lateralized visual stimuli, presented either near or far from the body, had been presented first. Visual stimuli were preceded by nociceptive stimuli, either applied unilaterally (on one single hand) or bilaterally (on both hands simultaneously). In Experiment 1 participants’ hands were always placed next to the visual stimuli presented near the trunk, while in Experiment 2 they could also be placed next to the visual stimuli presented far from the trunk. In Experiment 1, the presence of unilateral nociceptive stimuli prioritized the perception of visual stimuli presented in the same side of space as the stimulated hand, with a significantly larger effect when visual stimuli were presented near the body than when presented farther away. Experiment 2 showed that these visuospatial biases were related to the spatial congruency between the hand on which nociceptive stimuli were applied and the visual stimuli, independently of the relative distance of both the stimulated hand and the visual stimuli from the trunk. Indeed, nociceptive stimuli mostly impacted the perception of the closest visual stimuli. It is hypothesized that these crossmodal interactions may rely on representations of the space directly surrounding specific body parts.

Simple Shapes Elicit Different Emotional Responses in Children with Autism Spectrum Disorder and Neurotypical Children and Adults

According to the literature, simple shapes induce emotional responses. Current evaluations suggest that humans consider angular shapes as “bad” and curvilinear forms as “good,” but no behavioral data are available to support this hypothesis. Atypical development, such as autism spectrum disorder (ASD), could modify humans’ perception of visual stimuli and thereby their emotional effect. This study assessed the effects of simple stimuli (i.e., jagged edges shape, disk, star, spiral, eye-like shape, and head character) on the emotional responses of different groups of humans. First, we assessed the effects of a looming movement on neurotypical adults’ emotional responses. Second, we assessed the effects of atypical development on emotional responses by comparing the reactions of neurotypical children and of children with ASD. We used different methodological approaches: self-evaluation through questionnaires and direct observation of participants’ behavior. We found that (1) neurotypical adults tended to perceive looming stimuli negatively as they associated more negative feelings with them although few behavioral responses could be evidenced and (2) the emotional responses of neurotypical children and of children with ASD differed significantly. Neurotypical children perceived the spiral stimulus positively, i.e., a curvilinear shape, whereas children with ASD perceived the jagged edges stimulus positively, i.e., an angular shape. Although neurotypical children and children with ASD presented some behavioral responses in common, children with ASD smiled and vocalized more than did neurotypical children during stimuli presentations. We discuss our results in relation to the literature on humans’ perception of simple shapes and we stress the importance of studying behavioral components for visual cognition research.

Spatial Frequency Training Modulates Neural Face Processing: Learning Transfers from Low- to High-Level Visual Features.

Perception of visual stimuli improves with training, but improvements are specific for trained stimuli rendering the development of generic training programs challenging. It remains unknown to which extent training of low-level visual features transfers to high-level visual perception, and whether this is accompanied by neuroplastic changes. The current event-related potential (ERP) study showed that training-induced increased sensitivity to a low-level feature, namely low spatial frequency (LSF), alters neural processing of this feature in high-level visual stimuli. Specifically, neural activity related to face processing (N170), was decreased for low (trained) but not high (untrained) SF content in faces following LSF training. These novel results suggest that: (1) SF discrimination learning transfers from simple stimuli to complex objects; and that (2) training the use of specific SF information affects neural processing of facial information. These findings may open up a new avenue to improve face recognition skills in individuals with atypical SF processing, such as in cataract or Autism Spectrum Disorder (ASD).

ФОРМУВАННЯ ДОВІЛЬНОЇ УВАГИ У ЧОЛОВІКІВ ТА ЖІНОК ПРИ ВИКОНАННІ ЗАВДАНЬ ІЗ ВИСОКИМ КОГНІТИВНИМ НАВАНТАЖЕННЯМ

The differences in brain mechanisms that underlie the switch between involuntary and voluntary attention associated with gender were investigated. We compared reaction time, the number of errors and the electrical activity of the brain during the Emotional Stroop test on the background of visual content that contained affective images when presenting stimuli through a dominant and non-dominant eye in 20 men and 20 women. The model of significant cognitive load was created, when it is quite difficult to correctly respond to the relevant characteristics of the stimulus. Different patterns of brain activity have been found: in women, this task is accompanied by an increase in spectral power in the theta range of the predominantly left hemisphere; in men, the power of alpha rhythm in the parietal-occipital associative cortex decreases with the local increase of theta rhythm in the posterior-frontal areas and beta-rhythm in left prefrontal zone. Under the conditions of high cognitive load created by the distracting visual content and the perception of visual stimuli through the non-dominant eye, the brain mechanisms of voluntary attention provide a more thorough analysis of the relevant stimuli in women that is seen in accurate responses over a longer period in comparison with men.

Individual differences in context-dependent effects reveal common mechanisms underlying the direction aftereffect and direction repulsion

Both spatial and temporal context influence our perception of visual stimuli. For instance, both nearby moving stimuli and recently viewed motion can lead to biases in the perceived direction of a moving stimulus. Due to similarities in the spatial tuning properties of these spatial and temporal context-dependent effects, it is often assumed that they share a functional goal in motion processing and arise from common neural mechanisms. However, the psychophysical evidence concerning this assumption is inconsistent. Here we used an individual differences approach to examine the relationship between different effects of contextual modulation on perception. We reasoned that if measures of contextual modulation share a common underlying mechanism, they should exhibit a strong positive correlation across participants. To test this hypothesis, estimates of the direction aftereffect, direction repulsion, the tilt aftereffect and contrast adaptation were obtained from 54 healthy participants. Our results show pronounced interindividual differences in the effect sizes of all four tasks. Furthermore, there was a strong positive correlation between the estimates of the direction aftereffect and direction repulsion. This correlation was also evident in the threshold elevations that accompanied these repulsive biases in perceived direction. While the effects of contrast adaptation did not correlate with any of the other tasks, there was a weak, but non-significant, correlation between the direction and tilt aftereffects. These results provide evidence for common mechanisms underlying the direction aftereffect and direction repulsion.

A Comparative Study of Mental Health of Normal and Visually Challenged Adolescents

Health is a state of complete physical, mental and social well-being and absence of disease. According to world health organization (WHO) mental health is a form of well-being where a person can recognize his / her own power, can overcome their daily stressful life and able to contribute his or her own society. Adolescence is a developmental period characterized by many hormonal changes, brain, and physical development, emotional and behavioral development. Mentally healthy children and adolescents enjoy their lives positively; they function well at home, school and their community. While visually impaired (absence of visual ability or loss of perception of visual stimuli) adolescents experience severe psychological and behavioral problems especially during adolescent period. The objective of the present study is to compare the normal and visually challenged adolescents in terms of mental health. For measuring the mental health of both groups well-being scale (WEMWBS) was administered. The data was collected from blind school (Ahmadi school) and Aligarh Public School (N=100). For the statistical analysis t test was used. The result of this study revealed that there was a significant difference between both the groups of normal and visually challenged adolescents on mental health.

A framework for the first-person internal sensation of visual perception in mammals and a comparable circuitry for olfactory perception in Drosophila

Perception is a first-person internal sensation induced within the nervous system at the time of arrival of sensory stimuli from objects in the environment. Lack of access to the first-person properties has limited viewing perception as an emergent property and it is currently being studied using third-person observed findings from various levels. One feasible approach to understand its mechanism is to build a hypothesis for the specific conditions and required circuit features of the nodal points where the mechanistic operation of perception take place for one type of sensation in one species and to verify it for the presence of comparable circuit properties for perceiving a different sensation in a different species. The present work explains visual perception in mammalian nervous system from a first-person frame of reference and provides explanations for the homogeneity of perception of visual stimuli above flicker fusion frequency, the perception of objects at locations different from their actual position, the smooth pursuit and saccadic eye movements, the perception of object borders, and perception of pressure phosphenes. Using results from temporal resolution studies and the known details of visual cortical circuitry, explanations are provided for (a) the perception of rapidly changing visual stimuli, (b) how the perception of objects occurs in the correct orientation even though, according to the third-person view, activity from the visual stimulus reaches the cortices in an inverted manner and (c) the functional significance of well-conserved columnar organization of the visual cortex. A comparable circuitry detected in a different nervous system in a remote species—the olfactory circuitry of the fruit fly Drosophila melanogaster—provides an opportunity to explore circuit functions using genetic manipulations, which, along with high-resolution microscopic techniques and lipid membrane interaction studies, will be able to verify the structure–function details of the presented mechanism of perception.

Visual Perception in Anterior Temporal Lobectomy.

To study visual perception in patients with anterior temporal lobectomy. We explored some aspects of visual perception and compared the results obtained from 14 control subjects and 14 patients with unilateral anterior temporal lobectomy. Each group included 7 men and 7 women and the same age distribution (patients and controls: age range 27-48 years; mean 37 years). All subjects underwent a conventional ophthalmic examination and were tested for color perception, stereopsis, texture perception, face recognition, and visual illusions. To quantify color, stereoscopic, and texture perception they performed a visuomotor task that required a rapid response to a visual stimulus. Reaction times were measured under several conditions. Mild visual field defects involving the superior quadrant contralateral to the lobectomy were found in five patients; two other patients presented more severe defects. Lobectomized patients showed a lower number of correct trials than normal subjects when performing tasks involving color and texture perception. These patients also had longer reaction times for color, stereoscopic, and texture stimulus detection. Face recognition and perception of illusory images were preserved after unilateral anterior temporal lobectomy. Our data indicate that patients with anterior temporal lobectomy show moderate deficits in color, stereo, and texture perception, with no impairment in complex visual stimuli perception.

Human perception of visual stimuli modulated by direction of linear polarization

This study explores both theoretically and experimentally the human perception of polarized light beyond that currently established. The radial analyser theory of Haidinger’s phenomenon (HP) is used to predict the effect of observing visual stimuli comprising patterned zones characterized by orthogonal planes of linear polarization (linear polarization direction fields, LPD-fields). Any pattern can be represented as an LPD-field including optotypes and geometric forms. Simulated percepts differ from the original patterns although edges are mostly preserved. In edge-rich images a cross of attenuating contrast spanning the field of view is predicted.The mathematical model is verified experimentally using a liquid crystal display (LCD)-based polarization modulator imaged through a tangential (azimuthal) analyser with properties complementary to a radial analyser. The LCD device is then used in vivo to elicit perceptual responses in human subjects. Normal humans are found to readily detect spatially and temporally modulated isoluminant spatially-isochromatic, highly polarized LPD stimuli. Most subjects match the stimuli to corresponding images of theoretically predicted percepts. In particular edge perception and the presence of the contrast cross was confirmed. Unlike HP, static patterned LPD stimuli are perceived without difficulty.The simplest manifestation of human polarization perception is HP which is the fundamental element of an open set of stimulus-dependent percepts. This study demonstrates that humans have the ability to perceive and identify visual pattern stimuli defined solely by polarization state modulation.

Spectral sensitivity of the compound eyes of Anomala corpulenta motschulsky (Coleoptera: Scarabaeoidea)

The scarab beetle, Anomala corpulenta Motschulsky (Coleoptera: Scarabaeoidea), is a widespread and destructive pest in China. Vision is one of the most important means of acquiring information about the external environment. In order to contribute to the understanding of the perception of visual stimuli in this species, the light sensitivity and spectral responses of the scarab beetle, A. corpulenta, were measured by using an electroretinogram (ERG) technique. In total, 14 monochromatic light intensities, between 340 and 605 nm, were applied to the compound eyes of A. corpulenta under varying levels of adaptation to dark and light conditions. The results showed that all light stimuli induced an ERG response, with varied amplitudes. The spectral sensitivity curve of dark-adapted eyes showed one major peak (~400 nm; near-ultraviolet), a secondary peak (from 498 to 562 nm; yellow-green) and the third peakat 460 nm. By contrast, in light-adapted eyes, only a near-UV peak was observed. From these results, we conclude that the compound eye of A. corpulenta is likely to have at least three spectral types of photoreceptor. Significance of differences were also recorded in the responses of male and female compound eyes, as well as diurnally and nocturnally. The amplitude of ERG in response to white-light stimuli varied with the light intensity: The stronger the luminance, the higher the ERG value. This suggests that the compound eye of A. corpulenta adapts quickly to changing light conditions, enabling A. corpulenta to maintain nocturnal activities.

Exploring the boundary conditions of unconscious numerical priming effects with continuous flash suppression.

The scope and limits of unconscious processing are a controversial topic of research in experimental psychology. Particularly within the visual domain, a wide range of paradigms have been used to experimentally manipulate perceptual awareness. A recent study reported unconscious numerical processing during continuous flash suppression (CFS), which is a powerful variant of interocular suppression and disrupts the conscious perception of visual stimuli for up to seconds. Since this finding of a distance-dependent priming effect contradicts earlier results showing that interocular suppression abolishes semantic processing, we sought to investigate the boundary conditions of this effect in two experiments. Using statistical analyses and experimental designs that precluded an effect of target numerosity, we found evidence for identity priming, but no conclusive evidence for distance-dependent numerical priming under CFS. Our results suggest that previous conclusions on high-level numerical priming under interocular suppression may have been premature.

Action-perception cycle learning for incremental emotion recognition in a movie clip using 3D fuzzy GIST based on visual and EEG signals

Emotions are regarded as the complex programs of internal actions triggered by the perception of visual stimuli. To understand human emotions in a more natural situation, we use dynamic stimuli such as movies for the analysis. Electroencephalography