Visual aspects of perception of multimedia messages on the web through the "eye tracker" method

Since the dawn of civilisation visual communication played a role in everyday life. In the early times there were simply shaped drawings of animals, pictograms explaining hunting tactics or strategies of attacking the enemies. Through evolution visual expression becomes an important component of communication process on several levels, from the existential and economic level to the artistic level. However, there was always a question of the level of user reception of such visual information in the medium transmitting the information. Does physical positioning of information in the medium contribute to the efficiency of the message? Do the same rules of content positioning apply for traditional (offline) and online media (Internet)? Rapid development of information technology and Internet in almost all segments of contemporary life calls for defining the rules of designing and positioning multimedia online contents on web sites. Recent research indicates beyond doubt that the physical positioning of an online content on a web site significantly determines the quality of user's perception of such content. By employing the "Eye tracking" method it is possible to objectively analyse the level of user perception of a multimedia content on a web site. What is the first thing observed by the user after opening the web site and how does he/she visually search the online content? By which methods can this be investigated subjectively and objectively? How can the survey results be used to improve the creation of web sites and to optimise the positioning of relevant contents on the site? The answers to these questions will significantly improve the presentation of multimedia interactive contents on the Web.     

Perceived object stability depends on multisensory estimates of gravity

Background

How does the brain estimate object stability? Objects fall over when the gravity-projected centre-of-mass lies outside the point or area of support. To estimate an object''s stability visually, the brain must integrate information across the shape and compare its orientation to gravity. When observers lie on their sides, gravity is perceived as tilted toward body orientation, consistent with a representation of gravity derived from multisensory information. We exploited this to test whether vestibular and kinesthetic information affect this visual task or whether the brain estimates object stability solely from visual information.

Methodology/Principal Findings

In three body orientations, participants viewed images of objects close to a table edge. We measured the critical angle at which each object appeared equally likely to fall over or right itself. Perceived gravity was measured using the subjective visual vertical. The results show that the perceived critical angle was significantly biased in the same direction as the subjective visual vertical (i.e., towards the multisensory estimate of gravity).

Conclusions/Significance

Our results rule out a general explanation that the brain depends solely on visual heuristics and assumptions about object stability. Instead, they suggest that multisensory estimates of gravity govern the perceived stability of objects, resulting in objects appearing more stable than they are when the head is tilted in the same direction in which they fall.     

Neuronal mechanisms for visual stability: progress and problems

How our vision remains stable in spite of the interruptions produced by saccadic eye movements has been a repeatedly revisited perceptual puzzle. The major hypothesis is that a corollary discharge (CD) or efference copy signal provides information that the eye has moved, and this information is used to compensate for the motion. There has been progress in the search for neuronal correlates of such a CD in the monkey brain, the best animal model of the human visual system. In this article, we briefly summarize the evidence for a CD pathway to frontal cortex, and then consider four questions on the relation of neuronal mechanisms in the monkey brain to stable visual perception. First, how can we determine whether the neuronal activity is related to stable visual perception? Second, is the activity a possible neuronal correlate of the proposed transsaccadic memory hypothesis of visual stability? Third, are the neuronal mechanisms modified by visual attention and does our perceived visual stability actually result from neuronal mechanisms related primarily to the central visual field? Fourth, does the pathway from superior colliculus through the pulvinar nucleus to visual cortex contribute to visual stability through suppression of the visual blur produced by saccades?     

Sensory loss and brain reorganization

It is without a doubt that humans are first and foremost visual beings. Even though the other sensory modalities provide us with valuable information, it is vision that generally offers the most reliable and detailed information concerning our immediate surroundings. It is therefore not surprising that nearly a third of the human brain processes, in one way or another, visual information. But what happens when the visual information no longer reaches these brain regions responsible for processing it? Indeed numerous medical conditions such as congenital glaucoma, retinis pigmentosa and retinal detachment, to name a few, can disrupt the visual system and lead to blindness. So, do the brain areas responsible for processing visual stimuli simply shut down and become non-functional? Do they become dead weight and simply stop contributing to cognitive and sensory processes? Current data suggests that this is not the case. Quite the contrary, it would seem that congenitally blind individuals benefit from the recruitment of these areas by other sensory modalities to carry out non-visual tasks. In fact, our laboratory has been studying blindness and its consequences on both the brain and behaviour for many years now. We have shown that blind individuals demonstrate exceptional hearing abilities. This finding holds true for stimuli originating from both near and far space. It also holds true, under certain circumstances, for those who lost their sight later in life, beyond a period generally believed to limit the brain changes following the loss of sight. In the case of the early blind, we have shown their ability to localize sounds is strongly correlated with activity in the occipital cortex (the location of the visual processing), demonstrating that these areas are functionally engaged by the task. Therefore it would seem that the plastic nature of the human brain allows them to make new use of the cerebral areas normally dedicated to visual processing.     

Distinct Visual Working Memory Systems for View-Dependent and View-Invariant Representation

Background

How do people sustain a visual representation of the environment? Currently, many researchers argue that a single visual working memory system sustains non-spatial object information such as colors and shapes. However, previous studies tested visual working memory for two-dimensional objects only. In consequence, the nature of visual working memory for three-dimensional (3D) object representation remains unknown.

Methodology/Principal Findings

Here, I show that when sustaining information about 3D objects, visual working memory clearly divides into two separate, specialized memory systems, rather than one system, as was previously thought. One memory system gradually accumulates sensory information, forming an increasingly precise view-dependent representation of the scene over the course of several seconds. A second memory system sustains view-invariant representations of 3D objects. The view-dependent memory system has a storage capacity of 3–4 representations and the view-invariant memory system has a storage capacity of 1–2 representations. These systems can operate independently from one another and do not compete for working memory storage resources.

Conclusions/Significance

These results provide evidence that visual working memory sustains object information in two separate, specialized memory systems. One memory system sustains view-dependent representations of the scene, akin to the view-specific representations that guide place recognition during navigation in humans, rodents and insects. The second memory system sustains view-invariant representations of 3D objects, akin to the object-based representations that underlie object cognition.     

Am I seeing my hand? Visual appearance and knowledge of controllability both contribute to the visual capture of a person's own body

When confronted with complex visual scenes in daily life, how do we know which visual information represents our own hand? We investigated the cues used to assign visual information to one''s own hand. Wrist tendon vibration elicits an illusory sensation of wrist movement. The intensity of this illusion attenuates when the actual motionless hand is visually presented. Testing what kind of visual stimuli attenuate this illusion will elucidate factors contributing to visual detection of one''s own hand. The illusion was reduced when a stationary object was shown, but only when participants knew it was controllable with their hands. In contrast, the visual image of their own hand attenuated the illusion even when participants knew that it was not controllable. We suggest that long-term knowledge about the appearance of the body and short-term knowledge about controllability of a visual object are combined to robustly extract our own body from a visual scene.     

Attention and visual perception

Somewhere between the retina and our conscious visual experience, the majority of the information impinging on the eye is lost. We are typically aware of only either the most salient parts of a visual scene or the parts that we are actively paying attention to. Recent research on visual neurons in monkeys is beginning to show how the brain both selects and discards incoming visual information. For example, what happens to the responses of visual neurons when attention is directed to one element, such as an oriented colored bar, embedded among an array of other oriented bars? Some of this research shows that attention to the oriented bar restricts the receptive field of visual neurons down to this single element. However, other research shows that attention to this single element affects the responses of neurons with receptive fields throughout the visual field. In this review, these two seemingly contradictory results are shown to actually be mutually consistent. A simple computational model is described that explains these results, and also provides a framework for predicting a variety of additional neurophysiological, neuroimaging and behavioral studies of attention.     

Exploring Memory Representations with Activity-Based Genetics

The brain is thought to represent specific memories through the activity of sparse and distributed neural ensembles. In this review, we examine the use of immediate early genes (IEGs), genes that are induced by neural activity, to specifically identify and genetically modify neurons activated naturally by environmental experience. Recent studies using this approach have identified cellular and molecular changes specific to neurons activated during learning relative to their inactive neighbors. By using opto- and chemogenetic regulators of neural activity, the neurons naturally recruited during learning can be artificially reactivated to directly test their role in coding external information. In contextual fear conditioning, artificial reactivation of learning-induced neural ensembles in the hippocampus or neocortex can substitute for the context itself. That is, artificial stimulation of these neurons can apparently cause the animals to “think” they are in the context. This represents a powerful approach to testing the principles by which the brain codes for the external world and how these circuits are modified with learning.A central feature of nervous systems is that, to function properly, specific neurons must become active in response to specific stimuli. The nature of this selective activation and its modification with experience is the focus of much neuroscience research, ranging from studies of sensory processing in experimental animals to disorders of thought such as schizophrenia in humans. The central dogma of neuroscience is that perceptions, memories, thoughts, and higher mental functions arise from the pattern and timing of the activity in neural ensembles in specific parts of the brain at specific points in time. Until quite recently, the investigation of these “circuit”-based questions has primarily been limited to observational techniques, such as single unit recording, functional magnetic resonance imagery (fMRI), and calcium imaging, to document the patterns of neural activity evoked by sensory experience or even complex psychological contingencies in human fMRI studies. These techniques have been enormously successful and created a framework for understanding information processing in the brain. For example, recordings in the visual system have indicated that, in the primary visual cortex, neurons are tuned to the orientation of linear stimuli (Hubel and Wiesel 1962). In contrast, neurons in higher brain areas can respond to discrete items. The most striking example of this specificity comes from in vivo recording in the human medial temporal lobe in which single units have been identified that respond to photos of the actress Halle Berry as well as her written name (Quiroga et al. 2005). This highly selective tuning of neural activity is suggestive of function, but how can this be directly tested? What would be the effect of stimulating just this rare population of neurons, a memory of the actress, a sensory illusion of her image? How does this type of specific firing arise? Do these neurons differ from their nonresponsive neighbors in terms of biochemistry, cell biology, or connectivity? Do they undergo molecular alterations when new information is learned about this individual and are these changes required for the learning? These types of questions have recently become accessible to study in mice through the use of activity-based genetic manipulation, in which neurons that are activated by a specific sensory stimulus can be altered to express any gene of experimental interest. These studies and approaches will be the focus of this work.     

Calcium dobesilate for diabetic retinopathy: a systematic review and meta-analysis

Many randomized clinical controlled trials have confirmed the efficacy and safety of calcium dobesilate in treating diabetic retinopathy(DR).This systematic review critically evaluated the evidence that links calcium dobesilate to DR.In this fixed-effects meta-analysis,a total of 221 pertinent English-language articles published between January 1975 and October 2013 were identified.Systematic searches of PUBMED,Springer Link and the Cochrane Clinical Trials Database were conducted using the keywords “diabetic retinopathy” and “calcium dobesilate”.The extracted information included the study design,inclusion and exclusion criteria,setting,sample size,participant mean age,treatment regime,mean change in best corrected visual acuity,laboratory parameters,capillary fragility,intraocular pressure and fundus manifestations based on the findings of fluorescent angiography.The summary statistics indicated that calcium dobesilate was significantly associated with improving retinal microaneurysms(RR: 0.62,95%CI: 0.42?0.90,P=0.01),retinalhemorrhages(RR: 0.39,95% CI: 0.17?0.88,P=0.02); exudates(RR: 0.31,95% CI: 0.12?0.81,P=0.02),reduction of whole blood viscosity(MD: ?0.57 CP,95% CI: ?0.75 to ?0.38,P<0.001),plasma viscosity(MD: ?0.36 CP,95% CI: ?0.63 to ?0.09,P=0.01) and blood cholesterol(MD: ?0.48 mg m L?1,95% CI: ?0.64?0.33,P<0.00001).Intraocular pressure was also significantly reduced(MD: ?5.59 mm Hg,95% CI: ?6.69 to ?4.50,P<0.00001).The results indicate that calcium dobesilate effectively treats DR at the systematic and local ocular levels.     

Visual Anthropology and Language

This essay addresses three questions: (1) What happens to information that cannot be recorded on film or videotape? (2) Is the “visual image” conceived to be an autonomous, universalized object of study, as if it exists prior to and independent of conventional human languages? (3) Who are the much-talked-about viewers of ethnographic films, and what is their relationship to visual anthropologists' investigations? The essay's focus is on Grimshaw's statement about visual anthropologists who “seek legitimation by turning away from the mainstream textual tradition” [Grimshaw 2001 Grimshaw , Anna 2001 The Ethnographer's Eye: Ways of Seeing in Modern Anthropology . Cambridge : Cambridge University Press .[Crossref] , [Google Scholar]: 172]. I have attempted to submit evidence that such a move weakens visual anthropologists' capacity to provide “mainstream anthropology” with a vital, growing and legitimate contribution.     

A neuron-inspired computational architecture for spatiotemporal visual processing

In this article, we present a neurologically motivated computational architecture for visual information processing. The computational architecture’s focus lies in multiple strategies: hierarchical processing, parallel and concurrent processing, and modularity. The architecture is modular and expandable in both hardware and software, so that it can also cope with multisensory integrations – making it an ideal tool for validating and applying computational neuroscience models in real time under real-world conditions. We apply our architecture in real time to validate a long-standing biologically inspired visual object recognition model, HMAX. In this context, the overall aim is to supply a humanoid robot with the ability to perceive and understand its environment with a focus on the active aspect of real-time spatiotemporal visual processing. We show that our approach is capable of simulating information processing in the visual cortex in real time and that our entropy-adaptive modification of HMAX has a higher efficiency and classification performance than the standard model (up to \(\sim \!+6\,\% \) ).     

Decision making: singin' in the brain

Which neurons in the brain "decide" to initiate particular behaviors in response to sensory information? In this issue of Neuron, two papers (Kohatsu et?al. and von Philipsborn et?al.) identify candidates in the courtship circuitry of Drosophila. The activity of these neurons is both regulated by sex pheromones and necessary and sufficient to trigger male love song.     

On visual detection of light sources

Experiments show that human beings are capable of detecting self-illuminating surfaces in their visual field, and that this capacity is based, to a great extend, on immediate processing by the visual system, rather than on a higher-level analysis. What are the physical parameters associated with this perception? The following factors are discussed; The highest intensity in the scene, absolute intensity value, local and global contrast, comparison with the average intensity, and lightness computation. All these factors are shown to be insufficient for explaining human's ability to identify light sources in their visual field. Finally, a method for accomplishing the source detection task in the so-called Mondrian world is presented.     

Rapid Extraction of Lexical Tone Phonology in Chinese Characters: A Visual Mismatch Negativity Study

Background

In alphabetic languages, emerging evidence from behavioral and neuroimaging studies shows the rapid and automatic activation of phonological information in visual word recognition. In the mapping from orthography to phonology, unlike most alphabetic languages in which there is a natural correspondence between the visual and phonological forms, in logographic Chinese, the mapping between visual and phonological forms is rather arbitrary and depends on learning and experience. The issue of whether the phonological information is rapidly and automatically extracted in Chinese characters by the brain has not yet been thoroughly addressed.

Methodology/Principal Findings

We continuously presented Chinese characters differing in orthography and meaning to adult native Mandarin Chinese speakers to construct a constant varying visual stream. In the stream, most stimuli were homophones of Chinese characters: The phonological features embedded in these visual characters were the same, including consonants, vowels and the lexical tone. Occasionally, the rule of phonology was randomly violated by characters whose phonological features differed in the lexical tone.

Conclusions/Significance

We showed that the violation of the lexical tone phonology evoked an early, robust visual response, as revealed by whole-head electrical recordings of the visual mismatch negativity (vMMN), indicating the rapid extraction of phonological information embedded in Chinese characters. Source analysis revealed that the vMMN was involved in neural activations of the visual cortex, suggesting that the visual sensory memory is sensitive to phonological information embedded in visual words at an early processing stage.     

The formation in the northern fur seal (Callorhinus ursinus L.) of flexible behavioral programs determined by the structure of the complex visual stimulus

In Callorhinus ursinus L. generalized rule was elaborated of perception of two-stimuli complex visual stimulus (CVS) presented in random and formed from a set of three differentiated stimuli. The animal was trained to perceive the visual information in linear sequence according to the rule of "reading" from top to bottom and make in conformity with this rule labile two-link visual-motor chains of actions signalled by CVS stimuli. Such behavioural strategies were called by authors ability to operate with CVS structure.     

立体图对匹配基元的心理物理学实验的探讨

Marr和Poggio等人从视觉信息加工理论中提出零交叉(Zero-Crossing)是视觉早期加工过程中首先得到的最基本的信息。这在生理上有二个高斯分布叠加的感受野以及侧抑现象等可以作为依据,但在心理物理上仍缺乏佐证。我们利用不同密度的随机点,加上了不同百分比的反差噪声的立体图对,观察了各种条件下体视对噪声的耐受特性,得出了有利于说明黑白相间的边(零交叉)为匹配基元的结果。本文报导了这些实验结果并进行了讨论。     

Conditions Complicating Parallel Recognition Processing

The issue in this paper is currently widely debated among American experimental psychologists concerned with the general problem of "information processing": Do human adults take in and process visual information one piece at a time (serial processing), or do they "chunk" information so that several stimuli may be processed simultaneously (parallel processing)?     

A contribution of synaptic plasticity in the basal ganglia to processing of visual information

The mechanism of involvement of the basal ganglia in processing of visual information on the basis of dopamine-dependent modulation of efficacy of synaptic transmission in interconnected parallel associative and limbic loops (cortex--basal ganglia--thalamus--cortex) is proposed. Each loop consists of one of the visual or prefrontal cortical areas connected with the thalamic nucleus and corresponding loci in different nuclei of the basal ganglia. Circulation of activity in such a loop provides reentrance of information into the thalamus and neocortex. Dopamine releasing in response to a visual stimulus oppositely modulates the efficacy of "strong" and "weak" corticostriatal inputs. Subsequent reorganization of activity in the loop leads to a disinhibition (inhibition) of activity of those cortical neurons that were "strongly" ("weakly)" excited by the visual stimulus simultaneously with activation of dopaminergic cells. A selected neuronal pattern in each cortical area represents a property of the visual stimulus processed by this area. Excitation of dopaminergic cells by the visual stimulus via the superior colliculi requires parallel activation of a disinhibitory input to the superior colliculi via the thalamus and a "direct" pathway through the basal ganglia. The prefrontal cortex excited by the visual stimulus via the mediodorsal thalamic nucleus performs a top-down control over the dopaminergic cell activity, supervising simultaneous dopamine release in different striatal loci and thus promotes the interconnected selection of neuronal representations of individual properties of the visual stimulus and their binding in an integrated image.     

Visual saliency and spike timing in the ventral visual pathway.

Visual saliency is a fundamental yet hard to define property of objects or locations in the visual world. In a context where objects and their representations compete to dominate our perception, saliency can be thought of as the "juice" that makes objects win the race. It is often assumed that saliency is extracted and represented in an explicit saliency map, which serves to determine the location of spatial attention at any given time. It is then by drawing attention to a salient object that it can be recognized or categorized. I argue against this classical view that visual "bottom-up" saliency automatically recruits the attentional system prior to object recognition. A number of visual processing tasks are clearly performed too fast for such a costly strategy to be employed. Rather, visual attention could simply act by biasing a saliency-based object recognition system. Under natural conditions of stimulation, saliency can be represented implicitly throughout the ventral visual pathway, independent of any explicit saliency map. At any given level, the most activated cells of the neural population simply represent the most salient locations. The notion of saliency itself grows increasingly complex throughout the system, mostly based on luminance contrast until information reaches visual cortex, gradually incorporating information about features such as orientation or color in primary visual cortex and early extrastriate areas, and finally the identity and behavioral relevance of objects in temporal cortex and beyond. Under these conditions the object that dominates perception, i.e. the object yielding the strongest (or the first) selective neural response, is by definition the one whose features are most "salient"--without the need for any external saliency map. In addition, I suggest that such an implicit representation of saliency can be best encoded in the relative times of the first spikes fired in a given neuronal population. In accordance with our subjective experience that saliency and attention do not modify the appearance of objects, the feed-forward propagation of this first spike wave could serve to trigger saliency-based object recognition outside the realm of awareness, while conscious perceptions could be mediated by the remaining discharges of longer neuronal spike trains.     

Humans exploit the biomechanics of bipedal gait during visually guided walking over complex terrain

How do humans achieve such remarkable energetic efficiency when walking over complex terrain such as a rocky trail? Recent research in biomechanics suggests that the efficiency of human walking over flat, obstacle-free terrain derives from the ability to exploit the physical dynamics of our bodies. In this study, we investigated whether this principle also applies to visually guided walking over complex terrain. We found that when humans can see the immediate foreground as little as two step lengths ahead, they are able to choose footholds that allow them to exploit their biomechanical structure as efficiently as they can with unlimited visual information. We conclude that when humans walk over complex terrain, they use visual information from two step lengths ahead to choose footholds that allow them to approximate the energetic efficiency of walking in flat, obstacle-free environments.