scholarly journals Colour and luminance contrasts predict the human detection of natural stimuli in complex visual environments

2017 ◽  
Vol 13 (9) ◽  
pp. 20170375 ◽  
Author(s):  
Thomas E. White ◽  
Bibiana Rojas ◽  
Johanna Mappes ◽  
Petri Rautiala ◽  
Darrell J. Kemp
Keyword(s):  
Visual Cues ◽  
Visual Experience ◽  
Human Detection ◽  
Human Vision ◽  
Forest Environment ◽  
Colour Perception ◽  
Stimulus Detection ◽  
Natural Noise ◽  
Psychophysical Studies

Much of what we know about human colour perception has come from psychophysical studies conducted in tightly-controlled laboratory settings. An enduring challenge, however, lies in extrapolating this knowledge to the noisy conditions that characterize our actual visual experience. Here we combine statistical models of visual perception with empirical data to explore how chromatic (hue/saturation) and achromatic (luminant) information underpins the detection and classification of stimuli in a complex forest environment. The data best support a simple linear model of stimulus detection as an additive function of both luminance and saturation contrast. The strength of each predictor is modest yet consistent across gross variation in viewing conditions, which accords with expectation based upon general primate psychophysics. Our findings implicate simple visual cues in the guidance of perception amidst natural noise, and highlight the potential for informing human vision via a fusion between psychophysical modelling and real-world behaviour.

Color naming, unique hues, and hue cancellation predicted from singularities in reflection properties

2006 ◽  
Vol 23 (3-4) ◽  
pp. 331-339 ◽  
Author(s):  
DAVID L. PHILIPONA ◽  
J. KEVIN O'REGAN
Keyword(s):  
Color Naming ◽  
Surface Reflection ◽  
Unique Hues ◽  
Neuronal Representation ◽  
Underlying Mechanisms ◽  
The One ◽  
Unique Green ◽  
Psychophysical Studies ◽  
Hue Cancellation

Psychophysical studies suggest that different colors have different perceptual status: red and blue for example are thought of as elementary sensations whereas yellowish green is not. The dominant account for such perceptual asymmetries attributes them to specificities of the neuronal representation of colors. Alternative accounts involve cultural or linguistic arguments. What these accounts have in common is the idea that there are no asymmetries in the physics of light and surfaces that could underlie the perceptual structure of colors, and this is why neuronal or cultural processes must be invoked as the essential underlying mechanisms that structure color perception. Here, we suggest a biological approach for surface reflection properties that takes into account only the information about light that is accessible to an organism given the photopigments it possesses, and we show that now asymmetries appear in the behavior of surfaces with respect to light. These asymmetries provide a classification of surface properties that turns out to be identical to the one observed in linguistic color categorization across numerous cultures, as pinned down by cross cultural studies. Further, we show that data from psychophysical studies about unique hues and hue cancellation are consistent with the viewpoint that stimuli reported by observers as special are those associated with this singularity-based categorization of surfaces under a standard illuminant. The approach predicts that unique blue and unique yellow should be aligned in chromatic space while unique red and unique green should not, a fact usually conjectured to result from nonlinearities in chromatic pathways.

Human Stereopsis, Fusion, and Stereoscopic Virtual Environments

1995 ◽  
Author(s):  
Elizabeth Thorpe Davis ◽  
Larry F. Hodges
Keyword(s):  
Virtual Environments ◽  
Visual Cues ◽  
Spatial Information ◽  
Spatial Perception ◽  
Human Perception ◽  
Stereoscopic Vision ◽  
Human Vision ◽  
Spatial Factors ◽  
Stereoscopic Displays ◽  
And Performance

Two fundamental purposes of human spatial perception, in either a real or virtual 3D environment, are to determine where objects are located in the environment and to distinguish one object from another. Although various sensory inputs, such as haptic and auditory inputs, can provide this spatial information, vision usually provides the most accurate, salient, and useful information (Welch and Warren, 1986). Moreover, of the visual cues available to humans, stereopsis provides an enhanced perception of depth and of three-dimensionality for a visual scene (Yeh and Silverstein, 1992). (Stereopsis or stereoscopic vision results from the fusion of the two slightly different views of the external world that our laterally displaced eyes receive (Schor, 1987; Tyler, 1983).) In fact, users often prefer using 3D stereoscopic displays (Spain and Holzhausen, 1991) and find that such displays provide more fun and excitement than do simpler monoscopic displays (Wichanski, 1991). Thus, in creating 3D virtual environments or 3D simulated displays, much attention recently has been devoted to visual 3D stereoscopic displays. Yet, given the costs and technical requirements of such displays, we should consider several issues. First, we should consider in what conditions and situations these stereoscopic displays enhance perception and performance. Second, we should consider how binocular geometry and various spatial factors can affect human stereoscopic vision and, thus, constrain the design and use of stereoscopic displays. Finally, we should consider the modeling geometry of the software, the display geometry of the hardware, and some technological limitations that constrain the design and use of stereoscopic displays by humans. In the following section we consider when 3D stereoscopic displays are useful and why they are useful in some conditions but not others. In the section after that we review some basic concepts about human stereopsis and fusion that are of interest to those who design or use 3D stereoscopic displays. Also in that section we point out some spatial factors that limit stereopsis and fusion in human vision as well as some potential problems that should be considered in designing and using 3D stereoscopic displays. Following that we discuss some software and hardware issues, such as modelling geometry and display geometry as well as geometric distortions and other artifacts that can affect human perception.

scholarly journals A desert ant's memory of recent visual experience and the control of route guidance

2014 ◽  
Vol 281 (1787) ◽  
pp. 20140634 ◽  
Author(s):  
Matthew Collett
Keyword(s):  
Conceptual Model ◽  
Visual Cues ◽  
Visual Experience ◽  
Control Element ◽  
Route Guidance ◽  
General Role ◽  
Simple Route ◽  
Guidance Cues ◽  
Desert Ants ◽  
Series Of Experiments

Insects such as desert ants learn stereotyped visual routes between their nests and reliable food sites. Studies here reveal an important control element for ensuring that the route memories are used appropriately. They find that visual route memories can be disengaged, so that they do not provide guidance, even when all appropriate visual cues are present and when there are no competing guidance cues. Ants were trained along a simple route dominated by a single isolated landmark. If returning ants were caught just before entering the nest and replaced at the feeder, then they often interrupted the recapitulation of their homeward route with a period of apparent confusion during which the route memories were ignored. A series of experiments showed that this confusion occurred in response to the repetition of the route, and that the ants must therefore maintain some kind of a memory of their visual experience on the current trip home. A conceptual model of route guidance is offered to explain the results here. It proposes how the memory might act and suggests a general role for disengagement in regulating route guidance.

Classification of Gold-Bearing Particles Using Visual Cues and Cost-Sensitive Machine Learning

2015 ◽  
Vol 47 (5) ◽  
pp. 521-545 ◽  
Author(s):  
Tom Horrocks ◽  
Daniel Wedge ◽  
Eun-Jung Holden ◽  
Peter Kovesi ◽  
Nick Clarke ◽  
...  
Keyword(s):  
Machine Learning ◽  
Visual Cues ◽  
Gold Bearing

OFFENSES AGAINST THE ENVIRONMENT, ESSENTIAL DAMAGE ASSESSMENT IN THEORY AND PRACTICE

2017 ◽  
Vol 1 (78) ◽  
pp. 30
Author(s):  
Silvija Kotāne
Keyword(s):  
Criminal Law ◽  
Significant Risk ◽  
Legal Protection ◽  
Theory And Practice ◽  
Forest Environment ◽  
Criminal Offense ◽  
Significant Damage ◽  
The Law ◽  
The Republic

This paper shall review of the development of environmental criminal – legal protection in the Republic of Latvia. One of the most complicated valuation terms in Criminal law is essential harm. The adverse effects of marking, used assessment concept – "essential harm" to the Criminal Law Section 11, provisions are included as a criminal offense frame sign. Valuation concept „essential harm” or “significant damage” is widely used. Material injury is one of the mandatory features of the objective of acriminal offence defining the legal classification of the offence and, inany particular case, to assess the nature and consequences of thedamage in relation to the interests laid down by the law. In all cases, regulation is not specified. Significant damage and other interests protected by law in nature and severity to determine the natural environment, human health can be an expert evaluation. In deciding the question of material injury, which is especially qualifying characteristic of the Criminal Law Article 109, followed to the Special Law Annex 1 "Criteria for the detectable threat or significant risk to the law protected the interests of the forest environment conservation." With regard to essential harm the forest environment, evaluation is embedded in the law and are applied in practice.

scholarly journals Exposure to visual cues of pathogen contagion changes preferences for masculinity and symmetry in opposite-sex faces

2010 ◽  
Vol 278 (1714) ◽  
pp. 2032-2039 ◽  
Author(s):  
Anthony C. Little ◽  
Lisa M. DeBruine ◽  
Benedict C. Jones
Keyword(s):  
Visual Cues ◽  
Visual Experience ◽  
Mate Preferences ◽  
Cross Cultural ◽  
Recent Experience ◽  
Cultural Variation ◽  
Gene Markers ◽  
Visual Preferences ◽  
Opposite Sex ◽  
Environmental Pathogens

Evolutionary approaches to human attractiveness have documented several traits that are proposed to be attractive across individuals and cultures, although both cross-individual and cross-cultural variations are also often found. Previous studies show that parasite prevalence and mortality/health are related to cultural variation in preferences for attractive traits. Visual experience of pathogen cues may mediate such variable preferences. Here we showed individuals slideshows of images with cues to low and high pathogen prevalence and measured their visual preferences for face traits. We found that both men and women moderated their preferences for facial masculinity and symmetry according to recent experience of visual cues to environmental pathogens. Change in preferences was seen mainly for opposite-sex faces, with women preferring more masculine and more symmetric male faces and men preferring more feminine and more symmetric female faces after exposure to pathogen cues than when not exposed to such cues. Cues to environmental pathogens had no significant effects on preferences for same-sex faces. These data complement studies of cross-cultural differences in preferences by suggesting a mechanism for variation in mate preferences. Similar visual experience could lead to within-cultural agreement and differing visual experience could lead to cross-cultural variation. Overall, our data demonstrate that preferences can be strategically flexible according to recent visual experience with pathogen cues. Given that cues to pathogens may signal an increase in contagion/mortality risk, it may be adaptive to shift visual preferences in favour of proposed good-gene markers in environments where such cues are more evident.

scholarly journals Middle Cerebral Artery Bifurcation Aneurysms: An Anatomic Classification Scheme for Planning Optimal Surgical Strategies

2013 ◽  
Vol 10 (1) ◽  
pp. 145-155 ◽  
Author(s):  
Chad W. Washington ◽  
Tao Ju ◽  
Gregory J. Zipfel ◽  
Ralph G. Dacey
Keyword(s):  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Visual Cues ◽  
Classification Scheme ◽  
Parent Vessel ◽  
3 Dimensional ◽  
Shape Pattern ◽  
Angiographic Data ◽  
The Relationship

Abstract BACKGROUND: Changing landscapes in neurosurgical training and increasing use of endovascular therapy have led to decreasing exposure in open cerebrovascular neurosurgery. To ensure the effective transition of medical students into competent practitioners, new training paradigms must be developed. OBJECTIVE: Using principles of pattern recognition, we created a classification scheme for middle cerebral artery (MCA) bifurcation aneurysms that allows their categorization into a small number of shape pattern groups. METHODS: Angiographic data from patients with MCA aneurysms between 1995 and 2012 were used to construct 3-dimensional models. Models were then analyzed and compared objectively by assessing the relationship between the aneurysm sac, parent vessel, and branch vessels. Aneurysms were then grouped on the basis of the similarity of their shape patterns in such a way that the in-class similarities were maximized while the total number of categories was minimized. For each category, a proposed clip strategy was developed. RESULTS: From the analysis of 61 MCA bifurcation aneurysms, 4 shape pattern categories were created that allowed the classification of 56 aneurysms (91.8%). The number of aneurysms allotted to each shape cluster was 10 (16.4%) in category 1, 24 (39.3%) in category 2, 7 (11.5%) in category 3, and 15 (24.6%) in category 4. CONCLUSION: This study demonstrates that through the use of anatomic visual cues, MCA bifurcation aneurysms can be grouped into a small number of shape patterns with an associated clip solution. Implementing these principles within current neurosurgery training paradigms can provide a tool that allows more efficient transition from novice to cerebrovascular expert.

Backscroll Illusion

2017 ◽  
Author(s):  
Kiyoshi Fujimoto
Keyword(s):  
Relative Motion ◽  
Translational Motion ◽  
Human Vision ◽  
Natural Images ◽  
Motion Pattern ◽  
Motion Representation ◽  
Object Based ◽  
High Level ◽  
Psychophysical Studies ◽  
Direction Opposite

Human vision recognizes the direction of a human, an animal, and objects in translational motion, even when they are displayed in a still position on a screen as filmed by a panning camera and with the background erased. Because there is no clue to relative motion between the object and the background, the recognition relies on a facing direction and/or movements of its internal parts like limbs. Such high-level object-based motion representation is capable of affecting lower-level motion perception. An ambiguous motion pattern is inserted to the screen behind the translating object. Then the pattern appears moving in a direction opposite to that which the object implies. This is called the backscroll illusion, and psychophysical studies were conducted to investigate phenomenal aspects with the hypothesis that the illusion reflects a strategy the visual system adopts in everyday circumstances. The backscroll illusion convincingly demonstrates that natural images contain visual illusions.

Classification of Disjunctivism about the Phenomenology of Visual Experience

2019 ◽  
Vol 44 ◽  
pp. 89-110
Author(s):  
Takuya Niikawa ◽  
Keyword(s):  
Perceptual Experience ◽  
Visual Experience ◽  
Coarse Grained ◽  
Veridical Perception ◽  
Explanatory Status

This paper proposes a classificatory framework for disjunctivism about the phenomenology of visual perceptual experience. Disjunctivism of this sort is typically divided into positive and negative disjunctivism. This distinction successfully reflects the disagreement amongst disjunctivists regarding the explanatory status of the introspective indiscriminability of veridical perception and hallucination. However, it is unsatisfactory in two respects. First, it cannot accommodate eliminativism about the phenomenology of hallucination. Second, the class of positive disjunctivism is too coarse-grained to provide an informative overview of the current dialectical landscape. Given this, I propose a classificatory framework which preserves the positive-negative distinction, but which also includes the distinction between eliminativism and non-eliminativism, as well as a distinction between two subclasses of positive disjunctivism. In describing each class in detail, I specify who takes up each position in the existing literature, and demonstrate that this classificatory framework can disambiguate some existing disjunctivist views.

Video-Based Human Activity Recognition for Elderly Using Convolutional Neural Network

2020 ◽  
Vol 12 (1) ◽  
pp. 36-48
Author(s):  
Vijayaprabakaran K. ◽  
Sathiyamurthy K. ◽  
Ponniamma M.
Keyword(s):  
Neural Network ◽  
Machine Learning ◽  
Convolutional Neural Network ◽  
Image Classification ◽  
Elderly People ◽  
Activity Recognition ◽  
Learning Algorithm ◽  
Machine Learning Algorithms ◽  
Human Vision

A typical healthcare application for elderly people involves monitoring daily activities and providing them with assistance. Automatic analysis and classification of an image by the system is difficult compared to human vision. Several challenging problems for activity recognition from the surveillance video involving the complexity of the scene analysis under observations from irregular lighting and low-quality frames. In this article, the authors system use machine learning algorithms to improve the accuracy of activity recognition. Their system presents a convolutional neural network (CNN), a machine learning algorithm being used for image classification. This system aims to recognize and assist human activities for elderly people using input surveillance videos. The RGB image in the dataset used for training purposes which requires more computational power for classification of the image. By using the CNN network for image classification, the authors obtain a 79.94% accuracy in the experimental part which shows their model obtains good accuracy for image classification when compared with other pre-trained models.

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