Weight modulation in top–down computational model for target search

2021 ◽  
pp. 1-13
Author(s):  
R. Aarthi ◽  
J. Amudha
Keyword(s):  
Visual Information ◽  
Computational Models ◽  
Target Identification ◽  
The Other ◽  
Visual Features ◽  
Biological Models ◽  
Top Down ◽  
Target Search ◽  
Optimal Weights ◽  
Building Models

Computer vision research aims at building models which mimic human systems. The recent development in visual information have been used to derive computational models which address a variety of applications. Biological models help to identify the salient objects in the image. But, the identification of non-salient objects in a heterogeneous environment is a challenging task that requires a better understanding of the visual system. In this work, a weight modulation based top-down model is proposed that integrates the visual features that depend on its importance for the target search application. The model is designed to learn the optimal weights such that it biases the features of the target from the other surrounding regions. Experimental analysis is performed on various scenes on a standard dataset with the selected object in the scene. Metrics such as area under curve, average hit number and correlation reveal that the method is more suitable in target identification, by suppressing the other region.

scholarly journals Contributions of magno- and parvocellular channels to conscious and non-conscious vision

2014 ◽  
Vol 369 (1641) ◽  
pp. 20130213 ◽  
Author(s):  
Bruno G. Breitmeyer
Keyword(s):  
Prefrontal Cortex ◽  
Neural Activity ◽  
Visual Information ◽  
Masked Priming ◽  
The Other ◽  
Future Research ◽  
Top Down ◽  
Pathway Activity ◽  
Feed Forward ◽  
Conscious Processing

The dorsal and ventral cortical pathways, driven predominantly by magnocellular (M) and parvocellular (P) inputs, respectively, assume leading roles in models of visual information processing. Although in prior proposals, the dorsal and ventral pathways support non-conscious and conscious vision, respectively, recent modelling and empirical developments indicate that each pathway plays important roles in both non-conscious and conscious vision. In these models, the ventral P-pathway consists of one subpathway processing an object's contour features, e.g. curvature, the other processing its surface attributes, e.g. colour. Masked priming studies have shown that feed-forward activity in the ventral P-pathway on its own supports non-conscious processing of contour and surface features. The dorsal M-pathway activity contributes directly to conscious vision of motion and indirectly to object vision by projecting to prefrontal cortex, which in turn injects top-down neural activity into the ventral P-pathway and there ‘ignites’ feed-forward–re-entrant loops deemed necessary for conscious vision. Moreover, an object's shape or contour remains invisible without the prior conscious registration of its surface properties, which for that reason are taken to comprise fundamental visual qualia. Besides suggesting avenues for future research, these developments bear on several recent and past philosophical issues.

scholarly journals Language Family Engineering with Product Lines of Multi-level Models

2021 ◽  
Author(s):  
Juan de Lara ◽  
Esther Guerra
Keyword(s):  
Software Engineering ◽  
Arbitrary Number ◽  
Formal Theory ◽  
The Other ◽  
Language Family ◽  
Top Down ◽  
Product Lines ◽  
Modelling Languages ◽  
Multi Level ◽  
Definition Of

AbstractModelling is an essential activity in software engineering. It typically involves two meta-levels: one includes meta-models that describe modelling languages, and the other contains models built by instantiating those meta-models. Multi-level modelling generalizes this approach by allowing models to span an arbitrary number of meta-levels. A scenario that profits from multi-level modelling is the definition of language families that can be specialized (e.g., for different domains) by successive refinements at subsequent meta-levels, hence promoting language reuse. This enables an open set of variability options given by all possible specializations of the language family. However, multi-level modelling lacks the ability to express closed variability regarding the availability of language primitives or the possibility to opt between alternative primitive realizations. This limits the reuse opportunities of a language family. To improve this situation, we propose a novel combination of product lines with multi-level modelling to cover both open and closed variability. Our proposal is backed by a formal theory that guarantees correctness, enables top-down and bottom-up language variability design, and is implemented atop the MetaDepth multi-level modelling tool.

scholarly journals Different Roles of Top-Down and Bottom-Up Processes in the Distribution of Size-Fractionated Phytoplankton in Gwangyang Bay

Water ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1682
Author(s):  
Yoonja Kang ◽  
Yeongji Oh
Keyword(s):  
Nutrient Availability ◽  
Fast Response ◽  
Nutrient Addition ◽  
The Other ◽  
Zooplankton Grazing ◽  
Top Down ◽  
Bottom Up ◽  
Phytoplankton Distribution ◽  
Summer Bloom ◽  
Gwangyang Bay

The interactive roles of zooplankton grazing (top-down) and nutrient (bottom-up) processes on phytoplankton distribution in a temperate estuary were investigated via dilution and nutrient addition experiments. The responses of size-fractionated phytoplankton and major phytoplankton groups, as determined by flow cytometry, were examined in association with zooplankton grazing and nutrient availability. The summer bloom was attributed to nanoplankton, and microplankton was largely responsible for the winter bloom, whereas the picoplankton biomass was relatively consistent throughout the sampling periods, except for the fall. The nutrient addition experiments illustrated that nanoplankton responded more quickly to phosphate than the other groups in the summer, whereas microplankton had a faster response to most nutrients in the winter. The dilution experiments ascribed that the grazing mortality rates of eukaryotes were low compared to those of the other groups, whereas autotrophic cyanobacteria were more palatable to zooplankton than cryptophytes and eukaryotes. Our experimental results indicate that efficient escape from zooplankton grazing and fast response to nutrient availability synergistically caused the microplankton to bloom in the winter, whereas the bottom-up process (i.e., the phosphate effect) largely governed the nanoplankton bloom in the summer.

Reproduction of Object Shape is More Accurate without the Continued Availability of Visual Information

Perception ◽  
1998 ◽  
Vol 27 (1) ◽  
pp. 69-86 ◽  
Author(s):  
Michel-Ange Amorim ◽  
Jack M Loomis ◽  
Sergio S Fukusima
Keyword(s):  
Visual Information ◽  
Internal Representation ◽  
Stimulus Configuration ◽  
The Other ◽  
Additional Information ◽  
Distant Stimulus ◽  
Perspective Change ◽  
Visual Presence ◽  
Viewpoint Change ◽  
Actual Change

An unfamiliar configuration lying in depth and viewed from a distance is typically seen as foreshortened. The hypothesis motivating this research was that a change in an observer's viewpoint even when the configuration is no longer visible induces an imaginal updating of the internal representation and thus reduces the degree of foreshortening. In experiment 1, observers attempted to reproduce configurations defined by three small glowing balls on a table 2 m distant under conditions of darkness following ‘viewpoint change’ instructions. In one condition, observers reproduced the continuously visible configuration using three other glowing balls on a nearer table while imagining standing at the distant table. In the other condition, observers viewed the configuration, it was then removed, and they walked in darkness to the far table and reproduced the configuration. Even though the observers received no additional information about the stimulus configuration in walking to the table, they were more accurate (less foreshortening) than in the other condition. In experiment 2, observers reproduced distant configurations on a nearer table more accurately when doing so from memory than when doing so while viewing the distant stimulus configuration. In experiment 3, observers performed both the real and imagined perspective change after memorizing the remote configuration. The results of the three experiments indicate that the continued visual presence of the target configuration impedes imaginary perspective-change performance and that an actual change in viewpoint does not increase reproduction accuracy substantially over that obtained with an imagined change in viewpoint.

scholarly journals The Neurophysiology of Backward Visual Masking: Information Analysis

1999 ◽  
Vol 11 (3) ◽  
pp. 300-311 ◽  
Author(s):  
Edmund T. Rolls ◽  
Martin J. Tovée ◽  
Stefano Panzeri
Keyword(s):  
Visual Processing ◽  
Visual Information ◽  
Computational Models ◽  
Direct Evidence ◽  
Visual Masking ◽  
Neuronal Response ◽  
Short Soas ◽  
Stimulus Onset ◽  
Backward Masking ◽  
Neuronal Responses

Backward masking can potentially provide evidence of the time needed for visual processing, a fundamental constraint that must be incorporated into computational models of vision. Although backward masking has been extensively used psychophysically, there is little direct evidence for the effects of visual masking on neuronal responses. To investigate the effects of a backward masking paradigm on the responses of neurons in the temporal visual cortex, we have shown that the response of the neurons is interrupted by the mask. Under conditions when humans can just identify the stimulus, with stimulus onset asynchronies (SOA) of 20 msec, neurons in macaques respond to their best stimulus for approximately 30 msec. We now quantify the information that is available from the responses of single neurons under backward masking conditions when two to six faces were shown. We show that the information available is greatly decreased as the mask is brought closer to the stimulus. The decrease is more marked than the decrease in firing rate because it is the selective part of the firing that is especially attenuated by the mask, not the spontaneous firing, and also because the neuronal response is more variable at short SOAs. However, even at the shortest SOA of 20 msec, the information available is on average 0.1 bits. This compares to 0.3 bits with only the 16-msec target stimulus shown and a typical value for such neurons of 0.4 to 0.5 bits with a 500-msec stimulus. The results thus show that considerable information is available from neuronal responses even under backward masking conditions that allow the neurons to have their main response in 30 msec. This provides evidence for how rapid the processing of visual information is in a cortical area and provides a fundamental constraint for understanding how cortical information processing operates.

Evoked Potentials by Letters in Printed and Script Forms

1984 ◽  
Vol 59 (1) ◽  
pp. 227-232 ◽  
Author(s):  
Luciano Mecacci ◽  
Dario Salmaso
Keyword(s):  
Information Processing ◽  
Evoked Potentials ◽  
Visual Evoked Potentials ◽  
Adult Male ◽  
Visual Information ◽  
The Other ◽  
Behavioral Data ◽  
Evoked Responses ◽  
Amplitude Component ◽  
Male Subjects

Visual evoked potentials were recorded for 6 adult male subjects in response to single vowels and consonants in printed and script forms. Analysis showed the vowels in the printed form to have evoked responses with shorter latency (component P1 at about 133 msec.) and larger amplitude (component P1-N1) than the other letter-typeface combinations. No hemispheric asymmetries were found. The results partially agree with the behavioral data on the visual information-processing of letters.

Towards a Lexically Oriented Automatic Parsing

1991 ◽  
Vol 15 (1) ◽  
pp. 1-40
Author(s):  
Lucio Costa
Keyword(s):  
Artificial Intelligence ◽  
Distributed Control ◽  
Data Structures ◽  
General Framework ◽  
Computational Models ◽  
The Other ◽  
Sono Stati ◽  
Use Context ◽  
And Linguistics ◽  
Context Free

RIASSUNTO La ricerca sul linguaggio naturale condotta in Intelligenza Artificiale si è sviluppata, malgrado le apparenze, in modo alquanto indipendente dal la-voro dei linguisti. Da un lato sono stati elaborati modelli computazionali delle facoltà di lunguaggio che si configurano come largamente autonomi rispetto a quelli sviluppati in linguistica. D'altro lato, l'implementazione dei sistemi è stata influenzata da soluzioni pragmatiche connesse all'efficacia computazionale delle regole indipendenti dal contesto, alla necessità di evitare componenti trasformazionali inversi e ad una concezione rappresenta-zionale del significato. Il presente articolo propone l'interesse dei lavori lin-guistici di Z. S. Harris e M. Gross ai fini dello sviluppo di un'analisi sintat-tica automatica che sia a controllo diffuso e incentrata sul comportamento idiosincratico delle unità lessicali. Essa è anche inquadrata nel tentativo di gettare luce sulla natura del processo denotazionale. SUMMARY In spite of the claim on the interactions between artificial intelligence (AI) and linguistics, AI research on natural language has developed independently from the work of linguists. On one hand, computational models of the faculties of language which are independent from the models developed in linguistics have been worked out. On the other hand, the AI system design has been oriented towards practical solutions, whose main motivations where to use context-free rules, to avoid an inverse transformational component, and to represent meanings by some data structures. This paper is about the linguistic works of Z.S. Harris and M. Gross to develop automatic distributed control parsing which takes seriously into account the indiosyncratic behaviour of the lexical items. The general framework for the discussion is the procedural nature of the denotational process.

scholarly journals Organization of the Drosophila larval visual circuit

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Ivan Larderet ◽  
Pauline MJ Fritsch ◽  
Nanae Gendre ◽  
G Larisa Neagu-Maier ◽  
Richard D Fetter ◽  
...  
Keyword(s):  
Visual Processing ◽  
Visual Information ◽  
Neural Circuit ◽  
Visual Features ◽  
Environmental Cues ◽  
Wiring Diagram ◽  
Visual Systems ◽  
Drosophila Larvae ◽  
Organizational Principles ◽  
Numerical Complexity

Visual systems transduce, process and transmit light-dependent environmental cues. Computation of visual features depends on photoreceptor neuron types (PR) present, organization of the eye and wiring of the underlying neural circuit. Here, we describe the circuit architecture of the visual system of Drosophila larvae by mapping the synaptic wiring diagram and neurotransmitters. By contacting different targets, the two larval PR-subtypes create two converging pathways potentially underlying the computation of ambient light intensity and temporal light changes already within this first visual processing center. Locally processed visual information then signals via dedicated projection interneurons to higher brain areas including the lateral horn and mushroom body. The stratified structure of the larval optic neuropil (LON) suggests common organizational principles with the adult fly and vertebrate visual systems. The complete synaptic wiring diagram of the LON paves the way to understanding how circuits with reduced numerical complexity control wide ranges of behaviors.

Twin Peaks

2016 ◽  
Author(s):  
David Colander ◽  
Roland Kupers
Keyword(s):  
Complexity Science ◽  
The Other ◽  
Policy Choice ◽  
Top Down ◽  
Twin Peaks ◽  
Control Actions ◽  
Evolving System ◽  
Policy Frame ◽  
The Government

This chapter provides an overview of the book’s main themes. It discusses the notion of a complexity frame, which is a fundamentally different policy frame provided by complexity science. The central policy choice in a complexity frame is not the market or the government. The goal of policy in the complexity frame is not to choose one or the other. Instead, policy is seen as affecting a complex evolving system that cannot be controlled. But while it cannot be controlled, it can be influenced, and policymakers have to continually think how to work with evolutionary pressures, and try to guide those pressures toward desirable ends. Within the complexity frame, top-down control actions are a last resort. Their use suggests that you have failed in your previous attempts to get the ecostructure right.

Sign in / Sign up

Export Citation Format

Share Document