arXiv subjects

Birgitta Dresp-Langley

Publications and source records attributed to Birgitta Dresp-Langley.

48 records · Page 3Linked to original sources

arXiv2018

Colour for behavioural success

Colour information not only helps sustain the survival of animal species by guiding sexual selection and foraging behaviour, but also is an important factor in the cultural and technological development of our own species. This is illustrated by examples from the visual arts and from state-of-the-art imaging technology, where the strategic use of colour has become a powerful tool for guiding the planning and execution of interventional procedures. The functional role of colour information in terms of its potential benefits to behavioural success across the species is addressed in the introduction here to clarify why colour perception may have evolved to generate behavioural success. It is argued that evolutionary and environmental pressures influence not only colour trait production in the different species, but also their ability to process and exploit colour information for goal-specific purposes. We then leap straight to the human primate with insight from current research on the facilitating role of colour cues on performance training with precision technology for image-guided surgical planning and intervention. It is shown that local colour cues in 2D images generated by a surgical fisheye camera help individuals become more precise rapidly across a limited number of trial sets in simulator training for specific manual gestures with a tool. The progressively facilitating effect of a local colour cue on performance evolution in a video controlled simulator task can be explained in terms of colour-based figure-ground segregation guiding attention towards local image parts, with an immediate cost on performance time, and a lasting long-term benefit in terms of greater task precision.

q-bio.NC↗

arXiv2018

Wayfinding through an unfamiliar environment

Strategies for finding one's way through an unfamiliar environment may be helped by computer generated 2D maps, 3D virtual environments, or other navigation aids. The relative effectiveness of 2D and 3D virtual navigation aids was investigated. The wayfinding experiments (navigation tests) were conducted in a large, park-like environment. 24 participants (12 men, 12 women; age range = 22-50 years; M=32, SD = 7.4) were divided into three groups of four individuals per gender, who 1) explored a computer generated 2D map of the given route prior to navigation, 2) received a silent guided tour by means of an interactive 3D virtual representation, or 3) acquired direct experience of the real-world route through a silent guided tour where they were accompanied by a human individual who had expert knowledge of all the routes in the park. Participants from the different preparation groups then had to find the same route again on their own. 12 observers (six men and six women) were given a "simple" route with only one critical turn, and the other 12 a "complex" route with six critical turns. Navigation performances were compared with those of three experts who were highly familiar with all the routes of the park. Those among the naive participants who had benefitted from a direct experience (guided tour) prior to navigation, all found their way again on the simple and complex routes. Those who had explored the interactive 3D virtual environment were all unable to find their way on the complex route. The relative scale representation in the virtual 3D environment may have given incorrect impressions of relative distances between salient objects along the itinerary, rendering important landmark information useless.

cs.HC↗

arXiv2018

Why the brain knows more than we do: non-conscious representations and their role in the construction of conscious experience

Scientific studies have shown that non-conscious stimuli and representations influence information processing during conscious experience. In the light of such evidence, questions about potential functional links between non-conscious brain representations and conscious experience arise. This article discusses a neural coding model capable of explaining how statistical learning mechanisms in dedicated resonant circuits could generate specific temporal activity traces of non-conscious representations in the brain. How reentrant signaling, top-down matching, and statistical coincidence of such activity traces may lead to the progressive consolidation of temporal patterns that constitute the neural signatures of conscious experience in networks extending across large distances beyond functionally specialized brain regions is then explained.

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arXiv2018

Visual spatial learning of complex object morphologies through interaction with virtual and real-world data

Conceptual design relies on extensive manipulation of morphological properties of real or virtual objects.This study investigates the nature of the perceptual information that could be retrieved from different representation modalities to reproduce structural properties of a complex object by drawing . The abstract and complex object (tensegrity simplex) was presented to two study populations (design experts/architects and non-experts) in three different representation modalities (2D image view explored visually only, digital 3D model explored visually using a computer mouse, the real object explored visually and manually. After viewing and exploring, observers had to draw the most critical parts of the structure by hand into a 2D reference frame. The results reveal a considerable performance advantage of digital 3D model exploration compared with real-world 3D object manipulation in the expert population.The results are discussed in terms of the specific nature of morphological cues made available through the different representation modalities.

cs.HC↗

arXiv2018

Neural computation of surface border ownership and relative surface depth from ambiguous contrast inputs

The segregation of image parts into foreground and background is an important aspect of the neural computation of 3D scene perception. To achieve such segregation, the brain needs information about border ownership; that is, the belongingness of a contour to a specific surface represented in the image. This article presents psychophysical data derived from 3D percepts of figure and ground that were generated by presenting 2D images composed of spatially disjoint shapes that pointed inward or outward relative to the continuous boundaries that they induced along their collinear edges. The shapes in some images had the same contrast (black or white) with respect to the background gray. Other images included opposite contrasts along each induced continuous boundary. Psychophysical results show that figure vs ground judgment probabilities in response to these ambiguous displays are determined by the orientation of contrasts only, not by their relative contrasts, despite the fact that many border ownership cells in cortical area V2 respond to a preferred relative contrast. The FACADE and 3D LAMINART models are used to explain these data.

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arXiv2018

Detection of Structural Change in Geographic Regions of Interest by Self Organized Mapping: Las Vegas City and Lake Mead across the Years

Time-series of satellite images may reveal important data about changes in environmental conditions and natural or urban landscape structures that are of potential interest to citizens, historians, or policymakers. We applied a fast method of image analysis using Self Organized Maps (SOM) and, more specifically, the quantization error (QE), for the visualization of critical changes in satellite images of Las Vegas, generated across the years 1984-2008, a period of major restructuration of the urban landscape. As shown in our previous work, the QE from the SOM output is a reliable measure of variability in local image contents. In the present work, we use statistical trend analysis to show how the QE from SOM run on specific geographic regions of interest extracted from satellite images can be exploited to detect both the magnitude and the direction of structural change across time at a glance. Significantly correlated demographic data for the same reference time period are highlighted. The approach is fast and reliable, and can be implemented for the rapid detection of potentially critical changes in time series of large bodies of image data.

cs.CY↗

arXiv2018

Effects of 2D and 3D image views on hand movement trajectories in the surgeons peripersonal space in a computer controlled simulator environment

In image-guided surgical tasks, the precision and timing of hand movements depend on the effectiveness of visual cues relative to specific target areas in the surgeons peri-personal space. Two-dimensional (2D) image views of real-world movements are known to negatively affect both constrained (with tool) and unconstrained(no tool) hand movements compared with direct action viewing. Task conditions where virtual 3D would generate and advantage for surgical eye-hand coordination are unclear. Here, we compared effects of 2D and 3D image views on the precision and timing of surgical hand movement trajectories in a simulator environment. Eight novices had to pick and place a small cube on target areas across different trajectory segments in the surgeons peri-personal space, with the dominant hand, with and without a tool, under conditions of: (1) direct (2) 2D fisheye camera and (3) virtual 3D viewing (headmounted). Significant effects of the location of trajectories in the surgeons peri-personal space on movement times and precision were found. Subjects were faster and more precise across specific target locations, depending on the viewing modality.

cs.HC↗

arXiv2018

Getting nowhere fast: trade-off between speed and precision in training to execute image-guided hand-tool movements

Background: The speed and precision with which objects are moved by hand or hand-tool interaction under image guidance depend on a specific type of visual and spatial sensorimotor learning. Novices have to learn to optimally control what their hands are doing in a real-world environment while looking at an image representation of the scene on a video monitor. Previous research has shown slower task execution times and lower performance scores under image-guidance compared with situations of direct action viewing. The cognitive processes for overcoming this drawback by training are not yet understood. Methods: We investigated the effects of training on the time and precision of direct view versus image guided object positioning on targets of a Real-world Action Field (RAF). Two men and two women had to learn to perform the task as swiftly and as precisely as possible with their dominant hand, using a tool or not and wearing a glove or not. Individuals were trained in sessions of mixed trial blocks with no feed-back. Results: As predicted, image-guidance produced significantly slower times and lesser precision in all trainees and sessionscompared with direct viewing. With training, all trainees get faster in all conditions, but only one of them gets reliably more precise in the image-guided conditions. Speed-accuracy trade-offs in the individual performance data show that the highest precision scores and steepest learning curve, for time and precision, were produced by the slowest starter.Conclusions: Performance evolution towards optimal precision is compromised when novices start by going as fast as they can. The findings have direct implications for individual skill monitoring in training programmes for image-guided technology applications with human operators.

cs.HC↗

arXiv2017

Using the quantization error from Self-Organized Map (SOM) output for detecting critical variability in large bodies of image time series in less than a minute

The quantization error (QE) from SOM applied on time series of spatial contrast images with variable relative amount of white and dark pixel contents, as in monochromatic medical images or satellite images, is proven a reliable indicator of potentially critical changes in image homogeneity. The QE is shown to increase linearly with the variability in spatial contrast contents across time when contrast intensity is kept constant.

cs.CY↗

arXiv2017

On the detectability by novices, radiologists, and computer algorithms of smallest increases in local single dot size in random-dot images

Time-series of images may reveal important information about changes in medical or environmental conditions, depending on context. Visual inspection of images by humans (experts or laymen) may fail in detecting very small differences between images, yet, small but visually undetectable differences may carry important significance. Computer algorithms may help overcome this problem, and the use of computer driven image analysis in medical practice or for the tracking of small but critical changes in natural environments attracts a lot of interest. In many contexts relevant to society, the preprocessing of large sets of image series will soon no longer be the exclusive realm of a few scientists. Here we show that a metric obtained from self-organizing map analysis (SOM) of image contents in time series of images of one and the same object or environment reliably signals potentially critical local changes in images that may not be detectable visually by a layman or even an expert.

cs.CY↗

arXiv2017

Curvature sensing by vision and touch

Brain representations of curvature may be formed on the basis of either vision or touch. Experimental and theoretical work by the author and her colleagues has shown that the processing underlying such representations directly depends on specific two-dimensional geometric properties of the curved object, and on the symmetry of curvature. Virtual representations of curves with mirror symmetry were displayed in 2D on a computer screen to sighted observers for visual scaling. For tactile (haptic) scaling, the physical counterparts of these curves were placed in the two hands of sighted observers, who were blindfolded during the sensing experiment, and of congenitally blind observers, who never had any visual experience. All results clearly show that curvature, whether haptically or visually sensed, is statistically linked to the same curve properties. Sensation is expressed psychophysically as a power function of any symmetrical curve's aspect ratio, a scale invariant geometric property of physical objects. The results of the author's work support biologically motivated models of sensory integration for curvature processing. They also promote the idea of a universal power law for adaptive brain control and balancing of motor responses to environmental stimuli across sensory modalities.

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arXiv2017

A temporal access code to consciousness?

While questions of a functional localization of consciousness in the brain have been the subject of myriad studies, the idea of a temporal access code as a specific brain mechanism for consciousness has remained a neglected possibility. Dresp-Langley and Durup (2009, 2012) proposed a theoretical approach in terms of a temporal access mechanism for consciousness based on its two universally recognized properties. Consciousness is limited in processing capacity and described by a unique processing stream across a single dimension, which is time. The time ordering function of conscious states is highlighted and neurobiological theories of the temporal brain activities likely to underlie such function are discussed, and the properties of the code model are then introduced. Spatial information is integrated into provisory topological maps at non-conscious levels through adaptive resonant matching, but does not form part of the temporal access code as such. The latter, de-correlated from the spatial code, operates without any need for firing synchrony on the sole basis of temporal coincidence probabilities in dedicated resonant circuits through progressively non-arbitrary selection of specific temporal activity patterns in the continuously developing brain.

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