scholarly journals Attack Behaviour and Distance Perception in the Australian Bulldog Ant Myrmecia Nigriceps

1985 ◽  
Vol 119 (1) ◽  
pp. 115-131 ◽  
Author(s):  
E. Sture Eriksson
Keyword(s):  
Binocular Disparity ◽  
Distance Perception ◽  
Zero Point ◽  
Effective Range ◽  
Moving Targets ◽  
Freely Moving ◽  
Movement Parallax ◽  
Extract Information

The behaviour of the Australian bulldog ant Myrmecia nigriceps (Fr. Smith) has been studied by using moving targets characterized by sizedistance equivalence in relation to a stationary zero-point. The attack behaviour of freely moving animals demonstrated that the ants can discriminate between different targets, in the range of 5–80 cm, using movement parallax to extract information about the targets. By studying the antenna response it was possible to demonstrate that the stationary bulldog ant can utilize binocular disparity information and that this mechanism has an effective range of about 90 mm.

Dynamics of Attention in Depth: Evidence from Multi-Element Tracking

Perception ◽  
10.1068/p3432 ◽  
2002 ◽  
Vol 31 (12) ◽  
pp. 1415-1437 ◽  
Author(s):  
Lavanya Viswanathan ◽  
Ennio Mingolla
Keyword(s):  
Binocular Disparity ◽  
Spatial Separation ◽  
Three Dimensions ◽  
Moving Targets ◽  
Improve Performance ◽  
Frontoparallel Plane ◽  
Surface Information ◽  
Depth Cues ◽  
Planar Surfaces ◽  
Improved Performance

We examined the allocation of attention in depth using a multi-element tracking paradigm. Observers were required to track a predefined subset of from two to eight elements in displays containing up to sixteen identical moving elements. We first show that depth cues, such as binocular disparity and occlusion through T-junctions, improve performance in a multi-element tracking task in the case where element boundaries are allowed to intersect in the depiction of motion in a single frontoparallel plane. We also show that the allocation of attention across two perceptually distinguishable planar surfaces, either frontoparallel or receding at a slanting angle and defined by coplanar elements, is easier than allocation of attention within a single surface. The same result was not found when attention was required to be deployed across items of two-color populations rather than across items of a single color. Our results suggest that, when surface information does not suffice to distinguish between targets and distractors that are embedded in these surfaces, division of attention across two surfaces aids in tracking moving targets. A final experiment with populations of elements moving within distinct volumes produced similar results, suggesting that spatial separation in three dimensions, rather than confinement to surfaces as such, may explain the improved performance for the two-surface case.

Monocular Movement Parallax and Near-Space Perception

Perception ◽  
1973 ◽  
Vol 2 (2) ◽  
pp. 135-146 ◽  
Author(s):  
G Johansson
Keyword(s):  
Distance Perception ◽  
Stimulus Change ◽  
Space Perception ◽  
Head Movements ◽  
Experimental Conditions ◽  
Distance Information ◽  
Near Space ◽  
Movement Parallax ◽  
Perceptual Systems ◽  
Pattern Transformation

Monocular perception of absolute distances in near space (<2 m) is discussed and studied experimentally. Stimulus change in time and sensory co-action (visual plus kinestethic) are in the theoretical analysis regarded as essential. Therefore movement parallax due to voluntary head movements has been introduced, in the experiments, as a hypothetical main cue, and perspective pattern transformation as a probably important side cue together with accommodation. (In ‘natural’ monocular perception these cues, in combination, are always available in near-space perception.) Under these experimental conditions all subjects exhibited approximately adequate (veridical) distance perception. This positive result, which diverges from the commonly accepted views about absolute-distance information, is tentatively regarded as an effect of the combination of cues and of methodological improvements introduced in the experiments. The result is taken as an indication of the fruitfulness of Gibson's conception of perceptual systems.

Modification of Depth and Distance Perception Caused by Long-Term Wearing of Left—Right Reversing Spectacles

Perception ◽  
10.1068/p3342 ◽  
2003 ◽  
Vol 32 (2) ◽  
pp. 131-153 ◽  
Author(s):  
Makoto Ichikawa ◽  
Takahiko Kimura ◽  
Hiroyuki Egusa ◽  
Makiko Nakatsuka ◽  
Jun Amano ◽  
...  
Keyword(s):  
Visual System ◽  
Relative Efficiency ◽  
Binocular Disparity ◽  
Distance Perception ◽  
Apparent Depth ◽  
Distance Information ◽  
Depth Order ◽  
Depth Cues ◽  
Monocular Depth

For 35 to 39 days, four observers wore continuously left–right reversing spectacles which pseudoscopically reverse the order of binocular disparity and direction of convergence. In three tests, we investigated how the visual system copes with the transformation of depth and distance information due to the reversing spectacles. In stereogram observation, after a few days of wearing the spectacles, the observers sometimes perceived a depth order which was opposite to the depth order that they had perceived in the pre-spectacle-wearing period. Monocular depth cues contributed more to depth perception in the spectacle-wearing period than they did in the pre-spectacle-wearing period. While the perceived distance significantly decreased during the spectacle-wearing period, we found no evidence of adaptive change in distance perception. The results indicate that the visual system adapts itself to the transformed situation by not only changing the processing of disparity but also by changing the relative efficiency of each cue in determining apparent depth.

Systematic effects in observed parallaxes

1978 ◽  
Vol 48 ◽  
pp. 31-35
Author(s):  
R. B. Hanson
Keyword(s):  
Error Estimates ◽  
Zero Point ◽  
Absolute Zero ◽  
Apparent Magnitude ◽  
Coherent System ◽  
Preliminary Results ◽  
General Catalogue ◽  
Systematic Effects ◽  
New Evidence ◽  
Right Ascension

Several outstanding problems affecting the existing parallaxes should be resolved to form a coherent system for the new General Catalogue proposed by van Altena, as well as to improve luminosity calibrations and other parallax applications. Lutz has reviewed several of these problems, such as: (A) systematic differences between observatories, (B) external error estimates, (C) the absolute zero point, and (D) systematic observational effects (in right ascension, declination, apparent magnitude, etc.). Here we explore the use of cluster and spectroscopic parallaxes, and the distributions of observed parallaxes, to bring new evidence to bear on these classic problems. Several preliminary results have been obtained.

Coherent electron nanodiffraction from clean silver nano particles in a UHV STEM

1993 ◽  
Vol 51 ◽  
pp. 1058-1059
Author(s):  
J. Liu ◽  
M. Pan ◽  
G. E. Spinnler
Keyword(s):  
Supported Catalysts ◽  
Imaging Techniques ◽  
Nano Particles ◽  
Metal Particles ◽  
Shape Structure ◽  
Dynamical Simulations ◽  
Small Metal Particles ◽  
Extract Information

Small metal particles have peculiar chemical and physical properties as compared to bulk materials. They are especially important in catalysis since metal particles are common constituents of supported catalysts. The structural characterization of small particles is of primary importance for the understanding of structure-catalytic activity relationships. The shape and size of metal particles larger than approximately 5 nm in diameter can be determined by several imaging techniques. It is difficult, however, to deduce the shape of smaller metal particles. Coherent electron nanodiffraction (CEND) patterns from nano particles contain information about the particle size, shape, structure and defects etc. As part of an on-going program of STEM characterization of supported catalysts we report some preliminary results of CEND study of Ag nano particles, deposited in situ in a UHV STEM instrument, and compare the experimental results with full dynamical simulations in order to extract information about the shape of Ag nano particles.

The Contribution of Phonon-Scattered Electrons to High-Resolution Electron Micrographs of Crystals

1990 ◽  
Vol 48 (1) ◽  
pp. 62-63
Author(s):  
H. Kohl
Keyword(s):  
High Resolution ◽  
Spherical Aberration ◽  
High Resolution Electron Microscopy ◽  
Static Potential ◽  
Qualitative Comparison ◽  
The Past ◽  
Resolution Electron ◽  
High Resolution Images ◽  
High Resolution Electron Micrographs ◽  
Extract Information

High-Resolution Electron Microscopy is able to determine structures of crystals and interfaces with a spatial resolution of somewhat less than 2 Å. As the image is strongly dependent on instrumental parameters, notably the defocus and the spherical aberration, the interpretation of micrographs necessitates a comparison with calculated images. Whereas one has often been content with a qualitative comparison of theory with experiment in the past, one is currently striving for quantitative procedures to extract information from the images [1,2]. For the calculations one starts by assuming a static potential, thus neglecting inelastic scattering processes.We shall confine the discussion to periodic specimens. All electrons, which have only been elastically scattered, are confined to very few directions, the Bragg spots. In-elastically scattered electrons, however, can be found in any direction. Therefore the influence of inelastic processes on the elastically (= Bragg) scattered electrons can be described as an attenuation [3]. For the calculation of high-resolution images this procedure would be correct only if we had an imaging energy filter capable of removing all phonon-scattered electrons. This is not realizable in practice. We are therefore forced to include the contribution of the phonon-scattered electrons.

The Use of Real-Time Visual Displays of Speech in the Training of a Profoundly Deaf, Nonspeaking Child: A Case Report

1971 ◽  
Vol 36 (3) ◽  
pp. 397-409 ◽  
Author(s):  
Rachel E. Stark
Keyword(s):  
Case Report ◽  
Real Time ◽  
Speech Production ◽  
Behavior Problem ◽  
Deaf Children ◽  
Developmental Sequence ◽  
Visual Displays ◽  
Individual Instruction ◽  
Academic Record ◽  
Extract Information

Real-time amplitude contour and spectral displays were used in teaching speech production skills to a profoundly deaf, nonspeaking boy. This child had a visual attention problem, a behavior problem, and a poor academic record. In individual instruction, he was first taught to produce features of speech, for example, friction, nasal, and stop, which are present in vocalizations of 6- to 9-month-old infants, and then to combine these features in syllables and words. He made progress in speech, although sign language and finger spelling were taught at the same time. Speech production skills were retained after instruction was terminated. The results suggest that deaf children are able to extract information about the features of speech from visual displays, and that a developmental sequence should be followed as far as possible in teaching speech production skills to them.

Sign in / Sign up

Export Citation Format

Share Document