Adaptation to Optically Reduced Size

Perception ◽  
1982 ◽  
Vol 11 (2) ◽  
pp. 139-152 ◽  
Author(s):  
Joseph Scheuhammer ◽  
Brian Timney
Keyword(s):  
Mental Rotation ◽  
Cylindrical Lens ◽  
One Dimension ◽  
Image Size ◽  
Size Distortion ◽  
The Third ◽  
Negative Aftereffect ◽  
Pointing Task ◽  
Adaptation Procedure ◽  
Rotation Procedure

Previous investigators have reported some difficulty in obtaining evidence for adaptation to optically reduced size. A study is reported in which a ballistic target-pointing task was used to examine such adaptation. In the first experiment size was reduced either by means of negative spherical lenses, or cylindrical lenses which reduced image size in only one dimension. Both lens types produced a negative aftereffect of adaptation, which increased as a function of lens strength. There was also a tendency for cylindrical lenses to give larger aftereffects. In a second experiment, in which a modified adaptation procedure was used, adaptation to cylindrical distortion was found to be significantly greater than adaptation to equivalent spherical distortion. These data are interpreted with respect to the relative amounts of distance distortion induced by viewing through the different lens types. The third experiment employed a cylindrical lens and a mental rotation procedure to determine whether adaptation in the first two experiments may have been visual or visuomotor in nature. Results indicated that adaptation was not purely visual. It is concluded that it is possible to demonstrate adaptation to size distortion by using an appropriate procedure.

On Anonymity and Appresentation

2020 ◽  
Vol 12 ◽  
pp. 45-67
Author(s):  
Max Gropper ◽  
Keyword(s):  
Social Identity ◽  
Everyday Life ◽  
Social Group ◽  
The Other ◽  
One Dimension ◽  
Alfred Schutz ◽  
Cultural Patterns ◽  
The Third ◽  
Alfred Schütz ◽  
The Stranger

In his famous work on the stranger, Alfred Schutz focuses on the interpretative discrepancies between in-groups and out-groups from the per­spective of a stranger approaching a new group. In doing so, Schutz emphasizes that strangers can overcome their strangeness within a social group by adapting to the prevalent cultural patterns. Shifting the perspective from the stranger to the in-group this essay aims to argue that the experience of the Other’s strangeness due to a discrepancy of interpretative schemes is only one dimension of how the stranger is perceived in everyday life. A second dimension can be derived from Schutz’ work on appresentation. This essay will follow four analytical steps. First, this essay summarizes the Schutzian approach on perceiving the Other as a taken-for-granted part of everyday life within an assumed intersubjective understanding based on an assumed reciprocity of perspectives. Referring to Eberle’s description of an irreciprocity of perspectives, the second section analyzes the Schutzian stranger based on an intersubjective understanding. The third section then focuses on the appresentational pro­cesses of perceiving the stranger in everyday life. By using Goffman’s distinction between virtual and actual social identity, the interplay of categorizing and experiencing the Other in everyday life can be described. Finally, considering the question of how it comes that people can find themselves strangers in their own society, this paper closes by merging the argumentation with a description of the Schutzian perspective on the processes of stigmatization.

Enhancing Visuomotor Adaptation by Reducing Error Signals: Single-step (Aware) versus Multiple-step (Unaware) Exposure to Wedge Prisms

2007 ◽  
Vol 19 (2) ◽  
pp. 341-350 ◽  
Author(s):  
Carine Michel ◽  
Laure Pisella ◽  
Claude Prablanc ◽  
Gilles Rode ◽  
Yves Rossetti
Keyword(s):  
Adaptive Capacity ◽  
Visuomotor Adaptation ◽  
Open Loop ◽  
Single Step ◽  
Prism Adaptation ◽  
After Effects ◽  
Pointing Task ◽  
Adaptation Procedure ◽  
Functional Mechanisms ◽  
Multiple Step

Neglect patients exhibit both a lack of awareness for the spatial distortions imposed during visuomanual prism adaptation procedures, and exaggerated postadaptation negative after-effects. To better understand this unexpected adaptive capacity in brain-lesioned patients, we investigated the contribution of awareness for the optical shift to the development of prism adaptation. The lack of awareness found in neglect was simulated in a multiple-step group where healthy subjects remained unaware of the optical deviation because of its progressive stepwise increase from 2° to 10°. We contrasted this method with the classical single-step group in which subjects were aware of the visual shift because they were directly exposed to the full 10° shift. Because the number of pointing trials was identical in the two groups, the total amount of deviation exposure was 50% larger in the single-step group. Negative after-effects were examined with an open-loop pointing task performed with the adapted hand, and generalization was tested with open-loop pointing with the nonexposed hand to visual and auditory targets. The robustness of adaptation was assessed by an open-loop pointing task after a simple de-adaptation procedure. The progressive, unaware condition was associated with larger negative after-effects, transfer to the non-exposed hand for the visual and auditory pointing tasks, and greater robustness. The amount of adaptation obtained remained, nevertheless, lower than the exaggerated adaptive capacity seen in patients with neglect. Implications for the functional mechanisms and the anatomical substrates of prism adaptation are discussed.

Effects of Age and Sex in Mental Rotation and Spatial Learning from Virtual Environments

2010 ◽  
Vol 31 (2) ◽  
pp. 78-82 ◽  
Author(s):  
Robby Schoenfeld ◽  
Wolfgang Lehmann ◽  
Bernd Leplow
Keyword(s):  
Mental Rotation ◽  
Virtual Environments ◽  
Spatial Learning ◽  
Spatial Abilities ◽  
Younger Adults ◽  
Navigation Task ◽  
Sex Effects ◽  
Learning Tasks ◽  
Pointing Task ◽  
Age And Sex

The study examined the age and sex effects in spatial learning and mental rotation in 58 adults. We developed two new spatial learning tasks using virtual reality (VR): a navigation task and a pointing task. The results show that younger adults outperformed older adults in both virtual tasks but not in mental rotation. Males outperformed females in the navigation task and mental rotation. We conclude that age generally drives differences in spatial learning, and that sex drives differences in spatial abilities, which were especially related to ability in navigating through virtual environments.

A Proximity-Contingent Stereoscopic Depth Aftereffect: Evidence for Adaptation to Disparity Gradients

Perception ◽  
1993 ◽  
Vol 22 (4) ◽  
pp. 403-418 ◽  
Author(s):  
Colin Ryan ◽  
Barbara Gillam
Keyword(s):  
Binocular Disparity ◽  
Visual Space ◽  
Stereoscopic Depth ◽  
Texture Gradient ◽  
Vertical Separation ◽  
The Third ◽  
Negative Aftereffect ◽  
Disparity Gradient ◽  
Per Se ◽  
Third Dimension

Prolonged inspection of a surface slanted in the third dimension of visual space typically results in a negative aftereffect such that, after adaptation, a surface in the fronto-parallel plane will appear slanted in the opposite direction. Binocular disparity is not necessary to generate such effects, since they can be obtained monocularly, presumably via adaptation to texture gradient. Six experiments demonstrated durable stereoscopic depth aftereffects in the absence of a texture gradient—by using discrete disparate objects rather than slanted surfaces— and demonstrated that adaptation was to the interobject disparity gradient rather than to the relative disparity of the objects per se. The disparity required to null the obtained aftereffects was inversely proportional to the horizontal separation of elements, for a constant disparity, and directly proportional to the separation of subsequently presented probes. When elements differed in depth (disparity), but were not laterally separated, nulling disparity was significant but invariant with changes in the horizontal separation of probe elements. In that case, adaptation was (i) either to the disparity gradient generated by the vertical separation of probe elements (of which the relative disparity component was tapped); or (ii) to relative disparity per se.

Optimal Bit Plane Arrangement for Image Size-Performance Tradeoff

2013 ◽  
Vol 705 ◽  
pp. 327-331
Author(s):  
Gwang Gil Jeon
Keyword(s):  
Experimental Results ◽  
Image Size ◽  
Least Significant Bit ◽  
The Third ◽  
Binary Signal ◽  
Plane Image ◽  
Bit Plane ◽  
And Performance ◽  
Bit Planes ◽  
Performance Tradeoff

This paper discusses the issue of tradeoff between image size and performance in PSNR on bit plane image. A bit plane of a digital discrete signal is a set of bits indicate a presented bit plane in each of the binary numbers depicting the image. Image can be converted into a series of binary signal by shattering them up into their bit planes. The 0thbit plane is the least significant bit and the last bit plane is the most significant bit. Experimental results show that the best tradeoff is using the third to the seventh bit planes.

Progress report on 21-cm observations at low latitude between longitudes (l 11) 0° and 66°

1967 ◽  
Vol 31 ◽  
pp. 177-179
Author(s):  
W. W. Shane
Keyword(s):  
Preliminary Report ◽  
Progress Report ◽  
Galactic Centre ◽  
Low Latitude ◽  
The Third ◽  
Introductory Lecture ◽  
Centre Region

In the course of several 21-cm observing programmes being carried out by the Leiden Observatory with the 25-meter telescope at Dwingeloo, a fairly complete, though inhomogeneous, survey of the regionl11= 0° to 66° at low galactic latitudes is becoming available. The essential data on this survey are presented in Table 1. Oort (1967) has given a preliminary report on the first and third investigations. The third is discussed briefly by Kerr in his introductory lecture on the galactic centre region (Paper 42). Burton (1966) has published provisional results of the fifth investigation, and I have discussed the sixth in Paper 19. All of the observations listed in the table have been completed, but we plan to extend investigation 3 to a much finer grid of positions.

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

Monte Carlo Algorithms for Moments of Transition Arrays

1988 ◽  
Vol 102 ◽  
pp. 79-81
Author(s):  
A. Goldberg ◽  
S.D. Bloom
Keyword(s):  
Monte Carlo ◽  
State Vector ◽  
Basis Vector ◽  
Collective State ◽  
Dispersion Characteristics ◽  
Dipole Strength ◽  
The Third ◽  
Monte Carlo Algorithms ◽  
Third Moment ◽  
Very High

AbstractClosed expressions for the first, second, and (in some cases) the third moment of atomic transition arrays now exist. Recently a method has been developed for getting to very high moments (up to the 12th and beyond) in cases where a “collective” state-vector (i.e. a state-vector containing the entire electric dipole strength) can be created from each eigenstate in the parent configuration. Both of these approaches give exact results. Herein we describe astatistical(or Monte Carlo) approach which requires onlyonerepresentative state-vector |RV> for the entire parent manifold to get estimates of transition moments of high order. The representation is achieved through the random amplitudes associated with each basis vector making up |RV>. This also gives rise to the dispersion characterizing the method, which has been applied to a system (in the M shell) with≈250,000 lines where we have calculated up to the 5th moment. It turns out that the dispersion in the moments decreases with the size of the manifold, making its application to very big systems statistically advantageous. A discussion of the method and these dispersion characteristics will be presented.

Reconstruction of Objects from their Projections Using Orthogonal Functions

1973 ◽  
Vol 31 ◽  
pp. 268-269
Author(s):  
Elrnar Zeitler
Keyword(s):  
Unit Area ◽  
Three Dimensional ◽  
One Dimension ◽  
Spatial Density ◽  
Dimensional Representation ◽  
Orthogonal Functions ◽  
Object A ◽  
Plane Normal ◽  
Dimensional Object ◽  
Spatial Density Distribution

Considering any finite three-dimensional object, a “projection” is here defined as a two-dimensional representation of the object's mass per unit area on a plane normal to a given projection axis, here taken as they-axis. Since the object can be seen as being built from parallel, thin slices, the relation between object structure and its projection can be reduced by one dimension. It is assumed that an electron microscope equipped with a tilting stage records the projectionWhere the object has a spatial density distribution p(r,ϕ) within a limiting radius taken to be unity, and the stage is tilted by an angle 9 with respect to the x-axis of the recording plane.

Sign in / Sign up

Export Citation Format

Share Document