Rehabilitation of a Classical Notion of Panum's Fusional Area

Perception ◽  
1982 ◽  
Vol 11 (5) ◽  
pp. 615-619 ◽  
Author(s):  
Jodi D Krol ◽  
Wim A van de Grind
Keyword(s):  
Depth Perception ◽  
Classical Concept ◽  
Classical Notion ◽  
Disparity Gradient ◽  
Limiting Case

It is argued that (1) the work of Burt and Julesz does not challenge the classical notion of Panum's fusional area; (2) their disparity gradient concept is contradicted by some of their own findings as well as by those of Krol and van de Grind; (3) their results can be accounted for by the classical concept of Panum's fusional area if eye vergence is taken into account; (4) the explanations suggested by Burt and Julesz for the depth perception aspects of Panum's limiting case and the double-nail illusion are based on unwarranted generalisation of results concerning binocular direction vision.

Modifications of the Classical Notion of Panum's Fusional Area

Perception ◽  
1980 ◽  
Vol 9 (6) ◽  
pp. 671-682 ◽  
Author(s):  
Peter Burt ◽  
Bela Julesz
Keyword(s):  
Visual Field ◽  
Angular Separation ◽  
Critical Value ◽  
Binocular Fusion ◽  
Classical Notion ◽  
Disparity Gradient ◽  
The Absolute ◽  
The Difference ◽  
The Individual ◽  
Limiting Case

It is generally believed that there is an absolute disparity limit for binocular fusion; objects with disparities within this limit, known as Panum's fusional area, will appear fused and single, while objects with disparities outside the limit appear double. It is demonstrated, however, that the disparity gradient, rather than the disparity magnitude, dictates binocular fusion when several objects occur near one another in the visual field. The disparity gradient is defined as the difference between the disparities of neighboring objects divided by their angular separation. If this ratio exceeds a critical value (∼1) then fusion does not occur, even though the absolute disparities of the individual objects may be well within the classical Panum's area. This discovery leads to the reinterpretation of several enigmatic phenomena in stereopsis, including Panum's limiting case.

Gradients Account for the Thresholds for Perceiving Motion and Depth in Observer-Produced Parallax Displays

Perception ◽  
2019 ◽  
Vol 48 (4) ◽  
pp. 338-345
Author(s):  
Soyogu Matsushita ◽  
Hiroshi Ono
Keyword(s):  
Depth Perception ◽  
Motion Parallax ◽  
Angular Separation ◽  
Disparity Gradient ◽  
Lower Depth ◽  
Perceived Motion

We examined whether the thresholds of motion and depth perception produced by motion parallax could be specified by the concept of a disparity gradient. We manipulated both the motion parallax amplitude and the angular separation of two dots and calculated the percentages of trials in which participants perceived motion or depth. The results showed that the amplitude of motion parallax for the threshold increased as the separation became larger with the gradients of 0.023, 0.072, and 0.430 for the lower depth, the lower motion, and the upper depth thresholds, respectively. These findings indicate that the gradient is a useful concept to specify the motion and depth thresholds together rather than parallax amplitude alone.

The neural correlates of vertical disparity gradient and cue conflict in Panum’s limiting case

2017 ◽  
Vol 114 ◽  
pp. 11-19 ◽  
Author(s):  
Huayun Li ◽  
Huibin Jia ◽  
Ashley Chung-Fat-Yim ◽  
Laipeng Jin ◽  
Dongchuan Yu
Keyword(s):  
Neural Correlates ◽  
Vertical Disparity ◽  
Disparity Gradient ◽  
Limiting Case ◽  
Cue Conflict

scholarly journals Virtue, habit and neuroscience

2021 ◽  
Vol 77 (Extra 295) ◽  
pp. 501-510
Author(s):  
Jose Ignacio Murillo
Keyword(s):  
Decision Making ◽  
Personal Identity ◽  
Human Behavior ◽  
Human Action ◽  
Moral Decision ◽  
Classical Concept ◽  
Contemporary Philosophy ◽  
Moral Decision Making ◽  
Classical Notion ◽  
Modern Thought

Neuroscience has much to offer to our understanding of human action, including its ethical dimensions. However, while neuroscience has been applied to questions of personal identity, emotion and moral decision-making, its implications for the classical notion of virtue have hardly been considered. This likely has much to do with the way in which the classical notion of virtue, together with closely related concepts of nature and habit, has been forgotten or distorted within the context of modern thought. As a consequence, the standard neuroscientific concept of habit as automatic and routine behavior is fundamentally opposed to teleological activity and thus cannot be reconciled with the classical concept of habit that is essential to virtue. The recovery of the classical notion of virtue in contemporary philosophy invites us to rethink the neuroscientific concept of habit in light of a different view of human behavior for which plasticity is not just indeterminacy but rather openness to freedom and growth.

scholarly journals The influence of vertical disparity gradient and cue conflict on EEG omega complexity in Panum’s limiting case

2018 ◽  
Vol 119 (3) ◽  
pp. 1201-1208 ◽  
Author(s):  
Huayun Li ◽  
Huibin Jia ◽  
Dongchuan Yu
Keyword(s):  
Event Related Potential ◽  
Eeg Signal ◽  
Occipital Region ◽  
Vertical Disparity ◽  
Neural Activities ◽  
Two Factors ◽  
Disparity Gradient ◽  
Limiting Case ◽  
Different Levels ◽  
Cue Conflict

Using behavioral measures and ERP technique, researchers discovered at least two factors could influence the final perception of depth in Panum’s limiting case, which are the vertical disparity gradient and the degree of cue conflict between two- and three-dimensional shapes. Although certain event-related potential components have been proved to be sensitive to the different levels of these two factors, some methodological limitations existed in this technique. In this study, we proposed that the omega complexity of EEG signal may serve as an important supplement of the traditional event-related potential technique. We found that the trials with lower vertical gradient disparity have lower omega complexity (i.e., higher global functional connectivity) of the occipital region, especially that of the right-occipital hemisphere. Moreover, for occipital omega complexity, the trials with low-cue conflict have significantly larger omega complexity than those with medium- and high-cue conflict. It is also found that the electrodes located in the middle line of the occipital region (i.e., POz and Oz) are more crucial to the impact of different levels of cue conflict on omega complexity than the other electrodes located in the left- and right-occipital hemispheres. These evidences demonstrated that the EEG omega complexity could reflect distinct neural activities evoked by Panum’s limiting case configurations, with different levels of vertical disparity gradient and cue conflict. Besides, the influence of vertical disparity gradient and cue conflict on omega complexity may be regional dependent. NEW & NOTEWORTHY The EEG omega complexity could reflect distinct neural activities evoked by Panum’s limiting case configurations with different levels of vertical disparity gradient and cue conflict. The influence of vertical disparity gradient and cue conflict on omega complexity is regional dependent. The omega complexity of EEG signal can serve as an important supplement of the traditional ERP technique.

Freeze fracture imaging and computer simulation of liposome structure: Membrane geometry and defects

1983 ◽  
Vol 41 ◽  
pp. 646-647
Author(s):  
Joseph A. Zasadzinski
Keyword(s):  
Liquid Crystalline ◽  
Freeze Fracture ◽  
Continuum Theory ◽  
Closed Surfaces ◽  
Straight Line ◽  
Low Weight ◽  
Concentric Spheres ◽  
Membrane Geometry ◽  
Dupin Cyclides ◽  
Limiting Case

At low weight fractions, many surfactant and biological amphiphiles form dispersions of lamellar liquid crystalline liposomes in water. Amphiphile molecules tend to align themselves in parallel bilayers which are free to bend. Bilayers must form closed surfaces to separate hydrophobic and hydrophilic domains completely. Continuum theory of liquid crystals requires that the constant spacing of bilayer surfaces be maintained except at singularities of no more than line extent. Maxwell demonstrated that only two types of closed surfaces can satisfy this constraint: concentric spheres and Dupin cyclides. Dupin cyclides (Figure 1) are parallel closed surfaces which have a conjugate ellipse (r1) and hyperbola (r2) as singularities in the bilayer spacing. Any straight line drawn from a point on the ellipse to a point on the hyperbola is normal to every surface it intersects (broken lines in Figure 1). A simple example, and limiting case, is a family of concentric tori (Figure 1b).To distinguish between the allowable arrangements, freeze fracture TEM micrographs of representative biological (L-α phosphotidylcholine: L-α PC) and surfactant (sodium heptylnonyl benzenesulfonate: SHBS)liposomes are compared to mathematically derived sections of Dupin cyclides and concentric spheres.

Suppression of γ’ Precipitation in a Laser-Melted Nickel-Base Alloy

1977 ◽  
Vol 35 ◽  
pp. 270-271
Author(s):  
J. M. Walsh ◽  
J. C. Whittles ◽  
B. H. Kear ◽  
E. M. Breinan
Keyword(s):  
Cooling Rate ◽  
Base Alloy ◽  
Material Surface ◽  
Intimate Contact ◽  
Absorbed Power ◽  
Perfect Contact ◽  
Nickel Base ◽  
Rapidly Solidified ◽  
Limiting Case ◽  
The Heat Transfer Coefficient

Conventionally cast γ’ precipitation hardened nickel-base superalloys possess well-defined dendritic structures and normally exhibit pronounced segregation. Splat quenched, or rapidly solidified alloys, on the other hand, show little or no evidence for phase decomposition and markedly reduced segregation. In what follows, it is shown that comparable results have been obtained in superalloys processed by the LASERGLAZE™ method.In laser glazing, a sharply focused laser beam is traversed across the material surface at a rate that induces surface localized melting, while avoiding significant surface vaporization. Under these conditions, computations of the average cooling rate can be made with confidence, since intimate contact between the melt and the self-substrate ensures that the heat transfer coefficient is reproducibly constant (h=∞ for perfect contact) in contrast to the variable h characteristic of splat quenching. Results of such computations for pure nickel are presented in Fig. 1, which shows that there is a maximum cooling rate for a given absorbed power density, corresponding to the limiting case in which melt depth approaches zero.

Three-dimensional image analysis and visualization in confocal light microscopy

1993 ◽  
Vol 51 ◽  
pp. 158-159
Author(s):  
J. K. Samarabandu ◽  
R. Acharya ◽  
D. R. Pareddy ◽  
P. C. Cheng
Keyword(s):  
Depth Perception ◽  
Computer Graphic ◽  
Three Dimensional ◽  
Cellular Organization ◽  
Data Set ◽  
Computational Burden ◽  
Interactive Operation ◽  
Cell Organization ◽  
Confocal Images ◽  
3D Digitization

In the study of cell organization in a maize meristem, direct viewing of confocal optical sections in 3D (by means of 3D projection of the volumetric data set, Figure 1) becomes very difficult and confusing because of the large number of nucleus involved. Numerical description of the cellular organization (e.g. position, size and orientation of each structure) and computer graphic presentation are some of the solutions to effectively study the structure of such a complex system. An attempt at data-reduction by means of manually contouring cell nucleus in 3D was reported (Summers et al., 1990). Apart from being labour intensive, this 3D digitization technique suffers from the inaccuracies of manual 3D tracing related to the depth perception of the operator. However, it does demonstrate that reducing stack of confocal images to a 3D graphic representation helps to visualize and analyze complex tissues (Figure 2). This procedure also significantly reduce computational burden in an interactive operation.

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