Influence of surrounding objects on the apparent direction of a line.

2012 ◽  
pp. 239-295
Author(s):  
Edmund Burke Delabarre
Keyword(s):  
Apparent Direction

scholarly journals Vibrations of rifle barrels

1901 ◽  
Vol 68 (442-450) ◽  
pp. 327-344 ◽  
Keyword(s):  
Initial Direction ◽  
Apparent Direction ◽  
The Right ◽  
First Moment

It has long been known that a shot fired from a rifle does not in general start from the muzzle in the direction occupied by the axis of the barrel at the first moment of ignition of the charge. The late W. E. Metford was, I believe, the first to point out the origin of this deviation, showing by experiment that it was due to the unsymmetrical position which the mass of the stock held as regards the barrel; and, further, that if the initial direction of the shot passed below the apparent direction of aim when the rifle was held in the ordinary position, the initial direction would be high if the rifle were aimed upside down, and to the right or left if the plane of the stock were horizontal and the stock itself to the left or right of the barrel.

Biological Motion Shown Backwards: The Apparent-Facing Effect

Perception ◽  
10.1068/p3262 ◽  
2002 ◽  
Vol 31 (4) ◽  
pp. 435-443 ◽  
Author(s):  
Marina Pavlova ◽  
Ingeborg Krägeloh-Mann ◽  
Niels Birbaumer ◽  
Alexander Sokolov
Keyword(s):  
Visual Perception ◽  
Biological Motion ◽  
Presentation Mode ◽  
Reverse Transformation ◽  
Perceptual Identification ◽  
Perceptual Development ◽  
Apparent Direction ◽  
Point Light ◽  
Perception Of Biological Motion ◽  
Order Of Presentation

We examined how showing a film backwards (reverse transformation) affects the visual perception of biological motion. Adults and 6-year-old children saw first a point-light quadruped moving normally as if on a treadmill, and then saw the same display in reverse transformation. For other groups the order of presentation was the opposite. Irrespective of the presentation mode (normal or reverse) and of the facing of the point-light figure (rightward or leftward), a pronounced apparent-facing effect was observed: the perceptual identification of a display was mainly determined by the apparent direction of locomotion. The findings suggest that in interpreting impoverished point-light biological-motion stimuli the visual system may neglect distortions caused by showing a film backwards. This property appears to be robust across perceptual development. Possible explanations of the apparent-facing effect are discussed.

The Kongsi

1987 ◽  
Vol 9 (1) ◽  
pp. 18-19
Author(s):  
Richard Reeves-Ellington
Keyword(s):  
Government Officials ◽  
Peking Duck ◽  
Early Evening ◽  
Apparent Direction

In the early evening in Jakarta, a group of Chinese businessmen meet in one of the city's better Chinese restaurants. Over succulent Peking duck, tasty pigeon, spicy sweet and sour pork, rich shrimp fried in butter and steaming fried rice, the group gossips with no apparent direction. Conversation touches on the latest political rumors, problems with government officials, the rate of inflation, the high cost of money, and the scarcity of opportunities these days.

scholarly journals Directional observations of atmospheric disturbances, 1920-21

1923 ◽  
Vol 102 (717) ◽  
pp. 460-478
Keyword(s):  
Seasonal Variations ◽  
Atmospheric Electricity ◽  
Direction Of Arrival ◽  
Close Correlation ◽  
Quantitative Relation ◽  
Solar Altitude ◽  
General Law ◽  
Apparent Direction ◽  
Atmospheric Disturbances ◽  
Modal Values

The paper analyses 12 months' observations of the intensity and apparent direction of arrival of atmospheric disturbances, carried out for the Radio Research Board at a station in S. E. England. Observations were made at 7 h., 13 h., and 16 h. daily, the average number of such disturbances heard being 80 per minute. The apparent direction of arrival is well marked, with unexpectedly simple diurnal and seasonal variations, following a general law of counter-clockwise swing in direction accompanying increase in solar altitude. The mean direction of greatest disturbance for the year is 153°, with a diurnal variation of 60° range, a seasonal of 100°. The numbers heard per unit-time have also comparatively simple diurnal and seasonal variations, March being the quietest, June the most disturbed month, with a disturbance twice that of March. Fourier coefficients for the monthly mean and modal values are tabulated. Close correlation between apparent direction of arrival and solar altitude is found, no local topographical effect is traced, and no quantitative relation with terrestrial magnetism, atmospheric electricity, or any of the surface meteorological elements (except temperature) has yet been established. Special observations during a solar eclipse are reported.

A Simultaneous Shift in Apparent Direction: Further Evidence for a “Distribution-Shift” Model of Direction Coding

1980 ◽  
Vol 32 (2) ◽  
pp. 325-333 ◽  
Author(s):  
George Mather ◽  
Bernard Moulden
Keyword(s):  
The Other ◽  
Movement Detection ◽  
Apparent Direction ◽  
Wide Range ◽  
Shift Model

When two superimposed moving dot fields are presented simultaneously, their axes of movement appear shifted away from each other. The shift only occurs when the two directions are within 90° of each other, and is directly comparable to that which results from adapting to one and testing on the other direction. This effect is taken as further evidence for a distribution-shift model in the direction domain. It is argued that the currently accepted model of movement detection, which restricts itself to comparisons only between oppositely-tuned direction detectors, should be elaborated to include comparisons across a very wide range of detectors.

The lines of evolution of the Bacillariophyta - II. The centric series

1984 ◽  
Vol 221 (1223) ◽  
pp. 169-188 ◽  
Keyword(s):  
Geological History ◽  
Punctuated Equilibria ◽  
Apparent Direction

Evolution is concentrated in very rapid events of speciation. . . Most species during their geological history either do not change in any appreciable way, or else they fluctuate mildly with no apparent direction.’ (Gould & Eldredge 1977) The evolution of the centric series of diatoms from simple Ur-diatoms is discussed. Evidence from ecology and fossil studies which may help is briefly evaluated together with a discussion of phylogenetic considerations and of ‘punctuated equilibria’. The evolution of centric morphology, origin and development of areolae, occluding plates, rimoportulae, fultoportulae, ocelli and pseudocelli are discussed, and the possible lines of development of these is documented.

Motion Aftereffects of Wagon Wheels: Motion Aftereffects Follow Apparent Rather Than Real Movement

1994 ◽  
Vol 79 (1) ◽  
pp. 131-140
Author(s):  
Roderick P. Power
Keyword(s):  
Apparent Movement ◽  
Motion Aftereffect ◽  
Flickering Light ◽  
Wagon Wheel ◽  
True Motion ◽  
Apparent Direction ◽  
Illusory Movement ◽  
Motion Aftereffects ◽  
Direction Opposite ◽  
True Direction

Power and Moulden have proposed a model which accounts for the movement of gratings in apertures including the barber pole illusion. It predicts the direction of motion aftereffects which follow from perceived veridical motion and the direction of these aftereffects which follow from the illusory movement experienced during the barber pole illusion. At a perceptual level, the model predicts motion aftereffects will follow direction of apparent movement rather than veridical direction. Four experiments tested this prediction. In Exp. 1 a spiral was viewed under flickering light so it appeared to be moving in the direction opposite to true motion, and the aftereffect was opposite to the apparent direction. In Exp. 2 the spiral was viewed through a narrow aperture so that it was effectively a grating appearing to move in the opposite direction to veridical motion. Again, the motion aftereffect was opposite to the apparent rather than true direction of rotation. In Exp. 3 a sectored disc was used, and similar results were obtained. In Exp. 4 the sectored disc was videotaped so that it appeared to be rotating in the direction opposite to true motion. The after motion to this “wagon wheel” effect was opposite to its apparent direction of rotation on the screen. In all experiments the predictions were confirmed, thereby confirming the general principle that motion aftereffecrs follow apparent rather than real direction of movemenr.

Some Tests of the Marr-Ullman Model of Movement Detection

Perception ◽  
1986 ◽  
Vol 15 (2) ◽  
pp. 139-155 ◽  
Author(s):  
Bernard Moulden ◽  
Helena Begg
Keyword(s):  
Sudden Onset ◽  
Homogeneous Field ◽  
Movement Detection ◽  
Contrast Polarity ◽  
Apparent Direction ◽  
Direction Of Movement ◽  
Spatially Homogeneous ◽  
The Moment ◽  
Sawtooth Waveform

Several psychophysical experiments are described which test and uphold predictions derived from the Marr–Ullman model of movement detection. First, we demonstrate the existence of adaptation which is specific not merely to the direction of movement of an edge, but also to its contrast polarity. Second, it is shown that adaptation to a spatially homogeneous field whose luminance is modulated according to a temporal sawtooth waveform produces predictable changes in sensitivity to the movement of an edge; these changes, too, are specific to particular conjunctions of direction and edge polarity. Third, similar changes in sensitivity are demonstrated to occur when the luminance of an edge is physically perturbed at the moment of its displacement. Finally, it is shown that, as predicted, the sudden onset of an edge can itself give rise to a momentary impression of movement, the apparent direction of which depends upon the change in luminance that accompanies the onset of the edge.

Human perception of apparent direction and movement of aircraft noise

1974 ◽  
Vol 55 (S1) ◽  
pp. S68-S68
Author(s):  
Walter J. Gunn ◽  
Harland F. Scholl ◽  
Thomas Dempsey ◽  
Fred Gibson ◽  
Nancy Whitted
Keyword(s):  
Human Perception ◽  
Aircraft Noise ◽  
Apparent Direction
Sign in / Sign up

Export Citation Format

Share Document