Does Brightness Contrast Really Affect the Mueller-Lyer Illusion

1981 ◽  
Vol 52 (2) ◽  
pp. 623-629 ◽  
Author(s):  
Darrell L. Butler
Keyword(s):  
Lateral Inhibition ◽  
Brightness Contrast ◽  
Lyer Illusion ◽  
Straight Lines

Several writers have hypothesized that the Mueller-Lyer illusion is influenced by brightness contrast between figure and background. According to them, lateral inhibition in the retina causes displacement in Mueller-Lyer figures at the intersections of lines. They argue that the strength of the displacement varies with brightness contrast between the background and the figure, and they cite research by Pollack and others for support. The experiments reported here show that the Mueller-Lyer illusion is no more affected by changes in contrast than are judgments of single straight lines. These results are not consistent with the view that lateral. inhibition in the retina has an effect on the illusion.

‘Reversed’ Illusion with Three-Dimensional Müller-Lyer Shapes

Perception ◽  
1995 ◽  
Vol 24 (11) ◽  
pp. 1281-1296 ◽  
Author(s):  
Romi Nijhawan
Keyword(s):  
Retinal Image ◽  
Three Dimensional ◽  
Retinal Images ◽  
Coordinate Frame ◽  
Illusion Figure ◽  
Lyer Illusion ◽  
Straight Line ◽  
Constancy Scaling ◽  
Image Shape ◽  
Straight Lines

The purpose of this study was to determine whether the Müller-Lyer illusion is produced by a mechanism which uses information defined in the retinal coordinates, or by a mechanism taking into account the three-dimensional (3-D) shape of the illusion figure. The classical Müller-Lyer figure could not be used to address this question since it is two-dimensional. Three-dimensional Müller-Lyer figures were created to see if the illusion they produce is correlated with the shape of the projected retinal image, or with the shape of these figures defined in a 3-D coordinate frame. In the experiments retinal image shape was juxtaposed against the 3-D shape of the illusion displays. For some displays the direction in which the fins pointed, relative to the shafts, in the 3-D frame was the ‘opposite’ of the direction in which they pointed in the retinal images. For such displays, the illusion predicted on the basis of the 3-D structure was the opposite of that predicted on the basis of retinal image shapes. For another 3-D display the fins were oriented such that each projected a single straight line in the retinal image, thus the typical retinal image (< >, > <) was replaced by straight lines (‖, ‖). For all the displays the observed illusion was consistent with how the fins were oriented relative to the shaft in the 3-D coordinate frame, ie with the 3-D shape of the illusion displays. The retinal image shape appeared to play little, if any, role. One conclusion that emerges is that the specific retinal image shape projected by the classical line-drawn pattern is neither necessary nor sufficient for producing the illusion. The present findings are inconsistent with two well known theories of the Müller-Lyer illusion: inappropriate constancy scaling and selective filtering.

Illusory Contours: Curious Cases of Simultaneous Brightness Contrast?

Perception ◽  
1975 ◽  
Vol 4 (3) ◽  
pp. 349-357 ◽  
Author(s):  
John P Frisby ◽  
Jeremy L Clatworthy
Keyword(s):  
Lateral Inhibition ◽  
Brightness Contrast ◽  
Retinal Images ◽  
Neural Encoding ◽  
Illusory Contours ◽  
Simultaneous Brightness Contrast

It is suggested that simultaneous brightness contrast mediated by lateral inhibition plays an important role in generating many illusory contours. These contours might reflect a further way in which lateral inhibition serves to clarify and sharpen the neural encoding of retinal images.

Domain Formation in Synthetic Quartz

1971 ◽  
Vol 29 ◽  
pp. 156-157
Author(s):  
Joseph J. Comer
Keyword(s):  
Electron Beam ◽  
Room Temperature ◽  
Domain Formation ◽  
Synthetic Quartz ◽  
Transmission Electron ◽  
Black Spots ◽  
Diffraction Mode ◽  
Domain Boundaries ◽  
Kikuchi Lines ◽  
Straight Lines

Domains visible by transmission electron microscopy, believed to be Dauphiné inversion twins, were found in some specimens of synthetic quartz heated to 680°C and cooled to room temperature. With the electron beam close to parallel to the [0001] direction the domain boundaries appeared as straight lines normal to <100> and <410> or <510> directions. In the selected area diffraction mode, a shift of the Kikuchi lines was observed when the electron beam was made to traverse the specimen across a boundary. This shift indicates a change in orientation which accounts for the visibility of the domain by diffraction contrast when the specimen is tilted. Upon exposure to a 100 KV electron beam with a flux of 5x 1018 electrons/cm2sec the boundaries are rapidly decorated by radiation damage centers appearing as black spots. Similar crystallographio boundaries were sometimes found in unannealed (0001) quartz damaged by electrons.

Cosmetology treatments on human hair: An SEM study

1996 ◽  
Vol 54 ◽  
pp. 940-941
Author(s):  
D.F. Bowling
Keyword(s):  
High School ◽  
High Resolution ◽  
Human Hair ◽  
Optical Microscope ◽  
Convincing Evidence ◽  
Brightness Contrast ◽  
Sem Study

High school cosmetology students study the methods and effects of various human hair treatments, including permanents, straightening, conditioning, coloring and cutting. Although they are provided with textbook examples of overtreatment and numerous hair disorders and diseases, a view of an individual hair at the high resolution offered by an SEM provides convincing evidence of the hair‘s altered structure. Magnifications up to 2000X provide dramatic differences in perspective. A good quality classroom optical microscope can be very informative at lower resolutions.Students in a cosmetology class are initially split into two groups. One group is taught basic controls on the SEM (focus, magnification, brightness, contrast, specimen X, Y, and Z axis movements). A healthy, untreated piece of hair is initially examined on the SEM The second group cements a piece of their own hair on a stub. The samples are dryed quickly using heat or vacuum while the groups trade places and activities.

Lateral inhibition in a recurrent network

1997 ◽  
Author(s):  
William T. Farrar ◽  
Guy C. Van Orden
Keyword(s):  
Lateral Inhibition ◽  
Recurrent Network

Automatic Tread Gaging Machine

1979 ◽  
Vol 7 (1) ◽  
pp. 31-39
Author(s):  
G. S. Ludwig ◽  
F. C. Brenner
Keyword(s):  
Experimental Tests ◽  
Automatic Machine ◽  
Wear Rates ◽  
Handling Device ◽  
Straight Line ◽  
Component Systems ◽  
Before And After ◽  
Good Repeatability ◽  
The Difference ◽  
Straight Lines

Abstract An automatic tread gaging machine has been developed. It consists of three component systems: (1) a laser gaging head, (2) a tire handling device, and (3) a computer that controls the movement of the tire handling machine, processes the data, and computes the least-squares straight line from which a wear rate may be estimated. Experimental tests show that the machine has good repeatability. In comparisons with measurements obtained by a hand gage, the automatic machine gives smaller average groove depths. The difference before and after a period of wear for both methods of measurement are the same. Wear rates estimated from the slopes of straight lines fitted to both sets of data are not significantly different.

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