the day the world stopped moving
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The Day the World Stopped Moving. Visual Intelligence Chapter 6. An Unusual Complaint. The permanent loss of movement vision in all 3 Dimensions. AKINETOPSIA. Transcranial Magnetic Stimulation (TMS). Made it possible to experience brief motion loss without causing brain damage - PowerPoint PPT PresentationTRANSCRIPT
The Day the World Stopped
MovingVisual Intelligence
Chapter 6
An Unusual Complaint
AKINETOPSIAThe permanent
loss of movement visionin all 3 Dimensions
Transcranial Magnetic Stimulation (TMS)• Made it possible to
experience brief motion loss without causing brain damage
• impairs normal electric functions in V5 with aid of magnetic fields
How do we recognize
objects without seeing
them move?Motion, like color, is constructed by our own visual intelligence.
The link between what is moving and how it is moving?Exner's Phi Motion offers some insight.
Two flashing dots may appear to be moving depending on their interstimulus interval (time and space)
Demonstrates motion and objects are created interdependently
Our construction of motion depends on whether we construct one object or two.
Wertheimer's Color Phi MotionUsed two different dot
colors
You should see second color appear in space
between two dots.
You not only construct the space and motions that you see, you also
construct the time sequence of what you see.
Rule 29. Create the simplest possible motions.
P.E. Linke's Discovery
• Discovered that you can construct motion over a curved path
Vittorio Benussi• Even without a
drawn curve, you can still construct this motion
Josef Ternus' Display with Flashing Dot Pairs
Depending on the ISI, you could see:
• Two dots moving together from left to right
• Long range motion of outside dot
Group Motion
Element Motion
Multilayered ConstructionGroup Motion
Element Motion
Paul von Schiller's InputYou can construct more than one type of motion.
But, only one is seen at a time for the sake of conserving number of objects.
Rule 30. When making motion, construct as fewobjects as possible, and conserve them as
much as possible.
Rule 30. When making motion, construct as few
objects as possible, and conserve them as much
as possible.
Rule 31. Construct motion to be as uniform over space as possible.
Max Wertheimer and his Rotating
Windmill
Clockwise or Counterclockwise?
1986 - Antsis and Ramachandran Display
You prefer to rotate the shortest distance, while also investing your motions with
inertia.
Clockwise? Counterclockwise?
Our Rotation Prowess
1937 - Brown and Roth
Long ISI's - straight line motions
Short ISI's - a continuous motion circle
Barber Poles• Presents us with the "aperture
problem" as stripes move upward while turning on horizontal axis
• the smoothest velocity field (path of motion) has the stripes moving straight up
• The smoothest path - velocity of motion changes the least
• constructed motion at one points depends on the motion at other points
• smoothness requires a correlated motion at different points
Rule 32. Construct the smoothest Velocity Field
• “Velocity Field” – the path of motion
• The smoothest path - velocity of the motion changes the least.Aperture Problem• The motion you construct at
one point depends on the motion you construct at nearby points.• Smoothness is a relation
between motions at different points.
Ted Adelson and Tony Movshon
Do you see the grates sliding past each other or one coherently moving object?
Difference in Two GratesYour creation of motions and objects is
intelligently coordinated by size, contrast, depth and color.
The greater the difference (size, contrast, color, or depth) between the two grates increases the probability of perceiving two independent gratings.
Rigid MotionPoints in space will move rigidly if all distances between point positioning remain constant during the motion.
As the dots move their positions slightly will from frame to frame, a 3 dimensional form will
be constructed.
Rule 33. If possible, and if other rules permit, interpret image motions as projections of rigid
motions in 3 dimensions
Ullman's Rigidity Theorem
“Suppose you are given three frames, each containing at least four points. If the points are placed at random in each frame, then
the probability is zero that they have a rigid interpretation in three dimensions. If the points do have a rigid interpretation, then
they almost surely have exactly two interpretations (which are mirror-
symmetric).”
All you need is as little as 3 frames each having 4 points to create a 3D object and its
motion.
Limits of Ullman's TheoryPredicting the movement of the human
body is not easy.
The Power of DotsPlacing dots on the joints of actors
While all joints do not move rigidly, thus going against rigidity principle, the 3 dimensional object
can still be created
Rule 34. If possible, and if other rules permit, interpret image motions as
projections of 3 dimensional motions that are rigid and planar.
Because of the biological make up of our joints, our bones swing on planes.
Rigidity and Planarity will usually work with other rules too such as rules about smoothness or dynamical constraints.
Dan Kersten's ConclustionVisually, we're clever! - We interpret a smooth diagonal movement along the checkerboard as the shadow moves.
http://gandalf.psych.umn.edu/users/kersten/kersten-lab/images/ball-in-a-box.mov
However, we still make mistakes. - We allow the shadow and ball to contradict - we create unusual movements based on the light source
Rule 35. Light sources move slowly.
Motion in 3D depends not only on the object, but also on how you interpret
the relation between it and its shadow.
COLOR!Tom Albright and Karen Dobkins claim
that there is a strong interaction between the magnocellular (motion, luminance, depth, and coarse form) and parvocellular (color, fine form).
We prefer that objects of the same color move in similar patterns.
Hoffman's Dynamic Color Spreading
Creating motion through color with stationary dots