the day the world stopped moving visual intelligence chapter 6

The Day the World Stopped

MovingVisual Intelligence

Chapter 6

An Unusual Complaint

AKINETO

PSIA

The 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 Motion

Used 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 Construction

Group

Motion

Element Motion

Paul von Schiller's Input

You 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 Grates

Your 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 Theory

Predicting 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 Conclustion

Visually, 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