Size Perception

Visual Angle:

Size Constancy:

• Size-distance scaling: S = k(R x D)

 

S=

R=

D=

k=

 

• keep R constant and increase D --

 

• if shrink R and increase D

 

 

• Importance of depth information shown in Holway & Boring Experiment (1941):

 

 

 

 

• Sit at junction of 2 hallways

 

• 4 conditions:

  1)

  2)

  3)

  4)

 

 

 

• Results:

 

 

Other Factors influencing Size constancy:

• Familiar Size

• Relative Size

• Textue Gradients:

Distance and Size Illusions: Instances when our perceptions are inaccurate due to inaccurate information

• Muller-Lyer Illusion:

 

Why it occurs:

• Conflicting Cues Theory:

 

 

 

• Horizontal-Vertical Illusion:

• Parallelograms & apparent depth:

• Ames Room: alters perceived size of objects/people in the room

  • distorted room is set up to provide information consistent with a rectangular room.

• Poggendorff Illusion:

• Moon illusion:

• apparent distance hypothesis

 

 

 

 

Motion Perception

Apparent motion:

Perception of Motion:

• optic array:

• optic flow field-

• Expansion:

• Contraction:

• Parallel Flow:

• Optic Flow on Retina:

• optic flow is depicted as motion vectors (points with arrows) -- length of arrow indicates how fast that visual element is moving.

• Types of optic flow:

• global flow:

 

 

• local flow:

Object Motion: an object in motion moving in a meaningful way.

• point light walkers

• point light wheel

Motion consists of 2 components:

• relative motion -

 

 

• common motion -