Part 1

Part 1:

Sensory ProcessingVision

Part 2:

Other Sensory Systems

Sensation Vs. Sensation Vs. PerceptionPerception

Psychophysics

• Absolute threshold

• Just Noticeable Difference (JND)– Weber’s Law

∆I/I

TransductionTransduction

The process by which sense organs convert energy from the environmental events into

neural activity

Receptors:

PhotoreceptorsHair cells

Taste receptor cellsCilia

The Visible Spectrum

The EyeThe Eye

• Photoreceptor Cells:– Rods– Cones

Color VisionColor Vision

• Wavelength• 3 Types of Cones:

– Blue (short)– Green (medium)– Red (long)

Theories of Color VisionTheories of Color Vision

• Young-Helmholtz Trichromatic Theory

• Opponent Process Theory– Negative Afterimages

Defects in Color VisionDefects in Color Vision

• Red/Green Color Blindness

• Blue/Yellow Color Blindness

• Cerebral Achromatopsia

Perception of FormPerception of Form

• Primitive Features

• Figure and Background (Ground)

• Gestalt Psychology and Perceptual Grouping

Perception of FormPerception of Form

Law of Proximity:

Perception of FormPerception of Form

• Law of Similarity:X X X O O O X X X O O O X X X X X X O O O X X X O O O X X X

X X X O O O X X X O O O X X X X X X O O O X X X O O O X X X

X X X O O O X X X O O O X X XX X X O O O X X X O O O X X X

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Perception of FormPerception of Form

• Law of Continuity:

Perception of FormPerception of Form

• Law of Closure:

Perception of FormPerception of Form

• Law of Pragnanz (Good Figure):

Types of ProcessingTypes of Processing

• Top Down Processing

• Bottom Up Processing

Depth Perception

• Binocular Cues

• Monocular Cues

Binocular Cues

• Retinal Disparity

• Convergence

Monocular CuesMonocular Cues

• Interposition• Linear Perspective• Relative Size• Texture Gradient• Relative Motion

– Motion Parallax

Some Fun Visual Illusions