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Vision: Perception & Pattern Recognition
Kimberley A. Clow
[email protected]://instruct.uwo.ca/psychology/130/
Outline Welcome to the EyeHow Long Do We Remember What We See?Perception
How do we perceive depth?How do we perceive form?
How Do We Identify Objects?Template TheoriesFeature TheoriesComponent Theories
Perceptual DevelopmentThe effects of experience
The Effects of Drugs
Welcome to the Eye
Why two eyes?Stereopsis
Basic anatomySee diagram
Rods and conesLocationAcuityDark adaptation
Eye Movements
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How Long Do We Remember What We See?
LightningSeries of separate bolts
Each lasts about 1ms with 50ms of darkness in between
Perception of LightningA half-second to a second duration of light
SperlingC 2 L E6 R P 5S 9 1 T
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So What Is Perception?
The means by which information acquired from the environment via the sense organs is transformed into experiences of objects
SightsSoundsTastes, etc.
How Do We Perceive Depth?Monocular Cues
Pictorial CuesFamiliar SizeLinear PerspectiveTexture GradientsInterposition or OverlapShadingAtmospheric Haze or Aerial PerspectiveRelative Height
Kinetic CuesMotion ParallaxKinetic Depth Effect
Binocular CuesPhysiological Cues
Binocular DisparityAccommodationConvergenceDivergence
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Pictorial Cues
Shape Constancy
Size Constancy
Familiar Size
Linear Perspective Texture Gradient
Size, Linear Perspective, and Texture
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Shading
Original Reversed
Atmospheric Hazeor
Aerial Perspective
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Allows for Depth Perception Can Create Illusions
Relative Height
Kinetic Cues
Motion Parallax
Physiological Cues
Binocular Disparity
Accommodation
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How Do We Perceive Form?
Change as a requirement for perceiving form
Snow BlindnessStabilized Retinal Images
Figure-Ground RelationsOrganization occurs in the mind, not on the retinaSmaller shapes more likely to become figure than ground
Gestalt Psychology
The whole is greater than the sum of its partsLaws of Perception
Figural OrganizationProximitySimilarityGood ContinuationClosureSymmetrySubjective Contours
How Are They Organized?
Similarity
Proximity
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Good ContinuationViolation
Closure
Symmetry Subjective Contours
How Do We Identify Objects?
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Template Theories
We identify objects by matching the current stimulus to a template (or model) in memory
Stimulus Templates
Feature Theories
Can You Identify This Shape?
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Component Theories
These Theories Are Not Enough
These theories are all data drivenbottom-up processing
Need to allow for the effects of context as welltop-down processing
In real life, we have expectancies and these exert an influence on what we perceive
The pile of clothes that looks like a person out of the corner of our eyeThe school classmate you don’t recognise in the mall
Perceptual Development
Testing Children2-3 Weeks
Blink when object approaches
4 MonthsBinocular depth cuesMonocular dependent on exp.
6-7 MonthsLinear perspectiveFamiliar size
3 YearsRelative heightShadingAdult acuity
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The Effects of Experience
The effects of deprivation and altering perception
Kittens reared with only vertical linesDark reared chimps Prism glasses
At birth, infants can perceive and discriminate between all human sounds
By 10-12 monthscannot differentiate between different phonemes that don’t exist in own language
Effects of Drugs
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