Depth PerceptionDepth Perception

Kimberley A. ClowKimberley A. Clow

kclow2@kclow2@uwouwo.ca.ca

http://instruct.uwo.ca/psychology/215a-570http://instruct.uwo.ca/psychology/215a-570

Outline Outline

Oculomotor CuesOculomotor Cues Pictorial CuesPictorial Cues Motion Based CuesMotion Based Cues StereopsisStereopsis Development of Depth PerceptionDevelopment of Depth Perception Effects of ExperienceEffects of Experience

TypesTypes

ImportanceImportance

Recognition of location in space is Recognition of location in space is essential for almost all activitiesessential for almost all activities navigating/avoiding objectsnavigating/avoiding objects jumpingjumping catching/throwingcatching/throwing reaching/graspingreaching/grasping size judgements and recognitionsize judgements and recognition

As a result, many redundant systems As a result, many redundant systems available for assessing depth and distanceavailable for assessing depth and distance

How Do We Perceive Depth?How Do We Perceive Depth?

Oculomotor CuesOculomotor Cues

AccomodationAccomodation

ConvergenceConvergence

Pictorial CuesPictorial Cues

OcclusionOcclusion

Height in Visual FieldHeight in Visual Field

Moon IllusionMoon Illusion

PossibilityPossibility

Relative SizeRelative Size

How it worksHow it works

Can Create Illusions...Can Create Illusions...

“Excuse me for shouting – I thought you were farther away.”

Which is Bigger?Which is Bigger?

Familiar SizeFamiliar Size

Effects of Familiar SizeEffects of Familiar Size

Shape ConstancyShape Constancy

Size ConstancySize Constancy

Atmospheric HazeAtmospheric Haze

Linear PerspectiveLinear Perspective

Which Line is Longer?Which Line is Longer?

Texture GradientTexture Gradient

Texture DiscontinuitiesTexture Discontinuities

ShadingShading

OriginalOriginal ReversedReversed

Pictorial Cues TogetherPictorial Cues Together

IllusionIllusion

ExplanationExplanation

Motion Based CuesMotion Based Cues

These cues depend onThese cues depend on Geometric changes in Geometric changes in

the scenethe scene Effects of self-motionEffects of self-motion Movement through the Movement through the

visual fieldvisual field

Motion ParallaxMotion Parallax

Biological MotionBiological Motion

Optic FlowOptic Flow

Binocular CuesBinocular Cues

Two eyesTwo eyes Slightly displaced images Slightly displaced images

in each eyein each eye Info about relative depthInfo about relative depth Based on the geometry of Based on the geometry of

the images reaching the the images reaching the eyeeye

Important TermsImportant Terms

Retinal DisparityRetinal Disparity

ExampleExample

Crossed & UncrossedCrossed & Uncrossed

DiplopiaDiplopia

StereopsisStereopsis

Physiological BasisPhysiological Basis

How can cortical neurons How can cortical neurons process disparity process disparity information?information? Cortical neurons that code Cortical neurons that code

retinal disparityretinal disparity Respond based on the Respond based on the

positions of the images on positions of the images on the two retinaethe two retinae

ExampleExample

Motion IllusionMotion Illusion

Size ConstancySize Constancy

Why does someone Why does someone walking away NOT walking away NOT appear to shrink?appear to shrink?

The Holway-Boring Experiment

Which Line is Longer?Which Line is Longer?

#1? #2?

ExplanationExplanation

#1 #2

DevelopmentDevelopment

The Effects of ExperienceThe Effects of Experience