Development of Depth Perception

Visual Cliff Experiment • Eleanor Gibson and Richard Walk (1960) constructed a

miniature cliff with a dropoff covered by glass in their laboratory. They placed infants on the edge of this visual cliff and had their mothers coax them to crawl onto the glass.

• (6-12 months old) Remained on the shallow side. Most infants would not crawl out on the glass, choosing instead to remain on the shallow side, an indication that they could perceive depth.

• (2-4 months old) Difference in heartbeat when place on the deep side.

(video)

Cue Theory

• We learn the connection between cue and depth through our previous experience with the environment.

• Three Major Groups1. Oculomotor2. Monocular3. Binocular

Oculomotor

• Cues based on our ability to sense the position of our eyes and tension in eye muscles

• Created by convergence (inward movement of the eyes that occurs when we look at nearby objects), and accommodation (change in the shape of the lens that occurs when focus on objects at various distances)

Monocular

• cues that work with one eye• Includes:

1. Accomodation2. Pictorial Cues3. Motion-Produced Cues

Pictorial Cues

• Sources of depth information that can be depicted in a picture

• Types:-occlusion-relative height-relative size-perspective convergence-familiar size-atmospheric perspective-texture gradient-shadows

Occlusion

• Occurs when one object hides or partially hides another view

Relative Height

• objects below the horizon and have their bases higher in the field of view are seen as being more distant

Relative Size

• when objects are of equal size, the one that is farther away will take up less of your view

Perspective Convergence

• parallel lines extend from an observer, they are perceived as converging as distance increases

Familiar Size

• we judged distance based on our prior knowledge of the sizes of objects

Atmospheric Perspective

• more distant objects appear less sharp and often have a slighter blue tint

Texture Gradient

• elements that are equally spaced in a scene appear to be more closely packed as distance increases

Shadow

• provide information regarding locations of these objects. It also enhance the three-dimensionality of objects

Motion-Produced Cues

• Motion Parallax• Deletion and Accretion• Optic Flow

Motion Parallax

• nearby objects appear to glide rapidly past us but more distant objects appear to move more slowly

(insert video)

Deletion and Accretion

• as an observer moves sideways, some things become covered and others become uncovered

(insert video)

Optic Flow

• refers to the relative motion of objects as the observer moves forward or backward in a scene (faraway objects may appear fixed in position; close objects in front rush by you at high speeds)

Learning Check

• What are the different monocular depth cues?

Name the pictorial cue!!!

Name the pictorial cue!!!

Name the pictorial cue!!!

Name the pictorial cue!!!

Name the pictorial cue!!!

Name the pictorial cue!!!

Name the pictorial cue!!!

What is wrong with the video?

(insert megaman)

Disorders that may affect depth perception

1.Amblyopia (lazy eye)• loss of the ability to see through one eye; vision of one eye is reduced

because it fails to work properly with the brain;

2.Optic Nerve Hypoplasia• Optic nerve hypoplasia (ONH) is a congenital condition in which the optic

nerve is underdeveloped• incidence of strabismus is increased with ONH

3.Strabismus• disorder in which both eyes do not line up in the same direction, so they do

not look at the same object at the same time (aka crossed eyes)

(video: mr no depth perception)