Visual Perceptual Principles

The way visual information is organised, grouped together and interpreted relies on how we apply visual perceptual principles.

Visual perceptual principles: a set of consistent instructions which helps organise and interpret visual stimuli in a reliable and meaningful manner.

Visual Perceptual Principles

Gestalt Principles

Figure ground

Closure

Proximity

Similarity

Depth Perception Principles

retinal disparity

Convergence

Accommodation

Pictorial depth cues

Constancies

Size

Shape

Orientation

Gestalt Principles.

Instructions we apply to interpret stimuli as a whole object.

There are 4 principle

Gestalt Principles.1) Figure Ground:

Involves distinguishing what is relevant and what is not. The relevant stimulus is identifies against the background.

2) ClosureTendency to fill in the

missing gaps of a stimulus to perceive a whole complete object.

3) ProximityObjects located

close to each other are perceived as one group/

4) SimilarityObjects that

share similar features are perceived as one group.

Depth Perception Principles.

Cues or signals that assist our ability to judge distance and depth.

Depth perception principles

Primary depth cues

Retinal disparity

Convergence

accommodation

Secondary depth cues

Pictorial depth cues

Linear perspective

Interposition

Texture gradient

Relative size

Height in visual field

Monocular Depth Cues (one eye)

Binocular Depth Cues (two eyes)

Primary Depth Cues Accommodation Retinal DisparityConvergence

Secondary Depth Cues Linear perspectiveInterpositionTexture gradientRelative sizeHeight in the visual field.

Primary Depth Cues page 97-98

Internal signals provided by our body that helps us judge distance and depth.

1) Retinal Disparity: fusing two slightly different images together because each eye sees something different. The bigger the difference the closer the object. (binocular)

http://www.youtube.com/watch?v=4VGVwOmn6bk

2) Convergence: the inward turning of the eyes to focus an object on the retina. The more they turn in the closer the object. (binocular) (looking at your nose example)

3) Accommodation: the changing shape of the lens. When an object is close the lens bulges. When an object is far away the lens stretches. This is due to the relaxation and contraction of the ciliary muscles around the lens. (monoculare)

http://www.youtube.com/watch?v=DMPyD1mcNW0&feature=related

Secondary Depth Cues

Signals provided by the environment that help us judge distance and depth.

1. Pictorial Depth Cues: these cues are present in signs and symbols as well as natural and man made environments. Artists also use them in their work to create depth. All pictorial depth cues are monocular.

Pictorial Depth Cues1) Linear Perspective:Two lines converging

together provide a cue for depth. Closer the lines are the further away it is.

2) InterpositionObjects that overlap.

The object in front is perceived as closer.

3) Texture GradientThe amount of detail.

The closer it is the more detail you can see.

4) Relative SizeThe size the image

casts on the retina. The bigger the image the closer it is.

5) Height in the Visual Field

Uses the horizon line a cue for depth. The closer an object is to the horizon line the further away it is.

• Do you think culture influences perception?

• If so, How????

Page 102

Visual Constancies• Constancy Principles: help us perceive the

world as remaining stable and unchanging even though the images projected onto our

retina show otherwise. There are 3 constancies.

1. Size2. Shape

3. Orientation

1) Size constancy:Even though the

size of the object changes on the retina it doesn’t mean that the actual size of the object changes.

2) Shape constancy:Even though the

shape of the object changes on the retina, it doesn’t mean that the actual shape of the object is changing.

3) Orientation constancy:Perceiving an objects true

orientation despite changes in the orientation of the object on the retina.

Eg: when you watch TV upside down you don’t believe that the world has turned upside down.