Basic processes in visual perception

Question 1

What is interposition?

Answer 1

If one object partly covers another we judge the partly covered object to be further away.

Question 2

What are size cues?

Answer 2

Past experiences with objects can help us to determine how close or far an object is by its size. (close vs far away cow)

Question 3

What is size constancy?

Answer 3

Perceiving an object as the same size even though it is far away

Question 4

Constructivist approach to visual perception (four points)

Answer 4

> Top down – Extraction of information from sensory input guided by prior knowledge.
Perception is an indirect process of construction
Perception is an interaction of external and internal sources
Expectations can lead to errors in perception (visual illusions)

Question 5

Evidence for constructivist approach Herman von Helmholtz

Answer 5

 The Ames room – Depth cues missing so one person appears larger than the other
 Einstein illusion – Assumptions about faces being convex, when mask of Einstein is shown concavely we still perceive it as convex
 Muller-Lyer – Angles in angles out effect. Gregory argued this effect is not innate, those that have no experience of corners will not see the effect.

Question 6

What is accommodation?

Answer 6

Lens changes according to distance:-
 Thin – distant
 Thick – nearby

Question 7

What is linear perspective?

Answer 7

Parallel lines that seem to meet in the distance

Question 8

What is atmospheric perspective?

Answer 8

Distant objects that look blurred and bluish

Question 9

What is shading?

Answer 9

A cue provided by shadow and light that tells you about distance. Can be misleading due to assumptions we have about light.

Question 10

What is convergence (Binocular cues) and Binocular disparity?

Answer 10

 Convergence - Eyes converge when looking at things that are nearby
 Binocular disparity – Both eyes have different views of the world due to their distance from one another, giving an impression of depth.

Question 11

What are height cues?

Answer 11

Objects nearer the horizon appear to be further away

Question 12

What is kinetic depth effect?

Answer 12

A figure that looks flat when static but appears to have depth when it moves

Question 13

What is the ecological approach (James Gibson) – 5 points

Answer 13

 Bottom up processing – All information obtained from sensory input
 The main function of perception is to facilitate interactions between observer and environment
 If environment is rich information can be extracted directly without the need for inference
 Potential use of objects are affordances
 Direct access to info is through resonance

Question 14

What is texture gradient?

Answer 14

Texture of surfaces becomes denser as distance increases (visual cliff). Texture gives info about:
	Shape
	Surface layout
	Distance
	Depth

Question 15

What is motion parallax (optic flow)?

Answer 15

As you move objects at different distances appear to move in different directions and speeds