Lecture 6 - Perception 2

Question 1

What is Depth Perception?

Answer 1

The ability to locate identified forms in space - specifically, it allows us to see objects in three dimensions and judge distance.

Question 2

What cues does Depth Perception use?

Answer 2

Binocular cues (require the use of both eyes), and Monocular cues (require the use of one eye)

Question 3

What are Binocular cues used for?

Answer 3

Primarily used for objects very close to the perceiver - there are two main binocular cues (retinal disparity and convergence)

Question 4

What is Retinal Disparity/Stereopsis?

Answer 4

When images from the two eyes differ - the closer the object the larger the disparity - e.g. when an object appears closer to the right eye then it does to the left eye

Question 5

What is Convergence?

Answer 5

A neuromuscular cue - the two eyes move inward for nearer objects. Lowest convergence is furthest away, highest convergence is very close - crosseyed.

Question 6

What are monocular cues used for?

Answer 6

Distant and depth - there are many monocular cues

Question 7

What monocular cues are there?

Answer 7

Relative size, interposition, linear perspective, relative clarity, texture, relative height, relative brightness, relative motion, and motion parallax.

Question 8

What is Relative Size?

Answer 8

The smaller image is further away, while larger images are closer.

Question 9

What is Interposition?

Answer 9

Closer objects block more distant objects.

Question 10

What is Linear Perspective?

Answer 10

Parallel lines converge with distance - appear to get closer together the further away they go.

Question 11

What is Relative Clarity?

Answer 11

Clearer objects seem closer - less clear objects seem more distant.
The clearer an object is the closer it seems.

Question 12

What is Texture?

Answer 12

Coarser objects seem closer, while finer objects seem more distant.
More texture can be perceived closer, and less farther away.

Question 13

What is Relative Height?

Answer 13

Higher objects are seen as more distant, while shorter objects are seen as closer.

Question 14

What is Relative Brightness?

Answer 14

Closer objects appear brighter, and further objects seem darker - BUT your visual system will tend to equalise the brightness.

Question 15

What is Relative Motion?

Answer 15

Closer objects seem to move faster - because distant objects can be seen for longer so SEEM slower.

Question 16

What is Motion Parallax?

Answer 16

The change of position of two stationary points relative to each other as seen by an observer caused by the motion of an observer.

By moving and changing YOUR perspective, the focus of your vision seems to move.

Question 17

Explain constancies in visual perception

Answer 17

The light that hits our eyes results in quite a diverse range of patterns on our retinas - but, our experience is of relatively stable perceptions. The forms in the world around us change much more than we are aware of, but our visual system expects certain changes in the light that hits our eyes from the
same objects

Question 18

What is Brightness Constancy?

Answer 18

Our visual system adjusts to variations in
light very well, e.g. Even though a grey sheet of paper may reflect more light on a sunny day than a white sheet on a cloudy day, we still see the grey sheet as grey and the white sheet as white
Our visual system works on the relative brightness of the object

Question 19

What is Size Constancy?

Answer 19

We expect the context within which we judge the size of an object not to change - if it does we can be tricked by perspective

Question 20

What is Form Constancy?

Answer 20

The same shape can look different from different angles and yet we experience a consistent perception - e.g. if we see a square from different angles its still recognisable as a square