Attention and perception part 2 unit 9

Question 1

What sources of information allow us to perceive depth and size?

Answer 1

Environmental information: Includes cues from light, shadows, and other visual details in the surroundings.
Physical sensations: Arise from eye movements and adjustments (e.g., muscle tension when focusing on near vs. far objects).

Question 2

Why is perceiving depth from a 2D retinal image challenging?

Answer 2

A single retinal image doesn’t inherently contain depth information; it represents the world in two dimensions. The brain must process and interpret this flat image to reconstruct a 3D perception of objects’ distances and locations.

Question 3

What is the cue approach to studying depth perception?

Answer 3

It examines information in the retinal image that provides cues about object depth.

Question 4

How does experience influence our use of depth cues?

Answer 4

With repeated exposure, we learn to associate certain visual patterns with depth. For instance, overlapping objects suggest one is closer than the other, and this understanding becomes automatic over time.

Question 5

What are the three main types of depth cues?

Answer 5

Oculomotor cues – Based on eye position and muscle tension.
Monocular cues – Use visual information from one eye.
Binocular cues – Use visual information from both eyes.

Question 6

What are oculomotor cues?

Answer 6

Depth cues based on the sensations we feel from the movements of our eyes and the tension in the muscles controlling them. These cues are especially useful for detecting depth at close distances.

Question 7

What is convergence, and how does it provide depth information?

Answer 7

A:

Convergence is the inward movement of the eyes when focusing on nearby objects.
The convergence angle (the angle at which both eyes align on the object) changes with the distance:
Closer objects require more inward eye movement, creating stronger physical sensations.
These sensations are processed by the nervous system to calculate the object’s distance.

Question 8

How does accommodation contribute to depth perception?

Answer 8

Accommodation refers to changes in the shape of the eye’s lens to focus on objects at different distances:
For closer objects, the lens becomes thicker.
For distant objects, the lens flattens.
The ciliary muscles controlling these changes produce tension, which the nervous system interprets as depth information.

Question 9

Between convergence and accommodation, which provides stronger depth information?

Answer 9

Convergence provides stronger depth cues than accommodation because it produces more pronounced physical sensations.
Both cues are most effective for objects located within an arm’s length.

Question 10

Why are oculomotor cues limited in detecting distant objects?

Answer 10

The physical sensations from convergence and accommodation become less noticeable as the distance increases.
For objects further than an arm’s length, we rely on other cues like monocular and binocular cues for depth perception.

Question 11

What are monocular cues?

Answer 11

Depth cues that can be obtained using just one eye. They include pictorial cues (depth information from still images) and motion cues (depth information from movement).

Question 12

What is occlusion, and how does it provide depth information?

Answer 12

Occlusion occurs when one object blocks another from view.
The object doing the blocking is perceived as closer, while the partially or fully hidden object is seen as further away.
Occlusion provides relative distance but not precise measurements of how far apart objects are.

Question 13

How does relative height inform depth perception?

Answer 13

Objects higher in the visual field (closer to the horizon) are generally perceived as further away.
However, this reverses for objects above the horizon: higher objects appear closer, and lower ones appear further away.

Question 14

What is the role of familiar size in depth perception?

Answer 14

Familiar size relies on prior knowledge of an object’s typical size to judge distance.
Example: If two coins of known sizes appear the same on the retina, the smaller coin (e.g., 1 cent) is judged to be closer than the larger coin (e.g., 50 cents).

Question 15

How does relative size work as a depth cue?

Answer 15

When two objects are known to be of equal size, the smaller object in the retinal image is perceived as further away.
Larger objects in the visual field are interpreted as closer.

Question 16

What is perspective convergence, and how does it aid depth perception?

Answer 16

Parallel lines appear to converge as they recede into the distance (e.g., railway tracks).
The point of convergence indicates greater distance, helping us perceive depth in 2D images.

Question 17

How does atmospheric perspective contribute to depth perception?

Answer 17

Distant objects appear less sharp and slightly blue-tinted due to particles (dust, water, air) scattering light.
This cue helps judge objects at far distances.

Question 18

What is a texture gradient, and what information does it provide?

Answer 18

A texture gradient occurs when equally spaced objects appear closer together as they recede into the distance.
This gradual change in texture helps us perceive depth.

Question 19

How do shadows inform depth perception?

Answer 19

Shadows provide clues about an object’s position relative to a surface (e.g., resting or hovering).
They also reveal the three-dimensional shape of objects (e.g., spheres appearing round due to shading).

Question 20

What are motion cues, and how do they differ from pictorial cues?

Answer 20

Motion cues are depth cues derived from movement, either of the observer or objects in the environment.
Unlike pictorial cues, they require changes over time to infer depth and distance.

Question 21

What is motion parallax, and how does it create depth perception?

Answer 21

Motion parallax occurs when nearby objects move faster across the visual field than distant objects as you move.
Example: When looking out of a car window, trees near the road seem to move faster than distant mountains.

Question 22

Why do close and distant objects move at different speeds during motion parallax?

Answer 22

The retinal image of closer objects shifts across a larger distance in the same period compared to distant objects.
Greater speed is associated with closer objects.

Question 23

What are deletion and accretion, and how do they provide depth information?

Answer 23

Deletion: Occurs when an object is covered as you or other objects move.
Accretion: Occurs when an object is uncovered during movement.
These effects help determine relative distances between objects.

Question 24

How can you experience deletion and accretion yourself?

Answer 24

Hold one hand at arm’s length and the other closer to your face.
Move your head side to side: the closer hand will alternately cover (deletion) and uncover (accretion) the further hand, providing depth information.

Question 25

How does the usefulness of monocular cues vary with distance?

Answer 25

Short distances: Accommodation and relative size are more useful.
Long distances: Atmospheric perspective and relative height become more important.

Question 26

What are monocular cues?

Answer 26

Depth cues that can be perceived with just one eye.

Question 27

What are the two types of monocular cues?

Answer 27

Pictorial cues: Found in static images (e.g., shadows, relative size).
Motion cues: Depth information from movement (e.g., motion parallax).

Question 28

How does accommodation work as a monocular cue?

Answer 28

A: The lens changes shape to focus on objects, and this physical sensation helps estimate distance.

Question 29

When are monocular cues most useful?

Answer 29

Short distances: Accommodation and relative size are helpful.
Long distances: Atmospheric perspective and shadows are more effective.

Question 30

What are binocular cues?

Answer 30

Depth cues that require both eyes and rely on the slight differences between the images each eye sees.

Question 31

What is binocular disparity?

Answer 31

The small difference in images seen by each eye; the brain combines these images to perceive depth.

Question 32

: How does binocular disparity work in 3D films?

Answer 32

Each eye sees a slightly different image through 3D glasses, mimicking natural depth perception.

Question 33

When are binocular cues most useful?

Answer 33

For judging depth at moderate distances, such as objects a few feet away.

Question 34

What is object recognition?

Answer 34

The process of identifying an object and placing it into a relevant category.

Question 35

What is Prototype Theory in object recognition? Rosch’s (1973) Prototype Theory

Answer 35

We recognize objects by comparing them to a prototype, which is an average representation of objects in that category.

Question 36

What is an example of a prototype?

Answer 36

A prototype for the category “birds” might combine features of sparrows, robins, and swallows but doesn’t exactly match any single bird.

Question 37

What does typicality mean in object recognition?

Answer 37

It refers to how closely an object matches the prototype for its category:

High typicality: Strong resemblance (e.g., a sparrow for “bird”).
Low typicality: Weak resemblance (e.g., a penguin for “bird”).

Question 38

What are the three levels of object categorization?

Answer 38

Global (Superordinate): Broad categories (e.g., “furniture”).
Basic: Everyday categories used most often (e.g., “chair”).
Specific (Subordinate): Detailed categories (e.g., “kitchen chair”).

Question 39

Why is the basic level of categorization most useful?

Answer 39

A: It provides enough detail to describe an object quickly without being too general or overly specific (e.g., calling a guitar “guitar” instead of “musical instrument” or “electric guitar”)

Question 40

How does experience affect object categorization?

Answer 40

Experts (e.g., furniture makers) may prefer the specific level (“kitchen chair”) because they can identify more detailed differences within a category.

Question 41

What was the experiment by Rosch & Mervis (1975) about?

Answer 41

The experiment investigated the relationship between family resemblance and typicality in object categories.
Participants listed features of objects in a category (e.g., “furniture”) and rated how representative each object was of the category.
Results showed that objects with high family resemblance (sharing many features with others) were rated as having high typicality (e.g., sparrows for “birds”).