percieving objects scenes and colour w3

Question 1

discuss 3 reasons why object perception is difficult

Answer 1

• the stimulus on the receptor is ambiguous
• objects can be hidden or blurred
• objects look different from different viewpoints

Question 2

inverse projection problem

Answer 2

particular image on the retina can be created by many different objects in the environment,
easy to see why the image on the retina is ambiguous.

Question 3

viewpoint invariance

Answer 3

The ability to recognize an object seen from different viewpoints is called viewpoint invariance.

Question 4

structuralism Wilhelm Wundt

Answer 4

sensation: elementary processes that occur in response to stimulation of the senses and perceptions
- atoms combine to create complex molecular structures = sensations combine to create complex perceptions.

perceptions: more complex conscious experiences such as our awareness of objects.

Question 5

Max Wertheimer, stroboscope

Answer 5

bought a toy a mechanical device that created an illusion of movement by rapidly alternating two slightly different pictures
- how the structuralist idea (experience is created from sensations) could explain the illusion of movement he observed

Question 6

apparent movement

Answer 6

illusion of movement
although movement is perceived, nothing is actually moving.
- (1) One light flashes (2) there is a period of darkness, lasting a fraction of a second and (3) the second image flashes
- there are two images flashing separated by a period of darkness. (we don’t see the darkness because our perceptual system adds the perception of an image moving through the space between the flashing lights)
- examples; moving advertisements or news headlines and movies.
1) apparent movement can’t be explained by sensations, because there is nothing in the dark space between the flashing lights.
2)basic principles of Gestalt psychology: The whole is different than the sum of its parts perceptual system creates the perception of movement where there actually is none.
perceptual system creates the perception of movement where there actually is none.

Question 7

basic principles of Gestalt psychology:

Answer 7

The whole is different than the sum of its parts

Question 8

illusory contours

Answer 8

• The edges that create the triangle are called illusory contours because there are actually no physical edges present. (we fill in these gaps)
• Sensations can’t explain illusory contours, because there aren’t any sensations along the contours.

Question 9

Gestalt laws of perceptual organization.

Answer 9

• Perception is not built up from sensations, but is a result of perceptual organization.
• perception depends on a number of principles of perceptual organization, which determine how elements in a scene become grouped together.
• During this process, incoming stimulation is organized into coherent units such as objects.

Question 10

grouping

Answer 10

Grouping visual events are “put together” into units or objects.

Question 11

segregation

Answer 11

The process of grouping works in conjunction with segregation, which is the process of separating one area or object from another.

Question 12

good continuation

Answer 12

• Points that, when connected, result in straight or smoothly curving lines are seen as belonging together they follow the smoothest path.
• objects that are partially covered by other objects are seen as continuing behind the covering object.

Question 13

Principle of pragmaz

Answer 13

• (principle of good figure/ principle of simplicity

- Every stimulus pattern  perceived as most simple structure as possible.

Question 14

Similarity

Answer 14

• Similar things appear to be grouped together.
• Grouping can also occur because of similarity of shape, size, or orientation.
• Grouping also occurs for auditory stimuli.

Question 15

common region

Answer 15

Elements that are within the same region of space appear to be grouped together.

Question 16

Proximity (Nearness) Our perception

Answer 16

Things that are near each other appear to be grouped together.

Question 17

Common Fate

Answer 17

• Things that are moving in the same direction appear to be grouped together.
• Note that common fate can work even if the objects in a group are dissimilar.
• key idea: group of objects are moving in the same direction.

Question 18

Uniform Connectedness

Answer 18

a connected region of the same visual properties, such as lightness, color, texture, or motion, is perceived as a single unit, the connected circles are perceived as grouped together, just as they were when they were in the same region
- Uniform Connectedness. Elements that are connected by uniform visual properties, such as color, are perceived to be more related than elements that are not connected.
connectedness overpowers proximity

Question 19

Synchrony

Answer 19

• elements occurring at the same time are seen as belonging together

Question 20

perceptual segregation

Answer 20

the perceptual separation of one object from another

Question 21

figure ground segregation

Answer 21

When we see a separate object, it is usually seen as a figure that stands out from its background, which is called the ground.

Question 22

Edgar Rubin reversible figure–ground:

Answer 22

it can be perceived alternately either as two dark blue faces looking at each other, in front of a Gray background, or as a gray vase on a dark blue background.

Question 23

what causes us to perceive one area as figure and the other as ground.

Answer 23

1. The figure is more “thing like” and more memorable than the ground.
2. The figure is seen as being in front of the ground.
3. figure shares the boarders whereas the ground is seen as unformed material, without a specific shape, and seems to extend behind the figure.
   4) The border separating the figure from the ground appears to belong to the figure.
4. Units that are symmetrical
5. Elements that are small
6. Units that are oriented vertically
7. Elements that have meaning
   1) areas lower in the field of view are more likely to be perceived as figure

Question 24

border ownership

Answer 24

This property of the border belonging to one area : border ownership. When perception shifts so the vase is perceived as figure, border ownership shifts as well, so now the border belongs to the vase.

Question 25

light-from-above assumption

Answer 25

: we usually assume that light is coming from above, because light in the environment, including the sun and most artificial light, usually comes from above - humans perceive and recognize better than computer- guided robots, because our perceptual system is adapted to respond to physical characteristics of our environment, such as the orientation of objects and the direction of light

Question 26

Physical Regularities

Answer 26

- regularly occurring physical properties of the environment. (there are more vertical and horizontal orientations in the environment than oblique (angled) orientations) (buildings contain many horizontals and verticals) - when one object partially covers another one, the contour of the partially covered object “comes out the other side, - Uniform connectedness – elements are defined by areas of the same colour or texture

Question 27

semantic regularities

Answer 27

- semantics refers to the meaning of a scene - related to what happens within a scene. - Semantic regularities are the characteristics associated with activities that are common in different types of scenes. - or example, food preparation, cooking, and perhaps eating occur in a kitchen; waiting around, buying tickets, checking luggage, and going through security checkpoints happen in airports. - Palmer’s observers were using their knowledge about kitchens to help them perceive the briefly flashed loaf of bread.

Question 28

scene schema

Answer 28

This knowledge of what a given scene typically contains is called a scene schema.

Question 29

the multiple personalities of the blob

Answer 29

. The blob (a) is perceived as different objects depending on its orientation and the context within which it is seen.

Question 30

Helmholtz’s Theory of Unconscious Inference

Answer 30

“How does the perceptual system ‘decide’ that this pattern on the retina was created by overlap- ping rectangles?” His answer was the likelihood principle, which states that we perceive the object that is most likely to have caused the pattern of stimuli we have received. This judgment of what is most likely occurs, according to Helmholtz, by a process called unconscious inference, in which our perceptions are the result of unconscious assumptions, or inferences, that we make about the environment

Question 31

likelihood principle

Answer 31

states that we perceive the object that is most likely to have caused the pattern of stimuli we have received.

Question 32

unconscious inference

Answer 32

our perceptions are the result of unconscious assumptions, or inferences, that we make about the environment

Question 33

bayesian inference

Answer 33

regularities in the environment provide information we can use to resolve ambiguities estimating the probability of an outcome is determined by two factors: prior probability likelihood of the outcome - we perceive what is most likely to have created the stimulation we have received in terms of probabilities. - prior is multiplied by the likelihood to determine the probability of the outcome. - people start with a prior, then use additional evidence to update the prior and reach a conclusion

Question 34

the prior probability (prior)

Answer 34

our initial estimate of the probability of an outcome

Question 35

likelihood of the outcome

Answer 35

the extent that available evidence is consistent with the outcome

Question 36

contextual modulation links to gestalt principles

Answer 36

- Neurons in the visual cortex respond to Gestalt grouping principles. - stimuli outside of a neuron’s receptive field can affect neural firing – Happens when these stimuli follow good continuation (form a chain in receptive field) - Happens when the stimuli are perceived as part of the figure (rather than ground)

Question 37

attention affects perception. binding - Binding - -

Answer 37

process by which features are combined to create perception of coherent objects

Question 38

Binding problem

Answer 38

features of objects are processed separately in different areas of the brain So, how does binding occur?

Question 39

Treisman’s feature integration theory:

Answer 39

- Feature Integration Theory - Preattentive stage - features of objects are separated - Focused attention stage - features are bound into a coherent perception - Attention serves as the “glue” between the physiology of the what and where streams. - Binding only occurs when we pay attention.

Question 40

- Illusory Conjunctions

Answer 40

Features that should be associated with an object become incorrectly associated with another

Question 41

Balint’s syndrome

Answer 41

patients with parietal lobe damage show lack of focused attention results in incorrect combinations of features

Question 42

conjunction search

Answer 42

finding target with two or more features Patients with parietal lobe damage cannot perform conjunction searches well compared to people without such damage. Parietal lobe is the destination for the where stream.