Task 5

Question 1

Inverse Projection Problem

Answer 1

determining the object responsible for a particular image on the retina; involves starting with the retinal image & extending rays out from the eye
 particular image on retina can be created by many different objects in the environment  image on retina is ambiguous (e.g. rectangular image on retina can be created by trapezoids & other nonrectangular objects)

Comittee: interconneted set of nuerons that takes input and because of benefit of its specific connections and produces an output
–>• Every image is ambiguous but perceptual committee agrees on one single interpretation (“rabbit – duck picture

Question 2

Hidden or Blurred Objects

Answer 2

people easily understand that the covered part of object continues to exist, are able to use knowledge of environment to determine what is likely to be present
• People can recognize objects that are not in sharp focus (blurred)  can often identify them nevertheless

Question 3

Viewpoint invariance

Answer 3

ability to recognize an object seen from different viewpoints; template theory can’t explain viewpoint invariance

e. g. enables people to tell whether faces seen from different angles are the same person
- ->Accidental viewpoint: Wrong perception created by special conditions (Stone picture) property of geon not visible

Question 4

Perceptual Organization

Grouping & Segregation

Answer 4

• Perceptual organization: process by which elements in environment become perceptually grouped to create our perception of objects; incoming stimulation is organized into coherent units e.g. objects;
• Involves two components:
1. Grouping: process by which visual events are “put together” into units or objects
2. Segregation: process of separating one area or object from another
 Both processes work in conjunction with another

Question 5

Middle Vision

Answer 5

stage in visual processing that combines all the basic features in the scene into distinct, recognizable object groups -> comes before high level vision (=understanding the whole scene) and before low level vision (=determining basic features of an image)
• Recognition must match to what we perceive to something we know from the past
• Edges gives us understanding of object -> pair of lines could be combined with other pair of lines and create a corner(edges) BUT more complex
• Sometimes lack of edges because of no luminance difference between object and background

Question 6

GP to Grouping

Strucutalism

Answer 6

• Structuralism: approach that came before Gestalt psychology; distinguished between:
a) Sensations: elementary processes that occur due to stimulation of the senses
b) Perceptions: more complex conscious experiences such as our awareness of objects; accounts for vast majority of our sensory experiences
first many sensations indicated by the small dots and than perceiving a face

• Sees combination of sensations to form perceptions as aided by the observer’s past experience;
 Gestalt psychologists rejected idea that perceptions were formed by “adding up” sensations & rejected past experience as playing a major role in perception

Question 7

Apparent Movement

Answer 7

: illusion of movement (e.g. created by stroboscope); although movement is perceived, nothing is actually moving
• See image right; three components to stimuli that create apparent movement:
1. One image flashes on and off (a)
2. Period of darkness, lasting a fraction of a second (b)
3. Second image flashes on and off (c)
 we don’t see the darkness (b)  during period of darkness, perceptual system adds perception of an image moving through space between the flashing images (d)
 Letters and numbers appear to move smoothly across the screen are created by hundreds of small lights that are blinking on and offmovement can’t be explained by sensations, because there is nothing in the dark space between the flashing images

Question 8

The whole is different than the sum of its parts

Answer 8

perceptual system creates perception of movement where there actually is none

Question 9

Illusionary Counters

Answer 9

seeing contours where actually no physical edges are present;
 Sensations can’t explain illusory contours, because there aren’t any sensations along the contours  whole is different than the sum of its parts

Question 10

G Organization Principles

Answer 10

• perception depends on a number of organizing principles, which determine how elements in a scene become grouped together

Question 11

Principle of good continuation

Answer 11

o Points that when connected result in straight or smoothly curving lines are seen as belonging together; the lines tend to be seen in such a way as to follow the smoothest path;
o Objects that are partially covered by other objects are seen as continuing behind the (fäden zusammengewurschtelt)

Question 12

Principle of pragnanz/good figure/simplicity

Answer 12

central principle
o Every stimulus pattern is seen in such a way that the resulting structure is as simple as possible
o E.g. image right: display is seen as five circles (a) and not as a larger number of more complicated shapes (b)

Question 13

Principle of similarity

Answer 13

Similar things (same colour) appear to be grouped together;
Grouping can also occur because of similarity of shape, size, or orientation (see either horizontal or vertical rows)

Question 14

Law of Closure

Answer 14

: Complete appearance even if absence of one or more of their parts either hidden or totally absent

Question 15

P of common fate

Answer 15

things that are moving in the same direction appear to be grouped together
 can work even if the objects in a group are dissimilar  key criterion: a group of objects are moving in same direction
 see hundreds of birds all flying together see one unit but if some birds fly in another direction it is another unit

Question 16

P of common region

Answer 16

: Elements that are within the same region of space appear to be grouped together (even though the circles inside the ovals are farther apart than the cicles next to each other neightbour cicles we see the circles inside the overals beloning together

Question 17

P of unifirm connetedness

Answer 17

connected region of the same visual properties, e.g. lightness, colour, texture, or motion, is perceived as a single unit connecters overpowers proximity

Question 18

Why Heuristics

Answer 18

–> a role that our brain uses to be quick in combining- heuristic because you cannot say that Is a nature law it just happens in our mind

Question 19

Perceptual Segregation and problem of figure- ground segregation

Answer 19

: question of what causes perceptual segregation

 a separate object is usually seen as a figure that stands out from its background, the ground

Question 20

Properties of Figure and Ground

Reversible figure- ground

Answer 20

: pattern that can be perceived alternately  there are many ways to look at a given pattern
• Figure is more “thinglike” & more memorable than the ground
• Figure is seen as being in front of the ground
• Near borders shared with the figure, the ground is seen as unformed material, without a specific shape, & seems to extend behind the figure;
 Grounds are often shaped by borders distant from those they share with the figure
(Vase, gesicht)

Question 21

Broader ownership

Answer 21

property of the border belonging to one area (when two faces are seen as figure, the border separating the blue faces from grey background belongs to the faces, when perception shift so vase is perceives as figure border ownership shifts as well so border belongs to the face)

Question 22

Parallelism, Symmetry, Extremal edges and relative motion

Answer 22

 Parallelism = a rule for figure-ground assignment stating that parallel contours are likely to belong to the same figure
 Symmetry = symmetrical regions are more likely to be seen as figure
 Extremal edges = figure-ground calculations are intended to answer the question “Is region A in front of region B” -> some cues are strong enough to overwhelm cues like surroundeness and shape
 Relative motion = how surface details move relative to an edge(Ecke/Grenze) can also determine which portion of a display is the foreground figure and which is the background

Question 23

Image based factors determine which area is figure

Answer 23

bottom half sen as figure, upper half is seen as ground(sky)

Question 24

Relatability

Answer 24

Degree to which two line segments appear to be part of the same contour -> heuristc ( mental shortcuts) when seeing S curves

Question 25

Gist of scene

Answer 25

general description of the type of scene;
 most scenes can be identified after viewing them for only a fraction of a second (flip from one TV channel to another)
–>overall gist of scene perceived first, followed by perception of detaisl

Question 26

Persistence of vision

Answer 26

perception of a visual stimulus continues for 250 ms (1/4 second) after the stimulus is extinguished

Question 27

Visual masking stimuus

Answer 27

usually a random pattern that covers the original stimulus; can eliminate persistence of vision

Question 28

Global image features

-degree of naturallness, openness,roughness,expansion, colour

Answer 28

information used to rapidly perceive the gist of a scene; can be perceived rapidly & are associated with specific types of scenes
o Degree of naturalness: natural scenes (e.g. forest) have textured zones & undulating contours  man-made scenes (e.g. street) are dominated by straight lines, horizontals & verticals
o Degree of openness: open scenes (e.g. ocean) often have a visible horizon line & contain few objects;
 e.g. forest is a scene with a low degree of openness
o Degree of roughness: smooth scenes (low roughness) e.g. ocean contain fewer small elements  scenes with high roughness (e.g. forest) contain many small elements  more complex
o Degree of expansion: convergence of parallel lines (e.g. in street scenes) indicates high degree of expansion;
 especially dependent on observer’s viewpoint
o Colour: some scenes have characteristic colours, e.g. ocean scene (blue), forest (green & brown)
 Global image features are holistic & rapidly perceived

Question 29

Regulations in Environment

Answer 29

Characteristics of environment which occur frequently (e.g. open sky associated with blue colour)

Question 30

1. Physical regularities

- light from above assumption

Answer 30

regularly occurring physical properties of the environment
• horizontal & vertical orientations (buildings or trees, plants) are more prevalent in environment than angled orientations;
 people can perceive horizontals and verticals more easily than other orientations
• objects in environment often have homogeneous colours & nearby objects have different colours
• light-from-above assumption: assumption that light is coming from above  most light in environment usually comes from above (sun, artificial light)
 our system is customized to respond to the physical characteristics of our environment

Question 31

2. sematic regulations

Answer 31

: characteristics associated with the functions carried out in different types of scenes
 semantics refers to meaning of a scene, often related to its function  what happens within it
 food preparation, cooking, eating occur in kitchen

Question 32

Theroes of Object Recognition

Theory of unconscious inference (Helmholz)

Answer 32

states that some of our perceptions are the result of unconscious assumptions we make about the environment (schlussfolgerung)
- Likelihood principle = perception of objects is influenced by our experience and we tend to see an object that is most likely to have caused the stimuli pattern we have received

Question 33

Baysesian inference

Answer 33

Statistical technique and takes probabilities into account that are based on experience
- Perception is a combination of the current stimulus and our knowledge about the conditions of the world BUT the longer you see a scene the more you are able to recognize

Question 34

Naive Template theory

Answer 34

match a perceived stimulus to a representation of a previously encountered object encoded in memory -> even low feature or low pixel representation are matched to memory
- Lock and key : a fixed structure (the lock), which exactly matched the structure of a specific substrate(Key) (Letter A)

Question 35

Bilderman´ Recognition by components model

Answer 35

Structural theory/description: specification of an object in terms of its parts and relationship between these parts

• Geons : geometric icons and collections of nonaccidental features(=properties of edges in the retinal image that correspond to the properties of edges in the 3D) environment
• Principle of componential recovery : If we can perceive an object’s geons, we can identify the object -> There are 36 geometric shapes and every object in the world is created by combining up to three geons
• Discriminability : fact that each geon has unique set of nonaccidental frequencies

Question 36

Subtracting theory

Answer 36

fMRI brain activity is measured in two conditions: one with and one without the involvement of the mental process of interest -> when subtracting both it shows regions of the brain activated by that process