Unit 8 Perceptual Organisation

Question 1

Perceptual organisation
-> grouping and segregation

Answer 1

-> the process by which elements in the environment become grouped together or separated to create our perception of objects

G - involves putting together individual elements into an object or groups of objects
S - involves separating one object from another, or one area from another

Question 2

Structuralism - Wilhelm Wundt

Answer 2

• earliest approaches to understanding how individual elements are organised to form the perception of an object
• views perception as the result of individual sensations combining, or summing together, like atoms adding up to create a complex molecule

=> Sensations: are elementary processes that occur in response to stimulation of the senses, such as detecting the presence of light
=> Perceptions: are more complex conscious experiences, such as awareness and recognition of objects

Question 3

the Gestalt psychologists
-> Max Wertheimer

Answer 3

-> rejected the idea that perceptions were simply formed by the summation of sensations

-> responsible for stroboscopic effect: how can rapidly alternating two images produce the illusion of movement if there is nothing actually moving in the images?

Question 4

stroboscopic effect

Answer 4

• Description: The stroboscopic effect occurs when one light flashes, followed by darkness, then another light flashes in a different location.
• Perception: Our perceptual system adds the perception of an object moving through space, so we do not see the period of darkness.
• Conclusions:
  
  1. The resulting perception is not the sum of individual sensations since there is no actual movement in the visual field.
  2. The whole is different from the sum of its parts, as the perceptual system creates the illusion of movement without actual movement.

Question 5

What is the argument against structuralism

Answer 5

Illusory contour effect
-> in the figure, the three pac-man like objects create the perception of a triangle
-> As there are no physical edges of a triable stimulating our visual receptors, the perception of a triangle cannot be simply the sum of sensation

Question 6

Principles of perceptual organisation

Answer 6

• Observations such as the illusory contour effect led Gestalt psychologists to conclude that perceptions are not created by simply summing individual sensations but by HOW the individuals sensations, or elements ARE ORGANISED

-> explain how elements in a scene are perceived to belong to the same object or the same group of objects

Question 7

What is the principles of perceptual organisation?

Answer 7

They help bring ORDER and COHERENCE out of potentially confusing stimuli, and by grouping elements together we can reduce the number of things that need to be processed (like chunking in memory)

Question 8

The principle of pragnanz (simplicity)

Answer 8

This principle is considered the most fundamental or over-arching of all the principles of organisation. It states that we tend to perceive the simplest possible configuration of individual elements

Question 9

The principle of good continuation

Answer 9

-> Elements that follow smooth, uninterrupted lines are grouped together as a whole object or groups of objects

Question 10

The principle of similarity

Answer 10

Similar things appear to be grouped together
-> example: we are equally likely to perceive the figure on the left as rows, columns or a grid of circles, but are much more likely to perceive the figure on the right only as columns of circles

Question 11

The principle of proximity
The principle of common fate

Answer 11

-> Elements close together are likely to be perceived as one unit or group compared to elements further away from each other
-> Objects moving in the same direction are perceived as one unit or group

Question 12

The principle of closure
The principle of symmetry

Answer 12

-> We tend to group individual elements of fragmented, or incomplete objects together to perceive a whole object: we perceptually ‘close them’ even though we only see parts of the object
-> Elements that are symmetrical to each other tend to be perceived as a unified group

Question 13

The principle of common region (Palmer, 1992)
-> added through more recent research (the original Gestalt principles were proposed in the early 1900s)

Answer 13

• Elements within the same region or space appear to be grouped together
• Even though the circles inside the ovals are further apart than circles in neighbouring ovals they are perceived as a group because they share the same region.

Question 14

The principle of uniform connectedness (Palmer & Rock, 1994)

Answer 14

A group of connected objects that have a constant property (e.g. colour) are perceived as a single
unit, rather than individual units
* E.g. the connected circles are perceived as grouped together (in this example connectedness also overpowers proximity)

Question 15

SEGREGATION

Answer 15

the separation of one object from another
-> figure-ground problem involves a figure (normally an object) and the ground (the surrounding area, normally the background)

Gestalt psychologists proposed some principles that determine how we perceive one area as figure and other areas as ground
* These principles can be observed when viewing ambiguous images:
* By alternating between perceiving both objects in the image, we can observe the properties that dictate whether you perceive either of the objects as the figure or ground

Question 16

Can we see figure-ground at the same time?

Answer 16

NO These perceptions are alternated because it is not possible to hold both perceptions at the same time:
we either see the faces as figures and the vase as ground, or vice versa.
-> the fact that we can switch between perceptions demonstrates the constructive (top-down) nature of perception:

If we were only engaging in bottom-up processing, we would always experience the same perception

Question 17

Border ownership

Answer 17

The contour separating the figure from the ground “belongs” to the figure, and not to the ground

Question 18

Lower visual fields are

Answer 18

more likely to be viewed as the figure that other areas of the visual field

Vecera et al. (2002) presented imaged that that were separated upper-lower and left-right
-> subjects were more likely to judge the lower area as figure
-> but when it was side to side subjects equally judged the left and right areas as figures

Question 19

Convex and concave

Answer 19

convex curves presented outwards = more likely to be perceived as a figure
concave curves presented inwards

Peterson & Salvagio (2008) - presented visual displays to subjects who had to decide whether a red square was “on” or “off” a perceived figure
-> Subjects judged the convex regions (in this case the dark regions) to be figure on 89% of trials.

Question 20

what did Gestalt psychologists deemphasise?

Answer 20

importance of past experience, knowledge, and learning in the perceptual process
-> the principles of organisation are innate concepts and over-ride, or dominate experience and knowledge

w and m example when written like handwriting we saw a w and a m but when they are put on top of each other the PRINCIPLE OF GOOD CONTINUATION DOMINATES the role of experience leading us to percieve and object that does not look like a w and a m

Question 21

Does experience also not count in figure-ground segregation

Answer 21

to gestalt it does not rely on knowledge

HOWEVER Bernese presented that familiar and unfamiliar objects to amnesia patients and healthy patients
-> healthy patients judged black region to be the figure in the familiar objects rather then the non familiar objects

-> amnesia patients had no difference

suggesting it DOES need experience to separate figure-ground

Question 22

scene schemas and semantic regularities

Answer 22

-> The knowledge of what a specific context contains is a scene schema
-> semantic regularities are characteristics we associate with specific contexts

Therefore, knowledge of what a kitchen contains seemed to help participants perceive objects that fit within the scene schema more accurately and quickly.

Question 23

Perceptual illusions

Answer 23

They suggest that the information detected by sensory receptors is not necessarily what we perceive in our minds
-> during the perceptual process it is likely that we use the sensory information to construct a perceptual representation

Question 24

müller-lyer illusion - lines

Answer 24

the line with outer legs appears to be longer than the arms vertical line, even though they are the same length

although it is misapplying “size constancy scaling” help us maintain stable perceptions of objects regardless of their distance
-> help us perceive the actual size of objects in 3d situation -> in the 2d we may perceive illusions

Question 25

Müller-Lyer illusion realise

Answer 25

exterior corners stick out, towards us
interior corners recede, away from us

Therefore, because we think the line of the arms is further away than the line of the legs, we perceive it as bigger than the line of the legs

Question 26

misapplied “size constancy scaling” can be seen in the Ponzo Illusion

Answer 26

The converging vertical lines appear to give depth information: the top of the lines seems to be further away than the bottom of the lines.
* Therefore, an object placed at the top of the lines appears further away than an object placed at the bottom of the lines

Question 27

Gregory’s explanation of the Müller-Lyon illusion has been challenged by other similar illusions

Answer 27

The same perceptual effect occurs even when the image contains no obvious cues for depth or distance