lecture 5

Question 1

what is the importance of form and oragnisation?

Answer 1

environment contains hundreds of overlapping objects yet perceptual experience is:

• structured
• made of coherent objects that we can recognise, use and usually name

Question 2

how does the distal image differ from the proximal image?

Answer 2

the image is inverted, tiny and flat

Question 3

why is the proximal stimulus inverted, distorted, tiny and flat?

Answer 3

to compensate for eye movement, body movement and object movement

Question 4

features of the retina that must be taken into consideration

Answer 4

the retina is curved

it is constantly moving

Question 5

how often does the retina move

Answer 5

up to 50 times a second

Question 6

what is marr’s approach concerned with?

Answer 6

representation of edged, contours and other areas of contrast chang e

Question 7

is marr’s approach bottom up or top down? how so?

Answer 7

bottom up
starts off with retinal input into perceptual system in form of retinal image and describes in stages of processing this image

Question 8

what type of model is marrs approach?

Answer 8

computational model

Question 9

what do you need to consider in computational theory?

Answer 9

what is the model trying to do? what are the processes for? what is the goal?

Question 10

what needs to be considered on the algorithmic level of a computational model ?

Answer 10

what algorithm is needed? what process?

Question 11

what needs to be considered on the mechanism level of computational model?

Answer 11

what mechanism is needed to implement the algorithm? eg. neural/ biological system

Question 12

importance of computational models?

Answer 12

algorithmic system is more likely to be understood by understanding the problem than explaining the mechanism in which it is embedded
(trying to understand perception by studying neurons is like trying to understand a bird in flight by studying only feathers)

Question 13

5 stages of retinal image analysis (Marr’s approach)

Answer 13

1) retinal image
2) grey level description
3) primal sketch
4) 2 1/2 D sketch
5) 3D representation

Question 14

grey level description

Answer 14

measuring the intensity of light at each point in the image

Question 15

primal sketch

Answer 15

-representation of contrast change over a range of spatial frequencies (blobs, edges, bars..)

Question 16

2 1/2 D sketch

Answer 16

representation of orientation, depth and colour relative to the observer
primal sketch combined with depth cues, colour, motion
not 3D because it is observer oriented

Question 17

3D representation

Answer 17

representation of objects independent of the observer
2 1/2 D sketch analysed for 3D volume primitives

produces a 3D representation that is independent from the observer

Question 18

what stage of Marr’s approach is teh conscious experience of vision

Answer 18

3D representation

Question 19

what is the Gestalt approach concerned with

Answer 19

rules of perceptual organisation

that we dont see in lines and figures but in forms and shapes

Question 20

what did Gestalt believe?

Answer 20

the whole is greater (different) than the sum of its parts

Question 21

What are Gestalt psychologists interested in?

Answer 21

how we group parts of a stimulus together and the way we separate figure from ground (segregation and grouping)

Question 22

is the Gestalt approach top down or bottom up?

Answer 22

top down

Question 23

what is insight learning?

Answer 23

sudden realisation of the solution to a problem

in the absence of trial and error-minimising teh gap between current state and goal

Question 24

what is important in insight learning?

Answer 24

you have to see the problem as a whole

Question 25

what is special about insight learning?

Answer 25

it is thought to be a uniquely human trait/ skill

Question 26

argument supporting the Gestalt approach

Answer 26

ambiguity does not arise in the real world, we see a stable and organised world. therefore we must have perceptual organisation
argument: we see objects according to all their elements taken together as a whole

Question 27

what are principles of perception?

Answer 27

seemingly innate laws that determine the ways in which objects are perceived

Question 28

what did gestalt psychologist seek to do?

Answer 28

isolate the principles of perception

Question 29

what are the gestalt laws of perceptual organisation?

Answer 29

1) similarity
2) good continuation
3) proximity
4) connectedness
5) closure
6) common fate
7) familiarity
8) invariance
9) pragnanz: good figure

Question 30

similarity

Answer 30

things that appear to be grouped together

Question 31

what can similarity occur due to?

Answer 31

shape, lightness, hue, orientation, size

Question 32

good continuation

Answer 32

points that, when connected, result in a straight or smoothly curved lines are seen as belonging together

lines tend to be seen in a way as to follow the smoothest path

Question 33

proximity

Answer 33

things that are near one another appear to be grouped together

Question 34

connectedness

Answer 34

things that are physically connected are seen as a unit

Question 35

closure

Answer 35

of several geometrically possible perceptual organisations, a closed figure will be preferred to an open figure

Question 36

why do we tend to complete a broken figure?

Answer 36

because of the strong closure cue for organising what we see

Question 37

common fate

Answer 37

things that are moving in the same direction are grouped together

objects with the same orientation are grouped together

Question 38

familiarity

Answer 38

things are more likely to form groups if the group feels more familiar or meaningful

Question 39

invariance

Answer 39

simple geometrical shapes are recognisable independent of rotation, translation and scale

Question 40

captcha test? what does it rely on?

Answer 40

completely automated public Turing test to tell humans apart from computers

relies on humans ability to perceptually organise images by invariance, and a computers lack of ability to do so

Question 41

what is the central law of gestalt psychology?

Answer 41

pragnanz

Question 42

pragnanz

Answer 42

of several geometrically possible organisations, one will occur that possesses the best, simplest and most stable shape

Question 43

properties that affect whether the area is seen as figure or ground

Answer 43

symmetry 
convexity 
area 
orientation 
meaning/ importance

Question 44

symmetry in figure-ground segregation

Answer 44

symmetrical areas are usually figures

Question 45

convexity figure-ground segregation

Answer 45

convex shapes usually figures

Question 46

area in figure-ground segregation

Answer 46

stimuli with comparatively smaller area usually the figure

Question 47

orientation in figure-ground segregation

Answer 47

vertical and horizontal orientations are usually figures

Question 48

meaning/ importance in figure-ground segregation? importance?

Answer 48

meaningful objects more likely to be seen as figures

infers top down process

Question 49

problems with the Gestalt approach?

Answer 49

1) underplays parallel processing and unconscious processing that the brain does
2) explanation of how some of their laws worked was wrong
3) laws provide a description rather than an explanation
4) laws ill defined (e.g. what is the simplest and most stable shape?)
5) stating the obvious?

Question 50

positives of the Gestalt approach

Answer 50

their laws appear to pe generally correct

1) percepts can be analysed into basic elements
2) the whole is greater than the sum of its parts
3) context and experience influence perception

Question 51

David Marr dates

Answer 51

1945- 1980

published 1982

Question 52

Wolfgang Kohler

Answer 52

1887-1967
series of experiments in Kohler and Koffka by Wertheimer
together they developed the Gestalt school
series of influential publications (1920s)