Perceiving Form and Perceptual Organisation Flashcards
True or False?
The retina is curved
True
What are unevenly distributed in the eye?
Receptors
Images perceived by the retina have 4 main characteristics. What are they?
1) Inverted
2) Distorted
3) Tiny
4) Flat
True or False?
There’s an even amount of cortex devoted to different parts of the visual field
False
There’s an uneven amount of cortex devoted to different parts of the visual field
What are the 2 approaches to the perception of form and organisation?
1) Marr’s approach
2) Gestalt approach
What is Marr’s approach concerned with?
The representation of edges, contours and other areas of contrast change
What is the Gestalt approach concerned with?
The rules of perceptual organisation
The representation of edges, contours and other areas of contrast change
Which form perception approach is concerned with this?
Marr’s approach
The rules of perceptual organisation
Which form perception approach is concerned with this?
Gestalt approach
Who thought of Marr’s approach?
David Marr
Which form of perception and organisation approach is bottom-up?
Marr’s approach
Which form of perception and organisation approach breaks down the computation between input and producing output between units of perception?
Marr’s approach
Which form of perception and organisation approach starts with input to the perceptual system in the form of a retinal image and describes the stages in processing this image?
Marr’s approach
What happens in each stage of Marr’s approach?
Each stage takes the input information from the previous stage and transforms it into a more complex description or representation of the image
Which form of perception and organisation approach is a computational model?
Marr’s approach
Computational models consist of 3 theories/levels. What are they?
1) Computational theory
2) Algorithmic level
3) Mechanism level
What does the computational theory look for in a model?
- What is the model trying to do?
- What are the processes for?
- What is the goal?
What does the algorithmic level look for in a model?
- What algorithm is needed
- What process is needed in order to recognise objects in the environment
What does the mechanism level look for in a model?
- What mechanism is needed to implement the algorithm?
- How is this mechanically done to perform such algorithms?
Define algorithms
Movements you make to achieve a certain output
How is retinal image analysed as suggested by Marr’s approach?
Sequentially at different levels
List the 5 stages of retinal image analysis according to Marr’s approach
1) Retinal image projected at the back of the eye
2) Grey-level description
3) Primal sketch
4) 2 1/2 D sketch
5) 3D representation
What happens in the grey-level description stage of retinal image analysis according to Marr’s approach?
Measure the intensity of light at each point in the image
What happens in the primal sketch stage of retinal image analysis according to Marr’s approach?
Representation of contrast change (blobs, edges, bars) over a range of spatial frequencies
What happens in the 2 1/2 D sketch stage of retinal image analysis according to Marr’s approach?
Representation of orientation, depth, and colour relative to the observer
What happens in the 3D representation stage of retinal image analysis according to Marr’s approach?
Representation of objects independent of the observer
Which stage of retinal image analysis involves the representation of objects independent of the observer?
3D representation
Which stage of retinal image analysis involves the representation of orientation, depth, and colour relative to the observer?
2 1/2 D sketch
Which stage of retinal image analysis involves the representation of contrast change (blobs, edges, bars) over a range of spatial frequencies?
Primal sketch
Which stage of retinal image analysis involves measuring the intensity of light at each point in the image?
Grey level description
What is 2 1/2 D sketch?
Primal sketch combined with depth cues, colour and motion
Why is 2 1/2 D sketch not 3D?
Because it is observer oriented (some parts of the scene and objects are unseen because the image is based on the observer’s pov angle)
What is 3D sketch?
A 2 1/2 D sketch analysed for 3D volume primitives (cylinder, cones, cubes)
True or False?
3D representation produces representation that is dependent on the observer
False
3D representation produces representation that is independent of the observer
True or False?
3D representation is an unconscious experience of vision
False
3D representation is a conscious experience of vision
Which stage of retinal analysis in Marr’s approach identifies edges and primitives?
Primal sketch
Which stage of retinal analysis in Marr’s approach identifies group primitives and processes?
2 1/2 D sketch
Which stage of retinal analysis in Marr’s approach perceives 3D objects?
3D representation
Why is the computational approach to the form of perception and organisation important? List 2 reasons
1) Algorithm/rule/system is more likely to be understood by understanding the problem that has to be solved, rather than the examining the mechanism (and hardware) which it is embodied
2) To understand perception by studying neurons is like trying to understand bird flight by studying only feathers: it studies function and not form (AI argument)
Which approach to the form of perception is top-down?
Gestalt approach
What is Gestalt psychology?
Believes the whole is greater/different than the sum of its parts
What are Gestalt psychologists interested in?
How we group parts of a stimulus together and the way we separate figure from ground (segregation and grouping)
Which approach to the form of perception emphasises segregation and grouping?
Gestalt approach
What does the necker cube suggest about perception?
Multistability
When we are presented with a 2D representation of a 3D cube, there’s not enough information for us to perceive the cube in only one particular orientation; instead, we perceive it in multiple, different orientations
Define multistability
Multistable perception is the spontaneous alternation between two or more perceptual states that occurs when sensory information is ambiguous
Simply = When we are presented with a 2D representation of a 3D cube, there’s not enough information for us to perceive the cube in only one particular orientation; instead, we perceive it in multiple, different orientations
Who were the developers of the Gestalt school?
1) Max Wertheimer
2) Kurt Koffka
3) Wolfgang Kohler
How was the Gestalt school developed?
Wertheimer ran a series of experiments on Kohler and Koffka
It was a series of influential publications in the 1920s
Who was the primate researcher investigating insight learning using chimps and bananas?
Wolfgang Kohler
Which form of perception approach does not see lines and figures but sees forms and shapes?
Gestalt approach
True or False?
Ambiguity generally does not arise in the real world. We usually see a stable and organised world.
True
What does the Gestalt approach argue about how we see objects?
We see objects according to all of their elements taken together as a whole
Which approach to the form of perception sought to isolate principles of perception?
Gestalt approach
Define the principles of perception
Innate “laws” which determine the way in which objects are perceived
What are the 9 Gestalt laws of the perceptual organisation?
1) Similarity
2) good continuation
3) Proximity
4) Connectedness
5) Closure
6) Common fate
7) Familiarity
8) Invariance
9) Prägnanz (good figure)
Similarity is one of the Gestalt laws of perceptual organisation. What does it mean?
Similar things appear to be grouped together
How can similar things appear to be grouped together?
This can occur die to shape, lightness, hue, orientation and size
Good continuation (viewing smooth lines) is one of the Gestalt laws of perceptual organisation. What does it mean?
Points that, when connected, result in straight or smoothly curving lines, are seen as belonging together and the lines tend to be seen in such a way as to follow the smoothest path
Define reification
When there’s more spatial info than is present
E.g. You see black spikes drawn around an imaginary sphere; even though the sphere is not outlined, you will still see it image as a spiky ball
When there’s more spatial info than is present
E.g. You see black spikes drawn around an imaginary sphere; even though the sphere is not outlined, you will still see it image as a spiky ball
This is known as…?
Reification
Proximity is one of the Gestalt laws of perceptual organisation. What does it mean?
Things that are near to one another appear to be grouped together
Connectedness is one of the Gestalt laws of perceptual organisation. What does it mean?
Things that are physically connected are perceived as a unit/group
Closure is one of the Gestalt laws of perceptual organisation. What does it mean?
Of several geometrically possible perceptual organisations, a closed figure will be preferred to an open figure
E.g. We prefer to perceive an image with 4 dots with lines connected together to form a closed shape (square) rather than 4 empty dots with no closure
Closure is one of the Gestalt laws of perceptual organisation. We tend to complete a broken figure. Why is this?
Because of the strong closure cue for organising what we see
Common fate is one of the Gestalt laws of perceptual organisation. What does it mean?
Things that are moving in the same direction or have the same orientation are grouped together
Familiarity is one of the Gestalt laws of perceptual organisation. What does it mean?
Things are more likely to be grouped if the groups appear familiar or meaningful to an observer
Familiarity is one of the Gestalt laws of perceptual organisation.
Things are more likely to be grouped if the groups appear familiar or meaningful to an observer.
Why is this?
Familiar things pop out as you don’t require a lot of visual scanning to recognise it
So you quickly scan through familiar images and group them together based on meaning derived from your past experiences, knowledge and expectations
Invariance is one of the Gestalt laws of perceptual organisation. What does it mean?
Even if an image is warped, turned, stretched, or distorted, we can still recognize that it is the same image.
A property of perception in which simple objects are recognized independent of their rotation, translation and scale.
Since we often encounter objects from different perspectives, we’ve developed an ability to recognize them despite their different appearance
Prägnanz or Good Figure is one of the Gestalt laws of perceptual organisation. What does it mean?
When people are presented with complex shapes or a set of ambiguous elements, their brains choose to interpret them in the easiest manner possible
E.g. Viewing the Olympic logo as a set of five overlapping circles. Interpreting it as a combination of connected lines would be unnecessarily taxing on our minds
The central law of Gestalt Psychology is known as…?
Prägnanz or Good Figure
Gestalt psychologists are also interested in how we separate figures from the ground
This is known as…?
Figure-Ground segregation
In a normal visual scene, how is figure-ground usually segregated?
Some objects (figures) may appear more prominent and other aspects of the visual scene recede into the background (ground)
Why are gestalt psychologists interested in Figure-Ground segregation?
Because it infers top-down processing
When people are presented with complex shapes or a set of ambiguous elements, their brains choose to interpret them in the easiest manner possible
Which Gestalt law is this?
Prägnanz or Good Figure
Even if an image is warped, turned, stretched, or distorted, we can still recognize that it is the same image.
Which Gestalt law is this?
Invariance
Things are more likely to be grouped if the groups appear familiar or meaningful to an observer
Which Gestalt law is this?
Familiarity
Things that are moving in the same direction or have the same orientation are grouped together
Which Gestalt law is this?
Common fate
Of several geometrically possible perceptual organisations, a closed figure will be preferred to an open figure
Which Gestalt law is this?
Closure
Things that are physically connected are perceived as a unit/group
Which Gestalt law is this?
Connectedness
Things that are near to one another appear to be grouped together
Which Gestalt law is this?
Proximity
Points that, when connected, result in straight or smoothly curving lines, are seen as belonging together and the lines tend to be seen in such a way as to follow the smoothest path
Which Gestalt law is this?
Good continuation
Similar things appear to be grouped together
Which Gestalt law is this?
Similarity
What are the 5 properties that affect whether an area is seen as a figure or ground?
1) Symmetry
2) Convexity
3) Area
4) Orientation
5) Meaning/importance
Symmetry is 1/5 of the properties that affect whether an area is seen as a figure or ground.
Are symmetrical areas usually seen as figures or grounds?
Symmetrical areas are usually seen as figures
Convexity is 1/5 of the properties that affect whether an area is seen as a figure or ground.
Are convex shapes usually seen as figures or grounds?
Convex shapes are usually seen as figures
Area is 1/5 of the properties that affect whether an area is seen as a figure or ground.
Are stimuli with comparatively smaller areas usually seen as figures or grounds?
Stimuli with comparatively smaller area are usually seen as figures
Orientation is 1/5 of the properties that affect whether an area is seen as a figure or ground.
Are vertical and horizontal orientations usually seen as figures or grounds?
Vertical and horizontal orientations are usually seen as figures
Meaning/importance is 1/5 of the properties that affect whether an area is seen as a figure or ground.
Are meaningful objects usually seen as figures or grounds?
Meaningful objects are more likely to be seen as figures
Meaning/importance is 1/5 of the properties that affect whether an area is seen as a figure or ground.
Meaningful objects are more likely to be seen as figures.
What does this suggest?
Suggests top-down processing and implies attention
What are the 5 problems with the Gestalt approach?
1) Underplay the parallel processing and unconscious processing that the brain does
2) Explanation of how some of the laws worked was wrong
3) Their laws provide a description of how things work rather than why they work/an explanation
4) Their laws are ill-defined (e.g. Prägnanz; what is the simplest and most stable shape)
5) Stating the obvious
What is the benefit of the Gestalt approach?
1) Their laws actually appear to be generally correct and are used in graphical designs
Such as:
- Percepts can be analysed into basic elements
- The whole is greater than the sum of its parts
- Context and experience affect perception
What do Gestalt laws tell us about the form of perception? List 3 points
- Percepts can be analysed into basic elements
- The whole is greater than the sum of its parts
- Context and experience affect perception
What is bottom-up processing?
Start from the bottom, considering physical stimuli being perceived and then working their way up to higher-order cognitive processes
Higher cognitive processes cannot directly influence processing at lower levels
What is top-down processing?
The perceiver builds a cognitive understanding or perception of a stimulus, using sensory info as the foundation for the structure but also using other sources of info such as memory, experience, knowledge, expectations and motivation to build perception
During perception, we quickly form and test various hypotheses regarding percepts based on…? List 4 hypotheses
1) What we sense (sensory data)
2) What we know (knowledge stored in memory)
3) What we can infer (using thinking)
4) What we can expect
