Week 11 (Perception) Flashcards
Sensation vs Perception
Sensation: The ability of the sense organs to detect various forms of energy (light and sound waves)
Perception: The analysis of this sensory information to describe the surrounding environment.
What is the top-down approach to perception?
-Emphasise existing knowledge and prior expectations (but not exclusively)
What is the bottom-up approach to perception?
-Emphasise the primacy of sensation and environment (to varying degrees)
What are the basics of the Ecological approach to perception?
-We should focus on real environments and not 2D stimuli
-All necessary info can be ‘picked up’ from the environment
What is the ambient optic array?
-The structure/pattern of light
-Light reflects of surface before reaching the eyes
-Information in optic array changes as you move through it.
What are invariants?
Properties of an environment that remain static, or (do not vary) as we move through them. E.g., size constancy
What did Gibson (1979) suggest about affordances?
That the patterns of light directly ‘afforded’ the use of objects, perception and action are directly linked.
-I.e, a banana ‘affords’ being eaten
-Theory is controversial as it discounts any knowledge or expectations on the part of the individual.
What are the two key principles of Constructivism?
- Information from sensations are incomplete and imperfect.
- Therefore, perceptual knowledge needed to unconsciously ‘construct’ our perceptions.
What is the hollow face illusion?
Despite knowing what we are seeing is hollow (concave)
We perceive it as projecting towards us (convex) and this is how faces are experienced
What year was the Kanisza illusion discovered?
1955
-Hypothesising a nearer surface which occludes objects below
-Accounts for surprising gaps and produces the illusory objects in the middle.
-The size, shape and colour of the occluding surface are determined by context.
What are two examples of evidence for top-down processing?
-The configurable superiority effect
-The object superiority effect
What is the object superiority effect
Counterintuitively, perceptual properties of a display are picked up faster if part of an object.
Argues for high order object knowledge
What is the configural superiority effect?
Similar to object superiority effect, however demonstrations are more concerned with context aiding perception, regardless of whether it forms a plausible object.
Argues that being “object-like” is less important than the context providing distinctive information.
What does Gestalt mean
Humans perceive things as ‘wholes’ rather than individual parts.
“the whole is different than the sum of it’s parts”
What are the five Gestalt laws of organisation?
- Proximity
- Similarity
- Closure
- Good continuation
- Common fate
Gestalt’s proximity
Elements that are close together are seen to group together
Gestalt’s similarity
Elements that are similar are perceived as grouping together.
Gestalt’s Closure
We ‘fill in’ gaps to see whole or complete objects
Gestalt’s Good continuation
No perceived break in continuation across intersections
Gestalt’s common fate
Objects moving in the same direction and speed are perceived as a group.
Limitations of Gestalt theories
-Too simplistic
-Largely descriptive, lacks predictive power
-Captures 2d displays but not easy to apply to 3d.
What are the constraints (phenomena they must be able to account for) of object recognition.
- Recognition occurs rapidly
- Objects can be recognised from novel viewpoints
- New examples of a known object can be recognised
- Occluded objects can still be recognised
- Objects can be recognised despite visual noise.
The process of object recognition
Decompose objects into structures and their relations
Create abstract representations (i.e doesn’t look like the thing)
Compare to other representations stored in memory
Best match = recognition
Viewer centred representations
-Idea that our mind stores multiple representations of an object
-Captures appearance of the object in individual moments (angle, visual noise, etc)
-Matching process involves rotating the current object until it ‘fits’ one of these pre-existing examples from the past.
Object-centred representations
-Idea that objects re represented in a unitary form (one central representation)
-Based on the shape of the object
-Representation is independent of of viewpoint, visual noise, etc, therefore object centred.
