Perception & Action
17 important questions on Perception & Action
What is Optic Array? (ecological approach)
- this array changes as we move through the environment
- the information is unambiguous i.e. it provides 100% accurate information about the spatial layout of the environment (i.e. you don't need to go through Marr's complex processing)
What is the Ecological Approach?
- perception relies on optic array (i.e. you only need light information, you don’t need anymore than the optic array to perceive the world around you)
- requires little information processing
- perception is not brought about by neural/mental representations
How does the ecological approach compare with Marr?
- Higher grades + faster learning
- Never study anything twice
- 100% sure, 100% understanding
Gibson stressed the importance of optic flow when moving towards a goal, who refuted this?
- they found that absence of motion (and therefore optic flow)had no effect on accurate judgements
What is a limitation of optic flow?
How do you get meaning from optic array?
- this will satisfy particular goals i.e. how do we know to sit at a table or stand on it?
2. Resonance
- no need for memory (unlike Marr)
- the mind resonates in response to invariant information in the optic array, allowing us to know what objects are present
= today, this theory seems a bit simplistic
What are 3 limitations of Gibson's Ecological approach?
2. Has problems with object meaning
3. Gibson's view that we have no internal representations (i.e. memories) of objects appears to be false
What did Ungerleider & Mishkin (1982) propose?
They proposed 2 visual pathways:
1. Ventral pathway for object recognition ("What")
2. Dorsal pathway for spatial perception ("Where")
What did Milner & Goodale propose?
- intimate relationship between perception and action
- they distinguish between vision for action (dorsal pathways) and vision for perception (ventral pathway)
According to Milner & Goodale, what are the differences between the ventral pathway and the dorsal pathway?
- viewpoint dependant representation
- brief representations
- used to guide actions in "here" and "now"
- unconscious vision
Ventral Pathway: Vision for Perception
- viewpoint independant representations
- long lasting representation (e.g. memories of objects)
- used to gain knowledge about the world (semantic)
- conscious vision
Note: Gibson would have argued that vision for perception would have gone through the dorsal pathway as this pathway has a viewpoint dependant representation
What evidence supports Milner & Goodale's theory of the dorsal and the ventral pathways?
Patient DF - had damage to ventral stream
= could not recognise objects
= she can interact with the world perfectly well i.e. she can guide action
Optic Ataxia - damage to dorsal stream
= can recognise objects
= cannot accurately reach objects i.e. cannot interact with the object properly
What are the limitations of the theory proposing completely separate dorsal & ventral pathways?
- the dorsal stream is more diverse than Milner & Goodale suggested
What is Glover's Planning-control model?
- development of Milner & Goodale's ideas by demonstrating how the ventral and dorsal streams interact
Describe the planning part of Glover's model.
- planning can overlap with early phases of movement
- integrates information from many sources
- can be slow
- based in the Inferior Parietal Lobe
Describe the control part of Glover's model.
- only uses spatial information about object i.e. doesn't care about identity
(treats a hosepipe and a snake in the same way!)
- not under conscious control
- very fast
- based in Superior Parietal Lobe
What evidence supports Glover's model?
Task: participants must make fast reaches to targets. On some trials the target moves. In some blocks participants must cancel the movement, in others they must correct the movement.
Results: If movements were fast (<250ms), P’s corrected, even when they should have cancelled
Damage to SPL leads to optic ataxia
What is 1 benefit of Glover's model and what are 2 limitations?
- lots of evidence for separate planning and control systems
Limitations
- model does not describe how actions are planned
- specific to arm and body movements - ignores eye movements
The question on the page originate from the summary of the following study material:
- A unique study and practice tool
- Never study anything twice again
- Get the grades you hope for
- 100% sure, 100% understanding