Object recognition, categorisation and achieving object constancy

  • Created by: The Shrew
  • Created on: 21-01-16 15:19
Achieving invariance across different views and body positions
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Selectivity and discrimination
see differences in individuals and generalise to a wider group
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Invariant features theory
speed of detecting if a picture is the same or rotated- time cost= view sensitivity/ no cost= view invariance
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Invariant features predict
view invariance
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No invariant features leads to
view sensitivity
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There are probably no invariant features that
uniquely discriminate all everyday objects and are visible under all viewing conditions
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No commonalities between games
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Template theory
Inputs of views are stored in 2D- lots of templates for each object- no transformation or decomposition of input
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Large LTM demands but
less online processing= faster
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Hierarchy of cortical neurones
respond to increasingly complex info, start with simple features
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Top of hierarchy
Grandmother cells respond to only specific and complex objects
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Evidence of specific face neurones in
monkey inferotemporal cortex
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fMRI studies
different regions in brain for faces, stick figures, body parts
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If stimuli less socially important
little evidence for templates
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Templates bad
too inflexible/ too much storage
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Multiple views and transformations
Input-> transform and normalise-> match to templates-> identify
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easies/ 180 degree plane rotation= hardest
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Deciding if letter inverted or not
Easiest when upright
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Fewer stores needed
but higher computational demands at transformation stage
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Structural descriptions
Biederman- visual systems extracts non-accidental features which are invariant across different views of an object- not sufficiently unique to identify object on their own but several together can be used to infer which geons are present in an objec
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Geon structure- internal reconstruction in 3D
produced by geons and spatial relations
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Computationally insensitive
too fast?
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Palmer et al
canonical view- view that is prefered
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Lawson et al
problems recognising unusual views of objects
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Bent wire stimulus/ wire frame/ blocks
hard to detect from different angles- supports multiple view theory and provides evidence against structural description theory
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Biederman and Gerhardstein
Canonical views preferred because they are more useful and informative rather than because they match template
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Results with novel objects
don't tell us much about recognising familiar, everyday objects- novel objects similar to each other
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Priming tasks
Objects named twice in 2 blocks- name objects faster second time
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Block 1= 820ms
Block 2= same exemplar= 610ms/ 135 degree rotation= 610ms/ different exemplar= 680ms/ different exemplar at 135 degree rotation= 710ms
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Lawson and Humphreys
Significantly more priming when object primed by identical view of that object compared to if it was primed by a different view
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Use all four
Depends on stimuli, complexity, familiarity
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Object categorisation
Rosch et al
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Subordinate level
Specific- extra work for little extra info
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Basic level
Input- generally preferred level
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little visual or semantic info
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Basic level preferred
Cognitive economy
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Jolicoeur et al
people name typical members of category faster at basic level
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Unusual members of categories
subordinate level rather than basic- maximise cognitive economy
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Rosch et al
experts more likely to use subordinate levels/ children more likely to use superordinate
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Johnson and Mervis
Fish and bird experts
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Card 2


Selectivity and discrimination


see differences in individuals and generalise to a wider group

Card 3


Invariant features theory


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Card 4


Invariant features predict


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Card 5


No invariant features leads to


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