What is a concept?

1
What is a concept?

• Part of semantic memory (vs. episodic memory)
• A class of items that seem to belong together
• dog, balloon, terrorist (things)
• tall, ugly (properties)
• walk, jump (actions)
• A mental construct (vs. the outside world)
• Abstract knowledge

2

• How are things clustered into categories?
• Based on similarity big birdn sesame jump)t
• Based on function
• Based on theories

Sesamestreet_bigbird
Sesametstree_jump
3

• German Shepherd

- Abstract representation - salient features -
prototype
4

• A prototype
• is an abstract representation (usually the
  average)
• contains salient features that are true of most
  instances
• e.g., birds usually can fly (but not always) gt
• ability to fly is a salient feature of the
  category bird
• A prototypical bird is one that flies ( have
  feathers, etc)
• A bird that doesnt fly is atypical (weird
  penguin, ostrich)
• How can we test the existence of a prototype?
  Use stimuli that you have never seen before
  (CogLab exp)

5
Prototype Only shown during test phase
Variants departures from the Prototype Their
average is the prototype Some displayed at study
and test, others only at test
6
Training Phase
Prototype (not shown)
Abstraction
Variants
7
Test Phase
Prototype
Old Variants
New Variants
Critical comparison ?
8
Prototype theory

• On the genesis of abstract ideas (Posner
  Keele, 1968)
• Stimulus
• Two displays of 25 dots each (Prototypes)
• Variants on each of these two displays (10 dots
  are randomly relocated)
• Training Phase
• Learn to classify variants into two categories
• Items were variants of the prototypes
• Test phase
• Old items
• New Items
• Prototypes
• Variants

9

• Prototype Theory (Rosch)
• specify the center of the category,
• leave fuzzy boundaries
• graded category membership (tea cup vs. Stanley
  cup)
• some categories dont obey these properties
• Things that have essence (next Monday)
• Phonemes (CogLab exp)

10

• Is Pluto a planet? npr
• Or is it a dwarf planet?
• Is this an important question?
• Or is it as dumb question?
• (hint dumb)