1. Class Schedule In-text Citations Long-term Memory: Organization
Experiment 2.3
Typicality in Categorization
Experiment 2.1
Lexical Decisions
en.wikiversity.org

3. Long-term Memory
Learning is the acquisition of new information or knowledge. Memory is the retention of learned information.
From daily experience (and laboratory experience), we know that some memories last longer than others.
Long-term memories are those that can be recalled days, months and years after they were stored.
Short-term memories are those that last on the order of seconds to hours.
Sensory memories last < 0.5s.
 Goal: study the organization of long-term memory
Consolidation
long-term
memory

4. Types of Long-term Memory
Evidence suggests that there are two distinct types of long-term memory. Memory for facts and personal events that can be consciously recalled is called declarative (or explicit) memory; this is what we usually mean by the word “memory”. Long-term memory for habits and skills that cannot be consciously recalled is called non-declarative (or procedural or implicit) memory.

5. Semantic Memory
Semantic memory refers to general world knowledge that we have accumulated throughout our lives.
Evidence suggests that semantic memory is stored in a distributed manner in cortex (e.g. sounds in/around auditory cortex; shapes in/around inferotemporal cortex). The anterior pole of the temporal cortex may act as a hub for convergence of information.
Somatosensory cortex:
Feel
Auditory cortex:
Sound
Inferotemporal cortex:
Shape
Hub

6. Organization of Semantic Memory
General Principles:
Organized around the concept of categories or nodes
Highly interconnected
Colors
Vehicles
Fruits

7. Categorization
tree
Categories are the basic elements of human cognition; they are “the glue that holds our mental world together” (Murphy, 2002, p. 1).
How are categories organized? Classical view vs. Prototype view

8. Categorization: The Classical View 1
What is a bird?
A bird is an animal.
It has feathers.
It has two wings.
It has a beak.
It lays eggs.
It can usually fly.
 Categories are defined by necessary and sufficient criteria (“logical”).

9. Categorization: The Classical View 2
What is a square?
A square is a closed, flat figure.
It has four sides.
All sides are equal in length.
All interior angles are equal.
 Clear-cut boundaries separate neighboring categories.
 All category members have equal status.

10. Classical View of Categorization: Issues
Which features should be included on the feature list?
Can all birds fly?
Not every member of a category shares all of its features
Is flying an exclusive feature of birds?
Some categories have fuzzy boundaries
Games are fun and played for amusement.
What is a game?
Ludwig Wittgenstein (1956)
Games have winners and losers.
Games involve opposing teams.

11. Categorization: The Prototype View 1
Eleanor Rosch (1975)
Is it a vehicle?
(i) train
(ii) bike
(iii) car
(iv) ship
(v) sled
(vi) plane

12. Categorization: The Prototype View 2

13. Categorization: Prototype and Culture
Culture can influence the prototype of a category
English breakfast
French breakfast

14. Categorization: Classical vs Prototype
Classical theory
Prototype theory
defined based on common features
defined based on a PROTOTYPE
categories have clear-cut boundaries
categories have fuzzy boundaries
all members of a category have equal status
the meaning of words and categories is invariable
some members are better examples of a certain category than others
the meaning of words/categories is culture and context dependent
Experiment 2.3 Typicality in Categorization

15. Network Model of Memory Organization
Long-term memory as large network of mental concepts (nodes) linked by associations Strength of association (distance) determines the speed at which one concept speeds up the ability to recall or recognize the other

16. Spreading Activation Spreading activation process:
activation of any one concept initiates a spreading of activity to nearby concepts and primes them so that they are more retrievable than they were before
closer concepts receive more activation than those further away
spreading activation declines with distance

17. Priming: Related Words
Lexical Decision Task
stimulus1: “bird”
bird is activated in the network
activation spreads
associated nodes become activated (primed)
stimulus2: “cardinal”
cardinal is already partly activated
little further activation is required
Later stimulus processing is facilitated (e.g. faster reaction time)
feathers
animal
fly
bird
duck
cardinal

18. Priming: Unrelated Words
Lexical Decision Task
stimulus1: “bird”
bird is activated in the network
activation spreads
associated nodes become primed
stimulus2: “toenail”
Toenail is farther away from bird than cardinal
Activation is already dispersed across nodes associated with bird
Activation must cross further distances to reach target
Later stimulus processing is not facilitated (e.g. slower reaction time)
feathers
animal
fly
bird
duck
cardinal
human
toenail

19. Experiments Expt 1: 2.3 Typicality in categorization
Expt 2: 2.1 Lexical Decisions
Write up both experiments together
Common introduction
Separate methods & results (Expt 1, Expt 2)
Is interpretation of RT data affected by speed-accuracy trade-off?
Statistics
Common discussion