W10: Concepts & Categorisation

Question 1

categorisation and cognition

Understanding of categorisation

Answer 1

Categorisation is the engine of cognition

Fundamental ideas for understanding categorisation:

1) Importance of categorisation
2) Generalization
3) Selective attention

Question 2

What is categorisation?

Ability

Answer 2

The ability to form equivalence classes (treat similarly) of discriminable (distinguishable) entities

Question 3

Categorisation is largely automatic

Reasons?

Answer 3

Survival:
Provides a basis of deciding what constitutes appropriate action

Facial categorisation: warm and competence

simple organisms categorize:
E. coli: cat nutrient source
Female Mouse: unfamiliar male mouse

Question 4

Benefits of categorisation

4

Answer 4

1) Provides a means for identification

2) Reduces the complexity of the environment:
World Color Survey

3) Allows organisation of knowledge
4) Allows for generalization

Question 5

Categorisation Induction:

meaning

Answer 5

Induction: Generalizing from the particular to the general

Generalization is sensitive to the elements in the category

Question 6

4 key empirical effects that help us understand generalization via induction

and their effect on generalization (how to get greater gen)

Answer 6

1) Typicality of Instances
(more strongly relate to category)
2) Typicality of category
(more typical category members)
3) Category Size
(greater to more specific (smaller) categories)
4) Category Variability 
(greater when the examples are more variable)

Question 7

Development of categorisation:

2 studies related to habituation

Answer 7

1) Habituation in Infants
Focusing more on “novel” stimuli during successive exposures
Fantz (1964)

2) Category Habituation: 
After a familiarization phase (keep showing animal from same cat), infant in general fixate on new cat images compared to horse
CATS -> 60.1%
ZEBRAS -> 62.1%
GIRAFFES -> 57.2%
Eimas & Quinn (1994)

Question 8

Development of Categorisation

Infants VS adults

Answer 8

Rudimentary categorisation is evident in infancy:
3-4 Month Old Infants have increased looking times for novel categories

There is amazing flexibility in categorisation:
Adults can acquire exceedingly complex, non-perceptual categories; children can not

Children’s categories are focused on perceptual grouping

Children seems to attend to all features.

Question 9

Abstract categories based on:

3

Answer 9

1) unobservable attributes (e.g., love, doubt, thought)
2) relational concepts (e.g., enemy or barrier)
3) rules (e.g., island, uncle, or acceleration)

Question 10

What may have contributed to the dif from adults and infants?

Answer 10

Children’s categories are focused on perceptual grouping

And the ability to represent things that aren’t perceptually available.

Selective attention:
Factor which determines the influence or weight of a stimulus dimension or attribute on categorisation

Categories which require you to pay attention to more dimensions are harder to learn (how does selective attention helps here)

Question 11

Different type of categories:
Type I (Easy)
Type II (mediam)
Type III-IV: (difficult)
Type 6: (Extremely difficult)

Answer 11

Type I: single dimension matters:
Color OR shape…

Type II: Two dimensions matter:
Color AND shape

Type III-IV: Rule + exceptions:
Learning a rule + exception is more difficult than learning a “stable” rule even if that rule requires more than one dimension

Type VI: Three dimensions relevant
No rule can be used to simplify the learning
Need hard learning (memorising)

Question 12

Category Learning Task
Shepard, Hovland & Jenkins (1961)
S37-44

Answer 12

P were presented 2 categories and they are to sort them to cat (cat A or B?)
Instant feedbacks were given

Results:
Type I: Very fast learning (after 4 blocks). Very easy
Type II: slower (after 10 blocks). more difficult
Type III-VI: much slower (~ 16 blocks). difficult
Type 6: very difficult to learn (still .1 error after 16 blocks)

CONCLUSION:
category learning difficulty depends on how many different dimensions are used to define the category

Question 13

What is the consequence of selective attention?

2

Answer 13

Selective attention has limited capacity:
cannot attend to everything
attending to one ==not attending to other aspects

Children have a hard time focusing attention on one important thing:
children seem to use all of the features

Question 14

Different dimensions of Categorisation for Selective attention
Handel & Imai (1972)

Answer 14

2 dimensions:
given 3 objects (same shape). ask them to sort them into cat: color OR size

sort on the basis of a single dimension:
SIZE

sort on the basis of similarity across both size and colour:
2D

Question 15

Categorisation between adults and children
Selective attention
Smith (1989)
S47 - S55

Conditions

Answer 15

2 dimensions:
3 object
color/size

Condition: 3
Discriminable (similarity increased between objects)
Standard (same as Handel & Imai (1972))
Extreme (similarity decreased)
S49

Looked through the whole lifespan.

Question 16

Categorisation between adults and children
Smith (1989)
S47 - S55

Results

Answer 16

Adults use a one dimensional grouping (mainly size)

2 and 3 year olds:
Standard: tend to group based on similarity (2D grping)
Discriminable: all in one grp > similarity
Extreme: All dif cat ~= similarity

4-yr & 5-yr olds:
continue to group by similarity when objects are less discriminable (and standard),
Use a one dimensional-grouping when the objects are far apart (Extreme)

8-yr olds:
use a one dimensional-grouping unless the objects are very similar (discriminable)

Question 17

Categorisation between adults and children
Smith (1989)
S47 - S55

conclusions

Answer 17

Children very different from adults
can’t resist the urge to look at other aspects

3 to 4 yr olds-> discriminate finer quantities starts to develop

Adults sort stimuli on the basis of a single individual dimensions of those stimuli:
Utilising their ability of selective attention to simplify the world

This ability takes time to develop:
Children tend to sort on the basis of overall similarity across all dimensions

Question 18

Different dimensions of Categorisation
Selective attention

Rehder & Hoffman (2005)

Answer 18

Eye-tracking reflects attention:

Similar to Shepard, Hovland & Jenkins (1961)
Eye-tracking movement showed that as blocks increases:
Type I: Fixated on 1D (6)
Type II: Fixated on 2D (10)
Type 3,4,5: slowly goes to 3D

All start ard 2D,3D then slowly fixate on respective Ds.

Question 19

Real word example:
Why is identifying recycling bins easy?
But recycling itself…

Answer 19

Identifying Bins is like a Type I problem

recycling is difficult (type 6) need to memorise….
Memorising the features of categories is difficult but knowing the reason why different categories exists makes them easier to learn

Question 20

Causal Models

Murphy & Medin (1985)

Answer 20

categorization should be seen as a process of explaining why an exemplar belongs with the rest of a category

Knowing the cause underlying the category provides an additional “deeper” dimension or feature that can be used to understand the category

Question 21

Real word example:
What is the best way to understand the dif cat. of pre- and post- renaissance paintings?

Hockney’s Hypothesis: Camera Obscura

Answer 21

the painters from this period may have used optics to achieve the photorealistic quality of their paintings. In particular, he hypothesized that painters from this latter period may have used a camera obscura in order to render the more true to life images

Question 22

Categorisation and Causal Reasoning

Answer 22

Defining the relevant features which separate the categories

Allows for the development of theories regarding the cause of those differences

Question 23

Categorisation and Causal Reasoning
Example: 
Camera Obscura
& 
Causal reasoning
S65 66, 67, 68
good and faults

Good model as it was falsifiable.

Answer 23

To-be-explained:
Difference between representational painting to photorealism

Theory:
Introduction of optics

Hypothesis:
Hockney’s Hypothesis: Camera Obscura

Proves and faults: 
provides quite a general explanation for a general behaviour
BUT
can be done without optics
light-colour issues

Question 24

Categorisation and Causal Reasoning
Example: 
comparative mirror technique
VS
Camera Obscura

Answer 24

To-be-explained:
How did Vermeer paint the photorealistic painting The Music Lesson?

Hypothesis:
Optics but specifically the comparative mirror technique

Comparative Mirror is better than the Camera Obscura hypothesis because it explains how one could get accurate detail and colour matching

Question 25

Comparative Mirror Hypothesis ->

A Causal Model

Answer 25

The simulation makes the comparative mirror theory a model:
It becomes a set of PROCEDURE, an ALGORITHM, for producing PREDICTIONS

produces data which look to an observer like the actual data we want to explain

Explains several well-known facts about Vermeer’s painting

Question 26

Causal Theory of Categorisation

Answer 26

Surface differences between categories are often assumed to be caused by some underlying deep difference
(Even if not understood)
- drive science and can lead to prejudice

Causal theories can drive generalisation

Simplify our understanding of the word