Simplicity and informativeness in the cultural evolution of … · 2017-09-14 · Centre for...

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Centre for Language Evolution School of Philosophy, Psychology and Language Sciences University of Edinburgh

Simplicity and informativeness in the cultural evolution of language

Jon W. Carr, Kenny Smith, Jennifer Culbertson, Simon Kirby

Language

Pressures shaping language

LanguageLearning

Pressures shaping language

Simple

Language CommunicationLearning

Pressures shaping language

Simple

Informative

English Northern Paiute

0 50 1000

1

2

3

4

⬅ In

form

ativ

e

⬅ Simple

Kinship terms are simple and informative

Kemp & Regier (2012)

English Northern Paiute

0 50 1000

1

2

3

4

⬅ In

form

ativ

e

⬅ Simple

Kinship terms are simple and informative

Kemp & Regier (2012)

Lab experiments

Learning-only

Lab experiments

Learning-only

Communication-only

Lab experiments

Learning-only

Learning + Communication

English Northern Paiute

0 50 1000

1

2

3

4

⬅ In

form

ativ

e

⬅ Simple

Kinship terms are simple and informative

Kemp & Regier (2012)

0 50 1000

1

2

3

4

Learning and communication pressures

⬅ In

form

ativ

e

⬅ Simple

0 50 1000

1

2

3

4

Learning and communication pressures

⬅ In

form

ativ

e

⬅ Simple

Learning-only

0 50 1000

1

2

3

4

Learning and communication pressures

⬅ In

form

ativ

e

⬅ Simple

Communication-only

Learning-only

0 50 1000

1

2

3

4

Learning and communication pressures

⬅ In

form

ativ

e

⬅ Simple

Learning + communication Communication-only

Learning-only

0 50 1000

1

2

3

4

Learning and communication pressures

⬅ In

form

ativ

e

⬅ Simple

Learning + communication Communication-only

Learning-only

newhomo kamone gaku hokako

kapa gakho wuwele nepi

pihino nemone piga kawake

gamenewawu gamenewawa gamenewuwu gamene

mega megawawa megawuwu wulagi

egewawu egewawa egewuwu ege

tuge tuge tugetuge tuge tugetuge tuge tuge

tupim tupim tupimminiku miniku minikutupin tupin tupin

poi poi poipoi poi poipoi poi poi

Kirby, Cornish, & Smith (2008)

Kirby, Tamariz, Cornish, & Smith (2015)

Kirby, Tamariz, Cornish, & Smith (2015)

Iterated learning gives rise to informative spatial terms

Carstensen, Xu, Smith, Regier (2015)

Iterated learning gives rise to informative spatial terms

Carstensen, Xu, Smith, Regier (2015)

Experiment 1

Stimuli

Ang

le

Size

Stimuli

Ang

le

Size

Stimuli

Ang

le

Size

Stimuli

Ang

le

Size

Conditions

Angle-only Size-only Angle & Size

Easy to learn but low informativeness Informative but hard to learn

Training phase

Test phase

Results

Angle-only

Results

Size-only

Results

Angle & Size

Result: Learnability advantage for the less informative systems

Experiment 2

Iterated learning

1 category 2 categories 4 categories3 categories

Results

Simplicity

Simplicity Informativeness

Simplicity Informativeness

Simplicity Informativeness

Measuring simplicity

Measuring simplicity

Measuring simplicity

4×8

4×8

Measuring simplicity

3×3 1×1

1×8

1×2

1×4

1×6

1×1

3×4

1×1

2×6

2×31×2

4×8

4×8

What makes language informative?

Expressivity A system of many categories is more informative than a system of few categories

Convexity A system of convex categories is more informative than a system of nonconvex categories

Learning Pressure for simplicity

Communication Pressure for informativeness

>

>

Property Example

What makes language informative?

Expressivity A system of many categories is more informative than a system of few categories

Convexity A system of convex categories is more informative than a system of nonconvex categories

Learning Pressure for simplicity

Communication Pressure for informativeness

>

>

Property Example

What makes language informative?

Expressivity A system of many categories is more informative than a system of few categories

Convexity A system of convex categories is more informative than a system of nonconvex categories

Learning Pressure for simplicity

Communication Pressure for informativeness

>

>

Property Example

What makes language informative?

Expressivity A system of many categories is more informative than a system of few categories

Convexity A system of convex categories is more informative than a system of nonconvex categories

Learning Pressure for simplicity

Communication Pressure for informativeness

>

>

Property Example

What makes language informative?

Expressivity A system of many categories is more informative than a system of few categories

Convexity A system of convex categories is more informative than a system of nonconvex categories

Learning Pressure for simplicity

Communication Pressure for informativeness

>

>

Property Example

What makes language informative?

Expressivity A system of many categories is more informative than a system of few categories

Convexity A system of convex categories is more informative than a system of nonconvex categories

Learning Pressure for simplicity

Communication Pressure for informativeness

>

>

Property Example

What makes language informative?

Expressivity A system of many categories is more informative than a system of few categories

Convexity A system of convex categories is more informative than a system of nonconvex categories

Learning Pressure for simplicity

Communication Pressure for informativeness

Our experiments

>

>

Property Example

What makes language informative?

Expressivity A system of many categories is more informative than a system of few categories

Convexity A system of convex categories is more informative than a system of nonconvex categories

Learning Pressure for simplicity

Communication Pressure for informativeness

Carstensen et al.

>

>

Property Example

Conclusions

The pressure from learning yields simple languages, but this can manifest itself through multiple semantic properties:

Expressivity Loss of words/categories to aid learning

Convexity Reorganization of the meaning space to aid learning

The pressure from communication has the same effect on convexity as learning does, making it difficult to identify the causal mechanism.

In iterated learning, the pressure for simplicity favours semantic category systems that are convex – informativeness comes along for the ride.

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