Download - Topics of Research
Modelling language origins and evolutionIJCAI-05
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Topics of ResearchTopics of Research
Evolution of communication
Evolution of signalling systems
Lexicon formation
Grounding
Language diversity
Emergence of grammar
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For each topicFor each topic
What it is. The main research question(s).
Achievements, examples, used techniques.
Open questions.
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Abbreviations of techniquesAbbreviations of techniques
BE Baldwin Effect
CM Competition Models
DS Dynamical Systems
GA Genetic Algorithms
GT Game Theory
HC Hill Climbing
ILM Iterated Learning Model
LA Language Acquisition
LG Language games
MBL Memory-Based Learning
MM Mathematical Modelling
NN Neural Networks
RNN Recurrent Neural Networks
ROB Robotics
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Topics of ResearchTopics of Research
Evolution of communication
Evolution of signalling systems
Lexicon formation
Grounding
Language diversity
Emergence of grammar
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Evolution of communicationEvolution of communication
How can communication as such arise as an evolutionary advantageous strategy?
What ecological pressures could have caused communication to have emerged?Based on biological theories, e.g., (Seyfart et al. 1980, Grafen
1990, Krebs & Dawkins 1984, Zahavi 1975, 1977)
Marilyn Monroes (Key West, Florida, 1995)by Peter Krogh (Nat. Geographic)
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ExamplesExamples
Evolution of alarm calls (de Jong 1999). 5 agents, 3 types of predators. Input: own location, type of predator (if any) Actions: move 1 horizontal step & and go to a
hiding place (vertical locations) 90% predators visible, 10% not detected to
an individual communication may help
eagle
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ExamplesExamples
Evolution of alarm calls (de Jong 1999). 5 agents, 3 types of predators. Input: own location, type of predator (if any) Actions: move 1 horizontal step & and go to a
hiding place (vertical locations) 90% predators visible, 10% not detected to
an individual communication may help
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ExamplesExamples
Evolving communication to – enhance cooperation.
• Mate finding, GA (Werner & Dyer 1991), • Predator-prey simulation, GA (MacLennan & Burghardt
1993)• Altruistic behaviour, GA & GT (Di Paolo 2000)• Alarm calls LG (De Jong 2000)• Handicap principle GA (Bullock 1998)
– enhance competition• Contests GA (Noble 2000)
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Open issuesOpen issues
What ecological pressures or cognitive factors could have facilitated the transition from using iconic to symbolic communication systems?
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Topics of ResearchTopics of Research
Evolution of communication
Evolution of signalling systems
Lexicon formation
Grounding
Language diversity
Emergence of grammar
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Evolution of signalling systemsEvolution of signalling systems
How can communication channels and sound systems evolve?
– How can sensory-motor systems evolve that are used in communication?
– How can particular sound systems evolve?
Based on phonetic theories & findings such as (Lindblom et al. 1984, Lindblom & Madieson 1988, Madieson 1984)
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ExamplesExamples Communication channels:
– Evolving communication without dedicated communication channels ROB & GA (Quinn 2001)2 Robots: Khepera, 2wheels, IR proximity sensorsTask: both robots have to move as far as possible while
remaining at close distance
(i)
(ii)
(iii)
(iv)
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ExamplesExamples
Sound systems:– Vowel systems LG (De Boer 1997; 2000), GA (Glotin
1995; Berrah et al. 1996)– Syllable systems GA (Redford et al. 2001), LG
(Oudeyer 2001)– Phonemic coding LG (De Boer & Zuidema 2003;
Oudeyer 2002)
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Open issuesOpen issues
Adaptation of (human) vocal tract, auditory
system and their connection.
Evolution of complex utterances and
consonants.
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Topics of ResearchTopics of Research
Evolution of communication
Evolution of signalling systems
Lexicon formation
Grounding
Language diversity
Emergence of grammar
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Lexicon formationLexicon formation
How can a shared vocabulary emerge in a population?
– Invention– Language acquisition
Based on language acquisition literature, such as, e.g., (Clark 1993, Markman…, Tomasello & Barton 1994).
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Basic approachBasic approach
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ExamplesExamples Evolution of the Saussurean sign (Hurford 1989) Searching for evolutionary good learning strategies 3 strategies:
Strategy Input from adult population
Learner’s acquired behaviour
Imitator TransmissionReception
TransmissionReception
Transmission’Reception’
Transmission’Reception’
Calculator
Transmission Transmission’
Reception’
Saussurean Transmission Transmission’
Reception’
Saussurean
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ExamplesExamples
Learning strategies– Saussurean sign GA (Hurford 1989)– Obverter learning LG (Batali & Oliphant 1996;
Oliphant 1998)– Learning biases ILM, NN, GA (K. Smith 2004)– Joint attention vs. corrective feedback vs. cross-
situational learning LG (Vogt & Coumans 2003)
Interaction strategies– Language games LG (Steels 1996)
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Open issuesOpen issues
How can we scale up to realistic lexicon sizes
and population sizes?
What learning biases have evolved and how?
How have interaction strategies evolved?
strategies for producing utterances, listening and
turn taking
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Topics of ResearchTopics of Research
Evolution of communication
Evolution of signalling systems
Lexicon formation
Grounding
Language diversity
Emergence of grammar
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GroundingGrounding How can individual agents
use, construct, interpret and share symbolic communication meaningfully?
– Intentionality (Brentano 1874) or Symbol grounding problem (Harnad 1990)
Take inspiration from, e.g., (Deacon 1997, Searle 1980, Peirce 1931 , Wittgenstein 1967, Lakoff 1987, Langacker 1987, Clark 1993, Tomasello 1999)
From: Pfeifer & Scheier 1999
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Setup with two cameras on a tripod.
Each camera resembles a Talking Head.
PowerMac for processing Environment:
geometrical figures on white-board.
Experiment: Language evolution on the Internet (largely uncontrolled, because interaction with human users)
Talking Heads Talking Heads (Belpaeme et al. 1998; Steels et al. 2002)(Belpaeme et al. 1998; Steels et al. 2002)
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Talking Heads Talking Heads (Belpaeme et al. 1998; Steels et al. 2002)(Belpaeme et al. 1998; Steels et al. 2002)
Evolution of the word-form “wogglesplat” over 90,000 games.
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ExamplesExamples Lexicon grounding
– Mushroom world NN, GA (Cangelosi et al. 2000)
– Naming• Mobile robots LG, ROB (Steels & Vogt 1997; Vogt
2000) LG, ROB, NN (Billard & Dautenhahn 1999)• Talking Heads LG, ROB (Belpaeme et al. 1998;
Steels et al. 2002)• Cross-situational learning LG (A.D.M. Smith 2003;
Vogt 2003)
– Survival task LG, ROB (Vogt 2002)– Emergence of colour categories LG, GA
(Belpaeme & Steels, BBS In press)
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ExamplesExamples Grounding grammar
– Construction grammars LG (Steels 2004)
– Compositionality LG, ILM (Vogt 2005)
– Verbs and nouns GA, ROB (Cangelosi & Parisi 2001; Marocco et al. 2003)
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Open issuesOpen issues
How can ‘real meaningful’ communication emerge in a realistic task environment?
Emergence of theory of mind or other intention reading skills.
Emergence of most linguistic aspects, such as verbs, case-systems, abstract concepts, function words, time, etc., largely unexplored (let alone understood).
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Topics of ResearchTopics of Research
Evolution of communication
Evolution of signalling systems
Lexicon formation
Grounding
Language diversity
Emergence of grammar
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Language diversity & changeLanguage diversity & change
What are the conditions that make languages so diverse?– Dialects– Languages– Language contact– Language change
Based on findings and theories from, e.g., (Dunbar 1996, Crystal 1987, Labov 1972, Chambers 1995)
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ExamplesExamplesSocial Impact Theory (Latané 1981) models of language
change (Nettle 1999a; 1999b)
Impact variant p: ip=bp Npa [(si/di
2)/Np]
Impact variant q: iq=bq Nqa [(si/di
2)/Nq]
– bp/q is a constant,
– Np/q is nr. of agents speaking p or q,
– a non-linear adoption factor (if linear, all agents will end up
speaking the dominant variant).
– [(si/di2)/Np/q] average impact of variant p or q.
Learner adopts p if ip>iq and q if iq>ip
Mutation rate – probability that the above rule is properly
used. (social distance factor)
Initial population has variant p.
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ExamplesExamples
Taken from (Nettle 1999b)
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Examples (linguistic diversity)Examples (linguistic diversity)
Social structures– Social impact theory CM (Nettle 1999a; 1999b)
Spatially distributed populations– Dialect diversity LG, NN (Livingstone 2002)– Lexicons LG (Steels & McIntyre 1999)
Ecological influences– Survival behaviours GA (Arita & Koyama 1996)
Stochastic dynamical processes– Macro models of language change MM, DS
(Niyogi & Berwick 1995; Niyogi 2000)– Micro models of language change DS, LA, GA
(Briscoe 2000a; 2000b)
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Examples (language change)Examples (language change) Individual level
– Aging structure in language acquisition LG (de Boer & Vogt 1999)
– Critical periods for language acquisition GA (Hurford 1991; Hurford & Kirby 1998)
Population level– Flux of agents, stochasticity in sensorimotor experiences
LG (Steels & Kaplan 1998) Language level
– Self-organisation LG, DS (de Jong 1999) LG (de Boer 2000)– Lexical change without population flux LG, NN (Stoness &
Dircks 1999)– Rate and pattern of change MM (Pagel 2000)– Lexical change over populations ILM, LG (A.D.M. Smith, in
press)– Iterated learning models ILM, LG (Brighton, Kirby, Smith,
Vogt, Zuidema)
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Examples (observations)Examples (observations)
Evolution of signalling abilities GA (Werner & Dyer 1991)
Emergence of conventionalised signals NN (Hutchins & Hazelhurst 1995) LG (Livingstone & Fyfe 2000)
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Open issuesOpen issues
What is the influence of language ecology?
(Livingstone 2002)
Population/language mix
Mixing of social structures
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Topics of ResearchTopics of Research
Evolution of communication
Evolution of signalling systems
Lexicon formation
Grounding
Language diversity
Emergence of grammar
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Emergence of syntax/grammarEmergence of syntax/grammar
Under what conditions can (aspects of) syntactic or grammatical structures emerge?
– Nativist accounts– Cultural accounts– Hybrid accounts– Grounding
Investigate theories from, e.g., (Bickerton 1990, Chomsky 1990, Pinker & Bloom 1990, Tomasello 2003, Wray 1998)
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Iterated learning (Kirby 2002)Iterated learning (Kirby 2002) Population dynamics with overlap (i.e. each generation
1 adult, 1 learner) Transmission bottleneck Predicate logic meaning representation Invention mechanism -> holistic, or exploiting existing
rules (words are random strings) Heuristic induction mechanism:
– Chunking
– Merging
S/love(m,j)->marylovesjohnS/love(h,j)->hannalovesjohn
S/love(x,j)->N/x lovesjohnN/m->maryN/h->hanna
N/m->maryM/m->mary
N/m->mary
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Iterated learning (Kirby 2002)Iterated learning (Kirby 2002)
Phase-space plot of expressivity vs. language size shows the emergence of syntactic language after many generations.
Picture courtesy of Simon Kirby.
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ExamplesExamples Nativist accounts
– Co-evolution of UG/LAD GA (Kirby & Hurford 1997; Briscoe 2000)
– Evolution of LAD GA (Turkel 2002) GA+BE (Yamauchi 2001)
– Evolutionary constraints for UG MM, GT (Nowak et al. 2000; 2001; Komarova et al. 2001)
Cultural accounts (transmission bottlenecks)– Heuristic grammar inducers ILM (Kirby 2000; 2001; 2002;
Zuidema 2001)– Minimum description length ILM (Teal & Taylor 1999;
Brighton & Kirby 2001)– Hebbian learners ILM, NN (K. Smith 2003; Kirby et al.
2002)– Static populations RNN (Batali 1998) MBL (Batali 2002)– Issues in Optimality Theory ILM (Jäger 2003)
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ExamplesExamples Hybrid approaches
– Constructivist evolution GA, LG (Hashimoto & Ikegami 1996; Zuidema & Hogeweg 2000)
– Learnable languages HC, RNN (Tonkes et al. 2000; Tonkes & Wiles 2002)
• Sequential learning– Word order constraints SL, RNN (Christiansen &
Devlin 1997; Christiansen & Ellefson 2002) Grounded approaches
– Construction grammars LG, ROB (Steels 2004)– Compositional structures LG, ILM, ROB (Vogt
2005)– Verbs and Nouns GA, NN, ROB (Cangelosi & Parisi
2001; 2004; Marroco et al. 2003)
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Open issuesOpen issues
Increasing complexity to human level
Is there a biological endowment for the emergence of grammar? How?
How much can cultural evolution explain with respect to the transition towards grammar?
Modelling co-evolution syntax & semantics
Evolution of language acquisition mechanisms (induction mechanism, Theory of Mind, …)
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One big open issue…One big open issue…
Did the human brain evolve to facilitate
language, was it the other way around or was
there a co-evolution between brain and
language, cf. (Deacon 1997)?
Few computational models start looking at
this problem (see, e.g., Dominey in press)
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Summary - achievementsSummary - achievements
Evolution of communication vowel systems lexicons compositional languages and other aspects of
grammar
Understand aspects of grounding Models of language change and diversity Some understanding of neural aspects
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Summary – open issuesSummary – open issues Ecological pressures/cognitive factors for evolution of
symbolic communication Biological and cultural endowment for emergence of
grammar Scaling towards human level complexity
Population sizes Population dynamics Vocalisations Grammars Semantics Etc.
Biological adaptation of Vocal tract/auditory system Language acquisition skills Intention reading skills Meaningful behaviour Co-evolution of language and brain
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Take home messageTake home messageThere are many models, based on hypotheses and
scenarios. Although some theories are mutually
exclusive, many are not.
Try not to focus on one model, hypothesis or
explanation when researching language
evolution; better combine the best bits of the
different models.
E.g., different language acquisition strategies can perform
better when applied together, rather than when used in
isolation.
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