Transcript The Nature of Words in Human Protolanguages

The Nature of Words in
Human Protolanguages
Mike Dowman
November 16, 2006
Protolanguage
• At some time in the past humans didn’t
have language.
• Was the emergence of human language
gradual or sudden?
• What did the first first human languages
look like?
Starting Small
• First humans could only articulate
and/or perceive a limited number of
distinct words
No phonology
Little or no syntax (one word
utterances)
• They only tried to convey limited
number of simple meanings
Bickerton (1990, 1996)
• Words in first languages were like
modern words
• Labeled preexisting concepts and
entities
• Words used in short strings
No fixed word order
Words can be omitted
Modern Day Examples of
Protlanguage
•
•
•
•
Children under two
Speakers of pidgins
Adults deprived of language in childhood
Trained apes:
Nim eat Nim eat
Tickle me Nim play
Me banana you banana me you give
Banana me me me eat
Wray (1998)
• The First Words in Protolanguages were
Holophrastic
Each word conveyed a whole complex
meaning (e.g. Give me the meat)
• Chimpanzee vocal noises and gestures are
holistic
Inform about location of food, threaten, get
another chimpanzee to do something
The Iterated Learning Model
(a.k.a. Expression-Induction
Model)
• Language is passed from generation to
generation through a limited number of
spoken examples
• Each new generation must try to infer
the underlying system
produce
L1
U1
learn
L2
U2
L3
U3
Nature of Utterances
• Each utterance consisted of only a
single word
• Agents could use only a small number
of words (limited communicative
capacity)
• Available words fixed throughout each
simulation
Meaning Representations
• Small number of semantic primitives
(limited conceptual capacity)
• Each utterance would try to express a
complex meaning represented by a
group of three different primitives
hunt, pig, forest means ‘Hunt pigs in the
forest’
dog, pig, sleep means ‘Dogs and pigs are
sleeping’
Agents’ Choice of Words
• Agents use the word whose past uses
have been most similar to the current
meaning
• If current meaning is: eat, house, pig
• Previously heard used to express:
eat, house, dog
hunt, forest, pig
Match = 4/9
hunt, forest, pig
Agent’s Choice of Words
• If degree of match is one, agent will
always use that word
• Otherwise will use any available unused
word (and the word-meaning pair
remembered)
• Otherwise pick highest degree of match
(choosing at random in the event of a
tie)
Simulations
• Each meaning contained 3 elements from a
set of 10 (so 120 distinct complex meanings)
• Each agent produced 1000 utterances for the
agent in the next generation (each expressing
a randomly chosen meaning)
• Simulations were run for ten generations
• The number of available words was varied
Emergence of Modern Types
of Word
• In the first simulation the agents could only
use 10 distinct words
• All the agents made use of all 10 available
words
• Most words were used only when one
particular semantic element was present
Their meanings appear to correspond to
those elements
Example Modern Type Words
Meanings Expressed by
Word (frequency in
brackets)
forest, pig, eat (12)
eat, dog, gather (10)
forest, gather, eat (11)
hunt, eat, pig (11)
fight, pig, eat (6)
gather, eat, pig (7)
house, eat, gather (9)
dog, fight, eat (7)
eat, hunt, fight (11)
gather, eat, fight (10)
gather, eat, sleep (13)
dog, eat, pig (4)
gather, hunt, eat (4)
Description of Word
Meaning
Word denotes eat
Meanings Expressed by Word
(frequency in brackets)
dog, river, forest (7)
pig, forest, dog (10)
river, dog, pig (17)
eat, dog, forest (10)
dog, forest, gather (5)
dog, pig,fight(7)
forest, dog, fight (6)
fight, river, dog (10)
forest, sleep, dog (5)
sleep, dog, river (5)
Description of Word Meaning
Word denotes dog
The words are like
modern nouns or
verbs
Emergence of Holophrastic
Words
• In the next simulation the agents could
use 150 distinct words
• All agents used 120 of these words
• Each word expresses a single complex
meaning
These words are all holophrastic
Example Holophrastic Words
Meanings Expressed by Word
Description of Word Meaning
(frequency in brackets)
sleep, pig, hunt (5)
Word denotes events or objects
containing all the elements sleep,
pig and hunt
pig, house, fight (9)
Word denotes events or objects
containing all the elements pig,
houseand fight
forest, fight, hunt(10)
Word denotes events or objects
containing all the elements forest,
fight and hunt
Emergence of Intermediate
Types of Language
• What happens when the number of available
words is in between the number of semantic
elements and the number of complex
meanings?
• Do we get a mixture of modern type and
holophrastic words?
A new simulation with 50 available words
tested this
All agents used all the available words
Meanings Expressed by Word
Description of Word Meaning
(frequency in brackets)
sleep, forest, gather (7)
Word denotes events or objects
containing all the elements sleep,
forest and gather
forest, river, house (5)
Word denotes river, but only in
house,river, fight (8)
relation to forest, house or fight
forest, river, fight(6)
sleep, hunt, eat (13)
Word denotes events or objects
sleep, eat, river (11)
containingboth of the elements
pig, eat, sleep (8)
sleep and eat
eat, gather, sleep (11)
sleep, fight, eat (6)
sleep, dog, eat (9)
forest, sleep, eat (6)
gather, sleep, pig (10)
Word denotes events or objects
pig, dog,sleep (10)
containingboth of the elements
pig, sleep, house (5)
sleep and pig, but only in relation
to gather, dog or house
dog, hunt, hous
e (5)
Denotes meanings containing
hunt, eat, dog (6)
three of the elements dog, hunt,
eat, dog, house (12)
houseand eat
house, hunt, eat (5)
Language contains
words with
varying degrees
of holophrasticity
It’s intermediate
between a
protolanguage
with modern
words and a
holophrastic one
Varying Degrees of
Holophrasticity
• The frequency of each type of word depended on
the number of distinct words available
• With 50 words there were:
10 holophrastic words, 35 words containing two
fixed semantic elements, 4 words containing one
fixed element, and 1word containing no fixed
elements at all
With a smaller number of distinct words, the
languages become less holophrastic
With more available words they became more
holophrastic
Fewer Words than Semantic
Elements
• What if the agents could not even
produce one distinct word for each
semantic element?
• (Or alternatively what if they knew so
many semantic elements they could use
more than there were words?)
• A new simulation was conducted with
only 5 distinct words available
Emergent Words
• Three words had one fixed semantic
element
• One word used any three of the other seven
semantic elements
• The final word contains at least two of the
elements eat, gather and pig
This is a new type of word, and is partly
holophrastic
Co-evolution of Agents and
Protolanguages
• What happens as agents
communicative and conceptual
capacities evolve phylogenetically?
• We would expect the agents’
protolanguages to rapidly adapt to the
agents new capacities
• How will the degree of holophrasticity
change over time?
Increasing Communicative
Capacity
• The first agents could use only a single
word
• After every 10 generations the number
of words they could use was increased
by 1
• Number of semantic elements fixed at
10
• 1300 generations simulated
Increasing Conceptual
Complexity
• In this simulation there were always 120
words available
• Initially there were 10 semantic elements
• After every 10 generations the number of
available semantic elements was increased
by 1
• This simulation was also run over 1300
generations (so there were 447,580 different
complex meanings at the end of the
simulation)
Transitions between Modern
and Holophrastic Words
• The first simulation showed a progression
from modern words to holophrasis
• The second from holophrasis to modern
words
So depending on the relative rates of monotonic
evolution of communicative and conceptual
capacity we could see multiple swings
between each type of protolanguage
E-Language and I-Language
• If we look at agents’ internal linguistic
representations (I-Language) we only see an
unanalyzed list of the past uses of a word
• However, if we could only observe the agents’
speech (E-Language) and the meanings they tried
to express we would (in some cases) be able to
identify the words with specific semantic elements
So a categorization ability is not necessary for a
language with categorical words to emerge
Key Points
• Modern type words or Holophrases are not
the only possibilities for Protolanguages.
• If agents try to express a limited number of
meanings (relative to their communicative
abilities) holophrasis will results.
• With more meanings or fewer words forms,
words become less holophrastic and more
like modern words.
The modern type word vs. holophrasis debate
is not as clear cut as it might at first seem