Psy1302 Psychology of Language Lecture 22 Evolution of Language.

Psy1302 Psy1302 Psychology of Psychology of LanguageLanguage

Lecture 22Lecture 22

Evolution of LanguageEvolution of Language

Exercise: Creating a Communicative Exercise: Creating a Communicative SystemSystem

Unique Things about Unique Things about Human LanguageHuman Language

How is Language Special

Unique Things about Unique Things about Human LanguageHuman Language Big, discrete vocabularyBig, discrete vocabulary

– 10,000-100,000 “words”… or more10,000-100,000 “words”… or more Recursive compositionalityRecursive compositionality

– making bigger messages by combining making bigger messages by combining smaller ones,smaller ones,

– more complex meanings by combining more complex meanings by combining simpler onessimpler ones

Action to “change others’ minds”Action to “change others’ minds”– we know others may have different we know others may have different

knowledge and beliefsknowledge and beliefs– we communicate to inform, persuade, we communicate to inform, persuade,

deceive, etc.deceive, etc.


A puzzle: why?A puzzle: why?

Quantitatively and qualitatively uniqueQuantitatively and qualitatively unique– like elephants’ trunkslike elephants’ trunks

No similar evolutionary trends in other speciesNo similar evolutionary trends in other species– other species don’t “want” to pick up peanuts with other species don’t “want” to pick up peanuts with

their nosestheir noses all mammals have noses, some use them as manipulatorsall mammals have noses, some use them as manipulators no general trend to develop anything like trunksno general trend to develop anything like trunks

– other species don’t “want” to exchange very complex other species don’t “want” to exchange very complex messagesmessages

(nearly) all mammals make noises, some use them to (nearly) all mammals make noises, some use them to communicatecommunicate

no general trend to develop anything like human speechno general trend to develop anything like human speech


Slide from Liberman

Why do humans have Why do humans have language?language? Any thoughts???Any thoughts???

– Because we’re smarter than other Because we’re smarter than other animals?animals?

– Because we have a bigger brain?Because we have a bigger brain?– Because our mouths have a special shape?Because our mouths have a special shape?– Because somebody took the time to teach Because somebody took the time to teach

us?us?– ……or because that’s just something that or because that’s just something that

humans do?humans do?

ChomskyChomsky If an animal had a capacity as If an animal had a capacity as

biologically advantageous as biologically advantageous as language but somehow hadn’t language but somehow hadn’t used it until now, it would be an used it until now, it would be an evolutionary miracle, like finding evolutionary miracle, like finding an island of humans who could be an island of humans who could be taught to fly.taught to fly.

Biology

Noam ChomskyThe biolinguistic enterprise: where does it stand today?3:00pm - Dec. 11, 2007 MIT BCS 46-3310 http://www.law.georgetown.edu/faculty/mikhail/documents/Noam_Chomsky_Biolinguistic_Explorations.pdf

A Comparative ApproachA Comparative Approach Can knowing how animals (non-Can knowing how animals (non-

human primates) communicate human primates) communicate inform us about the evolution of inform us about the evolution of language?language?

What’s different?What’s different?

HumanHuman Big vocabularyBig vocabulary Arbitrary form-meaningArbitrary form-meaning CompositionalityCompositionality Ability to attribute Ability to attribute

mental state:mental state:– InformingInforming– DeceivingDeceiving– TeachingTeaching

Animal CommunicationAnimal Communication Small vocabularySmall vocabulary Non-arbitrary form-meaningNon-arbitrary form-meaning Virtually no compositionalityVirtually no compositionality Poor (or lack of) ability to Poor (or lack of) ability to

attribute mental stateattribute mental state

Rhesus macaque mother,Japanese macaque infant

Japanese macaque mother,Rhesus macaque infant

Owren, M. J., J. A. Dieter, R. M. Seyfarth and D. L. Cheney (1992).

Control Children: Mainly COOSFoster Children:

Control Children: COOS & GRUFFSFoster Children:Mainly COOS COOS & GRUFFS (mid)

Limited Repertoire of Limited Repertoire of SignalsSignals(hardwired)(hardwired)

Animal Communication Systems

Production and Production and Perception AsymmetryPerception Asymmetry Limited Repertoire in ProductionLimited Repertoire in Production But greater comprehension abilityBut greater comprehension ability

Cross-fostered monkey produce own species signal Cross-fostered monkey produce own species signal and not foster parents. and not foster parents.

i.e., limited productive vocabulary, yet can i.e., limited productive vocabulary, yet can understand others’ calls.understand others’ calls.

Why is the speaker not tailoring signal to Why is the speaker not tailoring signal to the one used by listener?the one used by listener?

If tailoring (thinking about what others know & what If tailoring (thinking about what others know & what others know about what you know):others know about what you know):

– You call this “blicket.” If next time I call it “blicket,” You call this “blicket.” If next time I call it “blicket,” perhaps you’ll know that I am referring to the same perhaps you’ll know that I am referring to the same thing.thing.

Speaker Listener

It’s cold in here!!!

Harry probably means for me to close the door.

Communication and Communication and Mind ReadingMind Reading

Leopard…

Receiver - “Listener”

Leopard here… gotta

hide up in the tree

Signaler - “Speaker”

Ahhhhh……..

Signaler - “Speaker”

You: Receiver - “Listener”

Something must have

happened in the house

Intentions of the Animal SignalingIntentions of the Animal SignalingDennett (1987)Dennett (1987)

Zero-order intentional system:Zero-order intentional system:– Signaler has no beliefs or desires. Signaler has no beliefs or desires. – The animal only display involuntary, automatic responses in The animal only display involuntary, automatic responses in

front of different types of danger and different escape front of different types of danger and different escape strategies in front of different acoustic stimuli.strategies in front of different acoustic stimuli.

First-order intentional system:First-order intentional system:– Signaler has beliefs and desires (but not beliefs about beliefs). Signaler has beliefs and desires (but not beliefs about beliefs). – Calls have some meaning. Calls have some meaning. – E.g., A call “there is a snake around” may express the belief E.g., A call “there is a snake around” may express the belief

that there is one around (content oriented) or it may express that there is one around (content oriented) or it may express the desire that the audience follows escape strategy x (goal the desire that the audience follows escape strategy x (goal oriented).oriented).

Second or higher order intentional system:Second or higher order intentional system:– Signaler has some conception of their own mind and of the Signaler has some conception of their own mind and of the

mental states in others’ minds. mental states in others’ minds. – E.g., A call “there is a snake around” may be given not E.g., A call “there is a snake around” may be given not

because the caller believes so, but because he because the caller believes so, but because he wants wants the the others to others to believe believe that it is so.that it is so.

Some questions about Some questions about animal communication animal communication systemssystems Are signalers’ calls ‘triggered’ by specific events?Are signalers’ calls ‘triggered’ by specific events?

– Are calls involuntary or voluntary?Are calls involuntary or voluntary?

Do signalers call because they want to cause Do signalers call because they want to cause behavioral change in the listeners which they behavioral change in the listeners which they notice to be contingent upon calling?notice to be contingent upon calling?

Do speakers call with the Do speakers call with the intentintent of informing of informing ignorant listeners?ignorant listeners?

What do listeners understand from speakers’ What do listeners understand from speakers’ calls? calls?

Are signalers’ calls ‘triggered’ by Are signalers’ calls ‘triggered’ by specific events?specific events?– Emotional Reaction to Event?Emotional Reaction to Event?– Or Audience Design?Or Audience Design?

Experiment:Experiment:1. Play sound of leopard growls within earshot of an individual monkey.OR Use dummy leopard within field of vision of an individual monkey.

2. Test individual in several conditions (e.g.):

b. While individual is not alone and already in tree.a. While individual is alone and is already in tree.

3. Compare likelihood to alarm call in the various conditions.

Alarm call good for the audience, potentially bad for the one calling – attracting attention of predator.Will the individual call less if alone than if there is an audience present?

Emotional Response Emotional Response vs. Audience Designvs. Audience Design

Are signalers’ calls ‘triggered’ by Are signalers’ calls ‘triggered’ by specific events?specific events?

Some evidence suggest the calls are Some evidence suggest the calls are not involuntary not involuntary (Cheney & Seyfarth)(Cheney & Seyfarth)

– Females call more for kin than non-kin Females call more for kin than non-kin presentpresent

– Males call more with female than with Males call more with female than with another maleanother male

– High-rank vervets call more often than High-rank vervets call more often than subordinatessubordinates

Animal Communication Systems



Possible Experiment:Possible Experiment:

If mom is aware of offspring’s mental statemom should call more when offspring ignorant.

1. Introduce predator or food to mother in two conditionsa. In the presence of offspring (offspring informed condition)b. In the absence of offspring (offspring uninformed condition)

2. Offspring present for both conditions now.

vs.

3. Compare likelihood to call for 1(a) vs. 1(b).



Moms do not call more when offspring ignorant than when offspring not ignorant.You would think they would call in the case of the predator, but they don’t!!!

vs.

But see: PBS Animal Einsteins: Thinking about Thinkinghttp://vvi.onstreammedia.com/cgi-bin/visearch?user=pbs-saf&template=play220asf.html&query=Animal+Einsteins&squery=%2BClipID%3A7+%2BVideoAsset%3Apbssaf903&inputField=undefined&ccstart=2663400&ccend=3295300&videoID=pbssaf903

Onishi & Baillargeon (2005)

Infants watch as actor takes object, plays, puts in green box. [Pause, curtain]

Actor reaches into green box as if to take object. [Pause, curtain]

Belief induction trial:

e.g., False Belief (unseen switch): infant but not actor sees object move from green to yellow box.

Test trial: e.g., actor reaches into yellow box. [Pause until trial ends]

Other belief induction trials:Other belief induction trials:– True belief (seen switch):True belief (seen switch): actor watches as object moves actor watches as object moves

from green to yellow.from green to yellow.– True belief (no switch):True belief (no switch): actor watches as yellow box actor watches as yellow box

moves but object does not come out of green boxmoves but object does not come out of green box– False belief (one seen, then one unseen switch):False belief (one seen, then one unseen switch): actor actor

watches as object moves from green to yellow, then does watches as object moves from green to yellow, then does not watch as object moves back to green.not watch as object moves back to green.

– Test trial: for half the infants actor reached to yellow and Test trial: for half the infants actor reached to yellow and for half reached to green box.for half reached to green box.

ResultsResults– In each of the four conditions, infants looked longer during In each of the four conditions, infants looked longer during

the test when the actor reached to the location that was the test when the actor reached to the location that was inconsistent with where she thought the object was (where inconsistent with where she thought the object was (where she correctly or falsely believed - ? – it to be).she correctly or falsely believed - ? – it to be).

False belief understanding in 15-month-olds??False belief understanding in 15-month-olds??

Mental State Mental State AttributionAttribution The ability toThe ability to

– Attribute mental states Attribute mental states attribute mental states like ignorance, motives, beliefs to others

– recognize that your own beliefs, motives, emotions can be different from other individuals’

Mental state attribution permits informing, deception, teaching

http://vvi.onstreammedia.com/cgi-bin/http://vvi.onstreammedia.com/cgi-bin/visearch?user=pbs-visearch?user=pbs-saf&template=play220asf.html&query=saf&template=play220asf.html&query=%2A&squery=%2BClipID%3A2+%2A&squery=%2BClipID%3A2+%2BVideoAsset%2BVideoAsset%3Apbssaf1504&inputField=%3Apbssaf1504&inputField=%20&entire=No&ccstart=89502&ccend%20&entire=No&ccstart=89502&ccend=1088861&videoID=pbssaf1504=1088861&videoID=pbssaf1504

Main point: Imitation, No teaching. Main point: Imitation, No teaching. Lacking cooperative behavior.Lacking cooperative behavior.

Psy1302 Psychology of Language Lecture 22 Evolution of Language.

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