Announcements
• Clarifying Universal Grammar vs Internalized
Grammatical Rules
– UG = a theory that all languages rely on a set of highly
abstract, unconscious rules—innate knowledge of the
general form that language can take (Nature)
– IGR = learning through experience the specific
grammatical rules of a particular language but learning
the overall “rules” rather than word by word (Nurture)
• Fast-mapping (the word need not be contrasted
with anything, it is quick word to world
mapping/pairing through brief exposure or
incidental learning rather than direct teaching)
Mental State Reasoning:
‘Theory of Mind’
Today’s Plan:
• Last of Video on Non-human ‘language’ and symbol use
• A little Trivia Exercise
• Research on mental state reasoning or ‘Theory of Mind’
• How one’s ‘theory of mind’ can help learn language
Theory of mind is the ability to reason about
psychological/mental states in one’s self or in
someone else.
(e.g. “mind”-reading, not ESP)
How do infants, children, adults, non-human
animals (?), understand or reason about the mind
e.g. Emotions, Desires, Intentions, Knowledge,Thoughts/Beliefs, etc.
It is one thing to HAVE emotions, thoughts, etc.—it is quite
another to be able to THINK about them!
Why do we need a theory of mind?
Reason 1: Understanding what a person is thinking, feeling,
believes etc helps us predict how they will act and/or interpret their
behavior
For example:
• Sarah’s dog is missing.
• Sarah hears a scratching noise in the shed.
• She goes to the shed and opens the door and finds a squirrel.
• She begins to cry.
How do we make sense of behavior? (e.g. triangles moving clip,
Stewardess in the aisle that bumps herself on the forehead)
Why do we need a theory of mind?
Reason 2: Successful communication with another person
requires appreciating what the other person knows, doesn’t
know, and how knowledge can be acquired.
e.g. teaching
Reason 3: Learning through social transmission (knowing who
knows more, who to learn from)
e.g. deciding who or when to learn from someone
Others reasons: e.g. deception, surprises, tricks, jokes, etc.
How to test for a ‘Theory of Mind’?
• Historical Background: Research began in 1970s
with chimps—do they reason about the beliefs of
other chimps?
– Where will Chimp A think Chimp B will look?
Location A or Location B (where the food is)
– Chimp A expected Chimp B to look in Location B
– Interpretation: Chimp A thinks Chimp B believes the
food is in Location B
– Criticism: Could succeed without any understanding of
the mind of the other, to show theory of mind they must
reason about a false belief (counter to reality)
• The birth of the classic test: False Belief tasks as a
litmus test of a theory of mind
1. Displacement Tasks
(aka Sally-Ann or Maxi Tasks)
2. The Unexpected Contents Task
(aka the “Smarties” task)
3.
Appearance-Reality Tasks
Video Segment: A Change of Mind
False Belief Results
• Results
from the classic false belief tasks:
–4 year olds succeed at the task, 3 year olds fail!!
• What do the results mean?
–Children younger than four do not understand that people
can hold beliefs that are false?
• Or is there an alternative explanation?
Two Broad Theories
1) Radical Shift Theory—Conceptual Change View
– children prior to the age of four are unable to attribute belief
states to themselves and others.
– lack concept of false beliefs—kids have a ‘copy-theory’ of the
world (the mind = reality)
2) Processing Demands Theory
– More continuous view of development
– young children fail these tasks because they lack the attentional,
mneumonic, linguistic, or processing resources, rather than the
ability to attribute false beliefs.
An example of a Processing Demands View
A ‘Curse of Knowledge’ Account
Definition: A difficulty appreciating a more naïve
perspective as the result of being biased by one’s own
knowledge.
Examples
Car salesmen
Anagram Study
‘Sarcastic’ passages study
Parallels Between Adults’ and Children’s
Knowledge Reasoning
Predicting What Others will Think
• Subjects read descriptions of events that could have
various outcomes. In one condition, subjects were
told the outcome, in another condition they were not.
• They were asked to judge what others who did not
know the outcome would predict.
• Subjects who knew the outcome thought others would
be much more likely to predict that outcome.
.
Fischhoff (1975)
Like the children who claimed Sally would know that her
chocolate had been moved, adults claimed that others
would share their outcome knowledge.
Parallels Between Adults’ and Children’s
Knowledge Reasoning
Recalling Your Own Earlier Thoughts
• Subjects were asked prior to Nixon’s trip to China and the
USSR to estimate the probability of the various outcomes.
• 2 weeks - 6 months later they were asked to recall their
predictions
• Subjects remembered giving much higher probabilities than
they actually had to the outcomes that took place.
Fischhoff & Beyth (1975)
Like children who claimed they knew all along that there
were pencils in the box, adults showed a more subtle
effect by giving biased recollections of what they had
previously predicted.
Questions of Interest
• Do young children find it easier to assess what
someone else will know when they are not
“cursed” with knowledge?
• Are younger children more susceptible to the
curse of knowledge than older children?
• Is this why young children do poorly on false
belief tasks?
Method
Familiar
Unfamiliar
“Percy’s played with all of
these toys before! He brought
all of these from home.”
“Percy’s never ever
seen these toys before!
These are brand new.”
No Curse (Ignorant)
Cursed (Knowledgeable)
Children were told there was
a special little thing in each one.
Children were shown what was
inside each one before it was
closed again.
Experimenter: “Does Percy know what’s inside this one?”
Predictions
Children would judge that Percy knows what is inside
the toys he is familiar with, and will not know what is
inside the toys he is unfamiliar with.
But, the curse of knowledge would work against this
appreciation, leading children to overestimate Percy’s
knowledge when they knew what was inside.
The magnitude of the curse of knowledge would decline
with age.
"Yes" Responses
Yes Responses to “Does Percy Know What is Inside?”
6
Familiar
5
Unfamiliar
4
3
2
1
0
Age 3
Age 4
Age 5
Significant main effect of familiarity
Significant effect of familiarity at each age
“Does Percy know what is inside?” (for Unfamiliar toys)
Child Knowledgeable
6
Child Ignorant
"Yes" Responses
5
4
p < .05
p < .05
3
2
1
0
3
4
5
Age in Years
• 3- and 4-year-olds, but not 5-year-olds, overestimated Percy’s knowledge
when they were knowledgeable.
• The magnitude of the curse significantly decreased from age 3 to age 5.
Birch & Bloom (2003) Psychological Science
“Does Percy know what is inside?” (for Familiar toys)
Child Knowledgeable
Child Ignorant
6
"Yes" Responses
5
4
3
2
1
0
3
4
5
Age in Years
• an asymmetry in perspective-taking--No ‘curse of ignorance’
• when taking another point of view—it is harder to put aside one’s
knowledge than one’s ignorance.
•You get the same asymmetry pattern with adult’s reaction times and
trivia judgments
Percy’s Knowledge Study: Conclusions
• Children are sensitive to the knowledge states of others,
but the curse of knowledge can work against this sensitivity
• The magnitude of the curse of knowledge decreases significantly
from age 3 to age 5
• Children’s knowledge assessments are biased asymmetrically
and cannot be reduced to ‘egocentrism’.
– They are biased by their knowledge when assessing what someone else
knows, but are not biased by their ignorance (see Birch & Bloom, 2003,
Psychological Science)
False Belief Experiment
Would adults experience difficulty attributing false
beliefs if they were knowledgeable of the outcome,
compared to adults who did not know the outcome?
False Belief Experiment
Participants
• 210 Introductory Psychology Students
Design
• ‘Sally-Ann’ Questionnaire using 4 locations instead 2.
• Probability judgments were measured instead of where
will she look
False Belief Attribution
• Vicki places her violin in the blue box and
goes outside.
False Belief Attribution
• While Vicki is outside, her sister, Denise, comes in
and rearranges all the boxes.
False Belief Attribution
?
a
?
?
Cursed (standard) Condition = object is moved to “the red”
container (the participant knows where it is)
No Curse Condition = object is moved to “another” container
(the participant does not know where it is)
When Vicki comes back she wants to find her violin, what’s the
probability she will first look in each of the containers?
Red
Green
Purple
Blue
No Curse
23%
3%
2%
71%
Curse
34%
4%
6%
59%
Birch & Bloom (under review), Cognition;
see also Birch & Bloom (2004) Trends in Cognitive Science
Mechanisms and Implications
Mechanisms (Why the decrease with age?)
• Increasing inhibitory control?
• Increasing source memory?
Implications
• Decreased empathy? Increased guilt, shame?
• Indirect effects (social judgments)?
• Education, Law, Business, Politics, all
interpersonal communication
This is Linda.
This is Jeff.
Artwork by Susan Chen
Jeff pulls Linda’s hair.
How mean is Jeff?
Keep in mind…
•There is more to passing the false belief
task than theory of mind.
•There is more to theory of mind than
passing the false belief task
So how do they do it?
Solving the Reference Problem
•
•
•
•
•
Whole Object Bias
Taxonomic Bias
Basic-level Bias
Shape Bias
Linguistic Context (grammatical form of the
word)
• Syntactic Bootstrapping (grammatical structure of
sentence)
• Mutual Exclusivity Bias
• Theory of Mind and Pragmatics
Theory of Mind and Word Learning
• Pragmatic explanation of Lexical Contrast
• Joint attention and Inferred Intent?
• Sensitivity to when a goal is satisfied (Bucket Study)
• Deciding Who is More Knowledgeable. Who do I want
to learn from? (e.g. Tracking knowledge over time)
• Body language, gestures, and paralinguistic info
indicative of knowledge/confidence
Mutual Exclusivity (revisited)
Where is the blicket?
Theory of Mind and Word Learning
“Look at this one. It’s a jop!
See, it’s a jop. This is a jop”.
“Look at this one. It’s nice.
This one is cool. It’s neat.”
“Can you give me the bem?”
Pragmatic (Theory of Mind) account of Lexical Contrast
“Can you give me the bem?”
The speaker wants one of those two objects. If she wanted
me to give her the one she called jop she would have done
so in some way I would understand (e.g. She knows I know
what a jop is). But instead she used a different word--She
must intend to refer to something different.
“Look at this one. My uncle
gave me this one. My uncle
gave this to me. This is the
one my uncle gave to me.”
“Look at this one. It’s nice.
This one is cool. It’s neat.”
“Can you give me the one I keep in the kitchen?”
Same Speaker Results: The other one--not the one my uncle gave me
Different Speaker Results: 50/50
Not specific constraint to word learning, but specific to the mind of
the other person.
Theory of Mind and Word Learning
• Pragmatic explanation of Lexical Contrast
• Joint attention and Inferred Intent?
• Sensitivity to when a goal is satisfied (Bucket Study)
• Deciding Who is More Knowledgeable. Who do I want
to learn from?
• Body language, gestures, and paralinguistic info
indicative of knowledge/confidence
Joint Attention & Inferred intent/desire
Eyes as a Window to the Mind
What the eyes can say
Keeping Track of Previously Knowledgeable Speakers
History Phase
“I think that’s a spoon. Yeah, that’s a spoon.
I think that’s a comb. Yeah, that’s a comb.” etc.
History Phase
“I think that’s a fork. Yeah, that’s a fork.
I think that’s a shoe. Yeah, that’s a shoe.” etc.
Naming Phase
Ben:
“I think that’s a ferber.
Yeah, That’s a ferber.
Do you see the ferber?”
Jenny:
“I think that’s a ferber.
Yeah, That’s a ferber.
Do you see the ferber?”
Testing Phase
“Can you give me the ferber? Where’s the ferber?”
Testing Phase
?
Different Word Test Condition:
“Can you give me the koba? Where’s the koba?”
Word Learning: Paralinguistic and Nonverbal Cues
Imitation: Nonverbal Cues
Putting Cues together
Example: Learning a Proper Name
“There’s Jessie!”
Cues to a Proper Name’s Referent
• Syntax, Linguistic Context
(Katz, Baker, & Macnamara,
1974)
• Range of reference (Hall, 1996; Hall & Belanger, in press)
• Eye-Gaze, joint attention (Baldwin, 1991)
• Mutual Exclusivity (Clark, 1993; Hall & Graham, 1999; see
also Diesendruck & Markson, 2001)
• Animacy
(Gelman & Taylor, 1984; Hall, 1994; Katz et. al., 1974)
–Ownership/hierarchy of importance? (Hall)
• Knowing about knowledge, Familiarity, Theory
of Mind (e.g. Birch & Bloom, 2002)
Question of Interest
• Do children understand the relationship between knowledge and
familiarity? That one needs familiarity or experience with someone
to know about unobservable properties (e.g. siblings, proper
names)
• Are they sensitive to the speaker’s knowledge state, and can they
use this to help them learn the referent of a new word?
That is, if a speaker uses a proper name such as “Jessie”,
do they know it is more likely to apply to an individual
with whom she is familiar?
Method
Familiar
“I brought these from home.
I’ve played with all of these
animals before.”
Unfamiliar
This bag of animals is ‘discovered’.
“Wow! I’ve never seen that
dog before.”
Proper Name Condition:
“Where’s Jessie? Can you find Jessie?”
Common Noun Condition:
“Where’s the dog? Can you find the dog?”
Results
Proper Name Condition
Common Noun Condition
100%
100%
80%
80%
60%
60%
40%
40%
20%
20%
0%
0%
Adult s Age 4
Age 3
Age 2
Adult s
Age 4
Age 3
Age 2
Proper Name Study: Summary
Children as young as two are sensitive to the speaker’s
knowledge state when learning new words.
–They appreciate that the speaker must be familiar with
an individual in order to know its proper name.
–They appreciate that familiarity with a specific
individual is not necessary to know a common noun.
Book Recommendations
‘The Language Instinct’
by Steven Pinker
‘How Children Learning the Meanings of Words’
by Paul Bloom