1. Social cognition in young children and chimpanzees
Malinda Carpenter
Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany

2. Introduction to this course
Many differences between apes and humans
culture
artifacts
beliefs, customs, rituals
language
collaborative activities
institutions (collective beliefs, e.g., money, marriage, government)
skyscrapers
symphony orchestras
summer schools
everyday life
showing your vacation photos
holding a door open for someone
taking a walk together

3. X Where do these differences come from?
language
‘theory of mind’ (  )
shared intentionality 
We propose that all these abilities involve sharing and collaboration. The crucial difference between human cognition and that of other species is the ability to participate with others in collaborative activities with shared goals and intentions: shared intentionality (Tomasello, Carpenter, Call, Behne, & Moll, 2005).
Two components:
understanding of others’ psychological states
motivation to share psychological states with others X

4. Outline ‘theory of mind’ (understanding of others’ mental states)
beliefs, knowledge, desires
intentions, attention
shared intentionality
some types of social learning
some types of communication
motivation to share psychological states with others
collaboration
comparisons
infants and apes: collaborative vs. individual versions of each
children with autism
discussion, evolutionary story
questions, discussion welcome!

5. Part 1: False beliefs, knowledge, and desires
‘Theory of mind’: Children’s and chimpanzees’ understanding of others’ mental states
Part 1: False beliefs, knowledge, and desires

6. Theory of mind
Your roommate goes to her dresser, pulls on the handles of a drawer several times, harder and harder, hits the sides of the dresser, pulls again, and then walks away.
random pulling/hitting behavior? or
She thought something she wanted was in there and she was trying to open the drawer to get it out.
We make sense of others’ behavior by figuring out why they’re behaving the way they are – by figuring out what they’re thinking, what they want, what they are intending.

7. Theory of mind
Your roommate goes to her dresser, pulls on the handles of a drawer several times, harder and harder, hits the sides of the dresser, pulls again, and then walks away.
random pulling/hitting behavior? or
She thought something she wanted was in there and she was trying to open the drawer to get it out.
We make sense of others’ behavior by figuring out why they’re behaving the way they are – by figuring out what they’re thinking, what they want, what they are intending.

8. ‘Theory of mind’: the attribution of mental states (e. g
‘Theory of mind’: the attribution of mental states (e.g., thoughts, beliefs, desires, intentions) to others (and self) (Premack & Woodruff, 1978).
Understanding of mental states (‘mindreading’) allows us to explain observable events (actions) by inferring unobservable entities (beliefs, desires, etc.).
Also involves understanding that others’ mental states may differ from one’s own, and may differ from reality (e.g., false belief, unfulfilled attempt).
We use it everyday: make sense of others’ behavior, deception, prediction, etc.

9. Debate over whether really a theory, and how children do this (acquire rules and principles vs. use own imagination to simulate other’s mind).
Original definition included all mental states, but most tests are of beliefs, especially false beliefs.
one reason: beliefs are often less directly observable in behavior, can be more detached from reality
great interest in this: search  729 papers on false belief
Generally accepted criterion for crediting someone with a theory of mind is an understanding of others’ false beliefs
important that the other’s belief does not match reality, so cannot answer based on own belief/knowledge – if ask about other’s true beliefs, children could respond correctly even if didn’t know anything about others’ minds, by answering according to what they know

10. Understanding of others’ beliefs
Children begin to explain others’ behavior in terms of their beliefs around age 3 years. For example:
Sam wants to find his puppy. The puppy might be hiding in the garage or under the porch. But Sam thinks the puppy is under the porch. Where will Sam look for the puppy: in the garage or under the porch? (Wellman & Bartsch, 1988)
Three-year-olds pass this test. But 3-year-olds do badly on tests of false beliefs.

11. False Beliefs standard tests:
Sally-Anne or Maxi test (change of location): Baron-Cohen, Leslie, & Frith (1985); Wimmer & Perner (1983)
Smarties test (deceptive box): Perner, Leekam, & Wimmer (1987)

12. Sally-Anne (Maxi) test
False Beliefs:
Sally-Anne (Maxi) test
(Baron-Cohen, Leslie, & Frith, 1985; Wimmer & Perner, 1983)
control questions:
Where is the marble really?
Where did Sally put the marble at the beginning of the story?
3-year-olds say box, where it is (fail); 4+-year-olds say basket
from Frith (1989)

13. (Perner, Leekam, & Wimmer, 1987)
False Beliefs:
Smarties test
(Perner, Leekam, & Wimmer, 1987)
tests self and other: self & other answers related (Gopnik & Astington, 1988)
control questions:
Is that what’s really in here?
What is really in here?
again, 3-year-olds fail (say pencil); 4+-year-old pass (say Smarties) ? ?
from Frith (1989)

14. Development of understanding of false beliefs
Meta-analysis on over 100 studies using the standard, verbal tests (Wellman, Cross, & Watson, 2001):
younger than 3½ years: below chance (choose incorrect)
3½-4 years: at chance
older than 4 years: above chance (choose correct)
‘Implicit’ tests
Clements & Perner (1994): standard ‘Sally-Anne’ scenario, but measured to which location children looked in anticipation of the protagonist’s return. Evidence of implicit understanding at age 2;11.
Onishi & Baillargeon (2005): 15-month-olds looked longer at displays in which an actor’s search for a toy was inconsistent with her belief about the toy’s location.

15. 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]

16. Other belief induction trials:
True belief (seen switch): actor watches as object moves from green to yellow.
True belief (no switch): actor watches as yellow box moves but object does not come out of green box
False belief (one seen, then one unseen switch): actor watches as object moves from green to yellow, then does not watch as object moves back to green.
Test trial: for half the infants actor reached to yellow and for half reached to green box.
Results
In each of the four conditions, infants looked longer during the test when the actor reached to the location that was inconsistent with where she thought the object was (where she correctly or falsely believed - ? – it to be).
False belief understanding in 15-month-olds??

17. Given these findings, why do 3-year-olds fail the standard tests?
Zaitchik (1990): compared out-of-date beliefs to out-of-date photographs (same structure, cognitive demands)
3-year-olds fail this too
executive function problems? (difficulty inhibiting the perceptually salient response? – not a problem in tasks using looking measures)
from Happé (1994)

18. Factors influencing children’s performance
Executive function
performance on false belief tasks is related to performance on executive function tasks (e.g., inhibition, working memory)
in versions with no ‘pull of the real’ (the object is no longer in the container), many 3-year-olds pass (Carpenter, Call, & Tomasello, 2002; Gergely & colleagues ‘eating the Smarties task’).
Language
question asked (“where will she look first?” helps a little)
but verbal and nonverbal tests yield similar results
correlations between false belief understanding and language skills (especially the types of constructions that include mental state terms: ‘I know that x’; ‘She thinks x’)
deaf children of nonsigning parents show delays in false belief understanding
Family
children with older (but not younger) siblings do better (Perner, Ruffman, & Leekam, 1994).
children whose mothers generally talk more about mental states do better (Dunn et al., 1991).

20. Understanding of others’ knowledge
e.g., Povinelli & deBlois (1992): guesser vs. knower
3- and 4-year-olds
the ‘hider’ E hid a surprise in one of two cups while the ‘leaver’ E was out of the room.
When the ‘leaver’ E returned, both Es pointed to a cup (hider to correct and leaver to incorrect).
4-year-olds chose the correct cup; 3-year-olds did not.

21. Sometimes their parent witnessed the hiding too; sometimes not.
O’Neill (1996)
2-year-olds
Children watched as a toy was hidden in one of two out-of-reach containers.
Sometimes their parent witnessed the hiding too; sometimes not.
Children’s requests were more informative when parents were ignorant than knowledgable (more gestures, identifying verbalizations).
But: if the parent‘s eyes are covered at an irrelevant point in the hiding process (before but not during the hiding), young 2-year-olds treat the parent as ignorant (Dunham, Dunham, & O‘Keefe, 2000).

22. E returns and shows excitement toward the group of three toys.
Tomasello & Haberl (2003)
12- and 18-month-olds
E and the child play with two toys successively. While E2 and the child play with a third toy,
E is out of the room (experimental condition)
E stands near the door and watches (control condition).
E returns and shows excitement toward the group of three toys.
E tells the child “Give it to me.”

23. In the experimental condition, children of both ages chose the new object significantly more often than would be expected by chance.
12- and 18-month-olds can identify which of several objects is new to another person based on her past visual experience (knowledge by acquaintance).
18-month-olds

25. Understanding of others’ desires
Repacholi & Gopnik (1997):
14- and 18-month-olds
E presents two bowls of food: one of crackers (appealing food), one of broccoli (unappealing food).
Child tastes each food and tells E which he prefers.
Then E tastes each food and produces either a happy emotional expression (“Mmm!”) or a disgusted expression (“Eww!”), depending on the experimental condition.
E holds her hand out in between the two bowls and asks the child “Can you give me some?” (without looking at or indicating either bowl).
18-month-olds gave the food E was happy about, even if it was not the one they themselves preferred. 14-month-olds gave the food they preferred.

26. Summary: It depends on the measure
False belief:
verbal tests: 4+ years
less verbal, but still action measure tests: 3 years
implicit, looking measure tests: 15 months
Knowledge/ignorance:
guesser vs. knower: 4 years
tailor communication: 2 years
knowledge by acquaintance: 12 months
Desire
18 months

27. Apes False beliefs Knowledge/ignorance
few nonverbal tests (mostly Call & Tomasello et al.)
only one study showing evidence consistent with false belief understanding (Call, Hare, Tomasello) – but other explanations are possible
Knowledge/ignorance
guesser vs. knower (Povinelli)
what have seen in past (Call, Hare, Tomasello)
informing (Call & Tomasello, Gomez, Whiten)

28. Apes
Desires
Buttelmann, Call, & Tomasello (in preparation): Ape knows that E hid two pieces of (good) food. Ape sees E react happily to one container and with disgust to the other, then sees E eating. Ape is allowed to choose a container. Apes choose the container E reacted to with disgust, assuming that he ate the food he reacted to happily.  Apes know something about the relation between desire (emotion?) and action.

29. Children with autism False beliefs
many studies, consistent results: children with autism have difficulty with false belief tests
why?
some evidence of difficulty with executive function, but not so clear-cut
in addition, they pass the out-of-date photo test, which has the same executive function demands (Leslie & Thaiss, 1992).
also not because trouble with representations in general (they pass the out-of-date photo test; Leslie & Thaiss, 1992)
seems to be trouble with mental representations specifically – but not all mental states…

30. Children with autism Knowledge/ignorance Desires
understanding knowledge easier than false belief
e.g., Leslie & Frith (1988): E2 watched as E1 hid a counter in one hiding place. E2 left. E1 hid another counter in another hiding place. Child asked “where will E2 look for a counter when she comes back?” Few passed (23-44%) but more children passed this than false belief.
Desires
Baron-Cohen (1991): children with autism understand the relation between desire and emotion
If Jane wanted x and was given x she would be happy; if she wanted x and was given y she would be sad

31. Summary
Apes, children with autism have trouble understanding false beliefs
also deaf children raised by nonsigning parents
Three-year-old and younger children have trouble understanding false beliefs too (depending on the study), but probably for different reasons.
apes, children with autism: no understanding of complex mental states
younger children: task demands (?)
Seminar: We’ll discuss the different false belief tests, trying to figure out whether they really measure false belief understanding (alternative explanations, methodological issues, other problems). We’ll also discuss ways to test understanding of (unobservable) mental states nonverbally (in the meantime, please try to think of some!).
(plus any other questions you have…)

33. Seminar questions? discussion of false belief tests:
do they really test understanding of false belief?
might not need false belief understanding to pass: instead learned rules of thumb, e.g., people usually look for things in the last place they saw them
Lohmann, Carpenter, Call, & Tomasello (2005): update by telling
(Moll, Carpenter, & Tomasello: sound)
standard tests have other demands besides false belief understanding: verbal, executive function demands
other problem with standard tests: tests don’t always correlate
what does Onishi & Baillargeon show?
how to design nonverbal theory of mind tests?
control condition: true belief (chance issue)
measures?