The development of infants' ability to use verbal

informationwhen understanding others’ goals

Hyun-joo Song Yonsei University, Korea

Seminar on Child Language Development, Kyoto Institute of Technology

July 11, 2015

Do infants also attribute goals to others?

• Infants can detect goals that involve acting on an object(e.g., Csibra et al., 1999; Gergely et al., 1995; Kiraly et al., in press; Luo & Baillargeon, in press; Onishi et al., 2005; Phillips et al., 2002; Song et al., 2005; Thoermer & Sodian, 2001; Woodward, 1998, 1999; Woodward & Somerville, 2000)

Woodward (1998)

Habituation Event

New-goal Test EventOld-goal Test Event

Infants attribute goals to others

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• Previous actions (e.g., Woodward, 1998)

• Eye gaze and emotional expressions(e.g., Carpenter, Akhtar, & Tomasello, 1998; Phillips,Wellman, & Spelke, 2002)

• Verbal information (Martin, Onishi, & Vouloumanos, 2012)

What information do infants useto determine others’ goals?

Martin, Onishi, & Vouloumanos (2012)

Familiarization event

Pre-test display event

<Test event>

Old-object test event

New-object test event

“Koba! Koba!”

“Koba! Koba!”

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the infants assumed(1)agent1’s communication specifically referred to the target object (since agent2 was absent during the familiarization trials, the word ‘‘koba’’ had to convey sufficient information to identify the target object)

(2) expected agent2 to know the referent of the word ‘‘koba’’

(3) detected a violation when agent2 picked up the non-target as opposed to the target object

Martin, Onishi, & Vouloumanos (2012)

The present research

• Question:– Can infants interpret a change in

communication as signaling a possible change in the agent’s upcoming actions?

“A dax!”

“A pilk!”

Song, Baillargeon, & Fisher (2014, Expt 3)

• 7.5-month-olds

• Word or no-word condition

• New-goal or old-goal event

Song, Baillargeon, & Fisher (2014). The Development of Infants’ Use of Novel Verbal Information when Reasoning about Others’ Actions. PLoS ONE 9(3): e92387. doi:10.1371/journal.pone.0092387

Results: 7.5-month-olds

0

5

10

15

20

25

30

35

40

Mea

n Lo

okin

g T

ime

(sec

)

New-goalEventOld-goalEvent

No-word Condition Word Condition

* *

So,

• 7.5-month-olds ignored the actor’s words when reasoning about her goal object.

Song, Baillargeon, & Fisher (2014, Expt 1)

• 12-month-olds

• Word or no-word condition

• New-goal or old-goal event

Results: 12-month-olds

0

5

10

15

20

25

30

35

40

Mea

n Lo

okin

g T

ime

(sec

)

New-goalEventOld-goalEvent

No-word Condition Word Condition

*

Two possible interpretations of 12-month-olds’ data

1. Infants were confused by the verbal information

2. Infants attempted to use the verbal information when reasoning about the actor’s actions.

Perhaps Infants realized that the actor’s change in word signaled a possible change in her actions

1) Upon hearing the new word, they cancelled their expectation that she would reach for the same object (egg)

2) The infants did not have the ability or the time to develop a specific expectation as to what the actor might do next

Which of these two possibilitiesis correct?

Song et al. (2014, Expt 2)

• 12-month-olds

• Word, mixed-word, or delayed-word condition

• New-goal event during test

Word Condition

“A pilk! A pilk!”

“A dax! A dax!”

Mixed-word condition- Words varied across familiarization trials

Mixed-Word Condition

“A pilk! A pilk!”

“A dax! A dax!” or “A corp! A corp!”

Predictions

• If the infants in the word condition were confused by the words, then those in the mixed-word condition should also be confused.– Therefore, the infants in the word and mixed-word

conditions should look equally at the new-goal test event.

Predictions

If the infants in the word condition used the actor’s words to reason about her actions, then the infants in the mixed-word condition might ignore the words, which were not clearly related to her actions.

– Therefore, the infants in the mixed-word condition might look reliably longer at the new-goal test event than those in the word condition.

Results: 12-month-oldsMean Looking Times at New-goal Test Event

0

10

20

30

Word (Experiment1)

Mixed-word .

Mean L

ookin

g T

ime (

sec)

*

Word Condition

Mixed-Word Condition

New-goal Test Event

*

Delayed-word condition– The actor said the words after, rather than before,

reaching for and grasping one of the toys.

Delayed-Word Condition

“A dax! A dax!”

“A pilk! A pilk!”

Predictions

• If the infants in the word condition were confused by the words, then those in the delayed-word condition should also be confused.

– Therefore, the infants in the word and delayed-word conditions should look equally at the new-goal test event.

Predictions

• If the infants in the word condition used the actor’s words to predict her actions, then the infants in the delayed-word condition should be unable to do so, because the words arrived too late to be of use.

– Therefore, the infants in the delayed-word condition might look reliably longer at the new-goal test event than those in the word condition.

Results: 12-month-oldsMean Looking Times at New-goal Test Event

0

10

20

30

Word (Experiment1)

Mixed-word Delayed-word

Mean L

ookin

g T

ime (

sec)

*

Word Condition

Mixed-Word Condition

Delayed-Word Condition

New-goal Test Event

*

So,

• The infants chose not to use the actor’s words to reason about her actions,

– When words varied (Mixed-word condition).– When words arrived after the action

(Delayed-word condition).

Two possible interpretations of 12-month-olds’ data

1. Infants in the word condition were confused by the verbal information

2. Infants attempted to use the verbal information when reasoning about the actor’s action

• Upon hearing the new word, they cancelled their expectation that she would reach for the same object

Kim & Song (2015)

• 10-month-olds

• Two-word conditionWord in a sentence context“Papu-ga it-ne”There is a papu

10-month-olds

0

5

10

15

20

25m

ean

look

ing

time(

sec)

new-goal old-goalnew-goal old-goal

* 6 familiarization trials

Conclusion• Infants can use not only an actor’s previous actions

and emotional expressions but also her words to reason about her goals and actions

– By 12 months, infants expect a change in word to signal a change in goal object

– By 10 months, infants possess some sensitivity to verbal information, but they need more exposure & have difficulty forming new expectations.

Special thanks to…• National Research Foundation of Korea (NRF-2012-S1A3-A2033375)

• Undergraduate and graduate research assistants of Child Development Lab at Yonsei University

• Babies and parents in Seoul, Korea

• Renée BaillargeonUniversity of Illinois

• Cynthia FisherUniversity of Illinois

• Kristine H. OnishiMcGill University