Do 9-month-old Infants Expect Distinct Words to Refer to Kinds? Kathryn Dewar

“Imagine a language with only proper names. A new word that names a dog must refer to that particular dog and nothing else. Learning this language would require the ability to track individuals over time, but it wouldn’t require any ability to generalize, to recognize how collies are different from terriers or how dogs are different from tables. Such languages don’t exist, of course.” (Bloom, 2000)

Early Words: Proper Names or Count Nouns?  Proper names such as Fido refer to specific individuals  Count nouns such as dog refer to kinds of individuals or object categories  Controversial issue:  Whether infants interpret these early words as count nouns that refer to kinds or as proper names that refer to individual objects  What is the assumption of an early word-learner?  Does this word refer to THAT (individual) object? (PN)  Does this word refer to that KIND of object? (CN)

Are Early Words Proper Names that Designate Individuals? Locke: –At this early stage, children know only proper names Anecdotal Evidence: –Only own rubber ducky is called duck ( label is not generalized to other members of the kind “duck”)

Are Early Words Count Nouns that Refer to Kinds?  There are 3 lines of research used to support this claim:  Generalization Studies  Categorization Studies  Object Individuation Studies  While these studies are suggestive, ambiguity remains

 Will a newly learned word for an object be extended to other members of the object’s kind?  Woodward, Markman, & Fitzsimmons (1994)  13-month-olds & 18-month-olds Children heard a new label 9 times in a 5 min training session & their comprehension was later assessed Children generalized this newly learned label to novel exemplars of the training category Generalized to objects that differed in colour  What about younger children? Are Early Words Count Nouns that Refer to Kinds? Generalization Studies

Are Early Words Count Nouns that Refer to Kinds? Categorization Studies  Does labeling objects with novel nouns highlight object categories?  Balaban & Waxman (1997)  9-month-olds “A RABBIT”

Are Early Words Count Nouns that Refer to Kinds? Categorization Studies  Does labeling objects with novel nouns highlight object categories?  Balaban & Waxman (1997)  9-month-olds Familiarized to slides of animals (rabbits) while hearing either labeling information (word condition) or tones (tone condition) On test trials, a new exemplar from the familiar category (a rabbit) was paired with a novel animal (a pig)  Infants in the word condition showed greater attention to novelty  It seems that the noun label facilitated categorization

A Brief Detour… Object Individuation Studies  The process that assigns segregated objects seen on different occasions to single or multiple objects.  Example: You see a dog at the park. The dog runs into the woods and a while later, a dog runs out of the woods Did you see the same dog or two different dogs??? -OR-

Object Individuation Studies Xu & Carey (1996) Occluder opened to reveal… -OR- UNEXPECTED EXPECTED

Object Individuation Studies Xu & Carey (1996)  10-month-olds: did not look longer at the unexpected vs. the expected outcome –Did not use PROPERTY/KIND information to conclude there was two distinct objects involved  12-month-olds: looked longer at the unexpected vs. the expected event –Did use PROPERTY/KIND information for object individuation

Back on Track… Are Early Words Count Nouns that Refer to Kinds? Object Individuation Studies  Can language assist infants in the task of object individuation?  Xu (2002):  9-month-olds What if the objects were given distinctive noun labels with each emergence?

Object Individuation Studies Xu (2002) Occluder opened to reveal… -OR- UNEXPECTED EXPECTED “Look, a DUCK!” “Look, a BALL!”

Are Early Words Count Nouns that Refer to Kinds? Object Individuation Studies  Xu (2002)  Infants succeed at 9 months if given contrastive labels  Giving the objects noun labels facilitates object individuation  Xu suggests that the reason language helps is because distinct words refer to different KINDS of things  2 distinct noun labels = 2 kinds of objects  But, the evidence is also consistent with the “early words as proper names” hypothesis

Early Words: PNs or CNs? Remaining questions from the previous research…  Did infants interpret the distinct words as referring to distinct kinds of objects (TYPES) or distinct individual objects (TOKENS)  Do they expect:  2 objects (could be identical, as long as there’s 2)  2 different objects (different in property? Or kind?)  These are the very questions we address in the current set of studies

The Interactive Bit: What are Adults Expectations? “I see a ZAV! I see a ZAV!” ??????

The Interactive Bit: What are Adults Expectations? “I see a FEP! I see a WUG!” ??????

Study 1 Questions to be addressed….  Do infants expect distinct labels refer to different objects? -AND-  Do infants expect one repeated label refers to identical objects “I see a ZAV!” “I see a FEP!” “I see a DAK!”

Study 1 Procedure: Familiarizations Identical Object Outcome Different Object Outcome

Study 1 Procedure: Familiarizations  8 familiarization trials: 4 identical object outcomes 4 different object outcomes  4 kinds of object-pairs shown:  Familiarization trials 5-8 are a repeat of trials 1-4  The 4 object-pairs presented during familiarization are presented during the test trials  The same object-pairs are used for both phases in order to: Diminish the novelty of the object-pairs Give infants a sense of what is inside the box (what they can expect to see)

Study 1 Procedure: Test Trials “I see a FEP! I see a FEP!” EXPECTED outcome UNEXPECTED outcome ONE LABEL

Study 1 Procedure: Test Trials “I see a DAX! I see a WUG!” EXPECTED outcome UNEXPECTED outcome TWO LABELS

Study 1: Experimental Design EXPECTED UNEXPECTED EXPECTED ONE LABEL (Fep, Fep) TWO LABELS (Dax, Wug) IDENTICAL OBJECTS DIFFERENT OBJECTS

Study 1 Results: Familiarizations 12.61s SD = s SD = 6.03 Identical Objects Different Objects n.s. t (23) = -1.14, p =.27

Study 1: Results EXPECTED 5.41s (SD=3.57) UNEXPECTED 11.20s (SD=10.04) UNEXPECTED 10.02s (SD=7.86) EXPECTED 8.38s (SD=9.53) ONE LABEL (Fep, Fep) TWO LABELS (Dax, Wug) IDENTICAL OBJECTS DIFFERENT OBJECTS (n=24)

Study 1: Results EXPECTED 5.41s UNEXPECTE D 11.20s UNEXPECTE D 10.02s EXPECTED 8.38s ONE LABELTWO LABELS IDENTI CAL OBJECT S DIFFERENT OBJECTS  No Main Effect of number of labels (one vs two) f (1,23) = 2.58, p =.12  No Main Effect of object outcome (identical vs different) f (1,23) =.49, p =.49  Interaction between number of labels & object outcome f (1, 23) = 5.06, p =.03   Paired-sample t-tests  Wilcoxon signed ranks test  t (1, 23) = -2.93, p <.01t (1, 23) = 1.13, p =.14p =.02p =.05(1 tailed)

Study 1 What is still not yet known… In this first study:  Pairs of objects were either identical or completely different  dissimilar colour, shape, texture, material, etc  However… For the different object pair:  Are all property differences created equal?  Is any dissimilarity between the “different objects” sufficient?  Must the objects simply be different in some respect or is the way in which the objects differ important?

Why all property differences might NOT be created equal  Different words are used to designate different KINDS of things  Objects differing along a property dimension that does not effect kind membership are not given distinct labels  However, the property difference of SHAPE is closely connected with kind membership (Rosch et al., 1976; Soja, Carey & Spelke, 1991)  Generally speaking, objects that differ in shape are usually different kinds of things & are marked by different labels

Predictions…  Hearing two distinct labels should suggest two different kinds of objects in the box  Infants will look longer to the unexpected outcomes if: –The property difference between the objects implies a difference in kind (e.g. SHAPE) Infants will NOT look longer to the unexpected outcome if: –The property difference between the objects does NOT imply a difference in kind membership (e.g. COLOUR)

Study 2: SHAPE

Used the same procedure as Study 1, except objects were either:  Identical --or--  Identical in every property but SHAPE “I see a ZAV! I see a ZAV!” “I see a FEP! I see a WUG!”

Study 2 Procedure: Test Trials “I see a ZAV! I see a ZAV!” EXPECTED outcome UNEXPECTED outcome ONE LABEL

Study 2 Procedure: Test Trials “I see a DAX! I see a WUG!” EXPECTED outcome UNEXPECTED outcome TWO LABELS

Study 2: Experimental Design EXPECTEDUNEXPECTED EXPECTED ONE LABEL (Fep, Fep) TWO LABELS (Dax, Wug) IDENTICAL OBJECTS DIFFERENT OBJECTS

Study 2 Results: Familiarizations 12.93s SD = 3.75s 12.52s SD = 3.42s Identical Objects Different Objects n.s. t (15) =.44, p =.66

Study 2: Results EXPECTED 6.89s (SD=3.41) UNEXPECTED 10.04s (SD=8.84) UNEXPECTED 10.34s (SD=6.06) EXPECTED 5.72s (SD=3.72) ONE LABEL (Fep, Fep) TWO LABELS (Dax, Wug) IDENTICAL OBJECTS DIFFERENT OBJECTS (n=16)

Study 2: Results EXPECTED 6.89s UNEXPECTE D 10.04s UNEXPECTE D 10.34s EXPECTED 5.72s ONE LABELTWO LABELS IDENTI CAL OBJECT S DIFFERENT OBJECTS  No Main Effect of number of labels (one vs two) f (1, 15) =.47, p =.51  No Main Effect of object outcome (identical vs different) f (1, 15) =.11, p =.75  Interaction between number of labels & object outcome f (1, 15) = 8.16, p =.01   Paired-sample t-tests  t (15) = -2.14, p =.02t (15) = 2.03, p =.03 (1 tailed)

Study 2 (Shape): Discussion  Results mirrored those of the first study (replication) Study 1Study 2  Infants seem to expect that:  A distinct (repeated) label denotes identical objects  Two distinct labels denote two different (shaped) objects  Different-shaped objects pairs were equivalent to completely different object pairs

What we STILL do not know…  Are all property differences created equal? Shape differences between object pairs are just as good as using totally different kinds of objects  Shape differences are salient cues to kind membership  The results of the shape study are NOT enough! Does not demonstrate that infants expect distinct labels to refer to distinct KINDS  Need to show that another property difference (that is independent of kind membership) does not elicit this pattern of looking  Must demonstrate that not just any property difference between the object pairs will create this result

Returning to our Predictions…  Hearing two distinct labels should suggest two different kinds of objects in the box  Infants will look longer to the unexpected outcomes if: –The property difference between the objects implies a difference in kind (e.g. SHAPE) ? Infants will NOT look longer to the unexpected outcome if: –The property difference between the objects does NOT imply a difference in kind membership (e.g. COLOUR)

Study 3: COLOUR

Used the same procedure as previous studies, except objects were either:  Identical --or--  Identical in every property but COLOUR “I see a ZAV! I see a ZAV!” “I see a FEP! I see a WUG!”

Study 3 Procedure: Test Trials “I see a ZAV! I see a ZAV!” EXPECTED outcome UNEXPECTED? outcome ONE LABEL

Study 3 Procedure: Test Trials “I see a DAX! I see a WUG!” EXPECTED? outcome UNEXPECTED outcome TWO LABELS

Study 3: Experimental Design EXPECTEDUNEXPECTED UNEXPECTED?EXPECTED? ONE LABEL (Zav, Zav) TWO LABELS (Dax, Wug) IDENTICAL OBJECTS DIFFERENT OBJECTS

Study 3 Results: Familiarizations 11.24s SD = s SD = 4.11 Identical Objects Different Objects n.s. t (15) =.92, p =.37

Study 3: Results EXPECTED 6.83s (SD=6.04) UNEXPECTED 6.09s (SD=4.15) UNEXPECTED? 8.09s (SD=6.50) EXPECTED? 10.31s (SD=8.93) ONE LABEL (Zav, Zav) TWO LABELS (Dax, Wug) IDENTICAL OBJECTS DIFFERENT OBJECTS (n=16)

Study 3: Results EXPECTED 6.83s UNEXPECTE D 6.09s UNEXPECTE D? 8.09s EXPECTED? 10.31s ONE LABELTWO LABELS IDENTI CAL OBJECT S DIFFERENT OBJECTS  No Main Effect of number of labels (one vs two) f (1, 15) =.20, p =.66  Main Effect of object outcome (identical vs different) (p=.02) f (1, 15) = 7.61, p = s SD = s SD = 6.24  No Interaction between number of labels & object outcome f (1, 15) = 1.88, p =.19

Study 3: Results  This pattern of results differs from that of Study 1 & Study 2 Study 1 Completely Different Study 2 Shape Study 3 Colour  Not just ANY property difference between the “different object pair” produces the expectation that the objects should be marked by distinct labels  A difference related to kind membership (SHAPE) produced the effect  A difference unrelated to kind membership (COLOUR) did not

Returning to our Predictions Again…  Hearing two distinct labels should suggest two different kinds of objects in the box  Infants will look longer to the unexpected outcomes if: –The property difference between the objects implies a difference in kind (e.g. SHAPE)  Infants will NOT look longer to the unexpected outcome if: –The property difference between the objects does NOT imply a difference in kind membership (e.g. COLOUR)

Comparing All Three Studies  Conducted a repeated-measures ANOVA with “study” as the between-subjects factor  There was a 3-way interaction (study X word X outcome) Study 1 Completely Different Study 2 Shape Study 3 Colour  Looking only at Study 1 & Study 2: – No three-way interaction (Result pattern is the same)  Looking only at Study 1 & Study 3: – Three-way interaction (Result pattern is different)  Looking only at Study 2 & Study 3: – Three-way interaction (Result pattern is different)

Familiarizations: Establishing Possible Object Outcomes  Study 1 & 2 (totally different & different- shape) : –Object-pairs alternate between identical and different kinds –Possible Outcomes: either pairs of the same kind or pairs of different kinds of objects –Labeling a CUE to which object outcome will be revealed

Familiarizations: Establishing Possible Object Outcomes  Study 3 (different colour) : –Different-colour pairs are seen as the same kind of objects –Here, both identical & different-colour pairs represent the SAME kind of object –Possible Outcome: pairs of the same kind of object –Labeling adds no predictive information –Looking-pattern reflects baseline preferences

Early Words: Proper Names or Count Nouns?  It’s been claimed that early nouns are: Proper names (designate INDIVIDUALS) --as opposed to-- Count nouns that refer to object categories (KINDS)  If early labels simply pick out individuals: You would not expect differential looking between identical and different object outcomes (both represent 2 individuals) All three studies should have the same looking- time pattern  Early nouns are likely count nouns that refer to kinds

Special Thanks to: Dr. Fei Xu Laura Kerlin Vashti Garcia Anjula Joshi Stephanie Denison Henny Yeung