Developing Mutual
Exclusivity in the Lab
Seán Roberts
s.g.roberts@sms.ed.ac.uk
Language Evolution and Computation Research Unit
Introduction
Monolingual children exhibit Mutual Exclusivity (a heuristic which
assumes that each object only has one name and each name only
refers to one object) but bilingual children do not [1-4].
ME may be more productive when exposed to one language from
each parent than when exposed to parents using two languages
interchangeably (Children may apply ME within speaker). Controlling
for the distribution of variation over speakers is difficult in child
studies. Can an artificial language learning experiment run on
monolingual adults be used to explore the factors that effect the
development of ME?
Method
Train:
6
Test :
Both speakers name all objects in all the languages
they know
A speaker says a word and the participant makes a
forced-choice decision between two known objects
Linguistic test:
Old tests:
Known word, Known Object, Known Object
Check tests:
Known word,
Adult participants were exposed to two ‘alien’ speakers naming ‘alien’ objects in four
conditions, each of which had a different distribution of words over speakers.
Testing Training
Participants completed a series of training and testing blocks
until they were familiarised with a set of objects and labels.
They were then given two sets of final tests:
Speaker appears
Known Object, Unknown Object
Mutual Exclusivity tests:
Unknown word,Known Object, Unknown Object
Po
Po
Feedback
Po
Po
Participant chooses one
Speakers use one
different label
for each object
Bilingual
Speakers use two
common labels
for each object
Check Tests
Same as One Language, but with double the number of objects.
(Number of words to learn is equal to the conditions below)
Po
Be
Po
Po
Be Be
Speakers only use one word per trial
Condition
1.51 0.220
Test Type
0.84 0.362
Sex
0.49 0.484
Handedness
3.58 0.062
2.75 0.049
0.36 0.783
5.18 0.026
0.98 0.325
0.80 0.374
Significant interaction between test type and condition: Subjects in the One
Language condition perform poorly at choosing known objects. Interaction is
not significant excluding One Language condition (F(2,56)=0.6, p = 0.5).
Reaction Time
ANOVA
Choose Unknown Object
F
p
Condition
5.65 0.002
Test Type
0.20
0.655
Sex
0.29
0.59
Handedness
0.22
0.637
Condition x
0.35 0.787
Type
Condition x
3.10 0.032
Sex
Type x
0.001 0.975
Sex
Condition x
0.08 0.775
Handedness
Type x
0.13 0.720
Handedness
Conclusion
Po
Mean
ME - Old:
p
One Language and One Language x2 participants are slower to react than
Two Languages and Bilingual conditions.
ME Tests
Conditions
Po
✔
*
Old Tests
F
Condition x
Type
Condition x
Sex
Type x
Sex
Condition x
Handedness
Type x
Handedness
Subjects reported
being ‘attracted’ to
the novel objects
Accuracy: in ME test all participants choose novel object at ceiling
Reaction Time:
Two objects appear
ANOVA
Choose Unknown Object
*
Results: Linguistic task
Speaker names object
Two Languages
Choose Known Object
Choose the Known Object / Unknown Object
Speaker appears
One Language x2
Prediction: Variation in labels may affect attitude towards meanings [5].
Accuracy
Non-linguistic test:
Speaker names object
Speakers use one
common label
for each object
Results: Non-Linguistic task
Choose Known Object
Object appears
One Language
[ES/G010277/1]
745ms
142ms
810ms
232ms
658ms
143ms
705ms
146ms
Prediction: Participants with reduced ME bias will respond slower in ME task
Result: Main effect of condition and type. F(3,111)=5.4, p<0.01; F(2,111)=20.6, p<0.001
No interaction between test type and condition.
Except, with LMER analysis, participants in the One Language x2 condition
were slower that those in other groups.
(Random slopes by Type, log likelihood difference = 2.8, df = 2, χ2=5.8, p =0.05)
Prediction not supported
This study was unable to replicate differences in ME behaviour
found in child studies. There were no differences between the two
languages and the bilingual conditions. Any differences between
those conditions and the one language conditions may be due to
different approaches to the task. Participants in the one language
condition can complete the familiarisation phase learning a
shallower impression of the labels (e.g. the first letter) while the
other conditions need to pay more attention to the labels and
objects. This shallow learning puts them at a disadvantage when
tested in the linguistic and non-linguistic tasks. However, the factors
that cause differences in ME behaviour in this adult study are
probably different to those in child learning.
References
[1] Byers-Heinlein, K. and Werker, J. F. (2009). Developmental Science, 12(5):815–823.
[2] Healey, E. and Skarabela, B. (2009). Proceedings of the Child Language Seminar, University of Reading.
[3] Houston-Price, C., Caloghiris, Z., and Raviglione, E. (2010). Infancy, 15(2):125–150.
[4] Markman, E. M. and Wachtel, G. A. (1988). Cognitive Psychology, 20:121–57.
[5] Mather, E., Schafer, G., and Houston-Price, C. (in press). British Journal of Developmental Psychology.