Developing Mutual Exclusivity in the Lab Seán Roberts [email protected] 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 . 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. 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