Kalashnikova, M. 1 , Mattock, K. 2 & Monaghan, P. 1
1 Lancaster University
2 University of Western Sydney
Mutual Exclusivity (ME) refers to children?s tendency to establish one-to-one relations between basic-level labels and their referents. It is employed as a default word-learning strategy, but it remains unknown whether ME is present at the onset of lexical acquisition or is developed as infants? linguistic experience increases. The present study assessed early use of ME in tasks of exclusivity and lexical overlap in relation to infants? receptive vocabulary and through fixation pattern analyses in these tasks. Eighteen-month-old infants completed an eye-tracking preferential looking ME paradigm. In the Exclusivity condition, a speaker assigned a novel label to an unfamiliar object. This object appeared next to another unfamiliar object, and the speaker made a request using a different novel label, requiring infants to reason by exclusion. The Overlap condition was identical except that two speakers each assigned a novel label for the same unfamiliar object, and each used the label that they had introduced for the request stage, requiring infants to accept lexical overlap. Infants maintained ME in the Exclusivity condition, but their performance was related to receptive vocabulary scores (r=.546, p=.005). Their fixations followed a quadratic trend since initial fixations at target were interrupted by fixations at distracter followed by further fixations at target. Infants? performance was at chance in the Overlap condition showing fixations at target and distracter but no clear one-to-one or overlapping mappings. These findings indicate that ME does not operate at the onset of word learning but emerges as the infants? linguistic experience increases. Furthermore, our fixation pattern analyses suggest that in maintaining ME, infants do not show a default bias towards one-to-one mappings by directly assigning one novel label to one unfamiliar object. Instead, they actively evaluate all the information available in the word-learning situation to correctly map a word to its referent.