The mutual exclusivity bias in children's word learning: By W. E. Merriman and L. L. Bowman. In Monographs of the Society for Research in Child Development, 54, Serial No. 220, 1989

Abstract

Merriman and Bowman (1989) explore one proposed constraint on word learning, mutual exclusivity, the assumption that each object has only one label. Chief among their contributions is treatment of mutual exclusivity as a default assumption—a probabilistic bias which can be overridden. We elaborate this view to address misconceptions of the notions of biological constraints that pervade recent discussions of constraints on word learning. Misconstruing constraints as rigid, absolute responses instead of probabilistic biases has led researchers to interpret any violation as invalidating a given constraint. More confusion surrounds questions about the origins of the constraints. We dispute the idea that the age of appearance of lexical constraints reveals whether the constraints are innate, and argue that current discussions of the innateness of constraints are over-simplified. In this case, we also question the appropriateness of Merriman and Bowman's methodology for use with 2-year-olds and challenge their conclusion that mutual exclusivity is absent in children under 2 1 2 . Merriman and Bowman's thoughtful conceptual analysis establishes several distinct ways in which mutual exclusivity can be manifested. Thus, putative counterexamples occur when an investigator tests for only one consequence of mutual exclusivity and ignores its other possible implications. Merriman and Bowman's studies with children from 2 1 2 on document that each of these alternative ways of preserving mutual exclusivity guides word learning.