Separating the chaff from the oats: Evidence for a conceptual distinction between count noun and mass noun aggregates

The English language makes a grammatical distinction between count nouns and mass nouns. For example, count nouns but not mass nouns can be pluralized and can appear with the indefinite article. Some scholars dismiss the distinction as an arbitrary convention of language whereas others suggest that it is conceptually based. The present studies examined this issue with respect to aggregates (i.e., entities composed of multiple constituents that are generally homogenous). Experiment 1 demonstrated that participants rate the elements of familiar count noun aggregates (e.g., grapes and toothpicks) as more perceptually distinguishable than those of familiar mass noun aggregates (e.g., rice and confetti). They also were more likely to interact with one or a few elements of count noun aggregates but with multiple elements of mass noun aggregates. Experiment 2 replicated these results using a different sample of aggregates. In Experiments 3 and 4 manipulation of these factors predicted whether participants labeled a novel aggregate with a novel count or mass noun. These results show that for aggregates, count and mass noun usage is to a large degree conceptually based. The conceptual basis is consistent with the principle of cognitive individuation: speakers conceptualize the referents of count nouns as distinct individuals and the referents of mass nouns as non-individuated entities. However, we also identified exceptions to this view and suggest that they arise from linguistic convention or competing linguistic functions.