This paper investigates Japanese speakers’ acquisition of the mass–count distinction in English. Learners judge whether two large objects/portions of stuff are more than six tiny objects/portions of stuff or vice versa. Results show that learners correctly base judgments on number for count nouns (judging that six small cups are more cups than two large cups) and object-mass nouns (e.g., furniture) and on volume for substance-mass nouns (judging that two large portions of mustard are more mustard than six tiny portions of it). For nouns that can be either mass or count in English (e.g., string(s)) or cross-linguistically (e.g., “spinach”), learners fail to shift judgments according to the mass–count syntax in which the words appear. Results suggest that Japanese learners have difficulty using mass–count syntactic cues to disambiguate the meanings and thus fail to acquire the mass–count distinction in English.
