Individuals previously identified as language-bound (LB) and language-optional (LO) participated in a series of experiments to study verbal fluency. The two groups showed a striking similarity in the number of responses they produced for categories with constraints at various levels (word form, word content, sentence, interpretation). This similarity occurred for both written and oral modes of response, and over a wide range of time intervals. Other types of measures, however, suggested that the forms in which a given category can be represented affected the ease with which the two groups produced their responses. LBs had more difficulty with categories that lent themselves readily to a spatial representation, while LOs had more difficulty with a category based on phonetic constraints. The results were considered in terms of their implications for the LB phenomenon, as well as general approaches to the study of verbal fluency. (Author)