In this study, 4-year-old children were tested in an object name generalization task with a stimulus comparison design. Performance in the generalization task was correlated with performance in a vocabulary test and three executive function tasks assessing inhibition, flexibility, and working memory. Correlational analyses revealed a significant association with flexibility but not with inhibition, working memory or vocabulary test. We interpret the results in terms of a capacity to flexibly generate novel dimensions rather than inhibiting irrelevant dimensions. Individual differences in working memory and inhibition did not significantly influence performance in the word extension task. Moreover, the absence of correlation with the vocabulary performance supports the idea that children did not rely on existing knowledge to find out the relevant dimension.