Information seeking by asking questions is fundamental to solving some problems. How quickly it proceeds can be important, especially if stakes are high. This experiment compared the processing times of three question types generated by early adolescents, middle adolescents, and young adults who sought to identify unknown target exemplars in a series of test arrays. Category questions, which eliminate alternatives based on their membership in contrasting mutually exclusive sets, were of two types: conceptual and perceptual. Conceptual category questions took longer to generate than perceptual category questions for all age groups. Syncretic questions, which refer to more than one category, took longer to generate than perceptual category questions for early adolescents, although they did not take longer to generate than perceptual category questions for the two older groups. Age-related changes in cognitive processing, syncretic thinking, and experience with hypothesis testing provide a framework for interpreting these results.Key words: processing time, 20 questions, adolescence, problem solving, categorization 1 Dorothy W. Jackson collaborated with the first author in designing and carrying out the study, and co-writing early drafts of this report. Unfortunately, she passed away before its completion. Timothy Drumm provided valuable assistance at the inception of the project. The authors also wish to thank the students, administrators, and faculty of the middle and senior high schools in northwestern Ohio for their part in this research.