Clopper Materials

Free Classification Workshop

Northwestern University

Spring 2008

Recommended Readings

Bradlow, A., Clopper, C., & Smiljanic, R. (2007). A perceptual similarity space for languages. Proceedings of the 16th International Congress of Phonetic Sciences, 1373-1376.

Carroll, J. D., & Chang, J.-J. (1970). Analysis of individual differences in multidimensional scaling via an n-way generalization of "Eckart-Young" decomposition. Psychometrika, 35, 283-319.

Clopper, C. G. (2008). Auditory free classification: Methods and analysis. Behavior Research Methods, 40, 575-581.

Clopper, C. G., & Pisoni, D. B. (2007). Free classification of regional dialects of American English. Journal of Phonetics, 35, 421-438.

Corter, J. E. (1982). ADDTREE/P: A Pascal program for fitting additive trees based on Sattath and Tversky's ADDTREE algorithm. Behavior Research Methods and Instrumentation, 14, 353-354.

Esposito, C. M. (2006). Chapter 3: Free-sort experiment. The Effects of Linguistic Experience on the Perception of Phonation.Doctoral dissertation, University of California, Los Angeles.

Additional Preparation for the Workshop

During the workshop, we will complete a free classification experiment, from experimental design and setup, through data collection, to data analysis. To prepare for the workshop, please read the papers listed above and complete the following two tasks as a group.

  1. Decide on the dimension of similarity that you want to investigate. Bradlow et al. (2007) examined language similarity, Clopper & Pisoni (2007) examined dialect similarity, and Esposito (2006) examined voice quality similarity. Clopper (2008) provided some other suggestions for possible dimensions of similarity that could be explored using the free classification technique. If you would like to use the materials that you are developing for Matt Gordon's portion of the workshop for the free classification task, that would be fine, or you can develop a different set of materials and explore an unrelated research question.

  2. Select the auditory stimulus materials. To make the project manageable, you should aim for approximately 20 stimulus items. Each stimulus item should be no longer than 2 seconds in duration to reduce the memory load for the participants. You do not need to prepare the stimulus materials in advance.