Koch et al. (1999) presented two studies in which cluster analysis was used to examine individual differences in Stroop processing. Stafford (2000) raised two questions concerning the methodology of Study I and the results from Study II. This reply addresses those issues. It is concluded that cluster analysis can be used examine individual differences but that multiple methods of cluster analysis may be appropriate when analyzing data. Further, the results from Study II are consistent with current research on working memory when comparing across participants. The results, however, do suggest that additional research is needed to determine the role of working memory in tasks involving contradictory pieces of information.
Previously published in Psycoloquy, 2001, 12(025), pp. 1-5. http://www.cogsci.ecs.soton.ac.uk/cgi/psyc/newpsy?12.025