used to solve the problem. That information remains to be discovered by researchers who analyze the protocol. (See Ericsson and Simon, 1984, for an elaboration of this fundamental point.)
Verbal reports have been used effectively with a range of age groups, starting as early as kindergarten (Klahr and Robinson, 1981). Inter-rater reliabilities are often in the 0.6–0.7 range, depending on the complexity of the report and the training of the people who interpret it. There is a substantial trade-off between the reliability and richness of the record. Also, the analysis of verbal reports is extremely labor-intensive.
An equally rich but potentially more problematic source of data is the analysis of verbal interactions when two or more people work on a series of problems (Okada and Simon, 1997; Palincsar and Magnusson, 2001; Teasley, 1995). Obvious difficulties arise when these data are used to evaluate individual performance. However, the communicative demands of group problem solving may reveal certain kinds of knowledge that might otherwise not easily be assessed. Although it might be difficult to apply group problem-solving situations to large-scale assessment, it could be informative to ask individuals to respond to—or interpret others’ responses to—such multiple-player contexts. Indeed, several studies of cognitive development have used the technique of asking children to explain why another child responded erroneously to a question (Siegler, in press). These probes often yield highly diagnostic information about how well the child doing the explaining understands a domain.
An increasingly refined and popular method of investigating cognitive development is microgenetic analysis.1 In this kind of fine-grained analysis, researchers closely observe people at densely spaced time intervals to view minute processes that could be obscured during less-frequent and less-detailed assessments. The properties of microgenetic analysis include (1) observations that span as much as possible of the period during which rapid change in competence occurs; (2) a density of observations within this period that is high relative to the rate of change in the phenomenon; and (3) observations that are examined on an intensive, trial-by-trial basis, with the goal of understanding the process of change in detail. Microgenetic observations may span weeks or months and hundreds of problems. The process
This terminology is an artifact of Piaget’s view of his own focus of research as “genetic epistemology,” with “genetic” meaning simply growth over the life span. The method has no particular connection to or implications for the role of genetics in cognitive development. It could just as well be dubbed “microtemporal analysis” or “microdevelopmental analysis.”