9511757 GENTNER Similarity is a central aspect of cognitive processing. It influences category learning, transfer of knowledge, inductive inference, decision-making, and case-based reasoning and planning. Because of its centrality, it is important to understand the psychology of similarity. The approach on which this research is based models similarity as a process rather than considering it as a simple value to be measured. Thus, the approach departs from prior research by others in its emphasis on dynamic models of the psychological processes that underlie similarity, and also in utilizing rich representations of the items being compared. The research involves two computational models of the process of similarity comparison, SME and SIAM, that show how the comparison process proceeds from local to global alignment. A focus of the research is further exploration of the time course of similarity comparison and analysis of its implications for on-line processing. For example, speeded similarity judgments show sensitivity patterns different from slow judgments, an observation relevant to interface design in contexts where humans are placed under speed stress. Previous work on this project investigated two key factors in similarity processing. The first was interconnectivity, the fact that interactions between features can make some features more salient in similarity judgments and even change the psychological interpretation of the features. The second issue was the effect of alignment on judgments of the perceptual similarity of two figures. The new research to be performed under this Accomplishment-Based Renewal is organized around two major questions: 1. How do structure and process interact to determine similarity; and 2. How do results on similarity processing extend to other tasks that use similarity as a component. For example, new experiments will investigate how the seeming similarity between two figures changes with context, by manipulati ng the kind of alignment that is easy or hard to do. Yet another line of research will examine the effect of similarity comparisons on constructive induction associated with similarity judgments, category-based induction, memory retrieval, and decision making. Overall, the project will inform our understanding of the range and flexibility of similarity processing and examine its role in other cognitive functions. ***
