Similarity-based and abstraction-based processes in judgments from multiple information sources

In this dissertation, I propose that similarity-based processes are an integral part of the judgment process and that they are sequentially integrated and interact with abstraction-based processes in a weighted, additive fashion. This theoretical stance challenges the state-of-the-art in the judgment domain that people shift between similarity-based and abstraction-based processes depending on several factors. As such, this dissertation provides new explanations for how judgments are formed and empirical evidence in support of the theoretical foundations. Specifically, it explains the empirical finding that people are in general able to abstract knowledge about the relationship between objects and associated outcomes and that at the same time similarities to known situations bias judgments, although they are assumed to be not informative. In the first paper, I present an anchoring-and-adjustment model which assumes that a judgment is the result of recalling one known instance from memory that is then adjusted based on abstracted knowledge. This model explains how both types of processes interact without the additional need to assume that people actively switch between different processes. In the second paper, I present an anchoring-and-adjustment model that assumes that repeated probability judgments are the result of weighing and adding single probabilities that are the result of a similarity-based process. The result of the weighing-and-adding process is adjusted depending on the similarity between previous judgments and the current context. This model explains how non-informative information influences judgments. In the third paper, I present a general approach designed to understand how people learn to coordinate and apply several different processes. Empirical investigations conclude that people build a weighted average of different cognitive processes and do not switch from one to the other. All in all, the results presented in this dissertation bring important new insights about the combination of different information sources and the coordination of similarity-based and abstraction-based cognitive processes.