Making good judgments is a core competence and a prerequisite for success in personal and professional contexts. Making a wrong call when deciding to invest in a new business idea, or when assessing the probability that a prisoner will commit a crime when released on parole, can ruin many people’s lives. However, in order to improve people’s judgments, it is crucial to understand the cognitive processes underlying judgments.
Past research suggests that people use at least two different kinds of strategies when making judgments: rule-­ and memory-­based strategies. For instance, a doctor could evaluate a patient’s speed of recovery as a linear function of the severity of symptoms and the age of the patient. In this case, he would rely on a rule-­based strategy. In contrast, he could also rely on a memory-­based strategy, assessing recovery by comparing the current patient to similar patients he has treated before and how fast they recovered. There is good evidence that people use both strategies when making judgments. Past research suggests that in general, people seem to prefer rule-­based strategies, but rely on memory-­based strategies in tasks where rule-­based strategies fail, or are too difficult or too demanding to apply. This research relies on the assumption that people choose between the strategies. However, instead of choosing between strategies, people might employ both strategies simultaneously. For instance, we found that people were influenced by similarity to previously encountered persons even though they used a rule-­based strategy to integrate information about their characteristics. In the current project we aim to develop a computational model that can describe how people learn to rely on a rule-­based or a memory-­based strategy and how they integrate the output of both strategies. Furthermore, a computational model encompassing both rule-­ and memory-­based processes will enable us to determine the contribution of rule and memory-­based strategies and how they relate to individual differences in cognitive abilities such as working memory capacity or episodic memory.