Sadder but Wiser Induction? Situation-Personality Interaction Revealed by an Inductive Reasoning Model

We have developed a computational model of inductive reasoning that includes both positive and negative premises (Sakamoto & Nakagawa, 2007; 2008). The model explains argument strength ratings in terms of two kinds of similarities; the similarity between positive premises and the conclusion, and the similarity between negative premises and the conclusion. In the model, the similarity functions for positive premises and negatives are represented respectively by two parameters that model the emphasis balance between the two kinds of similarity on argument strength ratings. Emphasis balance has been shown to reflect differences in situational ratings for identical argument strengths (Sakamoto & Nakagawa, 2007; 2008). The present study stresses the further potential for the representation of emphasis balance in our model to also account for the interactions between situational differences and individual personality differences in argument strength ratings. Parameters estimated from individual argument strength data provide two insights into the situation-personality relationship. Specifically, while neurotic individuals (sadder) are not affected by the situation (wiser induction), extrovert individuals tend to place greater emphasize on negative premise similarities regardless of the situation.