Instruction and belief effects on sentential reasoning

Abstract

Research in humanreasoning has gathered increasing evidence that people tend to reason on the basis of contextualized representations, thus making conclusions compatible with previous knowledge and beliefs, regardless of the logical form of the arguments. This experiment aimed at investigating whether and to what extent sentential reasoning (i.e.reasoning based on compound sentences formed with connectives such as if/then, and, or) was sensitive to the phenomenon of belief effects, under different instruction sets. In a 3x2x2 mixed design (with the last variable as a within-subjects variable), connective sentence (conditional, conjunction and incompatible disjunction), instruction set (logical vs. pragmatic), and statement believability (high vs. low) were varied. Results showed that conjunctions were affected by both instruction set and statement believability, conditionals were affected only by statement believability, whereas no effect of experimental manipulation was found on incompatible disjunctions. Theoretical implications of these findings are discussed. © 2011 Springer.