Visual bias of diagram in logical reasoning

We analyze the information discrepancy between diagram- matic representations and logical reasoning, which we call visual biases in diagrammatic reasoning. Diagrammatic repre- sentations contain semantic information, which is based on the topological configurations of objects, and visual information, such as geometric location. In principle, visual information is unnecessary to the validity of logical reasoning. However, people are so sensitive to visual information such as size and shape in diagrams that they occasionally do not ignore irrele- vant information. This phenomenon leads to mistakes in logical reasoning. We addressed this issue in the present study. In Experiment 1, we assessed whether and how a visual bias of external diagrams affects reasoning performance. We asked participants to directly manipulate size-fixed (Euler) diagrams while solving syllogistic tasks. In Experiment 2, we tested whether size-scalable diagrams were able to reduce a visual bias of diagrams in logical reasoning.