Abstract: | ![]() This study has two main objectives. The first is to specify the nature of the mental representation and processes underlying spatial reasoning with diagrams and sentences. The second is to investigate whether mental representations reproduce geometrical relations relative to spatial reference frames. Forty participants solved 64 spatial reasoning problems that were displayed using diagrams or sentences. Problems varied with respect to their logical structure and geometrical content. We measured the premise's inspection times, the responses, and the response times. Problems were significantly (p < .01) easier to represent and solve when displayed as diagrams than as sentences, indicating that participants constructed mental models. Mental representations and spatial deductions also varied consistently with the geometrical content, suggesting that mental models reproduced this content relative to a viewer‐centred reference frame. |