Plunging into the pool of death: imagining a dangerous outcome influences distance perception.

We examined whether manipulating the imagined consequences of falling would influence the perception of height, distance, and size. In experiment 1, height and size perception were measured when participants stood at a short height (0.89 m) or a medium height (1.91 m) above either an empty pool or a pool filled with a bed of nails. Participants who viewed the bed of nails and imagined falling into it estimated both the height as taller and the size of the bed of nails as larger than participants who imagined falling into an empty pool. In a second experiment, participants overestimated the horizontal ground distance to and across the bed of nails after being told to imagine jumping over it. Overall, these experiments suggest that costs associated with imagined actions can influence the perception of both vertical and horizontal extents that are not inherently dangerous.