Schwartz compared performance of the water-pouring problem depicted in Figure 1c when people were sitting holding an empty glass upright with when they were lying down, holding the glass sideways (that is, in the same relation to their bodies but in a different relation to gravity). In both cases, they were to imagine that the glass was upright, that water reached a particular level in the glass, and they were to turn the glass until the imagined water would start to pour out. Subjects were able to make the correct inference when sitting upright, but not able to do so when lying down, indicating that they could not ignore the effects of gravity.
