Spatial prepositions are linguistic tools to exchange information about spatial location of objects. For instance “The book is over the table” indicates that the located object (LO) is somewhere “over” the reference object (RO). Assigning direction to space (selecting a reference frame) is a necessary precursor to understanding where the LO is located. Three experiments are reported which investigated the effect of the orientation of both the LO and the RO on the acceptability of the prepositions
. We found that when the LO was not vertically aligned, the appropriateness for a given spatial preposition changes. In general scenes with the LO pointing at the RO were judged less acceptable than scenes with the LO vertically oriented. These results suggest that people generate reference frames for both LO and RO prior to assigning direction to space. Modifications to Multiple Frame Activation theory  are discussed.