Three pairs of spatial antonyms (higher than/lower than, above/below, and rising away from/falling away from) were used in a task in which subjects judged whether a sentence accurately described a previously presented pictorial relationship. Subjects' reaction times were used as the dependent measure. Since all three word pairs were used synonymously to describe the same pictures (either a plus over a star or a star over a plus), significant differences between the pairs must reflect differences in ability to apply them to this task. Reaction-time differences indicated that, within each pair of antonyms, the member referring to "upness" was easier to comprehend and that the three pairs differed in the size of intra-pair differences, in overall comprehensibility, and in correspondence to a model of picture/sentence matching developed by Clark and Chase (1972) to describe the use of "above/below" in this task. (Author/AA)