Knowledge of spatial relations: Varying the precision with which locations must be specified

In previous studies, subjects have been asked whether one named town is north (say) of another. The results have shown that as the distance between the towns increases, reaction times decrease. Explanations have focused on a subject's disposition to derive an answer by using less precise information about location when the towns are far apart. In the present experiments, subjects who had memorized a map of Europe were asked whether an imaginary line connecting two named towns passes through a named country. The country was either large or small in area, and the distance between the towns was either long or short. It was expected that in the large country condition less precise information would be used when the distance was long than when it was short, as inferred in previous experiments. Accordingly, reaction times decreased as the distance increased. In the small country condition it was supposed that some degree of precision would be required to determine that the line ran through the country, regardless of the distance between the towns. Therefore, it was expected that the size of the country would limit the degree to which a decrease in precision could occur with an increase in distance. Consistent with this expectation, distance and size of country interacted, such that when the country was small an increase in distance did not cause a decrease in reaction time. Similar results were found in a second experiment.