Computing spatial relations in left and right visual fields

The paper reports a study in which subjects estimate whether a dot is left or right, above or below, near or far, or on or off the centre of a circle. Our results show that tasks vary in their difficulty and that, within a task, all decisions are not equally difficult. Specifically, near estimates are always slower than far estimates but especially so when presented to the left visual field-right hemisphere (LVF-RH). There was no evidence of an interaction between hemisphere and task. We discuss the data as showing a hemispheric difference in efficiency for computing spatial relations.