Deviations seem to increase with horizontal distance between the reference bar and the test bar.
In Kappers and Koenderink's experiments, subjects were not given any time constraints. We are especially interested in possible qualitative effects. These manipulations thus result in a total of four conditions. One would expect that presenting subjects with a short exploration time and no delay, forces them to use an implicit, egocentric representation. The delay conditions are expected to prompt the use of a more cognitive, explicit, allocentric spatial representation.