The development of landmarks in spatial memory: the role of differential experience.

To assess how differential experience with objects in a spatial array might serve to establish relative landmarks within the array, first and fifth graders learned models of a town and farm under two conditions. In a homogeneous condition, all elements in the array were visited an equal number of times. In a landmark condition, the relative landmark status of an element was established by distributing the same total number of visits unequally across the elements. The effects of such landmarks on spatial memory were assessed both in reconstructions of the entire array and by pairwise distance estimations. The landmark condition led to a general improvement in spatial recall accuracy as well as providing a relative landmark within the array to help organize the space. The results suggest that different levels of experience (controlling for overall experience and object salience) can establish elements as relative landmarks in spatial memory. Although there was clear developmental improvement in spatial memory, the specific landmark effects were similar for both first and fifth graders.