Spatial proximity determines overshadowing between landmarks in human spatial navigation

Abstract

Previous studies involving birds and humans have identified spatial proximity as a source of overshadowing between landmarks in navigation. In Herrera et al. (2024), subjects were trained in an open environment to locate a hidden goal with reference to an array of four landmarks placed at varying distances from it. Critically, two of the four landmarks (i.e., target landmarks) were placed at distances that were common among groups, whereas the remaining two were either proximal to, or distal from, them. Landmarks near the goal overshadowed (i.e., competed with) learning about the further ones, and this effect disappeared in the groups trained with distal landmarks. However, neither of these studies included a control group providing a baseline performance to assess the extent of competition; were the data indicative of overshadowing or facilitation of learning? Thus, we assessed whether spatial proximity determines overshadowing or facilitation between landmarks, including a control group trained with the target landmarks only. We conducted three experiments with varying training lengths: six training trials in Experiments 1 and 16 in Experiments 2 and 3. We also extended the landmark–goal distance in Experiment 3. In all experiments, we observed overshadowing in groups trained with closer nontarget landmarks (relative to the target) but no overshadowing when the nontarget landmarks were distal from the target landmarks. Overall, these experiments reveal that landmark–goal distance determines overshadowing between landmarks, a finding consistent with domain-general theories of learning, such as a modification of Pearce’s configural model.