Abstract
Despite receiving visual inputs based on retinotopic (gaze-centered) coordinates, we are able to perceive the spatiotopic (world-centered) locations of objects. Some previous studies have found purely retinotopic object-location binding. But more recently, we found that dynamic saccade context (i.e., multiple saccades) could trigger spatiotopic object-location binding. Are there other naturalistic factors that can trigger spatiotopic binding? In the real world, we may also make use of landmarks to help us achieve visual stability. In the current study, we explore how task-irrelevant landmarks influence spatiotopic localization and object-location binding. Participants were asked to conduct two tasks (in separate blocks): a spatiotopic location memory task and an object identity judgement task; we compared performance on both tasks when a task-irrelevant landmark was present or not. In the spatiotopic location memory task, participants viewed an initial object and then had to report its (spatiotopic) location by moving a second (probe) object to the remembered location. In the identity judgement task, we modified the ‘spatial congruency bias’ (SCB) paradigm where participants had to judge if the two objects were the same or different identity. If participants were asked to perform a single saccade during the delay between two stimuli (stimuli presented in a static context, Experiment 1), spatiotopic location memory precision increased with a landmark. But the SCB (a measure of object-location binding) was purely retinotopic and not different between landmark conditions (with vs. without). However, in a more dynamic saccade context (Experiment 2), the presence of a landmark triggered not only spatiotopic location memory improvement, but also a spatiotopic SCB. In summary, task-irrelevant landmarks alone aren’t enough to trigger spatiotopic object-location binding, but they can help in a more dynamic context. These results give us more insight of understanding how we achieve visual stability across eye movements in the complex and dynamic world.