Abstract
Despite receiving visual inputs based on eye-centered (retinotopic) coordinates, we are able to perceive the world-centered (spatiotopic) locations of objects. A long-standing debate has been how object representations are transferred from retinotopic to spatiotopic coordinates to achieve stable visual perception across eye movements. Many studies have found retinotopic effects even for higher level visual processes, like object-location binding. However, these studies often rely on fairly static contexts (prolonged fixation on one location, followed by a single saccade). What if spatiotopic object-location binding is triggered selectively in dynamic saccade contexts? To test this hypothesis, we modified the ‘spatial congruency bias’ (SCB) paradigm. Participants had to judge if two objects presented sequentially were the same or different. We conducted two experiments to investigate retinotopic vs spatiotopic object-location binding in two different states: dynamic saccade context (Experiment 1) versus static context (Experiment 2). In Experiment 1, participants performed repeated saccades throughout the task, whereas in Experiment 2, they only performed a single saccade per trial, during the delay between the two stimuli. We found that, in the static context, the SCB was purely retinotopic, consistent with previous studies. However, in the dynamic saccade context, we observed a strong spatiotopic SCB in addition to the retinotopic SCB. Thus, participants were biased to judge two objects as the same identity when they were presented in the same spatiotopic location (an indication of spatiotopic object-location binding) only in the dynamic context. Critically, the only difference between these experiments was the dynamic versus static context. Thus, these results provide strong evidence that repeated saccades can trigger spatiotopic (world-centered) object-location binding, such that object location representations appear to flip from retinotopic to spatiotopic coordinates specifically due to dynamic saccade context, a finding that is crucial to improved understanding of how the brain achieves visual stability across eye movements.