The Effects of Perceptual Load on Localization across Saccades

Humans make roughly three saccades per second during search or scene inspection, during which time the retinal information we receive changes dramatically. Despite this upheaval in sensory information, we are able to maintain a surprisingly accurate spatial scene representation. This study examines the effect of perceptual load on scene reconstruction across eye movements to determine whether high perceptual load causes a shift from encoding spatial location with a gaze-centered strategy to a more environment-centered strategy. In our experiment we manipulate perceptual load using a continuous vernier acuity detection task while presenting a probe and environment in a secondary localization task. We expected that subjects would be able to use both gaze coordinates and environmental coordinates under low load situations, but under high load, they would be forced to rely predominantly on environmental cues. The results show that the load manipulation disrupted localization. The presence of environment cues increased the accuracy of localization, but only in the low-load condition. These results suggest that using environmental coordinates to encode location requires attentional resources and interacts with remapping of gaze coordinates