Managing Gaze Competition during Simultaneous Manual Action Control and Environment Monitoring

Research on visually guided object manipulation has shown that participants fixate goal locations-including objects to be grasped and locations where they are placed-prior to hand arrival, with gaze serving two primary functions: directing the hand (or object in hand) to the vicinity of the goal using peripheral vision and gaze-related signals and guiding the hand using central vision as it approaches the goal. However, real-world manipulation tasks are often performed while concurrent monitoring of the environment, resulting in competition for gaze. We examined gaze-hand coordination under such conditions. Human participants of either sex performed a manipulation task that involved grasping balls and placing them at target locations, while concurrently monitoring a display to detect probabilistically occurring visual events, which required central vision. Participants managed gaze competition in two main ways. First, fixations allocated to the action task were brief and prioritized directing the hand toward the goal (object or target location); participants then relied on tactile feedback to complete the action (grasping or placing the object). When tactile feedback was reduced-by using a tool instead of the fingertips to perform the task-gaze additionally served the guiding function. Second, participants reduced gaze competition by exploiting temporal regularities of events in the monitoring task. Specifically, they adjusted both gaze allocation and hand movement timing to reduce the likelihood that action task fixations would coincide with visual events. These findings demonstrate how individuals flexibly integrate sensorimotor control with analysis of environmental statistics to manage competing visual demands.