Oculomotor control mechanisms are informed by non-retinotopic perceptual attributes of stimuli

Oculomotor behavior is ultimately controlled by patterns of activity in retinotopically organized populations of neurons in areas, such as the superior colliculus and frontal eye fields, that have visuomotor receptive fields. In contrast, gaze is guided by non-retinotopic variables including task goals, attentional state, and the perceived 3 dimensional structure of the environment. Understanding the mechanistic interface between retinotopic oculomotor control and non-retinotopic gaze control requires the characterization of specific effects of non-retinotopic variables on oculomotor behavior. We investigated how the implied extent of perceptually completed surfaces behind occluding surfaces impacts saccade landing position while searching for small targets. Each trial included four disks and four truncated disks. On half of the trials, rectangles abutted the truncated disks supporting the perception of completed disks behind occluding surfaces. The full disks were rendered in front of the surfaces. Observers searched among the disks for small red or green dots, which appeared only when a saccade landed within a disk region. This design leveraged the tendency for saccades to land near the center of objects (e.g., Melcher & Kowler, 1999) to ask what constitutes an “object” to the eye-movement control system, the perceptually extended whole disk or the optically explicit truncated disk? Distributions of landing position were centered around the centers of the whole disks, with and without occluding surfaces. They were also centered near the center of the truncated disks when no occluding surfaces were present. However, when there were occluding surfaces, landing positions were biased toward the center of the implied whole disks and away from the optically explicit portion of the disk. These results indicate that oculomotor control mechanisms incorporate information about the perceived extent of optically invisible surfaces, indicating that scene structure is factored into what is eventually a retinotopic oculomotor command.