Inhibition of Return in Three-Dimensional Space Can be Modulated by Depth and Object Membership

A cued target detection experiment measured inhibition of return (IOR) in a computer-simulated three-dimensional (3D) setting. Cues and targets appeared in the same or different depth planes and same or different sides. When the cue and target appeared at different depths, they were made to appear within the same object or between different objects. When the cue appeared in a farther location than that of the subsequent nearer target, IOR was smaller compared to the scenario where the cue and target appeared in the same depth plane. This depth-specific effect was only observed when the cue and target appeared in different objects separated along the depth axis, but not when the cue and target appeared within a single object stretched along the depth axis. The analogous depth- and object-based effect was not observed for a near-cue to far-target depth switch. These results suggest that IOR can be depth-specific when making a far-to-near depth switch, a finding made absent when cues and targets appear within a single object.