Inhibition of Return is Depth-Specific, Object-Based, and Relies on a World-Centered Frame of Reference in 3D Space

Abstract

The distribution of human attention in space can be modulated by spatial and temporal factors. This dissertation studied inhibition of return (IOR), a robust behavioural effect obtained through a spatial cueing paradigm where observers exhibit slower detection times to a target appearing over 300 ms after a cue in a previously cued location. Most research has studied the IOR effect in two-dimensional space; thus, it remains unclear whether, in three-dimensional space (3D) space, slower reaction times occur due to a target appearing in the same world location (defined in 3D coordinates) or in the same retinal location as the cue (i.e., anywhere along an observer’s line of sight to the cue). My thesis examines IOR in a computer-simulated 3D environment, with the location of the cue and target residing in the same versus different depth/distance position either within the same or different object and either relative to the observer or to the world environment. Following a general literature review (Chapter 1), the first empirical chapter (Chapter 2) demonstrates that IOR is depth-specific when the direction of depth switch between cue to target occurs from far-to-near space, suggesting a behavioural advantage for near space in the human attention system. Chapter 3 shows that this depth-specificity and depth-asymmetry of IOR is maintained only when cues and targets are not part of the same object; object membership can therefore override the depth-specific property of IOR in 3D scenes. Chapter 4 introduces motion of the viewpoint, showing that IOR is depth-specific when the cue and target appear in different depth locations in the world environment even when located at the same relative distance from the observer’s viewpoint. Thus, IOR could be the result of an inhibitory tag placed at a location relative to the environment rather than at a location relative to the viewpoint.