Abstract:  It has been well documented that inhibition of return (IOR) is much stronger in the periphery relative to the perifoveal visual field in two-dimensional (2D) space. However, we live in a three-dimensional (3D) space and operate objects that lie at different depth planes. Therefore, it seems to assume that our visual system is able to direct attention to object located at different depths. But now, it remains poorly understood whether IOR is homogeneously distributed throughout the visual field. In the present study, by constructing a virtual 3D environment and presenting the target either closer to or farther from the participants in an adapted version of the Posner spatial-cuing paradigm, we aimed to investigate the IOR at the different eccentricities in 3D space. The experimental design was a two (depth of target: near vs. far) by two (cue validity: cued vs. uncued) by three (stimulus eccentricity: foveal vs. perifoveal vs. periphery) within-participants design, resulting in 12 experimental conditions in total and 48 trials in each of the experimental conditions. The different target distances were simulated by adjusting the binocular disparity. The binocular disparity between the near and far depth planes was ±52.40 min of arc, relative to the fusion plane at which the central location in mid plane was presented (zero disparity). Participants reported that they could clearly perceive both the near and far depth planes when fixating the central location in the mid plane. Results showed that when secondary cued location was located at the central field, regardless of the target appeared at the near or far depth plane, the IOR effect was larger in the periphery filed than in the foveal and perifoveal fileds. When secondary cued location was located at the periphery field, the IOR in near and far depth planes appeared dissociated, specifically, when target appeared at the far depth plane, the IOR effect was reduced in periphery filed. The results indicated that the IOR is heterogeneity in different eccentricities in the visual field under the 3D space.

Key words:  three-dimensional (3D) space, visual field, depth plane, inhibition of return (IOR)