Brain Activity Underlying Visual Search in Depth when Viewing Volumetric Multiplanar Images

Abstract By developing several different methods to present 3-dimensional (3D) images, a demand to investigate the interaction with the human visual system is inevitable. Although current estimates centered on stereoscopic depth perception, still our knowledge is low about the effect of non-stereoscopic displays on the visual cortex, both at the sensory and cognitive brain reactions. In this study, we investigated the cortical activity correlated with a volumetric multiplanar image perception in both 3D and 2D by analyzing the event-related potentials (ERPs) and Power Spectral Density (PSD) analysis. The study was designed based on two conditions. The first condition (3D test) was arranged by presenting four constant angular size rings in which one of them was closer to the subjects. The second condition (2D test) was done by adding trials with the same ring features while all rings were presented on the same plane. A volumetric multiplanar display was employed to present the non-stereoscopic visual targets. Moreover, the brain signal was recorded via an EEG amplifier and then analyzed by the EEGLAB toolbox on MATLAB. Event-related potentials (ERPs) studied in three time windows, (50-100ms), (100-200ms), and (200-450ms), correspond with the N1, P2, and P3 components of ERPs. The analysis showed no significant differences in amplitude between two conditions across five occipital and parietal electrodes, even though there was only a significant difference in latency of the P3 component on the Pz electrode. Furthermore, the Power Spectral Density (PSD) of the alpha and the beta oscillation was analyzed. The analysis does not show significant differences between 3D and 2D tasks; nevertheless, slightly higher alpha and beta activities seemed in 2D visualization. To conclude, 3D image representation on the volumetric multiplanar display has no more sensory or cognitive load on the human brain that responded equally to both visual conditions with a slight difference in latency of the P3 component. Moreover, depth perception on a multiplanar display requires less brain activity.