Angular disparity and dimensionality in mental rotation : characteristics of saccadic eye movement and electroencephalogram

Abstract

Mental rotation is an essential aspect of visuospatial processing in playing computer-games. Computer gaming is one of the most common activities that individuals are indulged in their usual activities concerning interactive system-based entertainment. During computer-games, mental rotation ability can be used as a proper strategy for understanding and fulfilling specific requirements, like area measurement tasks, composing and decomposing two- or three-dimensional objects, proving symmetry, finding missing parts of an object, etc. The gaze behavior and neural activities can unfold plenty of valuable links and understanding about an individual’s cognitive state of mind during engagement in cognitive processing. Here, as the focus revolves around objects’ visuospatial characteristics and their processing during mental rotation, this dissertation provides insights on gaze parameters and neural activities during a mental rotation computer-game involving 2D and 3D isomorphic objects with varying angular disparity. Along with dimensionality (2D vs. 3D) of the object, angular disparity also has two levels, convex angle (between 00 to 1800 ) vs. reflex angle (between 1800 to 360 0 ). This dissertation comprises three different thematic analysis approaches for four groups with the unique combination of angular disparity and dimensionality with 60 healthy participants. The first theme of the analysis is focused on saccadic gaze behavior and provides insights on saccadic characteristics in gaming task performance that involves 2D and 3D isomorphic objects with varying angular disparity. Gaze behavior data of all participants were recorded during task execution and analyzed to find the changes in spatiotemporal characteristics of saccades associated with the variation in angular disparity and dimensionality. Results indicate that the spatial characteristics of the object affect the temporal aspect of the saccade (duration), whereas the spatial aspect of the saccade (amplitude) is influenced by the objects’ dimension. A longer saccade duration indicates a prolonged suppression of spatial information processing during the MR tasks with objects at convex range angular disparities. Therefore, the MR tasks with convex angular disparity become more complex to process compared to the tasks with reflex angular disparity. MR process is faster and more accurate with 3D objects than 2D objects. Hence, during the MR task, the longer saccade duration implies that the tasks with convex angular disparities become comparatively more challenging. Also, the lower saccadic amplitude for 2D objects indicates difficulties in processing due to deficient visual features. The second theme of the focus investigates how dimensionality and angular disparity affect spatio-spectral characteristics of electroencephalogram (EEG) during mental rotation in computer-games. Hemispheric laterality and significant clusters were identified using spectral power for the frequency range of 3.5–30 Hz EEG signals. The results indicated higher alpha desynchronization during mental rotation compared to baseline. Overall, the results showed different hemispheric lateralization dominance with respect to object characteristics in such a way that right hemispheric lateralization for convex angular disparity and 3D objects, whereas left-hemispheric lateralization for reflex angular disparity and 2D objects in the parietal region. Further, higher neural active areas as no. of clusters elicited by convex angular disparities and 3D objects in the game compared to the reflex angles and 2D objects.