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To better understand the impact of different screen sizes in cognitive training, study subjects performed an adaptive training task at three separate visual angles using a head-mounted display (HMD). Cognitive load was assessed using EEG and compared with task performance (accuracy and response time) for each condition. While previous studies found performance benefits corresponding to increased screen size in memory and learning tasks, our results suggest such benefits may only apply up to a visual angle of approximately 20°, after which increases in size become inversely correlated with task performance.

BACKGROUND Although the pursuit of improved cognitive function through working memory training has been the subject of decades of research, the recent growth in commercial adaptations of classic working memory tasks in the form of gamified apps warrants additional scrutiny. In particular, the emergence of virtual reality as a platform for cognitive training presents opportunities for the use of novel visual features. OBJECTIVE This study aimed to add to the body of knowledge regarding the use of game-like visual design elements by specifically examining the application of two particular visual features common to virtual reality environments: immersive, colorful backgrounds and the use of 3D depth. In addition, electroencephalography (EEG) data were collected to identify potential neural correlates of any observed changes in performance. METHODS A simple visual working memory task was presented to participants in several game-like adaptations, including the use of colorful, immersive backgrounds and 3D depth. The impact of each adaptation was separately assessed using both EEG and performance assessment outcomes and compared with an unmodified version of the task. RESULTS Results suggest that although accuracy and reaction time may be slightly affected by the introduction of such game elements, the effects were small and not statistically significant. Changes in EEG power, particularly in the beta and theta rhythms, were significant but failed to correlate with any corresponding changes in performance. Therefore, they may only reflect cognitive changes at the perceptual level. CONCLUSIONS Overall, the data suggest that the addition of these specific visual features to simple cognitive tasks does not appear to significantly affect performance or task-dependent cognitive load. CLINICALTRIAL

Head-mounted display (HMD) based cognitive training enables a number of unique visual features, including 3D depth and immersive visuals. We examine the impact of these features by measuring task performance and EEG power with a cognitive task that has been modified for use in virtual environments. Results were then compared with those obtained using an unmodified version of the task. Some modified versions of the task resulted in increased cognitive load, but the differences did not correlate with changes in task performance. The increased EEG power observed may therefore only reflect changes at the perceptual level, rather than task-contingent cognitive function. On the whole, these results suggest that adapting a standard cognitive training task to a virtual environment in order to take advantage of the inherent benefits of an HMD should pose few if any problems.