Research in multimodal interfaces aims to provide immersive solutions and to increase overall human performance. A promising direction is to combine auditory, visual and haptic interaction between the user and the simulated environment. However, no extensive comparison exists to show how combining audiovisuohaptic interfaces would affect human perception and by extent reflected on task performance. Our paper explores this idea and presents a thorough, full-factorial comparison of how all combinations of audio, visual and haptic interfaces affect performance during manipulation. We evaluated how each combination affects the performance in a study (N = 25) consisting of manipulation tasks with various difficulties. The overall performance was assessed using both subjective measures, by assessing cognitive workload and system usability, and objective measurements, by incorporating time and spatial accuracy-based metrics. The results showed that regardless of task complexity, the combination of stereoscopic-vision with the virtual reality headset increased performance across all measurements by 40%, compared to monocular-vision from a generic display monitor. Besides, using haptic feedback improved outcomes by 10% and auditory feedback accounted for approximately 5% improvement.

With the rapid growth in virtual reality technologies, object interaction is becoming increasingly more immersive, elucidating human perception and leading to promising directions towards evaluating human performance under different settings. This spike in technological growth exponentially increased the need for a human performance metric in 3D space. Fitts' law is perhaps the most widely used human prediction model in HCI history attempting to capture human movement in lower dimensions. Despite the collective effort towards deriving an advanced extension of a 3D human performance model based on Fitts' law, a standardized metric is still missing. Moreover, most of the extensions to date assume or limit their findings to certain settings, effectively disregarding important variables that are fundamental to 3D object interaction. In this review, we investigate and analyze the most prominent extensions of Fitts' law and compare their characteristics pinpointing to potentially important aspects for deriving a higher-dimensional performance model. Lastly, we mention the complexities, frontiers as well as potential challenges that may lay ahead. CCS CONCEPTS• Human-centered computing → Human computer interaction (HCI); Interaction techniques; HCI theory, concepts and models; Gestural input; HCI design and evaluation methods; Graphical user interfaces; Virtual reality; Mixed / augmented reality; Pointing.

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Assessing the performance of human movements during teleoperation and virtual reality is a challenging problem, particularly in 3D space due to complex spatial settings. Despite the presence of a multitude of metrics, a compelling standardized 3D metric is yet missing, aggravating inter-study comparability between different studies. Hence, evaluating human performance in virtual environments is a long-standing research goal, and a performance metric that combines two or more metrics under one formulation remains largely unexplored, particularly in higher dimensions. The absence of such a metric is primarily attributed to the discrepancies between pointing and manipulation, the complex spatial variables in 3D, and the combination of translational and rotational movements altogether. In this work, four experiments were designed and conducted with progressively higher spatial complexity to study and compare existing metrics thoroughly. The research goal was to quantify the difficulty of these 3D tasks and model human performance sufficiently in full 3D peripersonal space. Consequently, a new model extension has been proposed and its applicability has been validated across all the experimental results, showing improved modelling and representation of human performance in combined movements of 3D object pointing and manipulation tasks than existing work. Lastly, the implications on 3D interaction, teleoperation and object task design in virtual reality are discussed.