"The harder it gets" Exploring the interdependency of input modalities and task complexity in human-robot collaboration

To enhance successful cooperation in human-robot collaboration tasks, many factors have to be considered. We assume, that for specific levels of task complexity, there is always one complementing input modality which increases the corresponding user satisfaction and performance. In order to identify the ideal mix of these elements, we present two experiments in this paper. The first study was in a public space and the second in a controlled laboratory environment. Besides investigating the correlation of task complexity and input modality, we explored, whether the appearance of the robot also has an impact, within the lab environment. We identified strong interdependencies between task complexity and input modalities. Specifically with hard tasks, differences in performance and satisfaction were often highly significant. Additionally we found, that the perceived task complexity was strongly dependent on the cognitive workload, driven by the used input modality, which also emphasized the strong coherency of these factors. Regarding the influence of the appearance of the robot, we found, that the human-like shape increases users´ self confidence, to be able to solve a task without help.