Assessing a multimodal user interface in a target acquisition task

The goal of multimodal user interfaces is to assist users in completing tasks quicker or with fewer errors, by reducing their cognitive workload. Visual, auditory and tactile feedback modalities are commonly used as a means to provide users with information through different sensory channels. Understanding how visual, auditory and tactile feedback modalities complement each other is still an open research area for understanding how computers can help users to complete everyday tasks more efficiently. In this paper, we evaluate user performance on a target acquisition task that simulates a real life scenario: locating a book in a bookcase. We performed a comprehensive comparison among the seven possible combinations of three feedback channels (visual, auditory and tactile). Twenty-four volunteers participated in our experiment. Our results show that using the combination of the three feedback modalities improves user performance on this evidently visual task. However, using the visual modality alone does not increase user performance as much as the other feedback channels. By means of a post-experiment questionnaire, subjects reported that they perceived tactile modality as the most helpful feedback channel.