This paper describes a study investigating the influence of efficiency and effectiveness on modality selection and perceived mental effort. Each participant had to perform several tasks with a smart phone application offering touch screen and Wizard-of-Oz speech recognition simulation as input modalities. The results show that efficiency and effectiveness have a strong influence on modality selection. Speech usage increases with increasing efficiency of speech input. A lower effectiveness of speech input raised the threshold for changing the modality selection strategy. For effectiveness mental effort differed significantly between the groups presented with low and high speech recognition errors.
Bibliographic reference. Schaffer, Stefan / Jöckel, Benjamin / Wechsung, Ina / Schleicher, Robert / Möller, Sebastian (2011): "Modality selection and perceived mental effort in a mobile application", In INTERSPEECH-2011, 2253-2256.