Shift+Tap or Tap+LongPress?: The Upper Bound of Typing Speed on InScript
As part of an ongoing standardization effort, we were asked to evaluate Marathi text input mechanisms on smartphones. We undertook a between-subject longitudinal evaluation of four existing keyboards with 153 novice users who participated for 31 sessions each, spread over 3--4 weeks. In this paper, we present the empirical results of the performance of these keyboards and discuss them with respect to their designs. We found that keyboards with logical layouts performed marginally better than keyboards with partially frequency-based layouts. Results also showed that users performed poorly on keyboards that have word prediction features in comparison with keyboards that don't have prediction features while typing Marathi. We speculate that this difference in performance is related to a "cognitive toll" that the users pay to use word prediction. We identify several directions for future research.