Will it be a capital letter: signalling case mode in mobile phones

The first experiment manipulated the prompt in a text entry task using a web simulation of a novel mobile device. The results showed that users' expectations were influenced by the case of the letters in the prompt. Users took many more trials to learn to expect a case inconsistent with the model provided by the prompt. The second experiment manipulated both the case of the letters in the prompt and the case of the last letter displayed. The results replicated the findings above and demonstrated a strong effect of the case of the last letter displayed. Guidelines for signalling case mode and a notation (Interaction Units) are suggested that might be used to reason about low level interaction design with handheld devices.