A comparison of touch-screen interfaces and voice-user-interfaces : an explorative study for multi-modal design

Abstract

Modern mobile devices allow people to perform their day-to-day tasks anywhere in the world. Therefore, one would assume that these devices have interfaces which can accommodate the different contextual scenarios that users might find themselves in. However, generally mobile devices make use of a touch-screen, which uses a Graphical User Interface (GUI) to display information to the users. While this type of interface has been widely accepted, it does not cater for scenarios in which a user’s eyes and hands might be busy, and this scenario can be very common in mobile contexts. A user interface which can cater to these scenarios is a Voice User Interface (VUI). The aim of this dissertation is to build a GUI and a VUI for a small-screen mobile device, compare and evaluate them, and then combine them into Multi-Modal User Interface (MMUI) so that this interface can also be compared and evaluated against the previous two. The GUI and VUI are compared using, as a measure, the time it takes for a user to complete various tasks, and the user’s preference of input/output modalities. The results obtained are then used to evaluate the weaknesses and strengths of each UI in each test. Furthermore, the evaluation is used to determine whether the MMUI’s added flexibility in terms of I/O has made it simpler for users to perform tasks, or more complex, as well as to see whether having multiple modes of I/O promotes greater ‘safety’ of use in specific environmental contexts, while still allowing users to accomplish certain specific goals with the application. The results obtained show that users preferred having a MMUI rather than a unimodal interface, and that having different types of input and output possibilities made it easier to perform tasks and not more complex. Also, the MMUI did promote increased safety, as users could perform their tasks in an ‘eyes busy’ situation without risking injury to themselves or to others. The results also showed that, while users like having a VUI as part of the MMUI, they still have a ‘natural’ bias towards using GUIs – possibly due to their constant exposure to them.