Effect of key size and activation area on the performance of a regional error correction method in a touch-screen QWERTY keyboard

Manual text entry, which is one of the main features of mobile communications devices, decreases the competitive advantages of full touch-screen interfaces over physical interfaces. Especially for small full QWERTY keyboards, text entry becomes more problematic because of the small size of the virtual keys, absence of tactile feedback, and occlusion of virtual keys by fingers. One solution to this problem is the regional error correction, which is a predictive text entry method that activates the key corresponding to the actual activation point and also other keys within an activation area. This study investigates how the size of keys and of the activation area affect the accuracy of the regional error correction and compares the regional error correction method with the conventional finger touch method, for a touch-screen QWERTY keyboard. The regional error correction reduced both the time and the number of touches required to complete text entry when keys were small, but no difference was observed when keys were large. Users' subjective assessments of ease of use and preference indicated greater satisfaction with the regional error correction method than without it, regardless of key size. Relevance to industry: The result of this study can be used to speed and simplify text entry in mobile devices with full-QWERTY virtual keyboards. (C) 2009 Elsevier B.V. All rights reserved.