Effect of gestures and smartphone sizes on user experience of text input methods

This study evaluated the effect of gestures (text entry with thumbs of both hands and one-thumb text entry) and smartphone sizes (4.7, 5, and 5.5 inches) on the user experience during text entry with QWERTY and T9 input methods. Messaging using smartphones has become an important communication tool. Users change their gestures depending on the smartphone use context. Many different smartphone sizes are available, but suggestions from an ergonomic perspective are missing. Twenty-four participants used either two-thumb text entry or one-thumb text entry, using both QWERTY and T9. A different group of 24 participants entered text using QWERTY and T9 on smartphones with different sizes. Their performance, subjective rating, and physiological reactions were analyzed. Two-thumb text entry was more effective than one-thumb text entry. Better user experiences were achieved by using QWERTY for two-thumb text entry, by using T9 for one-thumb text entry, and by using QWERTY with a 5-inch smartphone compared with using a 4.7-inch smartphone. Using QWERTY with a 5.5-inch smartphone achieved a higher speed than using a 4.7-inch smartphone. Users who used T9 with a 5-inch smartphone achieved a better user experience than if using a 5.5-inch smartphone. QWERTY is more suitable for two-thumb text entry, while T9 is more suitable for one-thumb text entry. Different smartphone sizes affect the use of input methods. This study provides a reference for smartphone text input interface designers.