Smartphones have become a common tool of daily communication, and a number of text input methods are extensively used. Qwerty and T9 are two universally used smartphone input methods that differ in user experience (UX) when entering phrases with different complexity. Phrase complexity is an indication of the number and type of characters used in a phrase. This study evaluated the impact of both experience and phrase complexity on the UX of Qwerty and T9. Thirty-two participants with different experience levels (high and low) used both Qwerty or T9 to input 40 phrases (both simple and complex phrases). Input time, speed, error rate, galvanic skin response, heart rate, and perceived usability were analyzed as dependent variables. The results indicated that Qwerty was more effective than T9 for entering complex phrases, while no obvious difference was found for simple phrases. Experience had a positive impact on the input method, and Qwerty was more helpful for participants with low experience level. Performance, physiological reaction, and perceived usability data showed similar results. These findings aid the optimal design of text input systems for smartphones.
Keywords: Input method; Performance; Phrase complexity; Smartphone; User experience.
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