variation in importance of time-on-task with familiarity with mobile phone models
We studied the extent to which time-on-task is correlated with perception of usability for people who are familiar with a phone model and for those who are not. Our controlled experiment, conducted in Japan, correlated subjective usability assessments with time-on-task for expert and novice users on three different mobile phone models. We found that the correlation between perceived usability and time-on-task is stronger when participants are more familiar with the phone model. While not significant when initially inspecting a new phone model, a negative correlation between time-on-task and perceived usability becomes significant with as little as an hour's time doing tasks on the unfamiliar phone. This suggests that designing the UI to make time-on-task as short as possible may not have much effect on the purchase decision, but as experience increases, it may increase the loyalty of existing users.
mobile phone usability metrics time on task expertise