Handheld Augmented Reality: Does Size Matter?

Handheld devices have become extremely popular in recent years and represent attractive options for augmented reality (AR) research. Most modern devices now incorporate many of the necessary input and output capabilities and do so in self-contained packages of varying size, weight, and cost. But while most previous AR work with handhelds has focused on smaller form factors, we have been interested in further exploring the range of larger devices often referred to under the umbrella of 'tablets'. This paper presents the results from a study we conducted on the suitability of different form factors for mobile AR use. Three form factor categories were evaluated: smartphone, mini tablet, and tablet. Although most devices today are marketed as being either the first or last, we propose there needs to be a third, middle category that caters for the subtle differences between sizes. The study asked 15 participants to use a device from each category to complete a series of seven interactive tasks. The tasks were designed to incorporate typical AR interactions. Participants completed pre- and post-test questionnaires and were audio recorded during the testing process. Our results showed that no one form factor was best suited to all tasks but rather the 'right' form factor was influenced by task specifics and personal preferences. In terms of usability ratings, we found a significant difference between smartphone and tablet form factors but no such difference between other combinations. Finally, we noted a negative correlation between participants' fatigue rating and the ease with which they found completing the tasks.