After the paper-based task, each participant completed
seven brief activities (each lasting about 5min) on the multitouch
surface. The ordering of activities was randomized
between subjects. For each activity, the moderator first
explained the activity context (e.g., “Suppose the doctor made
an X-ray of your hand and now wants to review it with you.”).
Then she asked the participant how they would perform the
task (e.g., “If you want to make this X-ray larger, how might
you do that?”) and observed their behavior. The participant
was encouraged to try the action several times. After each
activity, the participant rated the activity’s usefulness (on a
five-point Likert scale) and gave qualitative feedback on the
idea.