The Effects of Task-Set Switching On Concurrent Verbal Protocol

Concurrent verbal protocol (CVP) is a common usability testing and analysis technique that requires people to continuously vocalize their thoughts as they complete a task. Given the widespread use of concurrent verbal protocols in applied domains, it is surprising how little is known regarding concurrent verbal protocol’s effect on task performance. In the current series of studies, we examined how concurrent verbal protocols affected performance on two tasks that required users to frequently switch between cognitive strategies. Data revealed that CVP slowed down participants in comparison with participants who completed tasks in silence. The number of strategy changes that were required to complete a task did not affect this performance decrement. We conclude by discussing the limitations of the experiments reported here, and with practical advice for usability experts who use CVP in their own work.