For the main project of my MSc in Human-Computer Interaction I chose to explore the domain of interruptions. This is an important area that has seen quite a lot of activity in recent years (see this list of resources on the subject). As more devices and applications vie for our attention, interruptions are the inevitable consequence. And no matter how well trained we might be, we remain susceptible to their disruptive effects and we make errors.
My study investigated how the deleterious effects of interruptions might be mitigated by the provision of a post-interruption cue – a visual hint to assist people in resuming their tasks. I found that cues were extremely effective in both minimising the resumption time and reducing the error rate.
I looked at two cue types: the first highlighted whichever action was taken by users prior to being interrupted; the second accentuated the next action that ought to be taken. The hypothesis was that the latter variety would be more effective because users would require less mental effort. But I found that, statistically speaking, there was no difference between the cue types.
This was an important finding: it is trivial for a computer program to log the last action taken by a user; it is easy to detect when a computer program loses focus in the operating system; and thus it is straightforward to provide a cue after an interruption that will be effective in helping users resume their tasks. By contrast, it is difficult if not impossible to know the intention of a user at any given time, so cueing the next action to take is unachievable. Since the effects were found to be equivalent, the use of last-action cueing can be recommended.
If you want to know the nitty gritty details, here’s my dissertation in full (PDF, 3.1MB).