Interval cues: can a regular signal keep you on task?

You sit down to work, and twenty minutes later you surface in another tab. Nothing interrupted you. You drifted, and noticed late. One popular fix is a chime every few minutes that asks only whether you are still doing what you meant to do. There is research behind the idea, and a cost.

What the evidence says

The clearest evidence comes from brain injury rehabilitation. Ten patients with brain injury were asked to do part of each of five sub-tasks within 15 minutes. When brief tones interrupted them, their performance improved significantly and no longer differed significantly from a control group on important variables ¹. In a second study, twenty people with brain injury had to phone a voicemail service at four set times a day. On five randomly chosen days they received eight text messages saying only “STOP!”, and performance on those days improved strikingly ².

Noticing may be the part that matters. In a community sample of 105 adults, awareness of one’s own mind wandering mediated the link between ADHD symptoms and harmful mind wandering. The authors suggest that strategies which aid noticing could reduce some of the harm ³. That is a statistical association, not a test of cues.

How often is not settled. Researchers interrupt laboratory tasks with “thought probes” that ask where attention is. In one study, people reported more mind wandering as the time between probes grew ⁴. In another, more frequent probes reduced reported mind wandering during low- and medium-load tasks but increased it during a high-load task ⁵. A third, with 270 students, found that probe frequency had no significant effect on mind-wandering reports, vigilance or cognitive control ⁶.

Signals can cost something. Phone notifications alone significantly disrupted performance on an attention-demanding task, even when participants did not interact with a device ⁷. In an experiment with university students, the two groups interrupted in three-quarters of their tasks resumed faster and more accurately than the group interrupted least. But the most interrupted group was slower on uninterrupted tasks than every other group ⁸. And 17 young adults with ADHD, compared with 17 controls, had difficulty damping the auditory cortex’s response to an irrelevant sound when working-memory demands were high ⁹.

What we don’t know

We found no trial of interval cues for focus in adults with ADHD. The two cueing studies were small and involved people with brain injury. The probe studies used laboratory tasks, and a probe asks a question where a chime does not. The interruptions in the student experiment were a second task, not a signal. The probe, notification and interruption studies are not described as studies of people with ADHD.

Things to try

No study tested these steps. They are our reading of the findings.

• Give the signal a meaning first. In the text-message study, participants were briefly trained to link “STOP!” with pausing and reviewing their goals ². Decide what your chime asks.
• Start sparse on hard work. Frequent probes went with more reported mind wandering on a high-load task ⁵, and the most interrupted group was slower on uninterrupted work ⁸. Neither tested a chime, so a longer interval is a guess.