Psychology explains why people who dislike being interrupted may be protecting more than just their train of thought

Imagine you are halfway through writing an important message when someone suddenly asks you a completely unrelated question. You answer, perhaps for only a few seconds, and return to your screen, only to stare at the sentence wondering what you were about to write.

The same thing can happen while cooking, reading, working or explaining something. The interruption may be brief, but the irritation it causes can feel surprisingly strong.

It is easy to interpret that reaction as impatience, rudeness or simply wanting to be left alone. But psychological research suggests there may be a more ordinary explanation: an interruption can force the brain to temporarily abandon an active train of thought, disrupt the sequence of a task and make it harder to recover exactly where it left off.

Why a few seconds can derail your thoughts

One of the clearest demonstrations came from Erik M. Altmann and colleagues in their 2014 study, “Momentary Interruptions Can Derail the Train of Thought,” published in the Journal of Experimental Psychology: General.

The researchers examined what happens when people are interrupted while trying to maintain their place in a sequence of actions. Their findings showed that the interruption did not need to last very long to cause problems.

Interruptions averaging 4.4 seconds tripled the rate of sequence errors, compared with uninterrupted performance. Even shorter interruptions, averaging 2.8 seconds, doubled the rate of sequence errors.

The participants were not necessarily forgetting the entire task. Instead, an interruption could interfere with their ability to remember where they were in the sequence and what they were supposed to do next.

In everyday terms, you may still remember what you were working on, but lose the exact mental thread that connected one step to another.

Your brain may be holding a task in place

The researchers suggested that interruptions are disruptive because they shift attention away from the active task. When attention moves elsewhere, the mental representations needed to continue the original sequence can become harder to access.

Think about reading a paragraph and mentally marking the exact point where you stopped. You may remember the subject of the article, but after being pulled into another conversation, you might not immediately remember the sentence, argument or idea you were developing.

That is why the familiar phrase “Where was I?” can have a psychological basis. The original thought may not have disappeared; reconnecting with the precise mental state you occupied before the interruption can simply take extra effort.

Why interruptions can make people annoyed

The effect is not purely cognitive. Interruptions can also influence how people feel while completing a task.

Brian P. Bailey and Joseph A. Konstan examined this in their 2006 study, “On the Need for Attention-Aware Systems: Measuring Effects of Interruption on Task Performance, Error Rate, and Affective State,” published in Computers in Human Behavior.

The controlled experiment involved 50 participants and compared situations in which people were interrupted during their primary task with situations in which secondary tasks were presented between primary tasks.

When participants were interrupted during their primary task, they took 3% to 27% longer to complete it and made about twice as many errors. They also reported 31% to 106% more annoyance and roughly twice the increase in anxiety compared with the alternative condition.

So when someone becomes irritated after being interrupted, the reaction may not simply reflect impatience. The interruption itself can impose an additional cognitive and emotional cost.

What your “train of thought” may really be protecting

The next time you feel irritated because someone interrupts you halfway through an email, recipe, conversation or difficult problem, there may be a surprisingly simple explanation.

You may not just be protecting your silence. You may be protecting an active mental goal, a sequence of ideas, decisions or actions that your brain was temporarily holding together.

Sometimes, therefore, “I just need to finish this thought” is not an overreaction. It may be your brain trying to preserve its place before switching tracks.

Research suggests interruptions can disrupt ongoing thoughts and tasks, but does not show that people who dislike them are specifically “protecting” their train of thought.