Sources and independent research

Journal of Information Management


Interruptions in the workplace:

A case study to reduce their effects


Dr. Edward Sykes, Ph.D.

Sykes studied a mid-sized Canadian software company using observational note-taking and a stopwatch. Dr. Sykes holds a Ph.D. from Brock University in Cognition and Learning, with an emphasis on machine learning algorithms.

Measurement scales


Quotes from the study:

Effort spent on interrupts required an average of 20 min for each occurrence

Approximately 1.5 h per day of the developer’s time was consumed on dealing with interruptions

By far the most popular form of interruption that computer users encounter on a day-to-day basis is email notifications and instant messenger client pop-up messages

Resumption Lag (RL) is defined as the time required to resume the primary task after completing the interrupting task. RL can be measured as the time from closing the interrupting task to the first keyboard or mouse action in the primary task in direction of the task goal.

Researchers have shown that if a user is interrupted during a high cognitive load task by being forced to switch tasks […] then the cost of interruption can be very high

Researchers have shown that users who multitask extensively have felt additional stress and are more likely to make errors


For high cognitive load tasks the cost of interruption is high. In these situations, it is best to wait until the task is complete or the user reaches a task boundary

These interruptions undoubtedly negatively affected the employee’s effectiveness and their overall satisfaction.

Aggregated data extrapolated over a typical 8-h work day translates into over 120 interruptions per day for Technical Lead/Senior Developers and accounts for 5.7 h of time working on interruption tasks. This translates into over 71% of their daily activity is spent on dealing with interruptions.

They said they were “overwhelmed at times and unable to concentrate on specific project tasks” because of a stream of interruptions that kept them from working on what they were intending to work on.

The cost of interruption can be enormous for someone deep in thought while solving a critical problem.

The Cost of Not Paying Attention:

How Interruptions Impact Knowledge Worker Productivity

Jonathan Spira & Joshua Feintuch

Quotes from the study:

The cost of interruptions: $588 billion per annum in the United States alone.

The majority of knowledge workers tend to open a new e-mail immediately upon notification.

Interruptions now consume 28% of the knowledge worker’s day

This translates into 28 billion lost man-hours per annum to companies in the United States alone. Assuming an average salary of $21/hour for a knowledge worker, the cost to business is $588 billion.

Waste of 28% of the typical worker’s day.

Close to a third of the cost of a knowledge worker’s salary and benefits is consumed by these unnecessary interruptions.