Though we may think we’re hiding it well, new research suggests that once we’ve made up our minds to hunt for a new job, we begin to exhibit certain ‘tells’, which could alert an observant boss long before you’ve slapped a notice on their desk.

But rather than the classics, such as looking dressier than normal on the same days you need to ‘pop out for a dentist appointment’ (wink, wink), the new study suggests that changes in behaviour are actually far more subtle.

So subtle, in fact, that most of us won't even realise we’re doing it.

Published in the Harvard Business Review, Timothy Gardner, of Utah State University, Chad H. Van Iddekinge, of Florida State University, and Peter W. Hom, of Arizona State University, conclude that there are thirteen sure-fire tells.

Whittled down from an exhaustive original list of 900 potential signs that an employee is looking elsewhere for work, the researchers interviewed both managers and employees about their experiences, to build the final guide.

Read more: Why and how you should ditch the job that's making you unhappy

Ready for the big reveal? Here are the ways in which employees may be letting things slip:

1. Their work productivity has decreased more than usual.
2. They have acted less like a team player than usual.
3. They have been doing the minimum amount of work more frequently than usual.
4. They have been less interested in pleasing their manager than usual.
5. They have been less willing to commit to long-term timelines than usual.
6. They have exhibited a negative change in attitude.
7. They have exhibited less effort and work motivation than usual.
8. They have exhibited less focus on job related matters than usual.
9. They have expressed dissatisfaction with their current job more frequently than usual.
10. They have expressed dissatisfaction with their supervisor more frequently than usual.
11. They have left early from work more frequently than usual.
12. They have lost enthusiasm for the mission of the organisation.
13. They have shown less interest in working with customers than usual.

Any of those sound familiar? While some may seem obvious, others, say the researchers, can be tricky to self-monitor. If you are preparing to jump ship however, they do have some advice.

“Hiding your own pre-quitting behaviors may prove difficult,” the team tells hbr.org. “Given the negative consequences of turnover, know that your managers and peers are likely watching for obvious and subtle changes in behavior—and that no single action is a dead giveaway. Instead, patterns of behavior over time that may seem subtle to you might tip off your boss.

“We suggest that you stay engaged with your work, continue to show enthusiasm for the mission of the organisation, and project a consistent level of relational energy to the members of your work team.”

Read more: Why and how to change career in your early thirties

If some of the pointers in the list have struck a more, ahem, personal chord however, it may come as no surprise to learn that the breakdown of romantic relationships served as an early research cue for the study.

“Our inquiry was inspired by a study by evolutionary psychologists David Buss and Todd Shackelford, showing that romantic partners give off cues that indicate whether they are committing infidelity,” write Gardner and Hom.

“A series of classic studies by psychologist John Gottman supports this, identifying how certain verbal and nonverbal cues expressed by married couples during brief videotaped interactions can forecast their eventual divorce.”

So the next time your suspicions are raised? Well, say the researchers, it may be worth referring back to the list for a little added insight.