Mental Models: Set Completion



How might this apply to great teams and cultures?

When something is certain and known then we feel comfortable and in control. When something is not complete, we cannot close that item in our mind as we have to keep thinking about it. This maintenance activity adds effort and leads to predictions that might give us cause for concern. This is the basis for the need for completion, and we will, therefore, seek to close off things that we do so we can forget them and move on to the next item of interest.

Some people have a particular need for completion and in teams will be the person who makes sure all jobs are done (often doing the jobs themselves). People who compulsively tidy up are "completer-finishers" as they see untidiness as a step before the completion of tidiness. Contrast this with people who are not completer-finishers and who will happily start something but will be unlikely to see things through to the end.

How might this apply to your business?

What can people collect in your system? How can these be organized into discrete sets to provide easier, achievable goals (and the motivation to continue completing the larger collection)? This principle also applies to incomplete puzzles or pictures—we desire to see the whole image completed. Look for logical groupings (like kinds of information) that can suggest set completion.


Are you a completer or a starter? What gaps do you seek to close? How do you leave things for people to complete. Start a sentence and see if they will complete it for you -- if they do, you have put the other person into the completer-finisher position. This can be a powerful tool in changing minds.Even if they do not verbally complete the sentence, they will do so in their minds. Watch their body language for signs of what they might be thinking.Likewise, you can use completion in physical tasks. Start something and give it to another to complete. Give rewards for completion, particularly if you have no completer-finishers who will end the job for you.

See Also

Chunking, Curiosity, Achievements, Collecting, Variable Rewards, Pattern Recognition, Status, Gifting, Reputation


In the whirl of our day-to-day interactions, it’s all too easy to forget the nuances that distinguish great teams, great cultures, and great products/services.

Mental Model Flash Cards bring together insights from psychology into an easy reference and brainstorming tool. Each card describes one insight into human behavior and suggests ways to apply this to your teams as well as the design of your products and services.