Mum Effect
People are more reluctant to communicate bad news than good news, which means unwelcome information can be delayed, softened, or withheld as it moves through an organization.
What Is It?
Psychologists Sidney Rosen and Abraham Tesser documented the effect in a 1970 paper, “On Reluctance to Communicate Undesirable Information.” Their experiments showed that people were more reluctant to transmit undesirable information than desirable information. Rosen and Tesser called it the MUM effect, for keeping “mum” about unwelcome information. Subsequent research found the same pattern in delayed, less complete, and less spontaneous transmission of bad news, and explored several reasons for the reluctance, including discomfort, anticipated reactions from the recipient, and concern about being evaluated negatively for delivering it.
Why Does It Matter?
Every layer of hierarchy an organization has is a place where the MUM effect can act as a filter on what travels upward. A project lead who suspects a deadline will slip delays telling their manager, hoping the numbers will improve before they have to say anything. A frontline employee who spots a quality problem hesitates to escalate it, unsure whether they’ll be blamed for noticing it. None of this requires dishonesty. It only requires that delivering the bad news feels costly to the messenger in a way that delivering good news doesn’t.
This is one of the quieter reasons senior leaders are often the last to learn about a problem everyone below them already knows about. Each person the information passes through is another point where discomfort, anticipated reactions, or fear of consequences can cause the message to be delayed or softened.
What Changes Once You See It?
You start noticing when bad news arrives later than it should have, and asking not “why didn’t they tell me” but “what made telling me costly.” You get more deliberate about separating the messenger from the message, explicitly and visibly, so that bringing a problem forward doesn’t come with a reputational tax. And you start treating a sudden absence of bad news as a signal worth investigating, not a sign that everything is fine.
Common Misunderstandings
- It is not a claim that people are lying or acting in bad faith. The delay and softening usually happen without anyone consciously deciding to withhold anything.
- It doesn’t only affect information flowing up a hierarchy. It also happens between peers, and even in delivering feedback to a friend; the direction that matters most for organizations is simply the one most consequential to get wrong.
- It is not solved by simply telling people to speak up. The reluctance is a response to real, often accurate, expectations about how bad news will be received.
- It isn’t the same as Psychological Safety, though the two can interact. Psychological Safety concerns whether people believe interpersonal risk-taking is safe; the MUM effect describes a more specific reluctance to transmit unwelcome information. Low psychological safety can intensify that reluctance, but it isn’t required for the effect to occur.
Diagnostic Question
The last time something went wrong, how long was it known by someone before it reached the person who needed to know it, and what would have made that person say something sooner?
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Field Notes
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Origin
Sidney Rosen and Abraham Tesser, “On Reluctance to Communicate Undesirable Information: The MUM Effect,” Sociometry, 1970.