MUM Effect: Find Where Bad News Loses Its Action Value

Communication · Executive Insight Brief · 323

Bad news can arrive empty

The MUM Effect explains why undesirable information can arrive later, softer, shorter, or through another messenger even when the messenger did not cause the bad news

Premise

Organizations can possess accurate bad news and still fail to deliver it in a form that permits action. The MUM Effect identifies a recurring interpersonal pressure: people are more reluctant to transmit undesirable information to the person for whom it is undesirable than they are to transmit favorable news.

The executive risk is subtler than silence. Negative information may travel while its decision value is progressively edited out—through delay, euphemism, selective uncertainty, shortened consequences, or delegation to another messenger. A dashboard can therefore show that escalation occurred while the meaning that required escalation has already disappeared.

The essential model

Sidney Rosen and Abraham Tesser introduced the MUM Effect in 1970 by stripping away obvious reasons for withholding. Participants overheard very good or very bad news intended for another person. Those holding good news conveyed it; those holding bad news transmitted less, with the difference reaching p < .001. They had not caused the outcome, had no prior relationship with the recipient, and faced no reward for silence or penalty for speaking. That design established the narrow finding: messenger reluctance survives after the obvious incentives are removed.

Tesser and Rosen’s later program showed several costs can operate together: guilt, anxiety, empathic distress, mood change, or fear of negative evaluation. A 1972 study with 72 women found good news was transmitted more often than bad news and that the bad-news/dissimilar-fate condition produced the greatest guilt and least transmission. Their 1975 review consolidated the wider program across guilt, evaluation, recipient desire, mood, shared fate, field behavior, and delegation. The messenger is therefore part of the information system, not a neutral pipe.

Why this matters

In an illustrative software program, a technical lead learns that a security dependency will delay certification by at least six weeks. She reports “a possible external dependency risk.” The program manager turns that into “some timing uncertainty” for the steering deck. An executive, unwilling to alarm the customer before every detail is confirmed, reports that “certification is being monitored.” No fabricated number appears, yet three interpersonal reductions convert a six-week minimum delay into a vague watch item.

Compare the first available evidence with the message that eventually reaches authority and mark where negative meaning changed shape: omitted consequences, softened adjectives, extra demands for certainty, delay, or delegated delivery. If an escalation protocol later produces earlier warning, that cannot establish that the MUM Effect caused every prior distortion. The case shows how social cost can degrade action value without making the message literally false.

Risks and limits

Negative information is not universally suppressed. Threats, scandal, outrage, rumors, and warnings can spread rapidly, especially when the communicator is not facing the person harmed by the news or when sharing serves protection or status. The original effect concerns reluctance to tell the direct target something undesirable.

The early evidence relied heavily on U.S. student samples and controlled encounters. Professional duty, law, culture, hierarchy, repeated relationships, retaliation risk, and formal escalation systems can strengthen, weaken, or reverse the pressure. MUM should therefore be treated as a recurrent transmission bias, not as a universal coefficient for every negative message.

Executive takeaway

Audit bad-news pathways for semantic loss, not just delivery. Reward early detection, separate the value of the message from the value of the messenger, and make the first response to unwelcome information clarification and containment rather than blame. The goal is not maximal bluntness; it is preservation of the negative meaning needed for a decision.

Key questions

• Where does an unpleasant fact become softer, later, shorter, or less consequential as it moves toward decision authority?
• What social cost does each messenger face for preserving the full negative meaning of the information?
• Do leaders demand more certainty before hearing bad news than they demand before accepting favorable news?
• Can we compare the first available evidence with the final executive message closely enough to detect attenuation rather than mere omission?

Selected sources

• Rosen, S., & Tesser, A. (1970). On reluctance to communicate undesirable information: The MUM effect. Sociometry, 33(3), 253-263.
• Tesser, A., & Rosen, S. (1972). Similarity of objective fate as a determinant of the reluctance to transmit unpleasant information: The MUM effect. Journal of Personality and Social Psychology, 23(1), 46-53.
• Tesser, A., & Rosen, S. (1975). The reluctance to transmit bad news. Advances in Experimental Social Psychology, 8, 193-232.