Two biases distort every negotiation: the messenger effect judges information by its source, illusory truth makes you believe whatever gets repeated.
"We can't do that. The CEO shut us down and said you're too expensive. Except he said it a bit more colorfully..."
Your deal negotiation was going fine. Well, as fine as one goes when the counterparty doesn't accept your proposals. But you felt momentum was on your side. And it was. That is, until they came back with the zinger about their CEO.
Ever been there? Where things were feeling good, then someone invokes the authority figure and everything shifts? The Grand Poobah says no. Cue panic.
You start re-thinking what you said, what you offered, what you wore to the meeting. Did they not like my shirt? What if we make another move? Or two, or three? Could we get them back to the table then?
Meanwhile, your counterparty is sitting in their office, fingers steepled like a cartoon villain, cackling at your sudden pliability and wondering if they should bother letting their boss know that it worked. Again.
That's the Messenger Effect. We judge the validity of information based on who it's allegedly from, rather than the substance of the message itself. A mid-level procurement manager says "your price is too high" and you push back. The CEO says the same thing (or more accurately, someone claims the CEO said it) and suddenly you're reconsidering your entire position.
The message didn't change. The perceived authority behind it did.
The messenger effect has a close cousin that operates on a different axis. Instead of distorting judgment based on WHO says something, the illusory truth effect distorts it based on HOW OFTEN it gets said.
"The synergy potential is enormous!" keeps getting tossed around in an M&A negotiation. By the eighth time, everyone buys into it. Fast forward six months into integration, and the cost savings and all that "synergy" are nowhere to be found. Budgets are blown. A process that was supposed to take ten months is on track to take eighteen.
Repetition creates familiarity, and familiarity feels a lot like truth. A claim gets repeated enough times and it stops getting questioned, not because anyone verified it, but because it sounds right by now. It just... becomes fact.
Ever been told "no" in a negotiation? What about "no" twelve times in a single conversation? Even if the "no" isn't really a no, even if it's posturing or a placeholder you'd recognize instantly in any other context, hearing it repeatedly changes your behavior. You start making moves you weren't planning to make.
These biases get really dangerous when they stack. The CEO (high-authority messenger) repeats a position (illusory truth reinforcement) and suddenly that position isn't just one person's view. It's received wisdom. It's gospel. It's the thing everyone on your side starts planning around, and nobody stops to ask whether it was ever actually tested.
I had coffee with a CEO recently who had the opposite problem. Because she had to be involved in every single deal and conversation her team undertook, every message to the counterparty carried the weight of the executive office. High stakes, high stress, and no air gap.
When the CEO is the messenger for everything, the team loses its ability to negotiate independently because the counterparty just waits for the boss to show up. And when a deal actually needs executive weight, there's nowhere left to escalate. Every message already came from the top.
Next time you're prepping, try these.
What has been repeated often enough on our side of the table that nobody's checking it anymore? If a number or a claim has survived three meetings without anyone asking "where did this actually come from?", that's worth flagging. It might be true. It might also be a narrative that hardened through repetition, and you're now planning around fiction.
And the second one: if the only thing that changed my position was learning that the CEO said "no," would I have flinched if the same words came from the person sitting across from me? If the answer is no, you're reacting to the messenger, not the message. And someone on the other side of that table knows it.
We work with commercial teams on exactly these kinds of problems.