We all like to think we make rational decisions at the table. That we assess the facts, weigh up the options, and choose the best path forward. But what if I told you that some of your worst negotiation mistakes weren’t about strategy or skill—but about the way your brain naturally processes information?
Cognitive biases—those mental shortcuts we rely on to make sense of the world—shape every interaction we have. They influence the way we process information, how we perceive the people we’re negotiating with, and even how we assess value and risk. Sometimes they serve us well, but more often, they lead us to sub optimal deals, unnecessary conflict, or value left on the table.
After 23 years running my own corporate training business, teaching communication skills at IESE, and coaching companies on high-stakes conversations, I’ve seen these biases play out in real time.
So let’s challenge our assumptions. Below, I’ve laid out 16 common cognitive biases that influence negotiations and the real-world ways they show up at the table.
We all like to think we make rational decisions at the table. That we assess the facts, weigh up the options, and choose the best path forward. But what if I told you that some of your worst negotiation mistakes weren’t about strategy or skill—but about the way your brain naturally processes information?
Cognitive biases—those mental shortcuts we all rely on—shape how we assess risk, read our counterparts, and even define what we consider a “good deal.” Sometimes, they help. More often, they quietly nudge us towards missed opportunities, bad calls, or unnecessary conflict.
After 23 years running my own business, teaching communication and negotiation skills at IESE, and coaching companies on high-stakes conversations, I’ve seen these biases play out in real time.
So, let’s call them out. Here are 16 common cognitive biases in negotiation—and how they might be sabotaging your deals.
Decision-Making Biases (How We Process Information)
Our brains are wired to take shortcuts. While this speeds up decision-making, it often leads us astray.
1.Anchoring Bias – The first number or offer presented in a negotiation skews our perception of what’s reasonable.
Example: A supplier starts with an inflated price, making a small discount seem like a win—even if the final price is still too high.
2. Availability Bias – We rely on recent or easily recalled information instead of objective facts.
Example: Because your last deal collapsed over pricing, you assume price will always be the biggest sticking point—ignoring other critical factors.
3. Recency Bias – The last piece of information we hear carries more weight than it should.
Example: A competitor’s last-minute offer suddenly makes you question the solid deal you’ve already negotiated.
4. Outcome Bias – We judge a decision by its final result rather than the process used to get there.
Example: You make a last-minute concession to close a deal and assume it was a smart move—without considering whether it left value on the table.
Relationship & Trust Biases (How We Perceive People)
In negotiations, we’re not just dealing with numbers—we’re dealing with people. And our biases about those people affect our decisions.
5.Halo Effect – A single positive trait influences our perception of a person or offer.
Example: A charismatic negotiator convinces you they’re trustworthy, leading you to overlook unfavourable contract terms.
6.Authority Bias – We give undue weight to opinions from perceived experts or senior figures.
Example: A senior executive pushes for a deal strategy, and no one challenges it—even though it ignores key risks.
7.False Consensus Effect – We assume others share our values, priorities, and way of thinking.
Example: You believe the other party values long-term partnerships as much as you do—only to find they’re focused on short-term gains.
8.Illusory Correlation – We link unrelated events or patterns, seeing cause-and-effect where none exists.
Example: You assume a client will be difficult this time just because negotiations with them were tense last time—ignoring signs of a shift in their approach.
Risk & Value Biases (How We Assess What’s Fair)
Negotiators frequently miscalculate risk and value, often in ways that benefit the other side.
9.Loss Aversion – We fear losing more than we value gaining, making us risk-averse.
Example: You hesitate to walk away from a bad deal because you’re more focused on what you might lose than what you stand to gain elsewhere.
10.Sunk Cost Fallacy – We stick with a bad decision just because we’ve already invested time or resources.
Example: You continue negotiating a failing deal simply because you’ve already spent months on it—when walking away would be the smarter move.
11.Endowment Effect – We overvalue things simply because we own them.
Example: You refuse to switch suppliers despite better offers because of the history you have with them.
12.Framing Effect – The way information is presented affects how we perceive it.
Example: A 10% discount sounds appealing—until you realize the supplier raised prices by 15% first.
Confidence & Perception Biases (How We See Ourselves)
Perhaps the trickiest biases to spot are the ones that warp how we see ourselves.
13.Dunning-Kruger Effect – The less we know, the more confident we are.
Example: A negotiator with minimal experience assumes they can “wing it,” dismissing the need for preparation—only to be outmanoeuvred.
14.Self-Serving Bias – We credit our successes to skill but blame failures on external factors.
Example: If a negotiation goes well, you take full credit. If it falls apart, you blame the other party’s stubbornness rather than reviewing your approach.
15.Spotlight Effect – We overestimate how much others notice our mistakes or weaknesses.
Example: You hesitate to push back on a bad offer, fearing you’ll look difficult—when in reality, the other party expects negotiation.
16.Choice-Supportive Bias”—where people defend past decisions, even when presented with evidence that a better option was available.
Example: A negotiator insists on sticking with a long-term supplier despite better offers, simply because they were the one who originally selected them.
What This Means for Negotiators
The best negotiators are just as good at reading themselves as they are at reading others. They spot their own biases, question their assumptions, and challenge their initial reactions.
The next time you’re in a negotiation, try this:
- Pause before reacting. Ask yourself: Am I responding to facts, or am I being influenced by bias?
- Check your assumptions. Just because something feels true doesn’t mean it is.
- Look for blind spots. If you think you’re immune to bias, you’re already falling into one (hello, Dunning-Kruger Effect).