Most negotiators prepare facts, pricing, and terms.
Many still leave value on the table.
The reason is simple. Bias changes what you notice, what you trust, and what you decide.
Bias does not feel irrational.
It feels like “good judgment.”
That is why it is expensive.
This article covers nine traps that show up in day-to-day negotiations.
Each section includes a plain definition, a real deal example, and a practical fix.
Anchoring bias
Anchoring happens when the first number sets the reference point.
People adjust away from it too little.
Example
A supplier opens a renewal with a 12% increase.
The buyer planned for 3%.
After two meetings, they “win” 6%.
That outcome still tracks the first number, not the market.
What to do
Walk in with your own anchor and your reasons.
Use benchmarks like last year’s price, competitor quotes, or input costs.
Name the anchor out loud when it is extreme.
Say, “That number is not a useful starting point. Here is ours.”
Confirmation bias
Confirmation bias makes you search for support and ignore friction.
You hear what fits your story.
Example
A sales team believes the client has budget.
One friendly manager said, “We should be fine this quarter.”
The team ignores two warnings from procurement about approvals.
The deal slips by 90 days, then the scope gets cut.
What to do
Run one “disproof” check before you commit.
Ask, “What fact would kill this deal?”
Then chase that fact on purpose.
Invite one colleague to argue the other side for ten minutes.
Framing effect
Framing changes choices through wording.
The facts stay the same.
Example
You propose a clause change.
You say, “This prevents a 5% revenue loss.”
The other side reacts fast and agrees to discuss it.
If you say, “This raises revenue by 5%,” they show less urgency.
What to do
Test two frames before you present a key ask.
Use a gain frame and a loss frame.
Then strip the words back to the numbers and the risk.
Decide based on substance, not emotion.
Fundamental attribution bias
This bias makes you judge others as “difficult” or “unreasonable.”
You ignore the situation shaping their behavior.
You also assume they see the deal like you do.
Example
A buyer asks for a discount on June 28.
The supplier refuses and sounds cold.
The buyer labels them stubborn.
The real issue is authority. The supplier’s rep cannot approve changes after month-end close.
What to do
Ask one clean question before you judge intent.
“What pressures or rules sit behind that position?”
Then listen for internal limits, incentives, and approval paths.
You can solve real constraints. You cannot solve a label.
Overconfidence bias
Overconfidence makes you overrate your read of the room.
It also cuts preparation time.
Example
A senior leader joins the final call and expects a quick close.
They skip the prep brief.
The counterpart adds legal and finance to the call.
New terms appear, and the timeline doubles.
What to do
Write down three things you do not know.
Turn each into a question for the other side.
Build two deal paths, one fast and one slow.
Treat certainty as a result of preparation, not a mood.
Loss aversion
People feel losses more strongly than gains of the same size.
A small concession can feel huge.
Example
A client asks to remove a minor penalty clause.
Your team refuses.
The clause has low value to you, but giving it up feels like losing.
The refusal blocks a larger win, a two-year extension worth €400,000.
What to do
Translate “losses” into trades.
Say, “If we remove that clause, we need X in return.”
Keep a simple trade list on paper: price, term, volume, payment, scope, service levels.
Move value across items instead of fighting on one point.
Sunk cost fallacy
Sunk costs trap you in a bad path.
Time spent feels like a reason to keep going.
Example
A team spends five months on a partnership deal.
New numbers show the margin will drop from 18% to 6%.
Leadership pushes to sign anyway.
They say, “We cannot waste five months.”
What to do
Set exit rules before talks start.
Write a floor on margin, risk, and cash terms.
Review those floors after each major change.
Past time is gone. Your signature decides future pain.
Halo and horn effects
A halo forms when you like or admire the other person.
A horn forms when you dislike them.
Both distort how you judge their proposals.
Example
A charismatic vendor rep presents a complex pricing model.
The buyer accepts it with light scrutiny.
A less liked rep presents a simpler model later.
The buyer rejects it on instinct, then misses savings.
What to do
Separate the person from the term sheet.
Score proposals against a short checklist: total cost, risk, timeline, exit terms.
Have a second reviewer check any deal that “feels right” fast.
Fast comfort often signals bias.
Fixed-pie bias
Fixed-pie bias treats negotiation as zero-sum.
You fight over one number and ignore other levers.
Example
Two parties argue for weeks over a 4% price gap.
They never discuss payment timing or contract length.
A 12-month prepay would solve cash needs for one side.
A longer term would justify the discount for the other.
What to do
Add at least three issues to the agenda.
Use the same list every time: price, volume, timing, scope, service, term.
Ask what matters most and least to each side.
Trade low-cost items for high-value items.
Conclusion – Take Action!
Bias does not show up as “bias.”
It shows up as a reasonable story you tell yourself.
That story shapes your numbers, your tone, and your choices.
Pick one bias from this list before your next negotiation.
Name it on your prep sheet.
Decide what you will do when it appears.
Marc Saris 
