What Sentence Would You Give?:
Watch for the Anchoring Bias


Two people can receive very different sentences for committing identical crimes. Learn about one hidden bias that can distort justice.


NARRATOR: We’ve all heard of cases where two people receive very different sentences for committing identical crimes. It’s perhaps one of life’s greatest injustices; and erodes our faith in a system that purports to be blind.

Now, there are many reasons why this might happen. One of them is a cognitive bias called The Anchoring Effect.

Here’s the study: psychologists Birte Englich and Thomas Mussweiler gave 19 judges (real judges, with robes, and courtrooms) information about a felony case and asked: “If you were the judge here, what sentence would you give?”.

Everyone got the same facts: details about the crime, relevant testimony, the penal code.

There was only 1 difference: the sentencing recommendation. Half the judges were told that the prosecutor was recommending a 2-month jail sentence; the other half were told the recommendation was for 34 months. “2” versus “34”. That’s it, the only difference. But this number stuck.

Even when all the other facts were identical, judges who saw “2 months” suggested an average prison sentence of 19 months. The judges who saw “34 months” suggested 29 months – that’s nearly a year longer in prison.

And if you’re thinking: Wait, the prosecutor’s an expert on the case. Doesn’t it make sense for judges to listen to their suggestion?

The researchers wondered that too. After all, judges are literal pros at being unbiased. They’re trained to take in facts objectively, to value expert opinion.

So the researchers ran more tests. What would happen if the recommendation now came from a computer science student – a freshman in college?

Or: What if judges just threw dice (secretly rigged to land on either a high number or a low number) right before making their decision?

In both of these experiments, the pattern stayed the same. Seeing a higher number (regardless of where it came from) led to a higher sentence at decision-time.

Clearly, there’s a mental blindspot at work. Critical decisions are being affected by numbers that shouldn’t matter!

So. What is this blindspot? It was named by Nobel-prize winning psychologist Daniel Kahneman and Amos Tversky : the anchoring bias.

Simply put: when we make decisions, we rely too much on the last piece of information we got. Think about that sentencing recommendation (or the dice) as an anchor: our minds put it down, much like a boat does. And then, just like that boat, our next moves, our decisions sort of float around that anchor… but they can’t get too far.

And if anchors can snag judges, they can snag us all. Research shows anchoring affects real estate agents’ estimates of property values, doctors’ medical diagnoses, and consumers’ purchases of everything from wine and chocolate to cars and stocks.

So, what can we do?

When you have to make a decision, consult broadly so that you’re not anchored on a single number. Check multiple sources, markets, companies, cases, to hone in on a range that’s right.

And if you don’t have the luxury of time? How do you stop an absurd number from snagging your mind? Here’s a negotiation tip from Daniel Kahneman: “Make…. A… Scene”. Go ahead! Shake your head; throw your hands down; say “I will not consider that number!” to wipe the slate clean. Even if you’re just alone in chambers!

Our minds will always be vulnerable to anchors. But by recognizing their influence and staying vigilant, we can loosen their hold.  That’s what outsmarting our minds is all about.


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Extra materials if you want to learn more


Should your social security number influence how much you’d pay for a bottle of wine? Of course not! But behavioral economist Dan Ariely shows otherwise in a study where he auctioned off everyday items to students. Watch Dan’s explanation of the study here to learn how the anchoring bias can influence consumer decisions.

Often, the anchoring effect is discussed in the context of numbers: in our video, we saw how judges’ sentencing decisions could be influenced by even random numbers (like a roll of the dice). But we can anchor on ideas too. The podcast DDx explores what this can mean for doctors in their episode “Anchoring bias and the frequent flyer” featuring Dr. Gita Pensa.


Ariely, D., Loewenstein, G., & Prelec, D. (2003). “Coherent arbitrariness”: Stable demand curves without stable preferences. The Quarterly Journal of Economics, 118(1), 73-106.

English, B., & Mussweilier, T. (2001). Sentencing under uncertainty: Anchoring effects in the courtroom. Journal of Applied Social Psychology, 31(7), 1535-1551.

Englich, B., Mussweiler, T., & Strack, F. (2006). Playing dice with criminal sentences: The influence of irrelevant anchors on experts’ judicial decision-making. Personality and Social Psychology Bulletin, 32(2), 188-200.

Kaustia, M., Alho, E., & Puttonen, V. (2008). How much does expertise reduce behavioral biases? The case of anchoring effects in stock return estimates. Financial Management, 37(3), 391-412.

Mussweiler, T., Strack, F., & Pfeiffer, T. (2000). Overcoming the inevitable anchoring effect: Considering the opposite compensates for selective accessibility. Personality and Social Psychology Bulletin, 26(9), 1142-1150.

Northcraft, G. B., & Neale, M. A. (1987). Experts, amateurs, and real estate: An anchoring-and-adjustment perspective on property pricing decisions. Organizational Behavior and Human Decision Processes, 39(1), 84-97.

Saposnik, G., Redelmeier, D., Ruff, C. C., & Tobler, P. N. (2016). Cognitive biases associated with medical decisions: A systematic review. BMC Medical Informatics and Decision Making, 16(1), 1-14.


“What Sentence Would You Give?: Watch for the Anchoring Bias” was created and developed by Olivia Kang, Alex Sanchez, Kirsten Morehouse, Evan Younger, and Mahzarin Banaji. Support for Outsmarting Human Minds comes from Harvard University and PwC.

Narration by Olivia Kang.

Animation and Editing by Evan Younger.

Images by Olivia Kang and Evan Younger, and adapted via Unsplash.

Music by Miracles of Modern Science.

Video footage via MSNBC, WKBW-TV (ABC7 Buffalo), and WIVB-TV (News 4 Buffalo).