Within Myside Bias
When Numbers Stop Feeling Neutral
The same data can look easier or harder to read when the conclusion touches political identity instead of a neutral question.
On this page
- Kahan's skin rash and policy data task
- Why numeracy helps less on identity linked questions
- Checking whether the frame is steering the math
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Introduction
Political framing can make the very same numbers seem easier or harder to interpret depending on whether the conclusion supports or threatens a person’s political identity. This is one of the clearest demonstrations that numbers are not automatically immune to myside bias. When identical data are presented as a neutral medical problem, many people can work through them correctly. When those same numbers are relabelled as evidence about a politically contentious policy, accuracy often falls and interpretations begin to split along ideological lines. The lesson is not that mathematics becomes subjective, but that people can selectively deploy their reasoning skills when identity is at stake. For anyone trying to improve analytical thinking, this research shows why apparently objective evidence still needs protection from motivated interpretation.
Kahan’s skin-rash and policy data task
The best-known demonstration comes from work by Dan Kahan and colleagues on what they called “motivated numeracy”. Participants were shown a simple 2×2 table that required comparing proportions rather than just comparing raw totals. Most people found the task surprisingly difficult because the largest numbers pointed towards the wrong answer unless the ratios were calculated correctly. [RCGD]rcgd.isr.umich.eduRCGDMotivated numeracy and enlightened self-governmentJune 24, 2017 — by DANM KAHAN · Cited by 1311 — The numbers in the 2 × 2 contingency table were kept the same, but the labels at the tops…
In the neutral version, participants were told the table described the effectiveness of a fictional skin cream for treating a rash. The correct answer depended entirely on comparing success rates between the treatment and control groups. Nothing about politics entered the task.
The researchers then changed only the story attached to the table. The numerical values stayed the same, but the labels now described whether a city that introduced a gun-control policy experienced more or less crime than a comparison city. Depending on the experimental condition, the numbers either supported or undermined the policy. Participants again had to compute the same ratios to reach the correct conclusion. [RCGD]rcgd.isr.umich.eduRCGDMotivated numeracy and enlightened self-governmentJune 24, 2017 — by DANM KAHAN · Cited by 1311 — The numbers in the 2 × 2 contingency table were kept the same, but the labels at the tops…
Because the arithmetic never changed, any difference in performance reflected the framing rather than the mathematics itself.
Why numeracy helps less on identity-linked questions
In the skin-rash version, people with stronger numeracy skills performed substantially better than those with weaker quantitative skills. Better mathematical reasoning translated into more accurate interpretation of the evidence, as would normally be expected. [IDEAS/RePEc]ideas.repec.orgstudy of a new skin rash treatment. Also as expected, subjects' responses became politically polarized – and even less accurate – when th…
The politically framed version produced a more surprising pattern. Participants were much more likely to reach the correct answer when it aligned with their political outlook than when the identical calculation pointed in the opposite direction. Highly numerate participants did not simply become more accurate across the board. Instead, their additional reasoning ability often appeared to help them reach the politically congenial interpretation while offering much less benefit when the data challenged their existing views. [IDEAS/RePEc]ideas.repec.orgstudy of a new skin rash treatment. Also as expected, subjects' responses became politically polarized – and even less accurate – when th…
This finding is important because it challenges a simple “knowledge deficit” explanation for political disagreement. If disagreement resulted only from poor mathematical ability, then stronger numeracy should reduce ideological differences. Instead, the original experiment suggested that reasoning ability can sometimes be recruited in defence of identity as well as in pursuit of accuracy. [SSRN]papers.ssrn.comWhy does public conflict over societal risks persist in the face of compelling and widely accessible scientific evidence?Read more…
The broader implication is not that skilled thinkers are irrational. Rather, they may be especially capable of constructing interpretations that satisfy both the numerical evidence and their preferred narrative whenever the evidence leaves room for selective emphasis.
What later studies found
The original study became highly influential, but it also attracted substantial replication efforts. Those later studies paint a more nuanced picture than either enthusiastic supporters or critics sometimes suggest.
Some replications have reproduced important aspects of the original effect, finding that politically relevant framing can reduce objective interpretation of identical numerical evidence, although often with smaller effects than originally reported. Research has also found similar patterns in other politically charged domains such as immigration. [Cambridge University Press & Assessment]cambridge.orgCambridge University Press & AssessmentMotivated numeracy and active reasoning in a Western…by P CONNOR · 2024 · Cited by 25 — In this…
Other preregistered replication studies have reported weaker evidence for motivated numeracy than the original paper. For example, a large preregistered replication concluded that the cumulative evidence was less robust than first believed, although it still found that prior attitudes could influence interpretation and that presenting the data in more cognitively supportive formats, such as number lines, substantially improved accuracy across conditions. [PubMed]pubmed.ncbi.nlm.nih.govA preregistered replication of motivated numeracyby E Persson · 2021 · Cited by 71 — Our findings suggest that the cumulative evide…
Researchers have also debated methodological details, including statistical power, measurement of political identity and the precise conditions under which motivated numeracy appears. Kahan and colleagues argued that some reported failures reflected design differences rather than genuine contradictions and published their own defence and additional evidence. [SSRN]papers.ssrn.comSSRN ID3032064 code45442Rumors of the “Nonreplication” of the “Motivated Numeracy…Consistent with existing literature, only 30% of the MN sample supplied…
The current evidence therefore supports a cautious conclusion. Political framing can distort numerical reasoning, but the size and consistency of the effect vary across studies, populations and experimental designs. It should not be treated as an inevitable law of human thinking.
Checking whether the frame is steering the maths
The practical value of this research lies less in politics than in recognising when identity may be steering your interpretation of evidence.
Useful questions include:
- Would I reach the same conclusion if these numbers described a skin treatment rather than a political issue?
- Have I actually compared the relevant proportions, or have I focused on the biggest raw numbers because they support my expectations?
- Would I trust this analysis if the policy labels were reversed?
- Could I explain the calculation without mentioning which political outcome I prefer?
Another useful technique is to remove the labels temporarily. Looking at a table with variables labelled simply “Group A” and “Group B” can reveal whether the apparent conclusion comes from the arithmetic or from the story attached to it.
Finally, deliberately calculating the ratios before reading the policy description can reduce the opportunity for motivated interpretation. The more the mathematical work is separated from the identity-laden framing, the harder it becomes for preferences to shape the conclusion.
Why this matters for analytical thinking
The motivated numeracy research illustrates a broader lesson about myside bias. Numbers are not a guarantee of objectivity if the interpretation of those numbers affects beliefs that are tied to identity, values or group membership.
Improving analytical thinking therefore involves more than becoming better at mathematics or statistics. It also requires recognising situations in which your motivation may quietly influence how you deploy those skills. The strongest protection is not assuming that political commitments disappear when numbers appear, but actively checking whether the framing is determining the calculation rather than the calculation determining the conclusion.
Amazon book picks
Further Reading
Books and field guides related to When Numbers Stop Feeling Neutral. Use these as the next step if you want deeper reading beyond the article.
Thinking, Fast and Slow
Explains cognitive biases and why reasoning often departs from objective evidence, providing the broader framework for motivated numeracy.
The Righteous Mind
Explores how moral intuitions and group identity shape political judgment and interpretation of evidence.
Mistakes Were Made (but Not by Me)
Examines self-justification, cognitive dissonance, and the mechanisms behind motivated reasoning.
How Minds Change
Shows why identity affects interpretation of evidence and how people can become more open to changing their minds.
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Endnotes
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Source: rcgd.isr.umich.edu
Title: RCGDMotivated numeracy and enlightened self-government
Link: https://rcgd.isr.umich.edu/wp-content/uploads/2018/07/motivated_numeracy_and_enlightened_selfgovernment.pdfSource snippet
June 24, 2017 — by DANM KAHAN · Cited by 1311 — The numbers in the 2 × 2 contingency table were kept the same, but the labels at the tops...
Published: June 24, 2017
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Source: ideas.repec.org
Link: https://ideas.repec.org/a/cup/bpubpo/v1y2017i01p54-86_00.htmlSource snippet
study of a new skin rash treatment. Also as expected, subjects' responses became politically polarized – and even less accurate – when th...
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Source: papers.ssrn.com
Link: https://papers.ssrn.com/sol3/papers.cfm?abstract_id=2319992Source snippet
Why does public conflict over societal risks persist in the face of compelling and widely accessible scientific evidence?Read more...
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Source: cambridge.org
Link: https://www.cambridge.org/core/journals/behavioural-public-policy/article/motivated-numeracy-and-active-reasoning-in-a-western-european-sample/5C462D05ED2D1FCAD2715F10287E6A0ASource snippet
Cambridge University Press & AssessmentMotivated numeracy and active reasoning in a Western...by P CONNOR · 2024 · Cited by 25 — In this...
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Source: papers.ssrn.com
Title: SSRN ID3032064 code45442
Link: https://papers.ssrn.com/sol3/Delivery.cfm/SSRN_ID3032064_code45442.pdf?abstractid=3026941&mirid=1Source snippet
Rumors of the “Nonreplication” of the “Motivated Numeracy...Consistent with existing literature, only 30% of the MN sample supplied...
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Source: pubmed.ncbi.nlm.nih.gov
Link: https://pubmed.ncbi.nlm.nih.gov/34051421/Source snippet
A preregistered replication of motivated numeracyby E Persson · 2021 · Cited by 71 — Our findings suggest that the cumulative evide...
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Source: pmc.ncbi.nlm.nih.gov
Link: https://pmc.ncbi.nlm.nih.gov/articles/PMC11478866/Source snippet
by S Yu · 2024 · Cited by 2 — In this pre-registered study, we sought to examine the replicability of motivated numeracy, and investig...
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Source: diva-portal.org
Title: Motivated Numeracy?
Link: https://www.diva-portal.org/smash/record.jsf?af=%5B%5D&aq=%5B%5B%5D%5D&aq2=%5B%5B%5D%5D&aqe=%5B%5D&faces-redirect=true&language=sv&noOfRows=50&onlyFullText=false&pid=diva2%3A1478949&query=&searchType=SIMPLE&sf=all&sortOrder=author_sort_asc&sortOrder2=title_sort_ascSource snippet
Well yes, but actually noMotivated Numeracy? Well yes, but actually no: A replication study on motivated reasoning, motivated numeracy, a...
Additional References
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Source: researchgate.net
Link: https://www.researchgate.net/publication/319698181Rumors_of_the%27Nonreplication%27of_the%27Motivated_Numeracy_Effect%27_are_Greatly_ExaggeratedSource snippet
Rumors of the 'Nonreplication' of the 'Motivated Numeracy...17 Sept 2017 — In evaluating the motivated numeracy effect, we also observed...
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Source: semanticscholar.org
Link: https://www.semanticscholar.org/paper/Motivated-numeracy-and-enlightened-self-government-Kahan-Peters/c31861537baeba1d6ea94fd67691b8e3d05a7c0fSource snippet
[PDF] Motivated numeracy and enlightened self-governmentThe findings suggest that the cumulative evidence for motivated numeracy is weake...
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Source: researchgate.net
Link: https://www.researchgate.net/publication/291069751_Motivated_Numeracy_and_Enlightened_Self-GovernmentSource snippet
He showed that greater intelligence increases the capacity to defend identity-based beliefs...Read more...
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Source: network.rawdatalibrary.net
Title: motivated numeracy and enlightened self government 2f7329
Link: https://network.rawdatalibrary.net/publication/motivated-numeracy-and-enlightened-self-government-2f7329Source snippet
Numeracy and Enlightened Self-Government7 days ago — We conducted an experiment to probe two alternative answers: the "Science Comprehens...
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Source: rpubs.com
Title: Kahan motivated reasoning reanalaysis
Link: https://rpubs.com/EmilOWK/Kahan_motivated_reasoning_reanalaysisSource snippet
Motivated numeracy reanalysis26 Mar 2026 — The three-way interaction tests whether the motivated numeracy effect (concordance × numeracy)...
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Source: youtube.com
Title: Dan Kahan- “Cultural Cognition of” or “Political Ideology in” Law- Part 1
Link: https://www.youtube.com/watch?v=8szmm5WzoM0Source snippet
Intuition: The Good, the Bad, and the Ugly - Scientific [Critical Thinking]({{ 'critical-skills/' | relative_url }})...
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Source: math.drexel.edu
Link: https://www.math.drexel.edu/~dp399/mathpolitics/MotivatedNumeracy.pdfSource snippet
AND POLITICS Motivated Numeracy & Enlightened...Mounting evidence that science literacy, numeracy, and education are actually associated...
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Source: youtube.com
Title: Dan Kahan: Science Literacy, Numeracy and Climate Change Risk Perceptions
Link: https://www.youtube.com/watch?v=LZah9G-7vxwSource snippet
Dan Kahan: How cultural values shape beliefs and perceptions of risk...
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Source: youtube.com
Title: Dan Kahan: How cultural values shape beliefs and perceptions of risk
Link: https://www.youtube.com/watch?v=3OFtNm3MlQkSource snippet
Dan Kahan- "Cultural Cognition of" or "Political Ideology in" Law- Part 1...
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Source: arxiv.org
Link: https://arxiv.org/abs/2011.02362
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