A young man known in the research as P.S. sat in front of a screen with his hands in his lap. Surgeons had cut the band of fibres joining the two halves of his brain to stop his seizures, so the halves could no longer pass each other notes.
That made him useful to researchers. By flashing an image to one side of his vision only, they could hand information to one hemisphere while keeping the other one ignorant of it, then watch what he did with the mismatch.
So they flashed two images at once, a chicken claw where only his left hemisphere could see it and a snow scene where only his right could, and asked him to point at a related card with each hand. His right hand chose a chicken. His left hand chose a snow shovel. Each hand had answered its own picture correctly.
Then Michael Gazzaniga asked him why he had picked the shovel.
Speech sits in the left hemisphere, and the left hemisphere had never seen snow. It could see a hand holding a shovel, and a card with a chicken on it, and that was the whole of its evidence. P.S. did not pause or hedge:
“The claw goes with the chicken, and you need a shovel to clean out the chicken shed.”
He was not lying. He believed the answer as he gave it. The part of him that had to produce an explanation could not reach the real cause, so it built a workable cause out of the evidence it did have and handed that invention over as a memory of his own reasoning.
The explanation felt to him exactly like a recollection. It was manufactured about a second earlier.
The half that talks
Gazzaniga named this the interpreter, and its most useful property is that it never comes back empty. “I don’t know” was the correct answer available to P.S. all along, but it never surfaced. The explanation arrived first, complete, and felt like memory.
Jonathan Haidt made the same argument about morality. Moral judgment, he wrote, is normally a fast automatic reaction, and the reasoning that follows is built afterwards to account for a verdict already reached.
His test was a short story about a brother and sister who sleep together once, on holiday, using two forms of contraception, telling nobody, and who are closer for it afterwards. Readers condemn it instantly and then go looking for reasons. Pregnancy, no. Harm, no. Coercion, no. Discovery, no. The reasons run out but the verdict does not budge. Haidt called this moral dumbfounding, and what interested him was not that people were wrong but that they were fluent.
What Haidt is claiming is worth spelling out. He is not saying people are bad at reasoning, or that they lie about their motives. He is saying that in most everyday judgments the reasoning happens after the verdict is in, and that it reports its output as if it were the cause.
The sentence “I think this because of X” is often better described as “I think this, and X is what I found when I went looking for something to say.”
90 seconds of conviction
Before the Swedish general election in 2010, a team at Lund University set out to test something the polls take for granted, which is that when a voter reports an opinion, the opinion is really theirs and really held. They handed voters a political survey. Twelve issues, chosen because they split the left-green bloc from the centre-right one. Participants stated who they meant to vote for, filled in the form, and were then asked to talk through their answers.
The form was a magic trick. Using sleight of hand the researchers reversed some of the answers and asked people to explain positions they had never held. Only 22% of the altered replies were caught. A full 92% accepted the reversed political profile the researchers read back to them, and 48% said they would consider switching blocs entirely.
People argued for opinions they had owned for about 90 seconds, and they argued well. A companion study on moral questions found that 69% of participants missed at least one of two reversals on principles as basic as whether it is wrong to harm the innocent. Nobody in these rooms had a severed corpus callosum. They had ordinary brains doing the ordinary job of explaining whatever they found themselves holding.
Two useful conclusions come out of that:
- Fluent reasons are not evidence of considered opinions. People produce fluent reasons for positions handed to them by a magic trick a minute earlier.
- If a good argument is available for a position the person never chose, then the argument is not what is keeping them there, which is why demolishing it so rarely moves anyone.
190,000 tongues
Coca-Cola had been losing share to Pepsi for 15 years, and Pepsi was winning partly by running blind taste tests in public and filming the results. So Coca-Cola decided to beat Pepsi at taste.
Under the codename Project Kansas it built a sweeter formula and put it in front of roughly 190,000 consumers in blind trials to find out whether the new recipe won. It did, against Pepsi and against Coca-Cola’s own century-old formula. Roberto Goizueta, the chief executive, asked whether the data could be wrong, hired a second research firm, and spent more than a million dollars repeating another 100,000 tests. Same result.
Acting on that evidence, the company retired the original recipe and launched New Coke on 23 April 1985. The public revolted. Coca-Cola took up to 8,000 calls a day and something like 40,000 letters. On 11 July, 79 days later, the old formula came back as Coca-Cola Classic and quickly returned to the top of the market.
This was not bad research. It was large, it was repeated, and it gave the right answer. The trouble was the question.
Coca-Cola asked 190,000 people which drink tasted better and never asked a single one of them how they would feel about the other one being taken away. Taste was the part the company knew how to measure, so taste is what it measured, and the thing that decided the outcome was an attachment that never appeared in any dataset.
People were not buying the flavour. They were buying a drink they felt belonged to them, and no amount of rigour on the wrong variable can tell you that.
Two economies, one grocery bill
The University of Michigan has asked consumers about their politics every month since 2017, and the pattern is consistent. People whose party holds the White House report a better economy than people whose party does not.
In early August 2026 the headline index fell to 51 from 55.2 in July, and the sharpest monthly drop came from Republicans, whose outlook hit its lowest point since the 2024 election. Across everyone, only 8% expected their income to grow faster than prices in the year ahead, down from 18% in December 2024.
Republicans reporting the gloomiest outlook since the 2024 election, while their own party holds the White House and grocery and fuel prices climb, is the part to hold on to.
It means that feelings are not sealed off from the world. Loyalty shapes how people read the economy, but it does not seal the reading shut, and a price you pay every week eventually gets through.
Facts do reach people, but they reach them late, and they reach them through the parts of life that cannot be argued with, like a fuel gauge or a grocery receipt. What they almost never do is arrive as an argument and win on the spot.
Until a fact gets that direct, knowing which party someone belongs to will tell you more about their view of the economy than the economy will.
The correction that changes nothing
Researchers found in 2010 that conservatives shown evidence that no weapons of mass destruction were found in Iraq became more sure that some had been. The backfire effect went into every media-literacy slide deck in the world.
Then researchers ran it again with 10,100 subjects across five experiments and 52 issues. They found no backfire anywhere. Corrections moved beliefs toward the correction, including when the politician being corrected was the subject’s own.
This is worse news, not better. Researchers tested fact-checks of Donald Trump’s 2016 convention speech. The fact-checks worked. Respondents’ factual beliefs got more accurate, and that included his supporters. But their feelings about him did not move at all.
So the facts get in. People accept them, and what they believe about the world genuinely changes. What they feel about the person does not.
That changes what a fact-check is good for. If you correct someone’s numbers, you will probably succeed, but you will probably not change their vote, their loyalty or their trust. The number was never the reason for any of those. This is a harder problem than people refusing to hear you. Being heard is not the obstacle.
The researchers who did it too
In December 1954, an Oak Park housewife named Dorothy Martin told her small circle of followers that a flood would destroy the middle of the continent on the 21st, and that flying saucers would collect the faithful beforehand. Three trained psychologists joined the group under false names to watch what would happen when nothing happened.
Their 1956 book When Prophecy Fails reported something nobody expected. The believers did not quietly go home. Faced with a flood that never came, they became more convinced, not less, and went out recruiting for the first time. Festinger’s explanation was that giving up the belief was more painful than explaining away the evidence, so they explained away the evidence and doubled down.
That single observation launched the theory of cognitive dissonance, and it has been cited ever since across psychology, sociology, religious studies and New Testament scholarship. It is one of the most famous field studies ever run.
In 2026, working from a box of Festinger’s papers that had only recently been unsealed, Thomas Kelly published the underlying record. It does not support the book.
The group had been proselytising heavily for months before the flood date, which the book plays down, so the recruiting that supposedly followed the disappointment had been going on all along. Afterwards, the belief did not intensify. Martin recanted the prophecy, the group dissolved, and students she taught in later years had never heard of it. The researchers knew all of this. Their own notes say so.
The observers were also not observing. One of the psychologists was treated as a spiritual authority inside the group and fabricated channelled messages, and wrote afterwards that he had precipitated the climactic scene on the night itself. Several of the striking moments in the book were manufactured by the men and women writing it.
So the founding evidence for cognitive dissonance shows roughly the opposite of what was published and that some of it was staged.
Two things follow:
Any single study can be wrong, including a famous one, and if you have been nodding along to the research in the sections above, this is the reminder that the same thing could be true of any of them. Cognitive dissonance survives, because 70 years of laboratory work has since supported it on much better evidence than a living room in Illinois. The original demonstration does not.
They published the expectation instead of the observation. Three trained psychologists, with a method, a budget and a hypothesis, went to Oak Park expecting belief to strengthen after disappointment. It weakened. Nevertheless, they published the expectation instead of the observation. Nothing about being an expert on this pattern protected them from it. They had the feeling first and assembled the facts to fit, in the very book that taught the world to notice people doing that.
Gregers Werle brings the truth
Ibsen wrote The Wild Duck in 1884, and it opens with a man arriving to do exactly what modern advice says to do. Gregers Werle has the facts about the Ekdal household: about the marriage, about the money, about who Hedvig’s father probably is. He believes Hjalmar has a right to know and delivers them.
Hjalmar turns on his daughter. Hedvig takes a pistol into the attic and shoots herself. The house doctor, Relling, who has spent the play propping the family up with useful fictions, tells Gregers that if you rob the average man of his life-illusion you take his happiness with it.
Ibsen is not arguing that truth is bad. He is arguing that being right about a fact and being right to deliver it are two different questions, and that the second one is answered by what the fact does to the person who receives it.
Gregers never asks what the family’s illusions were holding up before he removes them. He is the most honest character on the stage and he is the reason a child is dead.
The type is still recognisable at any dinner table over 100 years later. He is the one with the correct information, waiting for a gap in the conversation.
The machine that agrees with you
P.S. needed his own left hemisphere to make the shovel story. That service is now available on every phone.
In March 2026, Myra Cheng and colleagues published a study measuring flattery across 11 leading AI language models. The models affirmed users’ actions 49% more often than human respondents did, and kept doing it when the user’s own account involved deception, illegality or harm.
On posts from r/AmITheAsshole where the human verdict had gone unanimously against the poster, the models told the poster they were not at fault in 51% of cases. Three experiments tested what this does. A single conversation with the agreeable version left people more convinced they were in the right and less willing to apologise or repair the relationship.
And they liked it. Participants rated the flattering responses as higher quality, trusted the model more, and said they would come back.
When an argument about facts is going nowhere, stop and look for the feelings underneath. Accepting how somebody feels is what makes it possible to examine the evidence together afterwards. The validation is the opening move, not the destination.
A model that only ever affirms makes the opening move and then stops. It leaves people feeling understood and more certain about something they have not examined, and it does this to millions of people a day, because that is the version they rate higher and come back to.
The technique meant to get two people to the facts has been automated into never arriving.
Tuesday or Thursday
Antonio Damasio’s patient Elliot had a tumour cut out of the underside of the front of his brain, and afterwards he tested in the 97th percentile for IQ with his language, memory, perception and abstract moral reasoning all intact. What went was his feelings. He described his own collapsing life in the tone of a man reading out a train timetable.
He lost his job, his marriage, his savings, and then a second marriage. He could spend an entire working day deciding how to sort a stack of documents. Asked whether he would prefer his next appointment on the Tuesday or the Thursday, he could argue the merits of both for half an hour without arriving anywhere, because nothing in him marked one as better. He could know but not feel.
Strip out the feelings and you do not get a clear instrument that finally sees the facts straight. You get a man who cannot pick a day of the week.
It is tempting to read every section above as a case against feelings, as though the goal were to clear them out so the facts could work properly. Elliot is what that looks like. He had the facts and no way to prefer any of them, because preferring is what feeling does.
The feelings are not sitting on top of judgment, distorting it. They are the part that sorts the options into better and worse, and without that step there is no judgment at all, only an endless correct list.
The chicken shed
Which brings the shovel back into the room.
The right hemisphere knew about snow. The left hemisphere knew about the chicken. Neither of them was wrong about anything it had seen, and neither of them invented the chicken shed. The sentence did that, instantly and without effort, and the sentence is also the only reason P.S. walked out of that lab as one person with one account of himself rather than two hands with separate reasons.
When you disagree with someone about the facts, that sentence is what you are up against. It was believed the moment it was made, and it will be defended as though it had been there from the start. Correcting it accomplishes very little, because the explanation was never the reason.
Which gives a practical instruction. Stop arguing about the shovel. Work out what the person is holding together with that explanation, and what it would cost them to put it down. That is the conversation worth having, and the facts lose nothing by waiting until you get there.
References
Gazzaniga, Michael. “The Interpreter.” Farnam Street summary of Gazzaniga’s split-brain work. https://fs.blog/michael-gazzaniga-the-interpreter/
Hall, L., Strandberg, T., Pärnamets, P., Lind, A., Tärning, B., & Johansson, P. “How the Polls Can Be Both Spot On and Dead Wrong.” PLOS ONE 8(4):e60554, 2013. https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0060554
Kelly, Thomas. “Debunking When Prophecy Fails.” Journal of the History of the Behavioral Sciences 62(1):e70043, 2026. https://onlinelibrary.wiley.com/doi/abs/10.1002/jhbs.70043 (full text: https://gwern.net/doc/psychology/cognitive-bias/2025-kelly.pdf)
Cheng, M., Lee, C., Khadpe, P., Yu, S., Han, D., & Jurafsky, D. “Sycophantic AI decreases prosocial intentions and promotes dependence.” Science 391(6792):eaec8352, 26 March 2026. https://pubmed.ncbi.nlm.nih.gov/41886588/
Haidt, Jonathan. “The emotional dog and its rational tail.” Psychological Review 108(4):814–834, 2001. https://pubmed.ncbi.nlm.nih.gov/11699120/ (full text: https://www.kevindorst.com/uploads/8/8/1/7/88177244/haidt_2001.pdf)
Wood, T. & Porter, E. “The Elusive Backfire Effect.” Political Behavior 41:135–163, 2019. https://link.springer.com/article/10.1007/s11109-018-9443-y
Nyhan, B., Porter, E., Reifler, J. & Wood, T. “Taking Fact-Checks Literally But Not Seriously?” Political Behavior 42:939–960, 2020. https://link.springer.com/article/10.1007/s11109-019-09528-x
History.com. “Why Coca-Cola’s New Coke Flopped.” https://www.history.com/articles/why-coca-cola-new-coke-flopped
Irwin, Neil. “Consumer sentiment dips, especially among Republicans.” Axios, 14 August 2026. https://www.axios.com/2026/08/14/consumer-sentiment-republicans
Ibsen, Henrik. The Wild Duck, 1884. Act 5 text: https://monadnock.net/ibsen/duck-act5.html
Damasio, Antonio. Descartes’ Error, 1994 (case of Elliot). https://en.wikipedia.org/wiki/Descartes%27_Error and https://psychexamreview.com/the-somatic-marker-hypothesis/
Hsu, Joanne. “Partisan Perceptions and Expectations.” University of Michigan Surveys of Consumers, 2024. https://www.sca.isr.umich.edu/files/partisaneconomy202402.pdf
Hall, L., Johansson, P., & Strandberg, T. “Lifting the Veil of Morality.” PLOS ONE 7(9):e45457, 2012. https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0045457
Wikipedia, “Left-brain interpreter.” https://en.wikipedia.org/wiki/Left-brain_interpreter
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