Daniel Kahneman obituary
The psychologist Daniel Kahneman, who has died aged 90, won the 2002 Nobel prize for economics despite describing himself as “mostly cheering … from the sidelines” of the subject. He achieved celebrity status in 2011 with the pop psychology book Thinking, Fast and Slow, at the age of 77 and after a lifetime of rigorous academic research. Such unpredictable events were typical of his long and eclectic career, while also provoking him to ask the myriad questions about human behaviour that formed the basis of his often counterintuitive theories. His work revealed the extent to which human beings make erroneous judgments in everyday situations and base decisions on those judgments. Steven Pinker called him “the world’s most influential living psychologist”.
From early in his career, working at the Hebrew University in Jerusalem, Kahneman had been interested in obtaining results that could be applied to real-world situations. One of his first insights came when he was trying to persuade flight instructors that reward was more effective than punishment when training people in new skills. A member of his class flatly contradicted him, saying that cadets he praised for a successful manoeuvre invariably did worse the next time, and those he reprimanded for fluffing a skill did better.
Kahneman immediately realised that the instructor’s reaction had nothing to do with the second performance – it was simply a case of regression to the mean (the cadets reverting towards their average result). “It is part of the human condition,” he later wrote, “that we are statistically punished for rewarding others and rewarded for punishing them.”
During the 1970s Kahneman did most of his work in collaboration with a younger colleague, Amos Tversky. Their partnership, founded on incessant conversation, complementary skills, very high standards of evidence and “continuous mirth”, earned them the nickname “psychology’s Lennon and McCartney”. Between them they unleashed a torrent of examples to show how our largely unconscious perceptual and emotional predispositions merrily undermine our rational selves.
Kahneman and Tversky showed that if people toss a coin twice and get heads both times, they are far more likely to believe that the next toss will produce tails – even though the probability of heads on every toss is exactly 50/50. The same fallacy makes gamblers keep playing after a series of losses – surely the next spin must bring a win? They defined what they called “heuristics of judgment” – rules of thumb that systematically bias people in their decision-making. They went on to develop what became known as “prospect theory”, demonstrating that fear of losing was a much more powerful driver than hope of winning. People asked to bet $20 on the toss of a coin will typically not take the bet unless winning yields $40 or more.
Prospect theory, together with work showing that people make different choices between two equally probable outcomes depending on how the question is framed, took the world of economics by storm during the 80s. The economist Richard Thaler took up their ideas and the collaboration gave birth to the new field of behavioural economics. Up to that point, economists worked on the assumption that economic agents made rational decisions based on the utility, defined in statistical terms, of a particular course of action. Despite the obvious fact that such actors are usually people, the world of economics and the world of psychology had rarely interacted.
Kahneman’s collaboration with Tversky petered out when both researchers moved from Israel to North America: Tversky to Harvard and then Stanford in the US, and Kahneman to the University of British Columbia in Vancouver, Canada (1978-86), followed by the University of California at Berkeley (1986-94). As related in Michael Lewis’s 2016 joint biography of the two men, The Undoing Project, their relationship deteriorated to the point where Kahneman told Tversky they were no longer friends. Only days later, Tversky got in touch to say he had incurable cancer.
He died in 1996, aged 59. Kahneman gave the eulogy at his funeral, and included it along with his autobiographical essay on the Nobel website: Tversky would certainly have shared the prize had he lived.
The book Thinking, Fast and Slow brought to a wide readership Kahneman’s integration of his and Tversky’s results with a model of psychological processing that answered the question of how the human race had managed to survive and thrive despite its susceptibility to irrational biases. The model suggests that we initially assess a situation with a fast, intuitive process based on prior experience that in evolutionary terms is often the key to survival. On top of this is a slow, effortful, conscious process that can, but does not always, correct errors made by the first process.
Kahneman was born in Tel Aviv, while his mother was visiting family there. His parents, Rachel (nee Shenzon) and Efrayim, descended from Lithuanian Jews, lived in Paris, where Efrayim worked as a chemist for a branch of the cosmetics company L’Oréal. When Paris fell to the Nazis in 1940 Efrayim was detained in the transit camp at Drancy, but released after six weeks after his boss intervened. The family went on the run, living for part of the time in a chicken coop. They evaded capture but Daniel’s father died of the consequences of untreated diabetes in 1944, when Daniel was 10 years old, and only six weeks before the allied landings on D-day.
Having spent his early years being hunted, as he put it, like a rabbit, Kahneman described himself as a constant worrier. At the same time, his fascination with gossip and questions of behaviour, personality and faith set him up for a career in psychology. In 1946 his mother took him and his sister to live in Palestine, becoming some of the first citizens of the state of Israel. Armed with a degree in psychology from the Hebrew University, he undertook his national service in the Israeli Defence Forces, among other things designing a questionnaire for recruits that would improve the dismal predictions of existing tests as to their potential as soldiers.
After a PhD at Berkeley, Kahneman returned to Jerusalem as a junior lecturer, and began research in visual perception. During two years of sabbatical leave in the US, he switched his research interest to questions related to mental effort and attention, and their connections to emotional arousal.
His decade of collaboration with Tversky on decision-making set him up for his subsequent career in North America. Garlanded with many honours, he spent his later years as emeritus professor at Princeton University, New Jersey, publishing his final book, Noise (with two co-authors, Olivier Sibony and Cass Sunstein) in 2021.
Kahneman’s acute self-awareness included his acknowledgment that he shared all the impediments to rational decision-making that his research had revealed. Late in his life he attempted to tackle the often intemperate exchanges between competing social scientists by developing a method called “adversarial collaboration”. He hoped, he wrote, that “more efficient procedures for the conduct of controversies will be part of my legacy”. Even he, however, a leftwing Israeli who “hated the notion of occupation”, as he told David Shariatmadari in an article for the Guardian in 2015, could not think of an approach to resolving the Arab-Israeli conflict.
Kahneman married the educational psychologist Irah Kahn when they were students. After their divorce, in 1978 he married the British cognitive psychologist Anne Treisman. She died in 2018. He spent the final years of his life with Tversky’s widow, Barbara. She survives him, along with two children from his first marriage, Michael and Lenore, four stepchildren, Jessica, Deborah, Daniel and Stephen, from his second marriage, three grandchildren and four stepgrandchildren.
• Daniel Kahneman, psychologist, born 5 March 1934; died 27 March 2024
His partnership with Amos Tversky earned them the nickname 'psychology’s Lennon and McCartney'
diagnosed as autistic also exhibit ADHD symptoms, and that characteristics of autism are present in two-thirds of people with ADHD. “My clinical experience suggests it’s more than threequarters in both directions,” adds Dr Eccles.Online, the idea that autism and ADHD can coexist is so widely accepted that it has spawned its own label – “AuDHD” – and a groundswell of people who say they recognise its oxymoronic nature, perpetual internal war and rollercoaster of needs. There are tens of thousands of people in AuDHD self-help forums, and millions more watching AuDHD videos.Some of those videos come from Samantha Stein, a British YouTuber. “The fact that you can have both [autism and ADHD] at the same time is kind of paradoxical in nature,” she admits. “You think: ‘How can you be extremely rigid and need routines and structure, but also be completely incapable of maintaining a routine and structure?’”The 38-year-old started making videos on autism after her diagnosis in 2019, then began covering AuDHD after learning that she also had ADHD. “I realised that autistic adults – especially those who are diagnosed late in life – more often than not seem to have ADHD as well,” says Stein. Her first video on the subject, “5 signs you have ADHD and autism”, has now been viewed more than 2m times.
Some critics like to describe ADHD – and more recently autism – as a “fashionable” diagnosis, a misinformed excuse for life’s struggles. It’s almost inevitable that the new AuDHD label will cause a similar backlash. To see just how misguided this is, we must first understand both autism and ADHD. Both are lifelong neurodevelopmental conditions that affect how people think, perceive the world and interact with others, according to Embracing Complexity, an umbrella group of organisations that research neurodiversity.
Autism and ADHD affect people on a spectrum of severity, both are legally recognised as disabilities, and neither are mental illnesses to be “cured”, although the knock-on effects can lead to mental illness. People who experience ways of thinking that diverge from those experienced by the majority of people are described as “neurodivergent”.Autism spectrum disorder (ASD) is caused by multiple genetic factors that aren’t yet fully understood. Contrary to misconception, autism doesn’t equate to impaired intelligence, and only around half of people with autism also have a co-occurring intellectual disability. According to the National Autistic Society, autism is characterised by social challenges, repetitive behaviours, overor under-sensitivity to surroundings and highly focused interests.Autism is experienced in a multitude of ways. To empathise with the autistic trait of oversensitivity, for example, imagine that all your senses are amplified. The hum of your fridge is louder, the overhead lights are brighter, your itchy jumper is pricklier. It’s distracting while you’re trying to work, it’s draining to pretend it isn’t bothering you and you become increasingly stressed as a result.“For me, eating in a canteen is like eating in a nightclub for a neurotypical person,” says Jill Corbyn, who is autistic and the director of support organisation Neurodiverse Connection. “It’s unpleasantly loud, it’s going to distract you from your food, it’s anxiety-inducing.” Additionally, some autistic people may find social situations exhausting or overwhelming, or feel incompetent when they’re unable to decipher the subtleties of interpersonal communication, 60% of which is non-verbal. Charli Clement, 23, explains that while a non-autistic person may rehearse parts of a conversation before a date or a job interview, her autism leads her to “script significantly” before even ordering a drink at a bar.
“I try to make sure I’m not doing something that will be perceived as ‘wrong’, so focusing on what the person is saying and what I should be replying is overwhelming,” she says.
Compounding the experience is the feeling many autistic people have that it isn’t “normal” to feel this way and that they must camouflage their discomfort to fit in with the pack. This “masking”, as it’s known, is exhausting, invalidating and can lead to burnout.ADHD is also not fully understood. There’s evidence that the condition, involving an imbalance of neurotransmitters – including dopamine, in the brain – has both genetic and environmental causes. These chemical messengers are responsible for motivation, movement, planning, reward, memory, focus, alertness, impulse control and threat response, among others. People with untreated ADHD, whose reward pathways are therefore more dysregulated, can subsequently experience disordered moods, sleep, eating habits and dysfunction in almost every area of life.Some people with ADHD are like pinballs of external chaos – of lost keys, missed appointments and cluttered homes. Others may appear inattentive, distracted by balls of chaotic thoughts into which they frequently retreat from the world to untangle.ADHD affects people to different degrees. But many say their lives are marred by their brain’s misguided attempts to correct its chemical imbalances. They impulsively dopamine-spike with food, sex, drugs, booze, the internet, people, hobbies and novelty of all shades.“I am a slave to my own brain and it’s tiring,” writes one anonymous person on an ADHD Reddit support group. Another
asks: “Do you also feel like a slave to your desires?” She gives the examples of “chasing girls, gambling, chasing men, eating, hobby-hopping, extreme budgeting, falling in love [with] the wrong person, spending extravagantly”.
What frequently underpins the external and internal chaos, according to experts and many ADHDers alike, is a pervasive sense of deep shame and the quiet realisation that their potential in life is not being met.
When autism meets ADHD, it’s a curious form of alchemy, according to those who have both.Sometimes the conditions are in conflict; at other times they’re symbiotic. There is no such thing as a perfect 50/50 split, explains Sadiq, and the brain is often “seesawing” between both conditions. This makes the presentation of AuDHD a distinctive condition in its own right, “completely different from pure ADHD or pure ASD”, he adds.
In his Ted Talk, “When Order and Anarchy Live Together”, Sadiq describes the dualities of the condition: “Silence v noise; structure v chaos; repetition v novelty; caution v risk-taking …”Mattia Maurée, a non-binary composer and host of the AuDHD Flourishing podcast, discovered the AuDHD concept after following separate pieces of advice about autism and ADHD that “just weren’t working for me”. “It was like: ‘No, my life is still really, really hard,’” they tell me from Philadelphia.AuDHD is uniquely “cyclical”, says Maurée, with big bursts of energy followed by a crash. “AuDHDers can also be incredibly creative and innovative, maybe because of that brain hyper-connectivity.”Creativity is cited as the most positive AuDHD attribute by everyone I speak to, along with the subtle pairings of traits that “complement each other in a really nice way”, as Stein puts it. “ADHD gives me a love of novelty and a very creative side. And then autism allows me to focus on a topic that I’m really interested in. All of that allows me to be very self-directed.”
The paradoxes of AuDHD can camouflage each other or – on the surface at least – cancel each other out, which is why some AuDHDers experience missed or incorrect diagnoses.In February, Sadiq saw a patient who had been referred to his NHS clinic for an ADHD diagnosis. He realised 15 minutes into the consultation that the patient was autistic. “If I had no lived experience of autism and ADHD I would have missed it completely,” he says. “I would have diagnosed either social anxiety or a personality disorder.”In spite of his expertise, Sadiq is not formally qualified to make an autism diagnosis, and instead he had to refer the patient on to the autism service within the NHS trust. He believes that psychiatrists specialising in autism should also be trained in ADHD and vice versa, because otherwise “they’re going to be missing a lot”.
It’s not just the medical profession that needs more coordination. Charities such as ADHD UK and the National Autistic Societyalso work independently from one another. Legislation such as the government-backed The Buckland Review of Autism Employment, which recently called for employers to boost support for autistic people, scrutinises autism provisions but not ADHD ones. ADHD UK is one of many advocacy groups calling for the Autism Act, which legally compels the government to support autistic people, to be widened in scope to include other forms of neurodiversity.Once a correct dual diagnosis is obtained, there are still complications. ADHD can be successfully managed with medication and behavioural coaching, but some autistic people react badly to this medication. Research indicates that stimulants are overall less tolerable for AuDHDers than they are for people with ADHD, according to the global research platform Embrace Autism, with one report finding that side-effects doubled in those with both conditions.
Another quirk of AuDHD treatment is that in some cases, it’s only after “quietening” someone’s ADHD symptoms that their autism traits come to the fore. This is often when people realise their autistic side for the first time, and it could explain why rates of self-reported autism closely follow those of ADHD. The medical professionals I interviewed for this article were emphatic that ADHD medication cannot cause autism. Instead, Dr Eccles says: “It has just changed the balance of symptoms. The balance of masking has changed.”The prevalence of autism was widely believed to be 1% until last year, when a first of its kind study published in the Lancet found the true rate to be more than double that, with at least 1.2 million autistic people in the UK. The prevalence of ADHD in UK adults is around 4%, according to ADHD UK, and assessment waiting lists for both conditions are increasing year on year, with waits of a decade in some parts of the country for ADHD assessment.When naysayers argue that we are in the midst of an overdiagnosis epidemic, charities often point them to the statistics on suicide, and the fact that the ripple effects of ADHD and autism often lead to mental ill-health.Autistic adults without a learning disability are far more likely to die by suicide.In 2022, researchers from Cambridge and Nottingham University, analysing coroners’ inquest records, concluded that a significant number of people who had died by suicide were likely autistic but undiagnosed. Adults with ADHD, meanwhile, are five times more likely to attempt suicide than their neurotypical peers.Yet AuDHDers have been found to be at even greater risk of suicide than either those with only autism or ADHD, according to an academic study of more than 50,000 people.
For people like Clement, criticism about over-labelling is the least of her concerns. As a teenager she spent time in a psychiatric unit before the nature of her AuDHD was fully realised. “I’d already given myself labels,” she says. “I already thought that I was weird and broken. So having a label that actually made sense and encompassed my experience was so liberating.”
She now works part-time advising psychiatric hospitals on how to ensure their sensory environments are adequate for neurodiverse people.
Other AuDHDers give colourful analogies to describe the epiphany of diagnosis. Before the discovery, I’m told, it’s as if you are trying to fit in and be a horse rather than celebrating the fact that you’re a zebra. It’s like being trapped in a maze in the dark, then suddenly the lights are on and now there’s a way to navigate out.
Stein describes her life as “fundamentally walking parallel to, but never quite included in society”. Her diagnosis, however, “allowed me to look at my life through the lens of far more compassion – as a pretty good autistic person rather than a broken neurotypical person”.
“I think in some ways [AuDHD] can be a very beautiful thing,” she says.
“You just need the right support to be able to access those parts of you. And you need the label to know what the hell is going on in your brain.”
• In the UK and Ireland, Samaritans can be contacted on freephone 116 123, or email jo@samaritans.org or jo@samaritans.ie. In the US, you can call or text the National Suicide Prevention Lifeline on 988, chat on 988lifeline.org, or text HOME to 741741 to connect with a crisis counsellor. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found at befrienders.org
It’s like being trapped in a maze in the dark, then suddenly the lights are on and now there’s a way to navigate out