Our noisy world

Noise: A Flaw in Human Judgment by Daniel Kahneman, Olivier Sibony and Cass R. Sunstein (William Collins); reviewed by Aruna Sankaranarayanan.

Following his best-selling book, Thinking, Fast and Slow, Nobel laureate Daniel Kahneman teams up with behavioral scientists Olivier Sibony and Cass Sunstein to produce another seminal work, Noise: A Flaw in Human Judgment. While the earlier book focuses on cognitive fallibilities of the human mind, Noise zeroes in on one particular type of human error: noise in human judgements.

A teacher grading an essay, a judge assigning a sentence, a doctor reaching a diagnosis, an underwriter deciding on an insurance premium, a recruiter hiring a candidate, a banker signing off on a loan – each of these decisions, relying on human judgment, tend to be noisy. One teacher may assign an A, while her colleague may award a B minus. A judge may be more liberal, giving shorter sentences on average in the morning, but as the day wears on, the fatigued judge’s sentences may get more stringent for crimes of the same severity. 

In many situations, both significant and trivial, judgements are often a function of the person assessing as opposed to the person being assessed. It may depend on the individual’s personality, mood and other willy-nilly factors unrelated to the person or object being assessed. This should provoke us to acknowledge the existence of noise and motivate us to reduce it.

The book first examines noise through a statistical lens and is unlikely to grip the lay reader. However, as the book progresses, the authors delve into the psychological aspects of noisy decisions, highlighting the ubiquity of the problem and how it impacts every one of us. Take the good, old-fashioned job interview that is a staple of most hiring processes. According to the authors, traditional, unstructured interviews are ‘often useless’, providing very little predictive power on how a person will perform in a job. Even performance appraisals are noisy affairs, with only a weak correlation between a person’s performance and their ratings. 

More troubling are psychiatry’s noisy medical diagnoses. Despite refinements and additions to every subsequent edition of the Diagnostic and Statistical Manual, psychiatric diagnoses are replete with noise, with experts often disagreeing. Even forensic science, with its reputation for objectivity, often involves judgement calls that can swing a case in one direction over another.

While noise is pervasive, people are often blind to its existence. The authors coax us into conducting noise audits to appreciate the prevalence of the problems. They also provide strategies and guidelines to reduce noise in various situations involving judgements. Like Kahneman’s previous book, Noise highlights a glaring shortcoming of the human mind. Even experts, in an array of fields, are prone to making noisy decisions, though they may be loath to acknowledge it. As both books by Kahneman and his co-authors point out the frailties of the human mind and our collective denial of them, perhaps the next book by Kahneman and his team can shed more light on another panhuman weakness that needs to be addressed urgently – our lack of humility, both as individuals and as a species.

- Reviewed by Aruna Sankaranarayanan, Psychologist & Author, Zero Limits: Things Every 20-Something Should Know

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