The Expectation Effect, by David Robson

The Expectation Effect, by David Robson 18th January, 2022

There’s a fine line to walk between writing a book that argues that our mental state is surprisingly powerful, and writing a book that argues that if you ask the universe for a gift, the universe will respond.

But @D_A_Robson walks the line skilfully here with The Expectation Effect.

He deploys a deft mix of storytelling and scientific studies (many people try, not everyone succeeds) to argue that placebo-type effects are more common and more powerful than we expect. Here are a few that surprised me:

In the US, placebos are working better than ever. Why? Plausibly because a) Advertising endlessly sings the praises of wonder-drugs, so Americans expect a lot from their pills and b) People have been told about the placebo effect, so they expect even a placebo treatment to work well.

Nocebo effects can also be astonishingly powerful – Robson cites one case of a woman in a trial of acupuncture-before-C-section. She was told that the acupuncture could sometimes cause dizziness or fainting, or in rare cases “cardiovascular collapse”. Worrying. She promptly suffered a cardiovascular collapse, heart rate down to 23 beats a minute, and needed to be revived with a drip. What’s striking is that she never actually had any acupuncture – she was in the control group…

Robson notes that arachnophobes perceive spiders as objectively larger and faster. (As I explained to my non arachnophobic wife: her warped perceptions cause her to falsely see slow, tiny spiders.)

Another surprise: if you give people a milkshake and tell them it is “indulgent” and “decadent” and has 620 calories, people’s ghrelin levels respond, priming them to burn more calories and eat less. The same milkshake, branded as just 140 calories of “guilt free satisfaction”, induces no ghrelin response at all. More broadly, if you eat the same food but convince yourself you’re eating something indulgent, you feel less hungry afterwards. If you keep telling yourself you’re on a strict diet, you feel hungrier.

Lots of other interesting ideas in the book. I have no doubt that some of these studies will collapse on close inspection – that is the way of things – but Robson marshalls a huge range of diverse evidence here, and describes it very well. I learned a lot and enjoyed the book hugely.

The paperback of The Data Detective is out on 1 February in the US and Canada. Title elsewhere: How To Make The World Add Up.

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