Book Summary & Highlights: Supernormal Stimuli: How Primal Urges Overran Their Evolutionary Purpose By Deirdre Barrett

Book Summary & Highlights: Supernormal Stimuli: How Primal Urges Overran Their Evolutionary Purpose By Deirdre Barrett

Amazon Summary

How our once-helpful instincts got hijacked by our garish modern world.

Have you ever wondered why some men choose pornography over actual women? Why so many people watch Friends instead of going out with their own buddies? Why a person would “feed” a plastic Pocket Pet while shirking real duties? Why both sides of every war see the other as the aggressor against whom their “Department of Defense” must respond?

Harvard evolutionary psychologist Deirdre Barrett explains how human instincts—for food, sex, or territorial protection—developed for life on the savannah ten thousand years ago, not for today’s world of densely populated cities, technological innovations, and pollution. Evolution, quite simply, has been unable to keep pace with the rapid changes of modern life. We now have access to a glut of larger-than-life objects—from candy to pornography to atomic bombs—that gratify outmoded but persistent drives with dangerous results.

In the 1930s Dutch Nobel laureate Niko Tinbergen found that birds that lay small, pale-blue eggs speckled with gray preferred to sit on giant, bright-blue, plaster dummies with black polka dots. He coined the term “supernormal stimuli” to describe these imitations that appeal to primitive instincts and, oddly, exert a stronger attraction than real things. Obviously these hard-wired preferences pose a danger to a species’ survival. Barrett’s singular insight is to apply this phenomenon for the first time to the alarming disconnect between human instinct and our created environment. Her book adroitly demonstrates how supernormal stimuli are a driving force in many of today’s most pressing problems, including obesity, our addiction to television and video games, and the past century’s extraordinarily violent wars. Man-made imitations, it turns out, have wreaked havoc on how we nurture our children, what food we put into our bodies, how we make love and war, and even how we understand ourselves.

Barrett does more than pull the fire alarm to show how these unfettered instincts fuel dangerous excesses. There is a hopeful message here as well. Once we recognize how supernormal stimuli operate, we can craft new approaches to modern predicaments. Humans have one stupendous advantage over Tinbergen’s birds: a giant brain. The message of this book is that this gives us the unique ability to exercise self-control, override instincts that lead us astray, and save ourselves from civilization’s gaudy traps.

About Author: Deirdre Barrett

Deirdre Barrett, Ph.D. is a dream researcher at Harvard Medical School. She Past President of both the International Association for the Study of Dreams and the American Psychological Association's Div. 30, The Society for Psychological Hypnosis. Dr. Barrett has written five books: The Committee of Sleep (Random House, 2001), Pandemic Dreams (Oneirio Press, 2020), The Pregnant Man and Other Cases from a Hypnotherapist's Couch (Random House, 1998), Waistland (Norton, 2007) and Supernormal Stimuli (Norton, 2010). She is the editor of four additional books: Trauma and Dreams (Harvard University Press, 1996), The New Science of Dreaming (Praeger/Greenwood, 2007), Hypnosis and Hypnotherapy (Praeger/Greenwood, 2010), and The Encyclopedia of Sleep and Dreams (Greenwood, 2012). Dr. Barrett has published dozens of academic articles and chapters on health, hypnosis, and dreams. She is Editor-in-Chief of DREAMING: The Journal of the Association for the Study of Dreams.

Dr. Barrett's commentary on psychological issues has been featured on Good Morning America, The Today Show, CNN, Fox, and The Discovery Channel. She has been interviewed for dream articles in The Washington Post, The New York Times, Life, Time, and Newsweek. Her own articles have appeared in Psychology Today and Invention and Technology. Dr. Barrett has lectured at Esalen, the Smithsonian, and at universities around the world.

What Attracted Me To This Book

  • I’ve deeply explored the concept of cognitive biases and how our brain can make automated thinking mistakes.
  • I think supernormal stimuli is effectively the same thing in the sense that it can lead to super short-term decision-making, which can lead to bad decisions.
  • Supernormal stimuli are also interesting because they lead to a vicious cycle, because they are often highly addictive.

Examples Of Supernormal Stimuli


Birds give the baby cuckoo more attention than their own young
Unyielding, invulnerable fish in the mirror provokes such a violent attack
The faux-feathered lothario gets all the girls.

Bird Egg

Nobel Laureate Niko Tinbergen studied birds that lay small, pale blue eggs speckled with gray and found they preferred to sit on giant, bright blue ones with black polka dots.
Song birds abandoned their pale blue eggs dappled with gray to hop on black polka-dot Day-Glo blue dummies so large that the birds constantly slid off and had to climb back on. Once a chick hatched, parents preferred to feed a fake baby bird beak on a stick if the dummy beak was wider and redder than the real chick’s. Hatchlings begged a fake beak for food if it had more dramatic markings than their parents’.



  • Sugar (candy sweeter than any fruit)
  • Fats
  • Salt
  • Drugs
  • Stuffed animals with eyes wider than any baby


With information, we take in images, sounds, and text and our brain converts it into supernormal stimuli.

  • Pornography
  • Propaganda about menacing enemies
  • Entertainment (gaming / Brain teasers)


Chapter 1: What Are Supernormal Stimuli?

Chapter 2: Making The Ordinary Seem Strange

Chapter 3: Sex For Dummies

Chapter 4: Too Cute

Chapter 5: Foraging In Food Courts

Chapter 6: Depending Home, Heart, and Hedge Fund

Chapter 7: Vicarious Social Settings From Shakespeare To Survivor

Chapter 8: Intellectual Pursuits As Supernormal Stimuli


Most Popular Highlights From Kindle Users

Human instincts were designed for hunting and gathering on the savannahs of Africa 10,000 years ago. Our present world is incompatible with these instincts because of radical increases in population densities, technological inventions, and pollution. Evolution’s inability to keep pace with such rapid change plays a role in most modern problems. Animal biology developed a concept that is crucial to understanding the problems instincts create when disconnected from their natural environment—that of the supernormal stimulus. Nobel laureate Niko Tinbergen coined this term after his animal research revealed that experimenters could create phony targets that appealed to instincts more than the original objects for which they’d evolved. He studied birds that lay small, pale blue eggs speckled with gray and found they preferred to sit on giant, bright blue ones with black polka dots. The essence of the supernormal stimulus is that the exaggerated imitation can exert a stronger pull than the real thing.
Animals encounter supernormal stimuli mostly when experimenters build them. We humans can produce our own: candy sweeter than any fruit, stuffed animals with eyes wider than any baby, pornography, propaganda about menacing enemies. Instincts arose to call attention to rare necessities; now we let them dictate the manufacture of useless attention-grabbers.

The Fairer Sex

Two types of media for women serve as supernormal stimuli: (1) Images and advice on becoming ideally appealing and (2) romance novels, soap operas, and other media providing vicarious relationships. “Cosmo” models look suspiciously like male magazine centerfolds. Here, however, they are icons not for anonymous, casual sex, but instead for becoming the one irresistible date and mate choice. We hear how magazines like “Cosmo” hurt female self-esteem with their emphasis on beauty—as if the media had selected this goal at random and taught it to adolescent girls. Or critics suggest that media is doing this to push a commercial, capitalist agenda—a variation on the same fallacy. What sells is hardly random to biology. Anything that sells spectacularly well is probably some type of supernormal stimulus. The media commercially exploit these instincts, but they didn’t create them. Humans have always evaluated their personal attributes against those of their neighbors and, for women, physical appearance has always been a large part of these comparisons.

Fast Food

Fast-food and self-interested advertisers did not create our craving for fats, sugar, and salt, though they exploit them. On the African savannah, we evolved a desire for these substances because they were rare and survival depended on locating a bit of each. Now dummy foods loaded with these substances are as close as the vending machine down the hall. We’re basically hunter-gatherers lost in one giant food court.

Having High Intelligence Doesn’t Protect Against Supernormal Stimuli

P. T. Barnum said no one ever went broke underestimating the intelligence of the American public. I’d add: no one ever went broke overestimating the power of the supernormal stimulus. These are closely related statements. We humans aren’t actually stupid—just prone to following outdated instincts instead of stopping to think things through…which is what our giant brains are there for.

Supernormal Stimuli Addiction

Let’s return for a minute to the analogy of drug addiction. We all hear people talk about how they couldn’t possibly give up cheeseburgers and fries entirely or that it’s cruel or unreasonable to suggest they never eat dessert. But as a psychologist, I hear from addicts how completely unimaginable never shooting up again seems or how they just couldn’t get through the day without a certain number of drinks or pills. Both are compellingly heartfelt but not entirely accurate. People think I don’t really understand how much their boy loves ice cream if I suggest they skip it—but he’d love heroin if they were doling it out after dinner. The pleasure mechanism can be shaped as to what it responds to—it doesn’t have to be the other way around. When you begin to eat healthfully, within days, glucose and hunger-regulating hormones shift, diminishing cravings. Within weeks, a positive conditioned response becomes associated with fish or spinach and extinguishes to french fries or mousse. Hunter-gatherers on the savannah—or health-food enthusiasts in their chi-chi modern restaurants—really do enjoy their fish and broccoli as much as the connoisseurs of French pastry or donut shop regulars do their repasts. It’s only the continuing consumption of the supernormal stimulus that renders the natural one unappealing. Unlike the complex paths our nurturing, sexual, and romantic instincts have taken, the hijacking of our drive for nourishment clearly needs to be reined back right now toward something more like what our ancestors practiced.


Humans have a basic instinct to pay attention to any sudden or novel stimulus such as a movement or sound. In 1927, the legendary Russian neurologist Ivan Pavlov named this


Entertainment has always functioned as a supernormal stimulus for social instincts, playing upon our urges to get to know people and attend to compelling events. It is also an area where supernormal stimuli can potentially have supernormal payoffs. A great novelist constructs characters who act out a drama that will move us, teach us, and leave us better for the imaginary interaction than we’d be if we had spent the same amount of time interacting with those around us. But most entertainment is probably what Cascardi is calling “addictive”—less effortful but also less beneficial than real life.

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“Saying that pornography creates a desire for…trashy sex is like saying McDonald’s creates a desire for salty, greasy meat. Hugh Hefner did not invent the American fetish for women with large breasts; his Playmate of the month merely exploited a taste already well-established. —Joseph Slade, Pornography in America”
“As former senator Peter Fitzgerald noted, putting the USDA in charge of our nutritional guidelines is “like putting the fox in charge of the henhouse.” USDA subsidies to farmers for growing specific crops total $19 billion annually.”

Brain Teasers

I’ll get to the issue of how we use our giant brains in modern professions, but first I want to examine how we use them for fun. Mental play is the most clear, unbridled pursuit of supernormal stimuli for our neoteny, curiosity, and intellect. Humans have always poured enormous effort into solving puzzles and playing games. Perhaps the oldest, mazes—walled enclosures, hedges, stone patterns, or merely drawn on dirt or rock—have appeared across human history. Jigsaw puzzles have existed, at least in their wooden form, for about four centuries. Three-dimensional geometric puzzles have varied across time: Rubik’s cube was an obsession for my generation, while Soma cubes were the equivalent a decade before that. These concrete puzzles hook the brain’s desire to sort out configurations and patterns. Other puzzles play to different intellectual challenges. Mathematical puzzles and magic squares call on our knowledge of numbers, visual illusions our spatial perception, and logic puzzles our abstract reasoning. Word puzzles include riddles, anagrams, ciphers, and codes. These challenge vocabulary, spelling, definition, and sound associations between words. They require us to play with metaphor and figure out tricky cues. We hardly need to do this for practical communication, but we’re drawn in for hours at a time. In 1913, English journalist Arthur Wynne published a “word-cross” puzzle in the New York World. The rectangular grid with squares to be filled in with cued words became wildly popular and its name was altered a few years later to “crossword. Highbrow critics initially regarded the crossword puzzle as disdainfully as today’s do the playing of video games. The New York Times was to become its most famous forum, but a 1924 editorial in that paper decried the “sinful waste in the utterly futile finding of words the letters of which will fit into a prearranged pattern, more or less complex. This is not a game at all, and it hardly can be called a sport…and success or failure in any given attempt is irrelevant to mental development.8 A clergyman of the same period called the working of crosswords “the mark of a childish mentality”9—which is, of course, exactly what evolutionary psychologists would invoke to explain the puzzle’s appeal to humans. Games have a similarly long history with our species. The board game Go originated in China about 500 BC and called for a subtle balance of offensive and defensive strategies. Pachisi, now Anglicized in America as the familiar “Parcheesi,” was created in India around 500 BC and utilized similar strategies combined with a larger dose of chance by letting dice determine some options. Modern card games such as poker, bridge, or cribbage trace their exact rules back only a century or two, but the ancient Persian game of As Nas included key elements of betting, hand rankings, and bluffing. Dominoes, mahjong, and other tile games, which extend back centuries, call on quick pattern recognition. Charades and other cued guessing games have been played since hunter-gatherer times and involve social skills as well as intellectual inventiveness in depictions and interpretations. Chess is perhaps the most popular game of all time. Its current form emerged in southern Europe during the second half of the fifteenth century, but it evolved from similar, much older games in India and Persia. Spurred on by chess’s reputation as the most perfect illustration of the human intellect, in the 1960s computer scientists began to write programs that played chess. Many predicted that, before the sixties were over, a computer would be the world chess champion. By 1970, computer programs played at the strength level of an average high school chess player, and chess experts were emboldened to pontificate on how brute force searches could generate only routine play. Computers would never have the intuition or subtle intellectual skill to beat the best players, they predicted. By the early nineties, a computer defeated a chess master and then a grand master. In 1996, IBM’s Deep Blue won a game against reigning world champion Gary Kasparov though Kasparov rebounded later in the tournament. The next year, Deep Blue won the rematch. Today, commercial programs running on home PCs achieve this level of play, and if you want to beat your computer, you had better take up kickboxing.


“Our “pseudospecies” are those who look like us, believe the same things, or speak our language. Erikson said the pseudospecies provides people with a positive sense of identity but also obliterates our sense of other humans as our kin.” Any national or religious identity always involves a myth of being the superior or chosen ones. Its dark side is a projection of negative, inferior, or evil traits onto other groups.

Animal Sex

“Bonobo chimpanzees which enjoy an orgiastic variety of sexual partners have testes .3 percent of their body weight. Gorillas, whose females mate only with the dominant “gray-back” of their group, have modest testes only .02 percent of their weight.”
“And human males? .08 percent of body weight—four times that of gorillas but one-fourth that of chimps—again suggesting an intermediate pattern.”

Human Sex

“DNA studies across a wide variety of cultures find about 10 percent of children are not biologically the offspring of their socially identified father.”
“Holland has a legal code that recognizes sexual consent from the age of 12, but has special provisions for children or parents to bring charges if they can prove adults have used “coercion” on those aged 12 to 16.”
“Many other European countries and Canada set 14 as the age of consent.30 Great Britain is presently considering lowering its age of consent from 16 to 14. After the BBC broad-cast a program: “Sex Before 16: Why the Law is Failing,”
“Through most of human history female puberty took place at around 17.5 to 18. By 1900, it had fallen to 151/2 in the developed world. Over the last few decades, the drop has accelerated until 11 is now the average and many girls reach it at 9 or 10.”

Human Desire

“Television is the first truly democratic culture—the first culture available to everybody and entirely governed by what the people want. The most terrifying thing is what people do want. —Clive Barnes”