Our topic for this month is … zombies. Not the charmingly decayed corpses you encounter in movies and books, but zombie ideas. According to the economist Paul Krugman (2013), a zombie idea is a view that’s been thoroughly refuted by a mountain of empirical evidence but nonetheless refuses to die, being continually reanimated by our deeply held beliefs.
Zombie ideas abound in our culture, nibbling away at the brains of their victims. The mistaken belief that vaccinations cause autism — a celebrated zombie idea — is responsible for rising rates of vaccine-preventable diseases. The belief that a person’s personality type, assessed by the Myers-Briggs Type Indicator (MBTI), predicts job performance is another zombie idea that continues to lure otherwise capable managers into making decisions that benefit neither employees nor their companies.
If you think that formal science training will zombie-proof your mind, you’re out of luck, my friend. Hordes of zombie ideas flourish in science (Brockman, 2015). They also fester in our own field, quietly biding their time in peer-reviewed papers and textbooks, waiting to infect another generation of unsuspecting psychological scientists.
For example, evolutionary psychologists have argued for years that waist-to-hip ratio is a phenotypic cue to reproductive success. I’ve always felt there should be a special place in hell, filled with mirrors, reserved for people who suggest that waist or hip size predicts anything important about a woman! But I’d heard this claim repeated enough times that I assumed the empirical case was a done deal. The logic goes like this: Men supposedly prefer women with relatively smaller waists and broader hips, which supposedly aids conception and childbirth and, in turn, increase the males’ reproductive success. Nevertheless, there is no evidence that healthy women with larger waist-to-hip ratios are less fecund or fertile than women with smaller ratios (Bovet, 2019). It’s a zombie idea. Ditto for the “body symmetry” hypothesis, which survives despite the empirical evidence (Jennions & Møller, 2002; for cogent analysis, see Prum, 2017).
In honor of the first MetaScience symposium, exploring the science of doing science, I asked the APS staff to canvas APS members for zombie idea sightings. Alison Gopnik, a developmental psychologist, nominated “the nature/nurture distinction” as an undead idea that will not expire. “It’s commonplace in both scientific and popular writing to talk about innate human traits, ‘hard-wired’ behaviors or ‘genes for’ everything from alcoholism to intelligence,” writes Gopnik, in an aspirational obituary (Gopnik, 2015). She points to growing evidence, including the research of neurologist Michael Meaney, for the many complex ways that environmental factors govern gene expression and protein construction (i.e., epigenetics). There is also increasing evidence that certain genes tune, for better or for worse, the extent to which a person’s genes are sensitive to environmental impacts (so-called orchids vs. dandelions; for a review of evidence and discussion, see Boyce, 2019). And developmental neuroscience evidence clearly shows that infant brains wire themselves to their physical and social surroundings. These findings show that nature requires nurture, and nurture has its impact via nature. The two are biologically entwined and cannot be discussed in either-or terms or as independent factors that interact.
Joshua Buckholtz, a clinical neuroscientist, nominated the “hydraulic model of self-control,” the idea that within each of us lurks ancient brain circuits that, when triggered, cause us to do stuff that we later regret (more colorfully referred to as the four Fs — fighting, fleeing, feeding, and . . . sex). Our prodigious prefrontal cortex allegedly puts the brakes on our inner beast, protecting us from worst selves, and impaired self-control in psychological disorders is thought to result from a faulty brake. Buckholtz points out that this idea should have remained buried by mountains of neuroanatomy evidence showing that the relevant brain circuitry is not structured in a way that makes the hydraulic model plausible (e.g., Haber, Kim, Mailly, & Calzavara, 2006; Bilder, Volavka, Lachman, & Grace, 2004), not to mention the accumulating evidence that self-control, in and of itself, is a value-based choice (Berkman, Hutcherson, Livingston, Kahn, & Inzlicht, 2017; Buckholtz, 2015).
The hydraulic model of self-control is a close cousin to another zombie, the triune brain, the idea that evolution laid down brain circuitry like sedimentary rock, with reptilian, limbic, and neurocortical layers. It has been known since the 1970s in evolutionary and developmental neuroscience that this story is a myth (Striedter, 2005). Think about this the next time you read that emotions erupt from neurons in the amygdala and other parts of the fabled limbic system, or that rational thought emerges in the neocortex, with one struggling to regulate the other.
Here’s a shocker from APS Fellow Sari van Anders, social neuroendocrinologist: It’s time to bury the idea that “male” and “female” are genetically fixed, nonoverlapping categories (i.e., natural kinds). Evidence from numerous disciplines fundamentally disconfirms this common-sense view (Hyde, Bigler, Joel, Tate, & van Anders, 2019). For example, a variety of neuroscience findings refute sexual dimorphism of the human brain. Behavioral neuroendocrinology findings similarly challenge the notion that male and female are natural kind categories. Research from developmental and cultural psychology also suggests that our view of these biological categories as fixed and immutable is learned, malleable, and culturally variable. (For additional evidence and cogent analysis, see Dreger, 2000, 2015; Fine, 2010, 2014).
Our final example of a dead idea that continues to roam the psychological landscape is that people can read emotions in other people’s faces, because certain configurations of facial movements, commonly called “facial expressions,” reliably and specifically signal a specific emotional state. A team of five senior scientists (including myself) met weekly for over 2 years, reviewing more than 1,000 publications related to this topic. We began with starkly different priors, but nonetheless came to consensus over what the data show, and we published our conclusions in the July 2019 issue of Psychological Science in the Public Interest (Barrett, Adolphs, Marsella, Martinez, & Pollak, 2019). People do, indeed, spontaneously smile in happiness, frown in sadness, scowl in anger, and so on, more than would be expected by chance, but not with sufficient reliability or specificity across contexts, individuals, and cultures for these facial configurations to be considered prototypic displays of any emotional state. Nor do human perceivers infer emotions from particular configurations of facial muscle movements in a reliable and specific way (once certain methodological factors are considered and controlled). For example, a wide-eyed gasping face is not the facial expression of fear but is one of many configurations that can express fear, and frequently does not express fear at all. Human facial movements are much more variable than previously assumed, and the effects of context and culture have been insufficiently documented and accounted for in published experiments. Have your zombie detector ready the next time you encounter terms like “emotional displays” to refer to how people move their faces when they are emotional and “emotion recognition” to refer to how people infer the emotional meaning in facial movements.
To kill a zombie, you generally lop off its head or destroy its brain in some permanent way. Luckily, you don’t have to decapitate yourself to stop zombie ideas from eating your brain or infecting other psychological scientists. Instead, deploy the most powerful anti-zombie vaccine: curiosity (Firestein, 2012, 2015). Be curious about evidence that seems to disconfirm your strongly held hypotheses. Being wrong is an opportunity to discover something new.
So this October, be brave: Take a deeply held belief and put it to the test. Search for empirical evidence that it might be wrong. Seriously entertain at least one alternative hypothesis during your hunt. If you do, you might just uncover a zombie infestation.
Barrett, L. F., Adolphs, R., Marsella, S., Martinez, A., & Pollak, S. (2019). Emotional expressions reconsidered: Challenges to inferring emotion in human facial movements. Psychological Science in the Public Interest, 20, 1–68.
Berkman, E. T., Hutcherson, C. A., Livingston, J. L., Kahn, L. E., Inzlicht, M. (2017). Self-control as value-based choice. Current Directions in Psychological Science, 26, 422–428. https://doi.org/10.1177/0963721417704394
Bilder, R. M., Volavka, J., Lachman, H. M., & Grace, A. A. (2004). The catechol-O-methyltransferase polymorphism: Relations to the tonic–phasic dopamine hypothesis and neuropsychiatric phenotypes. Neuropsychopharmacolology, 29, 1943–1961. https://doi.org/10.1038/sj.npp.1300542
Bovet, J. (2019). Evolutionary theories and men’s preferences for women’s waist-to-hip ratio: Which hypotheses remain? A systematic review. Frontiers in Psychology, 10, Article 1221.https://doi.org/10.3389/fpsyg.2019.01221
Boyce, W. T. (2019). The orchid and the dandelion: Why some children struggle and how all can thrive. New York, NY: Penguin Random House.
Brockman, J. (Ed.) (2015). This idea must die: Scientific theories that are blocking progress. New York, NY: Harper.
Buckholtz, J. W. (2015). Social norms, self-control, and the value of antisocial behavior. Current Opinion in Behavioral Sciences, 3, 122–129.
Dreger, A. (2015). Galileo’s middle finger: Heretics, activists, and the search for justice in science. New York, NY: Penguin.
Dreger, A. D. (2000). Hermaphrodites and the medical invention of sex. Cambridge, MA: Harvard University Press.
Fine, C. (2010). Delusions of gender: How our minds, society and neurosexism create difference. New York, NY: Norton.
Fine, C. (2014). His brain, her brain? Science, 346, 915–916. https://doi.org/10.1126/science.1262061
Firestein, S. (2012). Ignorance: How it drives science. New York, NY: Oxford University Press.
Firestein, S. (2015). Failure: Why science is so successful. New York, NY: Oxford University Press.
Gopnik, A. (2015). Innateness. In J. Brockman (Ed.), This idea must die: Scientific theories that are blocking progress (pp. 192–195). New York, NY: Harper.
Haber, S. N., Kim, K.-S., Mailly, P., & Calzavara, R. (2006). Reward-related cortical inputs define a large striatal region in primates that interface with associative cortical connections, providing a substrate for incentive-based learning. The Journal of Neuroscience, 26, 8368–8376.
Hyde, J. S., Bigler, R. A., Joel, D., Tate, C. C., & van Anders, S. M. (2019). The future of sex and gender in psychology: Five challenges to the gender binary. American Psychologist, 74, 171–193. http://dx.doi.org/10.1037/amp0000307
Jennions, M. D., & Møller, A. P. (2002). Relationships fade with time: A meta-analysis of temporal trends in publication in ecology and evolution. Proceedings of the Royal Society B: Biological Sciences, 269, 43–48.
Krugman, P. (2013, February 14). Rubio and the zombies. The New York Times. Retrieved from
Prum, R. O. (2017). The evolution of beauty: How Darwin’s forgotten theory of mate choice shapes the animal world – and us. New York, NY: Anchor/Penguin.
Striedter, G. F. (2005). Principles of brain evolution. Sutherland, MA: Sinauer Associates.
This evidence largely comes from people living in larger scale, urban cultural contexts; there are no peer-reviewed, published studies that systematically observe spontaneous facial movements during emotional events of people from small-scale, remote cultures.
Lisa, what a swell article and fun read. “I knew that…” but now I have citations at my fingertips for the next time I must slay science zombies :-).
Thanks for your comment, Tom!!
An excellent theme! Let me send a few more into the October night — new avatars of Frankenstein’s monster. Namely, the laboratory creations called “mice”, “rats”, and “college sophomores” which could exist nowhere in nature.
These are fantastic additions to the motley crew of zombies! Thanks for your comment, Barb!!
Our field is certainly plagued by zombie ideas. They were in full display in this article, not simply in the work critiqued, but in the criticism as well. To pick out several:
1) Describing what she sees as a zombie idea in evolutionary psychology regarding “waist-to-hip ratio [as] a phenotypic cue to reproductive success” Feldman Barrett writes that she’s “heard this claim repeated enough times…” but clearly not enough times to get the details correct! In this one paragraph, she conflates reproductive success (an abstract quantity and the currency of natural selection), conception and childbirth (distinct events in sexual reproduction that are necessary but not sufficient for long term reproductive success), and fertility and fecundity (terms that have several meanings, but likely here refer to distinct properties that capture the likelihood of conception given sex during the ‘fertile window’ and the physiological potential to bear children, respectively), using them interchangeably in her argument. These are not the same thing, and are not even inclusive of the fitness-relevant information that evidence currently suggests that waist-to-hip ratio reliably indexes. Feldman Barrett cites Bovet (2019) for the claim of “no evidence that … women with larger waist-to-hip ratios are less fecund or fertile”. This is an astonishingly misleading reference to this paper, as Bovet summarizes extensive evidence that waist-to-hip ratio is an index of parity (the number of offspring a woman has produced), which indexes residual reproductive value, as well as the potential for existing offspring that would compete with future offspring for parental investment. That waist-to-hip ratio is a cue to parity has been a longstanding theory in the field (since at least Symons, 1979), and researchers are continuing to test its many implications (e.g., Lassek & Gaulin, 2019). This doesn’t sound like a zombie theory to me, this sounds like science. The only zombie I see here is our president’s treatment of one particular way that waist-to-hip ratio could predict reproductive value (fertility) as a stand-in for an entire family of competing theories as to whether, how, and why it does so, a misunderstanding likely related to her stated moral position against all such theories (“I’ve always felt there should be a special place in hell, filled with mirrors, reserved for people who suggest that waist or hip size predicts anything important about a woman!”). Perhaps our president could benefit from her own prescription for curiosity in this instance. I’d suggest the idea that ‘evolutionary psychologists all share exactly one thought on a topic, it’s probably sexist, and it never changes’ could be the next zombie to hunt.
Two others may be better described as ‘straw-zombies’, as she doesn’t specifically call out any work she sees as carrying the ‘zombie virus’ in question.
2) Alison Gopnik via Lisa Feldman Barrett on nurture vs nature: “It’s commonplace in both scientific and popular writing to talk about innate human traits, ‘hard-wired’ behaviors or ‘genes for’ everything from alcoholism to intelligence.” The problem here seems to be that Feldman Barret & Gopnik have the zombie idea that innate means ‘hard-wired’; it doesn’t. Much of the field uses a more robust, productive definition of ‘innate’ instead: design for reliable development. This definition is productive because it picks out things in the world that meet the intuition of innate—such as adult teeth, secondary sexual characteristics, and the capacity to learn a language—yet clearly develop after birth and are sensitive to environmental intervention. These traits are all reliably developing aspects of human nature, but knowing that they are innate in this way does not tell us how they develop, nor how physiological, environmental or other factors contribute to this development. Our job as scientists is to do the work of providing these explanations. It is less clear to me what Feldman Barrett & Gopnik object to regarding ‘genes for’ traits. Presumably they don’t dispute that genes are under natural selection because of their consequences for the phenotypes they build, or that there are genetic influences on brain and behavior. Is it not part of our job to study how this all works? It is unclear to me how having senior scientists punch down at straw zombies helps us do this job.
3) Citing Sari van Anders, Feldman Barrett criticizes work on sexual dimorphism, saying: “It’s time to bury the idea that “male” and “female” are genetically fixed, nonoverlapping categories (i.e., natural kinds).” Who believes in this straw zombie? Sexual dimorphism does not in any way imply non-overlapping categories. There is a robust sex difference in height but plenty of overlap between the sexes. Males are more frequently diagnosed with autism, but that doesn’t mean no female is ever diagnosed. As with “innateness,” the fact that sexual dimorphism is complex and influenced by multiple factors in the internal and external environments should inspire us to uncover how it works, not to abandon the concept. I worry that Feldman Barrett’s “nothing to see here” message will dissuade scientists from doing the hard, necessary work in this area.
We should certainly hunt the zombies in our midst, but we should also be careful not to underestimate the ability of scientists in a field to scrutinize and update their theories. Being (usefully) wrong and then refining our understanding isn’t to be demonized; it’s science. And we should also turn our curiosity to our own beliefs about what others believe. The zombie might be calling from inside the house.
Thanks for your comments, Max. These columns are meant to stimulate thought and discussion, and I’m happy to see this one did the trick (I’m resisting the urge to make a Halloween joke here). I think your various points are worth discussing (I don’t agree with them all, of course), so why don’t we grab a coffee sometime and discuss? We work just down the street from one another, after all.
Hi Lisa and Max,
If you do meet privately to discuss these ideas, would it be possible for you jointly write another column describing your points of agreement and disagreement? (Or at least share such a summary somewhere public.) As someone who would benefit from hearing both sides of this, it would be great if the discussion you have stimulated was public.
As an interested reader, I’d love to see the two of you discuss it further in this forum.
I would love this coffee based discussion to be nade public. After all the accusation of zombie ideas was public and high profile. Thus I believe Max comments are right, but I’d love to read what the president has to say
Oh, the irony that an article by the President of the APS about ‘zombie ideas’ contains so many of them!
Then, when these are pointed out above, the response is dismissive. Oh, well you see the article was not meant to be a substantive and objective review of the evidence, but instead it was tossed out “…to stimulate thought and discussion, and I’m happy to see this one did the trick.”
Decades ago I resigned from the APA because of these sorts of ideologically motivated antics.
So I became a charter member of APS. But now I find that the President of APS ‘hates’ a field of research? And believes that “there should be a special place in hell, filled with mirrors, reserved for people who suggest that waist or hip size predicts anything important about a woman!”
Sounds like a famous comment about evolution itself: Let’s hope it isn’t true. But if it is, let’s hope it does not become widely known.
I hope you guys got that coffee, but the rest of us might also benefit from hearing the conversation 🙂
To those interested, Lisa and I are indeed getting coffee! I for one would be happy to work together on a summary afterward, of whatever form.
Here is another fun zombie.
The circumplex of affect (Russell, 1980)
You tried to show that it fits (JPSP, 1998) with RMSEA > .10, which is bad fit.
I show that it doesn’t fit and that there are three correlated dimensions.
Schimmack, U., & Grob, A. (2000). Dimensional models of core affect: A quantitative comparison by means of structural equation modeling. European Journal of Personality, 14(4), 325-345.
Schimmack, U., & Rainer, R. (2002). Experiencing activation: Energetic arousal and tense arousal are not mixtures of valence and activation. Emotion, 2(4), 412-417.
Maybe it is time to put this zombie to rest.
I am surprised that social priming or ego-depletion are not on the list.
Or have they moved on from zombie to dead status?
It’s scary times.
I think the hip to weight ratio thing is about what men (feel is attractive) and not a science fact about reproduction. The theory I believe tries to explain why men find larger hip women attractive and does not present biological facts. Rather than spark my thinking on this topic, I am instead disappointed in the author’s unnecessary conflation.
Lisa I have enjoyed the paper immensely. Life is too short not to point out Zombie suspicious ideas, wait for the gurus to stand up and provide their opinions. Kind regards from Bloemfontein, South Africa
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