The Personality Parsimony Myth
by David Condon

I woke one recent morning to this text from my girlfriend: "Today's episode of Invisibilia is called 'The Personality Myth'!" She is, like many extraverts, easily enthused,[1] so there was no way to tell if the exclamation point indicated glee or dismay. Both emotions would've been reasonable. Our field — personality psychology — doesn't get much coverage from science journalists. Nor should it, I suppose. We don't search for new planets or cure epidemics or mash together previously unobserved physical matter. Still, use of the word "myth" was unsettling... "a widely held but false belief or idea."

For those of you who aren't familiar, Invisibilia is a podcast about the "invisible forces that shape human behavior" (whatever that means; no episodes yet about Adam Smith). I confess to having listened to most of the episodes released so far, mainly because I'd already burned through all the RadioLabs while driving back and forth from Chicago to St. Louis. While most of the storylines had good potential, I was frequently left frustrated by the show's tendency to posit fascinating questions and then leave me hanging (because the question was intractable in the first place) or — even worse — propose a lame answer that was only supported by the information covered in the podcast rather than all of the relevant facts. In many cases, I knew they were cherry-picking their facts. My girlfriend generously suggested that this was probably because I was more informed about the topics than most of the target audience. I suspected shoddy editing that eagerly sacrificed well-rounded objectivity for the sake of the storyline. Yes, that's a bit harsh, but I think the standards for science reporting should be higher than they are for commercial news coverage of less-complicated storylines. Especially in this case, where the crew is funded by National Public Radio and claims to provide coverage of scientific research on human behavior. Their work shouldn't be any less motivated by objective scientific curiosity than that of the scientists whose work they're covering. If anything, their obligation to objectivity is greater because they aim to reach a wider audience and most of that audience lacks scientific training (read: skepticism about pretty much everything). And yet, my opinion of Invisibilia was based on the show's first season. I had high expectations for their sophomore effort because I try to maintain a growth mindset.[2]

So, what qualifies me to judge? Good question. I have only dabbled in "theory of science" topics. But, I am a personality psychologist and, while I use that label somewhat reluctantly, I know for certain that this means I am, at least, a personality scientist. In fact, my reluctance about the personality label has contributed to my certainty about being a scientist... I've spent so much time considering the scientific legitimacy of our field that I ended up writing about 35 pages of academic text as the opening chapter of my dissertation. It's clear to me that use of the word "personality" as a scientific moniker is problematic for several reasons. The most succinct of these is that nearly everyone in the world already has pre-conceived notions about personality because the evidence for it has been more or less pervasive throughout most of human history.[3] Anyone who has ever been a friend or neighbor or spouse or parent has first-hand experience with the reality that people differ from one another. If you choose to study "personality" as a scientific endeavor — to study the generalizable ways in which individuals differ — well, you better be comfortable dealing with amateur scientists and dilettantes because it's likely that one of those acquaintances/friends/family members/spouses is gonna be hell bent on telling you all about their own model of personality. But the large number of pet theories about the matter does not prevent it from qualifying as a scientific discipline.

When it comes to figuring out whether or not something counts as a science, the likes of Thomas Kuhn and Karl Popper have already pointed the way. At the risk of criminal abbreviation,[4] here's what you need to know: Yes, the study of personality has moved beyond the confused morass of disconnected hypotheses and idiosyncratic lingo (if only just recently). Yes, there is a dominant and generalizable theory that is acknowledged by most researchers in the field as passably adequate, even if it is flawed and incomplete. And, yes, this theory is testable and falsifiable. Ergo: personality psychology is on solid footing as a (very young) scientific field, even if it remains dogged by a unfortunate label (I prefer differential psychology). So, what qualifies me to be a judge? I am a scientist whose active research focuses on topics in personality psychology.

But the main assertion of the Invisibilia episode in question isn't that personality is not scientific. It is that personality is a myth. Hollow, empty, not real. This assertion is so galling that I have a hard time responding to it intellectually. Fortunately, it becomes pretty clear throughout the course of the episode that — when using the word myth — they actually mean to say that personality theory sometimes sucks at explaining differences in behavior.[5] This idea is not totally ridiculous. It's just simplistic. By this logic, we could also say intelligence is a myth. Motivation, grit, attachment... all myths. Most ideas in psychology would be myths because — even if they are (or could be) well measured — they rarely explain more than a substantial minority of the variability in important outcomes outside of tightly-controlled laboratory settings. Hey, guess what else must be a myth? Medicine. And physics. Evolution. Most of science actually. It's a classic case of throwing the baby out with the bathwater. Science is supposed to be iterative. We start with a model, test it, identify the points of weakness and go back to the drawing board. To say that personality is a myth because it doesn't directly explain much of our behavior is unproductive (and, frankly, pretty juvenile), especially given all of the evidence that differences among people are real. (Are you equally interested in being friends with everyone? Co-workers? Long-term romantic partners? If you answered yes, I don't believe you.)

Don't mistake my arguments for blind defensiveness. I think there is a legitimate critique to be made here, even though Invisibilia missed it. It's not that personality is a myth, it's that personality science has advanced far less rapidly than other sciences over the last few centuries. I'm not saying we haven't made good progress; I am saying we have our work cut out for us. The bottleneck, in my opinion, has been caused by the fact that the development of highly predictive personality models requires big data and we are only at the dawn of the big data era. It requires big data because the number of domains on which individuals can differ is amazingly large.[6] AND, the number of criteria (outcomes) that are affected by these differences may even be more numerous, especially if one considers that many of these outcomes are unique across cultures and social circumstances. If the Very Large Number of differences and the Very Large Number of outcomes are not overwhelming enough, we also must acknowledge that these individual differences and most of the outcomes they might predict are highly dimensional (e.g., not dichotomous "yes/no" or "have/don't have") and multiply determined by the interaction of two or more (5? 50?) causal factors. And they're all mixed up in an iterative, dynamic soup that develops across the lifespan.

Now I am sounding a bit defensive... about the fact that personality scientists should probably be forgiven for having failed to make more progress than we already have. But I'm actually pretty optimistic. Active personality scientists get to play with data sets that are bigger than our predecessors could've imagined. This allows us to think seriously about the replicability and representativeness of our findings (frankly, this is a relatively recent luxury in a field that has historically tried to do representative research with samples that took a year to collect and contained 200 not-so-representative college students). And, we can actually deploy the cutting-edge statistical techniques developed by the famous pioneers of our field without feeling like we're just playing around, waiting for more data.

Most exciting of all is the fact that we are increasingly able to build and test some very complex longitudinal models. These will undoubtedly lead to better predictions for many of those numerous outcomes even though it will probably come at the expense of easy interpretation by people like my acquaintenances and friends and family and possibly even me. I welcome this trade-off because I want models that work and I don't think the universe cares as much about parsimony as humans do. So, while Invisibilia was implying, "hey, your personal theory of personality is bad at predicting stuff so... the whole idea of personality is bunk," they might have said, "hey, it's about time we started wondering why models of personality science aren't as good as we expect." A reasonable response to this would acknowledge that our models could be a whole lot better than they are and that the development of these models is much more difficult than most non-scientists can appreciate (and, yes, this clearly counts as science). I think we're making progress, and I'm optimistic about the future for personality research. I also think this bright future will include models of personality that are much more sophisticated and complex than anything our field has previously produced. Hopefully everyone — including the makers of Invisibilia — will be willing to embrace complexity, even if they yearn for parsimony.

[1] Almost certainly not a myth.
[2] Probably not a myth.
[3] The timelessness of personality might be presumptive but the oldest known written texts include a protracted section on personality. So, if not all of human history, at least as long as we've been writing down our thoughts.
[4] The alternative is shameless self-promotion.
[5] I think this interpretation is generous based solely on the episode but I'll give 'em the benefit of the doubt based on their Facebook response to critiques from several thought leaders in our field (Simine Vazire, Chris Soto, Sanjay Srivastava, Brent Roberts and others). A representative of the show stated: "The 'myth' we are pointing to is the enduring American popular belief that personality explains and determines everything." Like Brent, I don't know how I managed to avoid any prior exposure to this enduring popular belief, but... I guess it's possible.
[6] Please don't ask me if five or six traits is enough. I'm thinking more broadly than the constructs traditionally included among the traits — attitudes, interests, values, motivations, cognitive abilities, demographic background factors, attachment styles, etc. (And, no, five or six trait domains is not enough, but that's a discussion for another day.)

This page last modified on June 30th, 2016.