Perhaps more so than in other academic disciplines, people are interested in psychology. Most people possess a ‘lay’ understanding of what makes the others around them tick. In fact, some researchers have even argued that as humans we are hardwired to innately understand social interactions (Spelke, 2007). Whatever the reason, it seems that even non-psychologists spend a good deal of time thinking about psychological questions. In contrast, I rarely hear people express their interpretation of chemical bonds or how electricity works. However, psychological questions fascinate people: What made a person do that? What would someone do in this situation? In my opinion, this is great. It means we, as psychologists, are exploring topics that the general population finds interesting.
However, I am always a bit taken aback when people argue their opinions, intuitions, or anecdotes against decades of research. My frustration over this topic was recently exacerbated by two terribly misleading and uniformed articles published by a usually respectable news source (NPR; Personality change, Personality tests). This short post can hopefully orient people with some of the major understandings in personality research. Then, people can have informed conversations about a topic that I know is of interest to many people: how are people different from one another?
First, what are the important dimensions of personality? How do people differ from one another? There are thousands of adjectives describing individual differences of personality (Allport & Odbert, 1936). Each describes a certain nuanced characteristic of people. However research has shown time and time again (Goldberg, 1993, Costa & Mcrae, 1987) that a large proportion of the variation in personality (individual differences) can be described with just 5 traits: Extraversion (the extent to which one is social or dominant), Neuroticism (the extent to which someone is emotional or sensitive), Conscientiousness (the extent to which one is responsible and dutiful), Agreeable (the extent to which one is pleasant and not confrontational), and Openness (the extent to which one is open to new experiences and interested in the arts/intellectual endeavors). Numerous studies have shown the replicability of these dimensions of personality, and their ability to predict meaningful outcomes. Now, I am not asserting that these are the only dimensions of personality that matter, but any conversation of personality that neglects these dimensions is necessarily limited. Failing to measure these dimensions leaves researchers susceptible to the jingle jangle fallacy (renaming a well-known construct and purporting it as a new discovery; e.g. grit; or as psychologist have been calling it for decades, conscientiousness, article)
So we have established that if you want to talk personality, you need to at least include the Big 5 in your discussion, but what about personality tests? Are they meaningful? A recent article on NPR, (Personality tests) recently critiques personality tests implying they are not meaningful.  It is also not uncommon to hear people criticize the validity of tests; not understanding an item, not knowing how to answer a question. Despite these criticisms and people’s intuitive distrust of personality tests, personality (as measured largely by self-report personality tests) predicts basically everything: Health, financial and professional success, relationship satisfaction (Ozer & Bennet-Martinez, 2005; Roberts et al, 2007), and a number of other outcomes. The utility of (good) personality tests is really not up for debate, no matter how someone feels about a given item or two. As an extreme example, the Minnesota Multiphasic Personality Inventory (MMPI) includes an item ‘I prefer showers to baths.’ The psychologists who developed this test clearly were not interested in one’s bathing preferences. However, marking this item is an indicator of one’s empathy. Whether or not the person taking the test understands why he or she is being asked certain questions is not of concern. It is the extent to which those items are indicators of personality that matters.
Another common criticism of personality tests is their susceptibility to faking. This is especially common when personality tests are being used for some sort of screening procedure (e.g., employment). Often times people assume they can ‘beat’ the tests. However, in most cases this is false. One study tested this possibility in a real-world setting. Researchers told participants they failed a pre-employment personality tests and gave them another opportunity (Hogan & Hogan, 2007). It turns out that most participants—95%–scored the same. In fact, only 2.5% scored better, and actually 2.5% scored worse the second time. It turns out that people are not as good at ‘faking’ as they think.
Another common misconception (propagated by the Invisibilia podcast on NPR; Personality change) is the belief that it is situations or the environment that determines behavior, not personality. In a 1968 book, Walter Mischel declared that because personality traits—much like the Big 5 discussed earlier—could not strongly predict how people behave across situations, that the situation is what determines behavior. Since the publication of Mischel’s book, people have interpreted it to be evidence that personality is not important or, in the most extreme cases, that personality does not exist. Since 1968, numerous studies have shown that this simply is not the case (e.g., Sherman, Nave, & Funder, 2010). It turns out that although people behave differently at a party compared to a classroom, there is a large degree of rank-order consistency. In other words, the most social person at a party is probably also one of the most social in a classroom, despite the differing demands of these two situations. Further, over a large number of situations, people show a substantial degree of consistency and the effect sizes dismissed as trivial by Mischel have meaningful implications (aggregation effects; Abelson, 1985; Epstein, 1979). Also, remember, (two paragraphs ago) personality predicts nearly everything. It necessarily exists.
Since we established that people do behave consistently across situations, there is the question of whether or not personality changes throughout people’s lives. Everyone has anecdotes in which they know someone who completely turned their life around for the better. The Invisibilia podcast (Personality change) tells a story of a prisoner who has allegedly turned his life around. Aside from the fact that this is one person and hardly the rule, and he is still in prison. (We just have to take his word for it.) It is a nice story that anyone can turn their lives around (e.g., redemptive narrative; McAdams, 2004), and research has suggested that people can change their personality in an effortful manner (Hudson & Fraley, 2015), but these stories are the exception rather than the rule. People do change in predictable ways over the course of their lives, often becoming more conscientious and more emotionally stable (Roberts, Walton, & Viechtbauer, 2006; Caspi & Roberts, 2001). However, these changes are generally rather small, and people tend to maintain rank order consistency (i.e., the most conscientious people tend to stay fairly conscientious and the least conscientious people only increase slightly).
So to reiterate and hopefully clear up some all too common misconceptions about personality and people in general, let me summarize: 1) There are five really important dimensions of personality, and any discussion should include the Big Five. 2) Personality tests work. It doesn’t matter if you understand why they work. 3) Faking personality tests is difficult and you’re probably not as good at is as you think. 4. People behave differently in different situations, but across a lot of them people behave consistently. 5) Personality is relatively consistent throughout people’s lives. Your personality can change, but it is usually a slow process. While intuition or anecdotal experience may suggest otherwise, these findings have been supported by decades or research and hundreds (if not thousands) of studies.
 I am by no means the only (and far from the most qualified) personality psychologist to rebut these two articles. An informative piece by Chris Soto was published by NPR (link), and social media was alive with outrage among personality psychologist. However, the target audience here is not the academic psychologist, but anyone fascinated with personality (probably without a PhD).
 Indeed, the person who wrote the article was someone who has staked their career on demolishing personality tests. They wrote a book titled The Cult of Personality Testing. I’m not sure how much stock we can place in someone who stands to profit from bashing personality tests (i.e., selling books.)
 Though Mischel will claim that he never said that, see, Most Cited, Least Read? (DOI:10.1093/acprof:osobl/9780199778188.003.0001