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10 Important Psychological Concepts People Don't Understand

Where people go wrong in understanding behavior.

Here’s an interesting thing about psychology: For the most part, everyone, regardless of their educational background, feels like an expert in the field. This is not true of, say, biochemistry, geochemical engineering, or astrophysics.

As someone who both studies human psychology from a scientific standpoint for a living—and as a person who simply wants to understand what’s up with people—I get it. Not every Ph.D. in psychology is a genius when it comes to understanding the human condition. And plenty of “non-psychologists” have shed important light on the nature of human behavior—Kurt Vonnegut, Frida Kahlo, Bob Dylan, Mark Twain, William Shakespeare, etc.

This said, as someone from within the formal field of scientific psychology, and as someone who has taught university-level classes in the field for decades, I think it’s noteworthy that there are many popular misconceptions about human psychology. Put another way, there are concepts in the field that students of psychology regularly find difficult to understand.

Following is a list of 10 psychological concepts that students regularly struggle to understand:

1. Personality Types vs. Personality Dimensions

More often than not, psychologists who study personality concepts, such as narcissism, are talking about a continuous dimension that people vary on—not a categorical variable. For the lion’s share of personality traits, psychologists talk about the degree to which someone scores high on a dimension (e.g., Joe scored slightly above average on narcissism)—not whether someone is definitively “in this category” or not.

Rarely do psychologists consider the cause of some behavior as due solely to either “nature” (meaning, roughly, biology) or “nurture” (the environment). For the most part, psychologists will talk about some psychological feature (e.g., how extraverted someone is) as the product of the interaction of both nature and nurture across the lifespan. The idea of behavior being due exclusively to nature or nurture is, actually, something of a myth.

3. Psychologist vs. Therapist

The term “psychologist” is probably broader than you might realize. A psychologist is anyone who studies behavior (across any and all species) and/or works to apply ideas from research in the behavioral sciences to help address specific issues, such as the mental health of clients. The term “therapist” is more specific, applying only to individuals who apply psychological concepts to helping individuals deal with psychological issues (e.g., mental health counselors). The two terms are not interchangeable.

4. Psychologist vs. Psychiatrist

Psychologists are behavioral scientists or practitioners who study behavior from a scientific perspective or who apply such concepts to applied issues (such as helping individuals deal with personal problems). Psychiatrists are medical doctors who use a combination of medical and behavioral science training to help people deal with problems. A psychiatrist, then, is a particular kind of therapist. And the terms psychologist and psychiatrist are not interchangeable.

5. Type-1 Error

Psychological research is largely based on statistical findings. When a researcher obtains a finding in a study that shows as “significant,” he or she could be wrong—in fact, the finding could not be a valid representation of how things are in the world, in spite of what the researcher found. If a researcher finds something to be significant, but is actually wrong, we call this “Type-1 Error.”

6. Type-2 Error

When a researcher obtains a finding in a study that shows as “not significant,” he or she could be wrong. If a researcher finds something to be not significant, but is actually wrong, we call this “Type-2 Error.”

7. Experiment vs. Quasi-Experiment

A true experiment is the only way that we can make causal inferences regarding the relationship between variables. And a true experiment requires random assignment to different conditions.

If you are doing a study and want to see if people in one situation (e.g., those who drink a lot of coffee) behave differently from those in another condition (e.g., those who do not drink coffee), you need to randomly assign people to one of these two conditions. A study that looks for differences in some outcome between naturally occurring groups (e.g., people who regularly drink coffee versus those who don’t) is a “quasi-experiment” and cannot establish whether changes in one variable cause changes in the other variable.

8. Statistical Interactions

Sometimes, a variable will have one effect on one group of people and a totally different effect on some other group of people. Thus, the effects of some variable on some outcome variable often depend on some other variable.

If you want to see whether teenagers are more likely than other age groups to choose to be in the company of others, it would be helpful to know whether they have, for example, combed their hair within the last 24 hours, and whether they will be in the company of family members or strangers. Teens who have not combed their hair might be more likely to choose the company of others if they are going to be in the company of family members.

Sometimes, the effects of one variable (which people you would be spending time with) depend on some other variable (whether you have combed your hair) in determining some outcome (whether you choose to see those people). Understanding statistical interactions helps us understand nuances in behavior.

9. What Is “Natural” vs. What Is “Right”

Sometimes a student hears a behavior described as “natural” and misconstrues this as meaning that the behavior is morally right or justified. For instance, David Buss (2006) made a good case that homicide in humans has a strong evolutionary basis. Importantly, Buss is not arguing that homicide “should” happen in humans. Rather, his scientific analysis of the issues suggests that homicide is part of human nature.

Mistaking what “is” as what “ought to be” is an example of fallacious thinking. Scientifically trained psychologists are educated in this important distinction.

10. Multifactorial Causation

One of the most fundamental problems with how most people understand psychology is this: People often fall into the trap of thinking that there is a single cause of any behavioral outcome. In fact, trained psychologists know full well that multiple causes are often at play in shaping any behavior.

Mass shootings, which comprise a horrific facet of modern life, provide a clear example of this kind of reasoning. Some people argue that mass shootings are the result of mental health problems. Others argue that mass shootings are the result of poor laws regarding gun control. In fact, both issues have been shown to play a role. And several other factors have also been implicated in this complex societal issue. For the lion’s share of behaviors, multiple factors are at play.

Bottom Line

Whether others in our field like it or not, having a Ph.D. in psychology does not really qualify us to be experts on the entirety of human behavior. There are experts on human behavior, in fact, from across many fields.

This said, the formal field of scientific psychology has shed important light on what it means to be human. From the perspective of someone who has taught in this field for decades, I can say that the issues described here are concepts that students regularly find difficult to understand. To advance our knowledge of what it means to be human, we’d be wise to make sure that students of psychology demonstrate a strong understanding of

these concepts before going out into the world.


Buss, D. M. (2006). The murderer next door: Why the mind is designed to kill. New York: Penguin.


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