Understanding the World with Models – A Conceptual Introduction

A model train in New Orleans

My grandfather took me to a model train museum when I was a kid. I remember walking (or running) around and following the trains as they chugged along. I was never a train enthusiast, but I did think the models were neat! Over 20 years later, it turns out models are kinda how humans make sense of the world.

A model is a representation of something. The small train above is a model of a real train just like a globe is a model of the Earth. A globe isn’t the real Earth, but it conveys some truth about the location of land and water on the real Earth. A 2D map is also a model of the Earth! But why do we have two different models; why not just have the one model?

Most models are simplifications, and so you lose accuracy, but the simplification should serve a purpose. In a globe, one simplification is true size, but it preserves relative location of land and water. A common 2D map, the Mercator projection, simplifies size and relative position/size (it distorts area that is closer to the poles). But it was historically very useful for navigation at sea.

A model isn’t only defined by absolute accuracy. Interpretability, the ease with which we can use the model, is also a core feature. Obviously, if a model is simply wrong, it doesn’t matter how easy it is to use or interpret. But if a model does have some use and isn’t too wrong, that’s good.

The idea of a model may still sound abstract, but you actually use models all the time in your daily life. Think about a close friend: how would they react if you gave them an unexpected gift? The person in your mind and how you think they’d react is a mental model that represents your friend. This model is just like the model train or a globe: you lose some information (it’s not as accurate as simply seeing what your friend does), but ideally your mental model covers some core details. Hopefully.

Comparing mental models of how the mind works is fun, but it’s harder to figure out who is “right.” Instead, most psychologists test statistical models. It’s still just a model, it just happens to be a mathematical model instead of a purely abstract or conceptual model. What makes it mathematical is specifying the numbers involved. So perhaps I believe that men are, on average, taller than women. Mathematically, I’d say: μMaleHeight > μFemaleHeight or equivalently, μDifference = μMaleHeight – μFemaleHeight AND μDifference > 0.

There’s a bunch of rules and more math statisticians and others have established about these models that allows us to test them. In this post, I’m not focusing on those specifics, but on something broader that is absolutely essential to properly using statistics: we have to judge how good the model is before trusting what it says.

Think of a map (a model of a city’s layout). When we’re judging a map, the core criteria is that stuff should be on the map where it would be from a birds-eye-view. A map of a city could include information about the height of buildings, if you wanted. It could even be presented beautifully. People can marvel over how advanced and fancy this new map looks. And yet, if the map tells you to walk down a street that doesn’t exist, it doesn’t matter how impressive the additional information is: it’s a bad model.

When we’re judging statistical models, there’s also important features we need to pay attention to that, frankly, a lot of people don’t even check. I really want to emphasize the importance of actually checking that your model is a good one. It really comes down to appropriateness.

What do I mean by appropriateness? Let’s say I made a model of diabetes to try and find a new treatment. Excitedly, I tell you I have found a cheap treatment using my model. With great foresight, you ask not only to see my key statistics (effect size, t-statistic, p-value), but my model. Look, here it is!

Choo-Choo: a good model for a train, a bad model for diabetes

Who cares if the insights from this model are “significant” or have “large effect sizes” or “are cheap.” It’s a really stupid model, and there’s no way this model train actually portrays anything about diabetes.

If you don’t check the assumptions of the statistical model you’re running for your data, you could be making just as absurd of a claim without knowing it. Unfortunately, statistical training in psychological science is kind of all over the place, I think. So it probably isn’t properly emphasized what violating these assumptions really do, how to even check them, and, especially for complicated (fancy) analyses, it’s honestly pretty hard. But that’s the nature of science: it’s hard.

In summary, please check you’re not modeling diabetes with a model made for trains. Of course, I’ll go over how to do this for things I eventually post, to the extent I can. I’m still learning a lot myself!

What keeps us here

I’ll be posting sometime about treatment and mental illness, but this is something related to all that. I’m 29, and a week ago I went back in to see my doctor about my medication. Treatment is an ongoing process, and the goal isn’t to “finish,” it’s to continuously adapt, in my experience. Anyway, this psychologist asked me an interesting question that others haven’t asked me so directly: what keeps me safe? This is the warning that I’m discussing suicidal thoughts and feelings. But for more context, I’m discussing what keeps me safe even when I have those thoughts and feelings.

I wrote about it after reflecting on that question. The first answer is I’m stubborn. I refuse to lose to whatever it is inside my head that’s trying to kill me. There’s some personification going on. But I get satisfaction from knowing I’ve “won” every time so far. The second reason is the one I’m sharing: there are too many people I don’t want to say goodbye to yet.

If death is a door we walk through on our way to Oblivion,
I visit often.
Standing calmly before it,
I trace the grain of its wood with my fingertips as I consider
What keeps me from walking through?

The world is beautiful when I see clearly.
I enjoy a summer’s breeze
And the soft patter of rain in winter.
The trickling of a stream
And the crashing of waves upon the shore soothe and fill me.

But I am tired,
Struggling just to get out of bed,
To live when my heart wants death,
Year after year.
It’s not anger or despair that weighs upon me;
Just a heavy weariness.
I’m ready for the long sleep.

Yet I always turn away instead of turn the handle,
Stepping back instead of through.
I have no big dreams for tomorrow,
No deep yearnings to fulfill.
I’m just not ready to say goodbye to the people I love.
Can that be enough?

Mental Illness: A Beginner’s Guide

Big disclaimer that I am not a mental health expert, clinical psychologist or trained counselor of any kind. I do have a mental illness, and I’ve worked in mental health education, and I am a social psychologist (graduate student). So I have personal experience, some professional experience and I specifically study emotion, but I’m not a trained expert in clinical diagnoses or mental illness. What you’re going to read is partially what I’ve learned and partially my lived experience.

What is a mental illness? We don’t really know.

My answer is unsatisfying, I’m sure, but I believe it’s the truth. Not that we don’t know anything, but we don’t really know. For example, with the common cold we have a clear causal pathway between infectious agents, transmission, immune response and symptom presentation. We don’t have that for mental illnesses. We certainly have ideas and data, but we don’t know. This is inevitable because we just barely understand the brain. We will learn more through research.

So what are people referring to when they say mental illness? Typically, we are referring to abnormalities in the ABC’s of psychology: affect (feelings), behavior and cognition (thoughts). Key, defining aspects include but are not limited to: the symptoms cause suffering, they prevent the person from engaging in important activities, and it isn’t culturally expected or explained by other physical disorders. These definitions can, of course, still be pretty broad.

What do we know about mental illness? That’s a better question, and we know a lot! A lot of people have them at least once in their life (in any year, it could be as high as 1 in 5 people in the US). Mental illnesses are cross-cultural, but sometimes have culture specific presentations (depression exists in Asia just like it does in Europe, but the way people talk about it and express it may be a bit different). Mental illness is highly correlated with stressful experiences, but don’t have to be caused by any one experience. There are different kinds of mental illnesses, e.g. mood disorders versus psychotic disorders. Mental illness has a genetic component. I could go on, but my point is that we do know stuff. We just don’t know enough to say “Depression is caused by exactly X and has exactly ABC features.”

I heard mental illnesses are chemical imbalances in the brain. Even some well-meaning groups continue to say this, but this isn’t really true. First of all, there’s no such thing as a chemical brain balance. I mean, if you don’t have enough electrolytes or something, sure, that’s bad. But A) everyone’s brain has its own normal limits and B) if it was just an imbalance, medications should just work, but they don’t and it requires trial and error to find one that works; furthermore there’s usually a lag-time of some weeks before people notice improvement and C) psychological intervention wouldn’t work, but it does work for many people. The key thing is that brains are complicated. It’s not like balancing an equation for most mental illnesses, and because the brain is conscious, it can participate in its own treatment much of the time (but not always).

Why don’t mentally ill people just deal with it/control it better? There’s a lot of stigma involved with mental illness, particularly that mental illnesses are “all in people’s heads,” to which I say, “no shit.” Psychology is about brains, and brains are physical. It’s not magic. There’s no psychological space that is separate from the physical space. Mental illness is all in your head the same way that diabetes is all in your pancreas.

There’s a presumption that what is psychological is about “you” and must therefore be controllable. And this is one of those things where society has a view on something that doesn’t make sense. Experiences of color are psychological (for color-seeing folk), but me experiencing red doesn’t allow me to control it. I cannot unsee red with my willpower. Now imagine I have undesired experiences of intense fear just like how I see red without meaning to. That’s where things start to become mental illnesses.

A fundamental aspect of human experience is that we cannot control many of our experiences directly (which makes sense; there’s a lot of brain and only part of it is conscious). Active control takes effort, time and experience. It’s not an on/off switch you flick. And the best way to enable people with mental illnesses to “deal with it” is to accept them, help them get the treatment they need and be supportive. Studies show this works better than being a jerk.

How is mental illness different than a “physical” illness? Why is the common cold not a mental illness? Symptoms of the cold make you feel different, lay around (behave different) and perhaps think more slowly. Well, in my opinion, the difference is exaggerated or not yet known. We certainly understand colds better and don’t attribute any of the symptoms to the person experiencing them. But, in general, mental illnesses “look” psychological; they look like there are no external factors involved, like infectious agents or malfunctioning insulin production. But that’s mostly relying on our lack of knowledge. Someday, we may be able to describe depression and schizophrenia purely in terms of what is going on in the brain. Currently, we cannot. Though for schizophrenia, there are some data related to specific dopamine pathways in the brain. This is beyond my expertise.

Who gets mental illnesses? Anyone. One of the infuriating aspects of mental illness (in my opinion) is that it doesn’t even have to make sense! Now, the likelihood of “randomly” developing a mental illness is quite low. Mental illnesses have genetic components (it runs in families), and for many of them, stress seems to be a trigger. But even within a person (e.g., me) it can be really inconsistent. Sometimes I’m stressed but managing just fine, sometimes I feel like things are going great, but a depressive episode hits me anyway.

Critically, mental illness is an illness of the young. Let me explain: most people who will have a mental illness develop it before they are 18. Here’s a NAMI source.

50% of all lifetime mental illness begins by age 14, and 75% by age 24

National Alliance on Mental Illness, https://www.nami.org/learn-more/mental-health-by-the-numbers

To my knowledge, schizophrenia is one of the exceptions. People develop it typically after 18. This is just an average though; there are definitely cases of younger people developing schizophrenia.

But don’t a lot of people (kids especially) just act out for attention? One, I don’t think this is really true. The handful of cases people think about are just that: a handful of cases. Two, legitimately pretending to be mentally ill is itself a pretty worrying sign. They probably need help of some kind. I can’t think of any kids when I was in middle and high school who “acted out” for no reason. There was often something going on at home or they were also dealing with something psychologically.

Are two people’s depression/schizophrenia/etc the same? Personally, I think it’s better to think of mental illnesses as families of symptoms/experiences. They’re not all identical twins, but two people with depression will have similarities. Furthermore, a person with depression is probably more similar to someone with an anxiety disorder than someone with a psychotic disorder of some kind. Both are related primarily to abnormalities in emotion, whereas schizophrenia has psychotic (halluciations or delusions) elements that make it different.

But it’s still messy. For example, I have depression, but I also have psychotic symptoms. So do I fit in the psychotic disorder family or the mood disorder family? Am I depressed AND psychotic? What gives? As my psychologists and psychiatrists have discussed with me in the past, the best way to think about my specific symptoms are as manifestations of the same cause (whatever we want to call it). When I’m not depressed, no psychosis. When I am depressed, usually no psychosis. When I’m severely depressed, only then do I get psychotic symptoms (and anxiety). Perhaps this is broadly applicable to others, perhaps not. That’s also beyond my knowledge.

What is psychosis/ what does it mean to be psychotic? Psychosis and psychotic are words that people throw around for various reasons, but they refer to very specific things in psychiatry: delusions (fixed, false beliefs) and hallucinations. A delusion is something you can’t really convince someone to stop believing. Hallucinations are sensory perceptions (sound, sight, touch, taste, smell) that have no physical cause (e.g., hearing voices when no one is speaking is the one most people think of).

Psychotic people aren’t inherently more violent or likely to do bad things or anything like that. People with psychosis vary in how much they realize they’re experiencing a mental illness. This is called insight, and even within a person, it can vary. This part is my opinion, but honestly, I think the majority of people with psychosis are at least somewhat aware of what’s happening. It’s incredibly difficult to manage, and they certainly can have moments (or many moments) where they lack the insight. But my experience talking to people, a lot of them know more or less that they have something going on when they’re in a clearer mindset. Of course, my interactions are limited to people I see, which has some obvious confounds since I’m a graduate student who mostly will see other “high-functioning” mentally ill people.

Can I or someone I know get help? Yes.

There are a lot of treatment options available, and they range from learning how to help yourself manage your symptoms, reduce their intensity and make them happen less often to medication or other physical treatments.

Besides the fact that it is absolutely possible to live a nice, fulfilling life with mental illness, I think the next best thing I can communicate to someone seeking help is to acknowledge it can be hard. It’s hard to ask for help. I’m 29 and I still have trouble with that. Somehow, I manage to do it when I know I really need to. Going through the process of treatment can be another challenge, but it’s absolutely worth going through that process. My biggest regret is that it took me so long to try. The link to NAMI’s website I posted above is as good a place as any to start.

Observing Reality- Basic Concepts

In a first post about when is something true, I said something is true when it explains and predicts measurable/observable reality consistently. My goal here is to broadly discuss how complicated measurement/observation truly is. Throughout, you’re definitely getting my personal opinion on a lot of issues in psychological science: I often take a critical position. There are scientists who do not agree with me and some that do. But either way, I wanted to be clear that those are my opinions.

There are enormous obstacles to discovering “core truths” about human psychology, including philosophical questions about whether such truths exist. Here, I take the position there are some kinds of truth we can learn, and I also think the obstacles are not impossible to overcome. I do think that we would all benefit from carefully considering some basic issues more thoroughly. We must constantly challenge the validity of our constructs, a fancy word that basically means “concept” (e.g., happiness is a construct, and so is extraversion). In particular, we must be critical of how we measure our constructs and how much information those measures really provide. If we don’t, the best case is that we’re making an imprecise triangulation of the truth; at worst, we’re describing things that may be mathematically consistent but don’t relate to actual human psychology, the thing we claim to be studying.

For observations of simple gravity on Earth, observation may seem straightforward: junk falls. But the concept of observation can be complicated. Consider how exactly you should measure the time it takes for objects to fall:

  1. Unit: are we measuring in seconds? minutes? jiffies?
  2. Observers: is the measurement collected by a person on the ground with a stopwatch? the person dropping the object? a sophisticated laser? How do we calibrate the equipment? If I want to perform the same study, how do I ensure my equipment is calibrated the same way as the original? Do we have a universal clock that everyone agrees measures the “correct” unit of seconds? That’s not at trivial problem! In modern times, we have atomic clocks that vote on the time and determine it through consensus.
  3. Outcomes: are we measuring time until first contact with the ground? What is “first contact?” Electrons don’t normally touch in day-to-day life. Touching becomes sort of a non-concept at small scales anyway. The range of electromagnetic influence is also infinite, so they’re theoretically always in some kind of “contact.” We’ll have to pick some boundary that counts as a finish line, probably. People may argue about how we select the boundary or whether the boundary is meaningful. This is more of an issue with psychological constructs. The boundaries of what we mean are very important.
  4. Difficulty of observation: some events are rare. some are incredibly difficult to measure. Imagine needing to build miles of a particle accelerator just to hope to measure tiny, tiny particles we haven’t seen before. Maybe. In the psychological domain, observation is tricky because people often know they’re being observed!

For observations of gravity on the scale of human-sized reality, physicists have most of these issues solved. I think what often separates psychological science from hard sciences is that we have a lot of trouble with all these. And we never have perfect experimental control. I’m not allowed to assign my participants to random parent conditions at birth, and I can’t randomize their political beliefs or their religion either. Here are some other examples:

  • We’re assuming that a lot of abstract concepts are real and CAN be measured (e.g., that “love” is a thing, I can measure how much you feel it and it’s unique from the idea of liking).
  • Just because we can construct sentences we understand doesn’t mean they have a clear definition. E.g., I want to study “good conversations.” Easy to say, but what does that mean? Is the quality of a conversation determined by the people talking or by “objective” outside observers? Is it according to how much they like each other at the end? Whether they talk again later? The length of time they spoke? How do we factor in “depth” of the conversation? Does what counts as a “good conversation” depend on demographics (cultural changes related to generations, locations, shared history?). Maybe there’s no such thing as a good conversation. Imagine I have two people who went through a conversation and hated it. Maybe I can take two new people, have them engage in exactly the same conversation, and yet these new people will absolutely love it. So it’s really about the people, not the conversation.
  • There are standard units of time, but we lack truly standardized units for many of our phenomena (what is the standard unit of feeling happy? I vote for 7.5 smiley faces out of 7.5). This complicates comparing studies that use different kinds of measures. It also doesn’t help that we know people respond to scales differently (asking on a 1 to 7 scale can produce quite different answers than 1 to 100).
  • On that point, math doesn’t always make sense for our measurements: is a 10 on a happiness scale 2 times as much as a 5? Rarely, maybe never. Does one person’s 10 equate to another person’s 10? Probably not. So person A’s 5 may actually be “better” than person B’s 6. Even within a person, how consistently do they use the scale? Is my 5 on Monday truly the same as my 5 on Saturday?

That’s just a sampling of what makes psychological science hard, and some people think it’s impossible. As someone who does psychological research, I currently don’t think it’s impossible, but I’m sympathetic: we haven’t always done a good job tackling these first issues. In fairness, they are really difficult to solve. But still, as the people claiming to do psychological science, it’s literally our job to solve them.

If you’re into this kinda thing, these problems actually all relate to core statistical and research concepts.

  • Content and Construct validity: do our observations (measurements) actually capture the construct/concept we are trying to capture? Is it missing pieces of it? It would be weird, for example, to claim I’m measuring weight by only asking for your height. There actually is a relationship between weight and height, so at least I’m not asking for something totally irrelevant like your favorite color. But clearly I’m missing the most important aspect of the thing I want to study, and there are ways in which height relates to stuff that weight doesn’t. By using imperfect measures of the thing we really mean, we may be misled. Personally, I believe this is a big problem in social psychology. E.g., we study “culture” mostly by asking for people’s ethnic ancestry or country of origin. This doesn’t necessarily mean the results are invalid: even mediocre measurements still provide “signal” to the truth, provided you gather a lot of data. But I’ll have to talk about that later.
  • Test-retest Reliability: if you say your personality on some scale is a 7 today, by the theory of personality, you should give a very similar answer tomorrow. And five weeks from now. And two months from now. Similarly, a scale that measures “weight” but randomly adds or subtracts 0 to 100 pounds is not a very good scale. It would be hard to interpret a single measurement (though you could still interpret the average of many measurements). The same applies to our measures. They need to be consistent to be interpretable.
  • Internal reliability: If we’re averaging a bunch of stuff together in some way, do these things actually go together? E.g., if I’m measuring your height with two different measuring tapes, they may disagree a little (measurement error), but I’m pretty confident they’re measuring the same basic concept (distance), and therefore it is fair to average the two answers to together into a single (ideally more accurate) score. Internal reliability, however, is a mathematical kind of reliability. We calculate how reliable our scales are. Mathematical reliability doesn’t mean the scale is a good scale. Sometimes people forget this.

I can only speak about social psychology, but we all tend to study our own things. So we have similar constructs but we call them different names and use different measures. Sometimes our measures have passed some test of validity and reliability, but sometimes they’re still just convenient instead of accurate (my pet peeve is treating race as an indicator of culture in the US; another pet peeve is that I dislike the phrase “pet peeve”). With the proliferation of technology and computing, I think we can do a lot better than most people realize. It’s just a matter of introducing these advances to a field that isn’t primarily made of statisticians or computer scientists.

Maybe someday I’ll actually take on the job of sifting through our myriad measures and seeing what’s what myself. I actually think that’d be pretty neat. And as a final thought, even if I came across as very critical, I actually am fairly optimistic that these problems can be solved. Whether they will be is up to us (the scientists). And I think we are improving over time. Just like there’s a lag between scientific advances and communication to the broader public, there’s a lag between advances within psychological science and communication to other psychologists.

When feelings don’t work

Perhaps these days there’s somewhat better awareness about mental illness and mental health in general. But there’s still plenty of misconceptions and misunderstanding. I’m not an expert, but I have worked in mental health awareness, and I have a mental illness. Specifically, I’ve been diagnosed with major depressive disorder, but I’d like to talk broadly about mood disorders and what it means to have “disordered” moods or emotions.

Imagine working at a nuclear power plant. Not only do people depend on this plant for pretty much everything involved in modern life, if something goes wrong, it can go very wrong. It is life or death.

The alarms blare. The indicators show the nuclear core is heating up. The core can quickly escalate to meltdown, which would be a disaster. Luckily, there’s a protocol for this. You can follow the protocol and do what you were trained to do. There’s always one thing to keep in mind as you go through the steps: the nuclear core could be heating dangerously, but it’s also possible that the warning indicators are just malfunctioning. Both are problems, but they’re different.

This is an analogy for what my emotions can be like. A real nuclear power plant has protocols that cover both possibilities and ensures maximum safety. But as a person, I wasn’t really taught how to think of my feelings as being “faulty.” Of course, that assumes there is a “correct” kind of feeling. So let’s unpack that, at least a little.

What’s the purpose of feeling angry? Sad? Anxious? Why do we even have feelings? In a functionalist perspective, emotions evolved. This means there was a survival/reproductive benefit to having these responses. The theory suggests that negative emotions focus our attention toward solving critical survival challenges. Fear makes us pay attention to and react to threats quickly (fight or run). Anger can motivate us to be assertive and seek to fulfill a goal. Because we are a social species, a lot of our feelings have to do with social situations and how we relate to others.

But what happens when these “alarms” start when there is nothing to be afraid of or angry with or sad about? No matter the cause (or lack of cause), an emotion is immediate and real because we experience it: if I am sad about nothing, I still feel sad. That sadness affects what I see, what I notice, how I think, and what I want to do even if I know it doesn’t make sense.

In short, thinking of my emotions as faulty indicators is one way I understand myself. Sometimes they’re fine, just like anyone’s typical experience. But sometimes, they’re not about anything, and I know they don’t make sense. It’s a double loss for me: I feel bad AND I feel frustrated for feeling bad. Even when you know an alarm is broken, you can still hear it, right? I know things are going well, but I don’t feel well.

For me, that’s the final tension: balancing what I know against what I feel, and checking if what I feel is “reasonable.” Most of the time, I’ve got it handled. Sometimes, I’m confused and want to throw my hands up in frustration. I use my mind to monitor my feelings, but my mind is the thing that has a problem, so how do I know for sure if I’m doing it right? It’s impossible. And yet life goes on. I manage most days. Many days, I don’t even have to think about it. I’m actually really lucky, if you ask me. I made it this far, after all.

When is something true?

What color is the sky on an average, cloudless day? Blue is a fair answer, but how do we know that this is true? How do we know anything is true?

Maybe it’s strange to start off with a philosophical question, but it’s a vital first-step that helps bridge the gap between thinking about human psychology and psychological science. At the heart of science is the method used to decide what’s true. For anyone who has an introductory knowledge of epistemology (philosophy of knowledge) or philosophy of science, well you probably know more than I do. But I figured I should start here.

Science, like anything else, has some assumptions. One: the effects we observe in the world have causes (cause and effect exist). Two: observation (and measurement) gives us information about cause and effect. Three: the relationship between cause and effect has a stable pattern. So putting it all together, something is true when it explains and predicts measurable/observable reality consistently. Most accurately, it’s the closest approximation of the truth until a better idea improves or replaces it.

There are alternatives way to view the world, but the most scientific aspect of psychology is its use of the scientific method and the mutual understanding among scientists about what constitutes knowledge. If an idea fails to predict patterns in measurable reality, it just doesn’t pass the test. If a new idea makes better predictions, explains more or fixes inconsistencies, it replaces older ideas.

So how can we apply these concepts to the color of the sky? One of the first tasks is to determine what exactly we’re observing/measuring when we ask the question. There’s the physical aspect of the light, but that’s not what we really asked. We asked for the color: a subjective experience. How do we establish “truths” about something subjective?

There’s a history of debate about what psychology should study. There was a time the behaviorists won most arguments: psychologists should exclusively study what is observable externally (behavior). But modern psychology deals with the ABC’s of the mind: affect (feeling/emotion), behavior and cognition (thought). And it turns out there ARE patterns in subjective experience insofar as we can measure them. Our fully colorblind friends see the same dominant wavelengths of light in the sky (450-485 nm), but they lack subjective perception of color. Even if all we did was ask people to “name the color you personally perceive the sky to be,” we would find at least two groups of people: those who call it blue and those who do not.

This is the type of knowledge we can find about subjective experience: kinds (categories) of people, dimensions of experience (e.g., light intensity from dark to painfully blinding), correspondence between cause (wavelength of light) and effect (color perception). Inconsistencies merely represent research opportunities: is there another group of people we aren’t accounting for? Is there another factor that shapes color perception? Is it the perception that is truly different, or is it the way people communicate their perception? Is there a better way of thinking about color perception? Or perhaps the way we measure it needs to be improved?

So when is something true, and is the sky blue or not? It’s true in psychological science when the data shows a consistent pattern, preferably in multiple sample groups collected in a rigorous way. Interpreting the results, however, is tricky. It’s not like we can say “the sky is definitely blue” or “it definitely is not.” Instead, we have to talk about kinds of people and dimensions of possible perception. The sky is blue-ish for most color-seeing folk, but some see it as light grey. Does this complication mean there was nothing learned? I would say no; we definitely learned something about human minds. It may be complicated, but the answers should be complicated because people are complicated.