Expert Insights Series #4: The Foundations of Developmental Psychology and Cognitive Science with Dr. Phillip Zelazo

Peddie Psychology & Sociology Club | Special Feature reported by IO Kim, March 2025

Dr. Philip Zelazo is a leading developmental psychologist and neuroscientist whose groundbreaking research on executive function, the conscious self regulation of thought, emotion, and behavior, has significantly shaped the field of developmental cognitive neuroscience. Currently the Lindahl Professor at the University of Minnesota’s Institute of Child Development and co-director of the Developmental Social Cognitive Neuroscience Lab, Dr. Zelazo has authored over 160 scientific papers and edited major volumes on consciousness and developmental psychology. In this interview, he shares insights on the foundations of developmental psychology and cognitive science, exploring how executive function skills develop, how they shape behavior, and why they matter for parenting, education, and lifelong learning.

Personal Experience – The Journey into Cognitive Science

Q: Was there a moment in your childhood, education, or early career that made you realize you were fascinated by how people think?

Dr. Zelazo: "I guess I have a couple of answers. I think my approach to life—broadly speaking, to being a scientist, being interested in the arts, and so forth—was really fostered during my early childhood years, when I attended a Montessori school through Grade 5. If you're familiar with Montessori education, it's very much an autonomy-based approach to teaching. Rather than operating through direct instruction, in a Montessori classroom you’re invited to explore according to your interests, and the classroom is carefully designed to allow you to learn through experience—based on whatever it is you happen to be most passionate about at the time. And I think that’s really stuck with me over the course of my education and career.

More directly related to studying psychology and the development of the mind in particular: I went to McGill University as an undergraduate. In high school, I went to Milton Academy outside of Boston, and in our senior year we had an opportunity to do an independent project. I had the chance to work in a psychology lab with someone from Harvard—someone my father had worked with. In fact, my father is a developmental psychologist, and my mother is a nurse, so I really grew up around a lot of people talking about developmental psychology.

I was always interested in the topic, but I didn’t want to go into the 'family business,' so to speak, so I thought I would become a fiction writer. When I started at McGill, I was initially an English major, but I took some courses in psychology and was really reminded how much I liked them—and how naturally the field came to me, having been raised in that context.

There was one class in particular that I remember, taught by a very well-known psychologist named Michael Petrides. He studied the consequences of damage to the front part of the brain—the prefrontal cortex. He described how patients would show this pattern of behavior where, even though many of their cognitive skills were still intact, they had difficulty using those skills in a goal-directed way. They would say things like, 'I know I’m going to get this wrong, but here goes,' and then respond incorrectly. It was like there was this gap between what they knew and what they were able to put into practice.

That really struck me. From what I already knew about child development, these patients reminded me of kids. And so it occurred to me that there was quite a bit to be learned by studying the development of prefrontal cortical functioning in childhood—how that part of the brain gets wired up as a result of experience.

That’s how I got started studying what we now call executive function skills—EFS. These are the very skills that are affected when someone suffers an injury to the prefrontal cortex. And I think in the decades since I started doing this work, the field has learned a lot about how these executive function skills develop. It’s now increasingly recognized that the development of EFS may be the most prominent way cognition changes over the course of childhood.

You acquire language and basic memory skills relatively early in development, but what really takes time—through childhood, adolescence, and even into adulthood—is the ability to use those skills flexibly and strategically in the moment to solve problems."

• Did your former dream of being a writer end up helping you in the future? When you became interested in psychology?

  
  

Dr. Zelazo: "It helps a lot that I enjoy writing. As a psychologist, it’s a big part of my job– and lecturing, so forth, too. So I think that really helped. I think one of the things you learn early when you start studying literature is how to look at something– like a sentence, or a scene— from different POVs, and try to understand the full complexity of a phenomenon. A scene might say one thing, but in the context, it might imply a whole lot of other things. It’s very analogous to the problems you face as a scientist in the real world."

•  What are Executive Function Skills?

  
  

Dr. Zelazo: "They’re attention regulation skills. You can use your attention to modulate your behavior, emotions, and thoughts. You can shift your attention flexibly from one thing to another. You can take someone else’s point of view on the same situation you’re looking at—and that flexible use of attention is what we study as cognitive flexibility.

You can also attend selectively—focus on something and ignore distractions. That’s what we call inhibitory control, where you’re inhibiting attention to distracting information. You can also sustain your attention—like when you think of a phone number and rehearse it in your head so you can type it in later.

These are different ways of using attention intentionally, to help you apply your cognitive skills to solve problems. And as I’ve said, that turns out to be the most prominent dimension along which cognitive development unfolds— from childhood into adulthood.

Research shows it’s not so much what you know that matters—it’s whether you have the executive function skills to use what you know. If you measure a child’s IQ, their executive function skills, and socioeconomic status, all of those things predict outcomes like school performance or graduation rates. But executive function skills are the strongest predictors.

So again, it’s not about how much you know—it’s whether you have the attention regulation skills to use what you know, in the moment, flexibly"

Q: You’ve spent years studying executive function—the skills that help us plan, focus, and regulate our emotions. But what’s an aspect of executive function that you personally find challenging?

• Cognitive Flexibility

• Working Memory

• Inhibitory Control

  
  

Another aspect? So-called “Hot Executive Function” 

Dr. Zelazo: "You can use EFS (executive function skills) in laboratory-type tasks where you might be asked to respond one way when there’s an arrow pointing left and the other way, when it’s pointing right, or sort these pictures by color or by shape or whatever and those are kind of arbitrary, right? Kind of abstract. They’re decontextualized. They’re not real world things that you care about intrinsically. But when you do have to use EFS about things you really care about, for example, to regulate your emotions, like you’re getting frustrated and you need to figure out a way to calm down. Then you use Hot EFS, more emotional executive function skills., And those can be very challenging— regulating emotions to not be so stressed, for example. These are what I struggle with the most."

Q: Your research has shaped how we understand self-control, reflection, and flexible thinking in children. What’s one myth about child development that you wish more people understood?

Dr. Zelazo: "Very early on, when I was studying the development of executive function skills, I noticed that children really struggle to use these skills as they’re developing. One task that illustrates this well is the Dimensional Change Card Sort.

In this task, kids are shown cards with pictures—say, a red rabbit and a blue boat. Then they’re shown test cards like a blue rabbit or a red boat. If they’re playing the 'color game,' they match by color: red rabbit with red boat, blue rabbit with blue boat. If they’re playing the 'shape game,' they match by shape: red rabbit with blue rabbit, blue boat with red boat.

Kids can usually learn the first rule just fine. But when you ask them to switch—say, from color to shape—they often keep sorting by the first rule, without realizing it. It’s not intentional; they’re not being stubborn. They just haven’t yet developed the executive function skills to shift their attention and behavior flexibly.

This leads to a common myth: when kids don’t follow instructions—even when they seem to know the rules—it can look like they’re being willfully disobedient. But in many cases, it’s actually that their executive function skills, and the brain networks that support them, are still developing.

So yes, understanding these skills can absolutely help with parenting. Parents play a very important role in helping children develop EFS. Montessori education is one example of a system that encourages learning through experience and helps children feel like effective problem solvers.

Parents can do something similar by giving their kids challenges that are just hard enough—not too easy, not too difficult—so they’re practicing using their executive function skills. That’s how those skills grow: through experience. It’s also important to give children increasing autonomy as they get older. If a parent does everything for their child, the child might never get the chance to learn. On the other hand, if a parent does nothing, the child may not benefit from the structured experiences that support development. The key is finding that balance.

You can train EFS by giving kids lots of practice—like with the card sort task—but if you don’t explain what they’re learning or where they can apply those skills, they often won’t transfer them to other situations. If, instead, you help them understand the purpose behind what they’re practicing and show them how it connects to real life, it becomes more effective.

Executive function skills aren’t innate. They don’t just grow on their own. Very few skills develop without experience. While humans are prepared to acquire EFS, they still need practice in real-world contexts. Brain development isn’t just a natural unfolding of a blueprint—it’s a process of adapting to specific environmental challenges.

That’s why parenting and education matter so much: they provide structured opportunities to practice these skills at gradually increasing levels of challenge."

Work & Research – How We Think, Learn, and Adapt

Q: Your Hot vs. Cool Executive Function model explains how emotions shape decision-making. Could you briefly describe this distinction and how it applies to everyday challenges like stress, motivation, or even procrastination?

Dr. Zelazo: "Hot and cool are two dimensions of executive function skills (EFS). Most situations involve a mix of both. Both types of EFS depend on your prefrontal cortex—the front part of your brain—but they engage different areas. Cool EFS tend to rely more on the lateral parts of the prefrontal cortex, while hot EFS involve the ventral and medial areas, including the orbitofrontal cortex—that’s the area just behind your eyes.

The parts involved in hot EFS are more closely connected to the limbic system, which is where your emotions and strong motivations originate. So hot EFS are all about regulating those powerful emotional and motivational reactions.

The Dimensional Change Card Sort (DCCS) is a relatively cool task because it’s abstract and rule-based. On the other hand, a classic example of a hot EFS task is the delay of gratification test—like the well-known “marshmallow test.” A child is offered one marshmallow now, or two if they wait. Many kids will choose the one right away, even though they know they’ll get more by waiting.

Interestingly, if you ask kids what you should do in that situation, they’ll often say you should wait for the two marshmallows. But when it comes to what they want to do, the immediate reward becomes much harder to resist. So you can make the same task “hotter” by personalizing it, or “cooler” by distancing it—like asking about someone else. The more psychological distance, the more reflective and controlled the response.

Stress really interferes with EFS. It’s hard to be reflective, strategic, or flexible when you’re anxious, because stress hijacks your attention. If you’re worried about something—like seeing someone you like—you can’t focus on solving problems. Prolonged or uncontrollable stress even has biological effects. It releases hormones that are toxic to brain regions like the prefrontal cortex, making it harder to develop EFS over time."

• Can hot be controlled by cool?

Dr. Zelazo: "You can use cool EFS to support hot EFS. That’s one of the ways that in the marshmallow test, that was used by a guy named Walter Michelle. Kids were told to not think of it as a marshmallow and instead as a fluffy cloud — and subsequently waited and chose to wait a lot longer. 

Same way as it’s easier to give advice than it is to follow it. You can improve your hot EFS by practicing things like mindful attention and mindfulness meditation. You do something like, for example, pay attention to your breathing and try to focus on your breathing. Pretty soon, your mind will wander. In mindfulness practice, you say that’s my mind wandering, bring your attention back to your breathing, and keep repeating. You practice your ability to be calm but also pay attention deeply for longer and longer."

Q: Your Levels of Consciousness Model suggests that cognitive control develops in stages. Does this mean that adults continue to refine their thinking, or do we reach a point where our cognitive abilities plateau?

Dr. Zelazo: "Generally, these skills, when you measure them using a wide age range and the same tasks, what you see is that these skills improve (exponentially) during preschool years and continue to grow across childhood, rapid growth during the transition to adolescence, and they grow all the way through highschool. They reach peak levels of performance at around 25 years or so, and for many people, but not people who continue to exercise EFS, the skills start  to decline. So these skills take a long time to acquire — 25 years or so — but are also among the most vulnerable skills to disruption associated with aging. And so as people get much older they often show EFS mistakes, like blurting things out impulsively, etc. But you can keep practicing them. If you have a career, for example, and you problem solve on a regular basis, then you’re going to continue to exercise your EFS. They’re like muscles in that if you don’t exercise them, they tend to atrophy and go away."

Q: You helped create the NIH Toolbox and the Minnesota Executive Function Scale to measure cognitive skills. What’s the biggest mistake people make when trying to assess intelligence or cognitive ability?

Dr. Zelazo: "One big category of tests is self-report, or having other people report about you. For example, I could ask you, how good is your working memory or cognitive ability? You could say you’re good at it— but those types of measures aren’t that good, because there isn’t a good basis of comparison between the subject and other people in the world. You probably think you’re better than you actually are. There was this joke on Prairie Home Companion, Garrison Keillor, talking about Minnesota, where all the children were “above average”-- and you just can’t have every child be above average. There are biases. Similarly, if you ask teachers, teachers are also biased— they like this kid, they think he/she’s polite or cute or nice, then they think that they’re good at everything. So you really have to use direct behavioral assessments. Ex. Here’s a task that requires you to use your EFS. Then, you can compare your performance to thousands of other people."

Big Questions in Cognition – Nature, Nurture, and Language

Q: Language and thought are deeply connected, but which comes first? Does cognition shape language, or does language shape cognition?

Dr. Zelazo: "They mutually shape one another, but if you’re talking about EFS specifically, you’re very much talking about how much you can use language to regulate your attention. For example, if you’re sorting by shape and color (for adults) and put parameters like ‘do this as quickly and accurately as you can,’ adults tend to be pretty accurate but they slow when you swap between shape and color often. You can measure efficiency during switches, and that’s how you distinguish with adults.

However, as you add more parameters, it turns out that adults struggle to do it, because language is being used for something else. That shows even though they might be aware of it, when they do sort successfully on that task, they’re talking to themselves. They’re saying ‘okay, shape… I gotta pay attention… blue… rabbit… okay, color, blue.’ If you don’t use language in that way to control your response, to control your attention, and then to control your corresponding, you end up falling back on habits. So you’ll look like a three-year-old child who’ll persist in sorting by the same dimension that they just sorted by, even though they’re told to switch.

In other words, language and thought are deeply intertwined. There is definitely some thought going on in, say, babies before they can speak, and probably in non-human animals who don't appear to use language. But when you do acquire the ability to speak and use language and speak to yourself quietly and silently, that really changes the character of your thinking, and it allows you to be much more goal-directed and controlled."

Advice & Intellectual Influences – Inspiring the Next Generation

Recommended Reads on Developmental Psychology and Cognitive Science

Ellen Galinsky:

• Mind in the Making: 

Written for broad audiences, like teachers and parents. Child development.

• The Breakthrough Years: 

Adolescence and EFS in adolescence. Includes lots of interviews with MS and HS students. It takes an approach where the students themselves are asked, as a teenager, what do you want to know about how your brain develops and how you practice things? Very engaging and includes a lot of the relevant science and descriptions of the experiment. 

Other Piece of advice: 

Makes a big difference if you get involved in research directly. Find somebody at a university nearby, so in the city or in Newark in Princeton. There will undoubtedly be opportunities for you to volunteer to help with projects that are going on .Some studies that are going on in somebody’s laboratory and get a lot of insight into science.

Q: If you could give a TED Talk on any topic outside of psychology or neuroscience, what would it be?

Dr. Zelazo: "I think it would be about reflection, about the importance of pausing and thinking twice before responding. Thinking back to things that you did in the past and how they might be relevant to what you're doing. Currently I think that’s a kind of self awareness that’s underappreciated in part because it’s relatively difficult to study."