Next time you dream up what to cook for dinner, remember to buy everything on your mental grocery list and then resist buying a candy bar at the checkout (despite your rumbling stomach), take a moment to praise your executive function. Also known as executive control, this group of mental processes gives you the power to plan, remember, focus, multitask and keep your impulses in check.
But we’re not born with a full toolbox of executive function skills. Children develop and improve these abilities over time—and Sandra Wiebe, PhD, aims to find out precisely how that happens.
Wiebe heads the Alberta Brain & Cognitive Development Lab in the psychology department at the University of Alberta in Edmonton, Alberta, Canada. There, she uses behavioral studies and tools such as electroencephalography (EEG) to understand how young children develop the ability to regulate their thoughts, actions and emotions.
The preschool years are a critical period for the development of executive function. From ages 3 to 5, kids develop a deeper understanding of self, their language skills blossom and they become more adept at working toward a goal.
There’s much to learn about how those skills take shape during this incredible period of rapid learning and brain development, Wiebe says. Understanding these processes can ultimately lead to better ways to help children develop the executive function skills that are so important for success in school and beyond. "I want to understand the factors that influence the development of executive function, and the implications of that development for children’s lives," Wiebe says.
Structural surprise
Wiebe earned a PhD in child psychology at the University of Minnesota Twin Cities in 2003. Her first academic position took her to the University of Nebraska–Lincoln, where she worked as a research assistant professor until she relocated to her native Canada in 2009 for a tenure-track position at the University of Alberta.
One trajectory of her current research stems from a surprising finding she and her colleagues made while she was in Nebraska. The most widely accepted model of executive function describes it as composed of three distinct pieces: Working memory allows you to hold information in mind to inform your behavior, inhibitory control allows you to tune out irrelevant or distracting information and set shifting provides the mental flexibility to switch from one activity or task to another. But while studying executive function in preschool-age kids, Wiebe and her colleagues uncovered evidence that clashed with that three-part model.
The researchers tested 2- to 6-year-old children on a series of 10 cognitive tasks. In a test of working memory, for example, the children opened boxes to look for a hidden reward. The boxes were shuffled between trials, so the kids had to remember which boxes they had previously opened. In a test of inhibitory control, the children were told to freeze like a statue for 75 seconds while the examiner tried to distract them by coughing or dropping a pencil.
After collecting data from the battery of tests, the researchers used an established statistical method known as confirmatory factor analysis to compare the results using different models of executive function. They found that inhibition and working memory always seemed to go hand in hand in the children, rather than operating independently of one another as they do in adults (Developmental Psychologyopens in new window, Vol. 44, No. 2, 2008). "Rather than being two clearly separate factors, they seemed to be more of a unitary construct in young children," Wiebe says. "This wasn’t at all what we were expecting to find."
In a follow-up study, Wiebe and her colleagues focused on children who had just turned 3, the age when executive function skills begin to emerge. They found additional evidence that working memory and inhibition operate as a single intertwined construct (Journal of Experimental Child Psychologyopens in new window, Vol. 108, No. 3, 2011).
There’s no doubt that executive function becomes more efficient as children develop, Wiebe notes. But her work suggests the development of executive function isn’t just about efficiency. Rather, the very structure of executive function appears to undergo dramatic change during the preschool years, crystallizing into three distinct components sometime after early childhood.
Sorting seashells
Wiebe is continuing to study how the structure of executive function changes in childhood. In a current study, she’s tracking 4- to 7-year-olds over the course of a year to see whether the components of executive function remain stable over time. She’s also collecting measures of their math and reading abilities to assess how executive function might affect academic performance. "There’s a lot of evidence that executive function is especially important for learning math concepts," she says.
Meanwhile, she’s also taking a closer look at set shifting, the third component of executive function. "One thing that very young kids struggle with is switching between different rules," Wiebe says.
She and her doctoral student Sarah Elke designed a project to study how children shift their focus from one task to another. Specifically, they wanted to understand what prompts kids to engage the cognitive controls they’ll need to complete a task. "If they know they’re going to have to switch rules, do they prepare for that cognitive challenge in advance? Or do they just respond to things as they happen?" Wiebe asks.
To find out, she and Elke decided to compare task switching in two groups of children on either side of a major childhood milestone: 4- and 5-year-olds who hadn’t yet started school, and 7- and 8-year-olds who had already made the transition.
Elke and Wiebe devised a computer game that required the kids to sort seashells and starfish. When a gray dolphin appeared on the screen ahead of the sorting task, it was a cue that the kids should plan to sort the shells and starfish by shape. When a multihued octopus popped up, they were to sort the objects by color instead.
The researchers used EEG to measure event-related potentials (ERPs), small voltage changes generated in the brain in response to cognitive or sensory events. The results, Elke says, were another surprise. "We were expecting to see differences in ERPs between the younger kids and the older kids, but we didn’t see any big differences," she says. Older kids were faster and more accurate at the sorting task, but ERP measures showed that even the 4-year-olds could initiate cognitive control ahead of when they’d need to use it (Developmental Cognitive Neuroscienceopens in new window, Vol. 26, No. 1, 2017).
The findings suggest that kids in both age groups use the same underlying cognitive control processes, and that the system matures and improves with age, Wiebe says. To her, a key takeaway from the study is that even before kindergarten, children can engage in some impressive mental machinations.
"Four- and 5-year-olds have more advanced cognitive capabilities than we might have thought," Wiebe says.
Playing Spider-Man
Although it can be quite a feat to convince a 4-year-old to wear an electrode-studded EEG cap for the research, the technique is useful because of its sensitivity, Wiebe says. "Sometimes you can see differences at the brain level that you can’t see at the behavioral level."
Still, the tool takes practice, Elke says. If you want pristine EEG data, you need to convince your participants to sit perfectly still. When you’re working with squirmy preschoolers, noisy data are inevitable. Yet Elke credits the kids with helping her hone her data-analysis skills. "Instead of relying on the participants to give you clean data, you have to rely on your own abilities and work with what you’ve got," she says.
Though capturing the data from the children can be challenging, other aspects of the research are highly rewarding, Elke says.
"Everything you do has to have a fun atmosphere. You have to convince the kids they’ll look like Spider-Man to get them to put the EEG hat on." And the difficulties have given her a deeper appreciation of the participants, she adds. "It’s made me more aware of what we’re asking of our research participants, and made me more empathetic and grateful to them."
Elke is one of four graduate students working in Wiebe’s lab, along with a long list of undergraduate honor students and volunteers. Funding for the lab’s basic operating costs comes from the Natural Sciences and Engineering Research Council of Canada. In addition, the lab receives a variety of foundation grants to support individual projects.
Wiebe’s academic home is in the psychology department, but she is also a member of the university’s interdisciplinary Neuroscience and Mental Health Institute, which brings together scientists from fields such as cell biology, psychiatry, genetics and nursing. That involvement is well-suited to Wiebe’s interest in collaboration and fresh ideas.
Exercise and cognition
In a recent example of that collaborative spirit, Wiebe has been teaming up with Valerie Carson, PhD, an associate professor of kinesiology, sport and recreation at the University of Alberta. Together with Wiebe’s graduate student Aishah Abdul Rahman, they are studying how children’s physical activity affects their cognitive development. They started with a review of the existing research on the topic (Journal of Science and Medicine in Sportopens in new window, Vol. 19, No. 7, 2016). While they found evidence to suggest exercise in early childhood had a positive effect on cognitive development, only seven studies met their criteria for inclusion in the review, and of those, six used questionable methodology.
"There’s a real lack of research looking at physical activity and cognition in early childhood," Abdul Rahman says. Studies of older children, adolescents and adults more clearly suggest a link between physical activity and improved cognitive performance, she adds. But early childhood "has been sort of neglected."
To help address that gap, they recruited 100 children ages 2.5 to 4 and tested them on skills related to working memory, inhibitory control and language development. Parents reported the types of activities the kids participated in, and for a full week the children wore a device to measure their physical activity during waking hours. In this first wave of the study, the researchers didn’t find any evidence that the kids’ activity influenced their working memory or inhibitory control. They did, however, find that more physically active kids scored better on vocabulary tests (Mental Health and Physical Activityopens in new window, Vol. 13, No. 1, 2017).
The researchers repeated the tests with the same children six and 12 months later, and they are now analyzing those data. Abdul Rahman is also analyzing EEG data they collected while the children completed the cognitive tests in the lab. "We hope to see how things change together," Wiebe says. "If kids become more active or more sedentary, does that parallel changes in their cognitive abilities?"
Back to basics
Depending on their findings, Wiebe says a next step could be an intervention study to discover how children’s cognitive abilities change if they start spending more time moving and less time zoning out in front of the television or computer screen.
While Wiebe is open to possible interventions and applications of her work, she remains committed to answering the big, fundamental questions about the nature of executive function. That commitment sets her apart from many other researchers in this field, says doctoral student Daphne Vrantsidis.
"A lot of people study the neurological basis of executive function, or study how executive function is exhibited in certain situations," she says. "I was interested in working with Dr. Wiebe because she is answering basic questions about what executive function is."
Research foci
The Alberta Brain & Cognitive Development Lab is exploring:
- Brain development and cognitive flexibility in early childhood
- Physical activity and cognition in early childhood
- Executive function in the transition from early childhood to the school years
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