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The Source of Student Motivation: Deeper than We Know?
Andrew Watson
Andrew Watson

Usually I blog about specific research findings that inform education.

Today — to mix things up — I thought it would be helpful to talk about an under-discussed theory pertinent to education.

This theory helps us at least two ways:

First: it gives useful insights into student motivation. (Teachers want to know everything we can know about motivation.)

Second: it provides useful background for a second up-n-coming theory — as I’ll describe below.

Education and Evolution

Let’s zoom the camera WAY BACK and think about individual human development from an evolutionary perspective.

Certain human interests and abilities can promote our evolutionary fitness.

Tens of thousands of years ago, humans who — say — understood other people and worked with them effectively probably had a survival advantage.

So did humans who took time to make sense of the natural world around them.

Oh, and the physical world as well.

Given those probabilities, humans who learned about people, the natural world, and the physical world would — on average — thrive more than those who did not.

If that’s true, then we probably evolved to learn those things relatively easily. (Obviously, this is a great oversimplification of evolution’s complexities.)

For instance: we rarely teach children to recognize faces — our species evolved to be good at that. We don’t teach them to walk or talk; they do so naturally. (We encourage and celebrate, but we don’t need to teach.)

We don’t have to encourage people to explore the natural or physical world. Throwing rocks, climbing trees, jumping in puddles, chasing small animals: we evolved to be intrinsically interested in those things.

Primary and Secondary

Evolutionary Psychologist David Geary describes these interests as biologically primaryWe evolved to be interested in and learn about what he calls “folk psychology” (people), “folk biology” (the natural world), and “folk physics” (the physical world).

Geary contrasts these several topics with others that we learn because human culture developed them: geometry, grammar, the scientific method, reading. He calls such topics biologically secondary because need for them does not spring from our evolutionary heritage.

We are MUCH less likely to be interested in biologically secondary topics than biologically primary ones. We didn’t evolve to learn them. Our survival — understood on an evolutionary scale — does not depend on them.

Said the other way around: if I don’t explicitly teach my child to walk, she’s highly likely to do so anyway. If I don’t explicitly teach my child calculus, she’s highly unlikely to figure it out on her own. (Newton and Leibnitz did…but that’s about it.)

If you’re keen to understand its nuances, Geary’s 100 page introduction to his theory is here.

Implications: Motivation

If Geary’s correct, his theory helps answer a persistent question in education:

Why don’t students love learning X as much as they loved learning to climb trees/play games/mimic siblings/build stick forts/etc.?

This question usually implies that schools are doing something wrong.

“If only we didn’t get in the way of their natural curiosity,” the question implies, “children would love X as much as those other things.”

Geary’s answer is: playing games is biologically primary, doing X is biologically secondary.

We evolved to be motivated to play games. Our genes, in effect, “want” us to do that.

We did not evolve to learn calculus. Our culture, in effect, “wants” us to do that. But cultural motivations can’t match the power of genetic ones.

In effect, Geary’s argument allows teachers to stop beating ourselves up so much. We shouldn’t feel like terrible people because our students don’t revel in the topics we teach.

Schools focus on biologically secondary topics. Those will always be less intrinsically motivating (on average) than biologically primary ones.

Implications: Cognitive Load

A second theory — cognitive load theory (CLT) — has been getting increasing attention in recent months and years.

CLT helps explain the role of working memory in human cognition. (Frequent readers know: I think working memory is the essential topic for teachers to understand.)

In recent years, CLT’s founders have connected their theory to Geary’s work on biologically primary/secondary learning.

That connection takes too much time to explain here. But, if you’re interested in cognitive load, be aware that Geary’s work might be hovering in the background.

Watch this space.

Reactions

Some scholars just love the analytical power provided by the distinction between biologically primary and secondary learning.

Paul Kirschner (twitter handle: @P_A_Kirschner), for instance, speaks of Geary’s theory with genuine admiration. (In one interview I read, he wished he’d thought of it himself.)

Others: not so much.

Christian Bokhove (twitter handle: @cbokhove), for instance, worries that the theory hasn’t been tested and can’t be tested. (Geary cites research that plausibly aligns with his argument. But, like many evolutionary theories, it’s hard to test directly.)

I myself am drawn to this framework — in part because evolutionary arguments make lots of sense to me. I do however worry about the lack of more evidence.

And: I’m puzzled that so little work has been done with the theory since it was first published in 2007. If it makes so much sense to me (a non-specialist), why haven’t other specialists picked up the topic and run with it?

For the time being, I think teachers should at least know about this theory.

You might start considering your students’ interests and motivations in this light — perhaps Geary’s distinction will offer a helpful perspective.

And, I don’t doubt that — as cognitive load theory gets more attention — the distinction between biologically primary and secondary learning will be more and more a part of teacherly conversations.

Good Dog! Goodbye, Dog…
Andrew Watson
Andrew Watson

The New York Times is reporting the death of Chaser, a dog who changed the way we think about canine cognition.

We used to think that dogs could learn a handful of words, especially if they got treats afterwards.

Chaser learned over 1000 words — yes, 1000. And, she learned them not because she got treats, but because she enjoyed playing.

Importantly, Chaser learned not only nouns, but verbs. Even prepositions!

The video below shows one of Chaser’s most impressive challenges. In it, Neil DeGrasse Tyson lays down several toys that Chaser already knows. He also adds a new toy: a stuffed image of Charles Darwin.

What will Chaser do when Tyson asks her to “get Darwin”? Will she be able to figure out that the name she hasn’t heard before goes with the toy she hasn’t seen before?

Check it out.

https://www.youtube.com/watch?v=omaHv5sxiFI

 

“How You Got to Be So Smart”: The Evolution of our Brains
Andrew Watson
Andrew Watson

When did learning first begin?

For me, individually, you might say it began when I first attended preschool. But, truthfully, learning began well before then.

I learned how to walk and speak, and to do (a very few of) the things my parents told me to do.

In the womb, I even learned to recognize sounds – like my mother’s voice.

But, let’s go much further back.

When did our species start learning? Or, before then, great apes? Or, even earlier, mammals?

Did dinosaurs learn?

How about those little one-celled organisms that developed when life began, over 3.5 billion years ago? Did they do anything we could meaningfully call “learning”?

Paul Howard-Jones answers that question with a resounding yes. And, most intriguingly, the biological mechanisms that allowed them to learn still help us to do so…all these billions of years later.

As Howard-Jones writes, learning “changes not just our mental world but also our biological form.” The basic biological and chemical mechanisms necessary for the earliest kinds of learning still help us learn today.

The Story Begins

Let’s start with E. coli. This single cellular organism has a bad rep, but we’ve got lots of very useful E. coli in our guts. And, they can – in a manner of speaking – learn.

In order to eat, E. coli have to move. And, they have two options for movement. If they’re successfully getting nutrition as they move, they want to keep going straight. If they’re not, they want to move randomly about – until they stumble into a better path to follow. Once they do, they start going straight again.

To accomplish this goal, E coli need to “remember” how much nutrition they were getting a few seconds ago, and compare that level to the current intake. Remembering, of course, is a kind of learning.

Howard-Jones helpfully describes the cellular mechanism that allows this memory comparison to happen. It’s a little complicated: think “methyl groups” and “receptors.” But, this clever and efficient system allows cells to remember, and thereby to eat and flourish. (Check out pages 24-5 for a full version of this story.)

Learning gets even cooler from there.

As evolution brought single-cellular organisms together into eukaryotes – from which sprang reptiles and amphibians and mammals and you – it produced ever-more-intricate systems for learning.

For instance, neurons evolved to ensure that multi-cellular organisms could coordinate their movements. (If each cell did its own thing, then we’d get no benefits from having all those cells.)

And, of course, neurons now form the biological basis of learning that happens in our brains.

Vertebrates and Primates

As evolution led to the development of more-and-more complex organisms, so too it produced increasingly complex kinds of learning: the ability to organize information by association, for example, or to recall something that happened yesterday.

The Evolution of the Learning Brain, devotes considerable time to primate development. In particular, it asks this question: since most evolutionary developments favor specialization, why did our species prove so successful? After all, our brains allow for great cognitive flexibility – the ability to be generalists, not specialists.

Howard-Jones answers this question by looking at the extraordinary climatic and geological upheaval at the time of our evolution.

Primates developed cognitive complexity – probably – in order to keep track of larger and larger social networks.

For instance, female vervet monkeys recognize their own offsprings’ cries. When they hear their children cry, unsurprisingly, they look at the child. When they hear someone else’s child cry, amazingly, they look at that child’s mother.

The story gets even more complicated when we look at chimpanzee dominance networks.

At the same time, later primates developed basic “theory of mind”: the ability to think about what others are thinking.

In one astonishing study, chimpanzees preferred to steal back food when researchers weren’t present – or when the container from which they stole the food was opaque. That is, chimps can think about what others can see, and behave accordingly.

All this complexity – social intelligence, theory of mind – proved especially important during the opening of the Great Rift in Africa: geological changes that led to rapidly changing climate and terrain. In this unusual set of circumstances, a species (like, say, Homo sapiens) with extra cognitive complexity was in a better position to manage upheavals.

As Howard-Jones writes:

The unique geology of the Rift Valley …is thought to have produced extreme climate variability with cycles lasting 400,000 or 800,000 years. […]

This inconsistent environment provided a novel genetic testing ground in which different hominin species were pursuing different approaches to survival, including generalizing vs. specializing. […]

Rather than evolving to fit one change, [Homo sapiens] evolved greater ability to respond to change itself.

Wow.

Classroom Implications

How should this understanding of evolution and learning shape our classroom practice?

Howard-Jones remains helpfully modest in answering this question. As he writes:

Evolution cannot tell us how to teach and learn, but it can help us frame and understand this research.

In his closing chapters, therefore, Howard-Jones encourages us to think about teaching with this perspective.

He suggests several insights about a) engagement, b) building of knowledge, and c) consolidation of learning that have evolutionary and neuro-biological grounding.

For instance: engagement. How can we help students pay attention?

Teachers have long known that novelty helps students focus. (Evolution helps explain why. Anything new could be a threat. Or, it could be food!)

Howard-Jones points out that shared attention is itself motivating:

Our strong motivation to share attention is a uniquely human characteristic that may have played a key role in our ancient cultural accumulation of knowledge, as it does today. When self-initiated, this capturing of shared attention also leads to reward-related brain activation.

In other words: schooling works because we invite our students to look with us, and to look with each other.

Another practical application: embodied cognition. Howard-Jones details several studies where a particular kind of movement helps students learn particular content.

He also explains why numbers and reading – more cultural practices than evolved cognitive capabilities – prove an enduring challenge to our students.

In Sum

Howard-Jones brings together many disciplines and a few billion years of history to tell this story.

Some readers might wish for more immediate, concrete teaching strategies. Some specialists, no doubt, disagree with his interpretation of the evidence.

I recommend this book so highly not because it tells us to do particular things, but because it helps us think in new and fresh ways about the work we have to do.

If we understand the evolutionary and neuro-biological sources of our difficulties and our enormous potential, we can think more realistically about avenues of success in schools.

In the words of Howard-Jones’s subtitle, we’ll understand how we got to be so smart. We might even understand how to get smarter still.

Early Signs of Autism: “Joint Attention”
Andrew Watson
Andrew Watson

If you’re attending this weekend’s Learning and the Brain conference, you’ll have many opportunities to learn more about autism. In particular, you’ll hear how our understanding of autism gives us a broader understanding of human brains, cognition, and personality.

In this video, professor Simon Baron-Cohen discusses the importance of “joint attention” for early diagnosis of autism.

As you’ll see, joint attention occurs when the pre-verbal child points or looks at an object. Crucially, the child also checks to see if the parent is also looking. (The key passage begins at about 1:15 on the video.)

If you’re interested in joint attention, and especially its role in human evolution, I highly recommend Michael Tomasello’s book The Cultural Origins of Human Cognition.  In it, Tomasello does a masterly job sleuthing through primate behavior to discover uniquely human traits.

 

Uniquely Human: How Animals Differ From People
Andrew Watson
Andrew Watson

What separates humans from other animals? What makes us uniquely human?

uniquely humanThis question can be fun to debate. The most common answers — “tool use” and “language” — have their champions. However, lots of animals communicate with sounds. Several species use tools.

These abilities are rare among animals; however, they’re not uniquely human. So: what might be the key distinction?

M&Ms and Pencils

Imagine this scenario.

A young girl comes into your office with her father. You show her a box full of M&Ms. The father then leaves the room, and you — quite conspicuously — pour out the M&Ms and replace them with pencils.

When the father comes back into the room, you ask the young girl “What does your father think is in the box?”

A five-year-old answers this question quite easily. Even though she watched you put pencils in the box, she also knows that her father wasn’t there when that happened. As a result, his knowledge differs from hers. He (falsely) believes that the box contains M&Ms, although she (correctly) knows that it contains pencils.

A three-year-old, however, can’t manage this duality. If she knows there are pencils in the box, then she thinks everyone knows there are pencils in the box. She simply can’t process the idea that others have false factual beliefs.

This ability to distinguish between what I know and what you know goes by the awkward name “theory of mind.”

Most 5-year-olds have theory of mind; they know that you and I have different ideas in our heads. Most 3-year-olds don’t have theory of mind. They believe that everything they know is known by everyone else.

Uniquely Human: Candidate #1

In The Cultural Origins of Human Cognition, Michael Tomasello argues that theory of mind is the uniquely human cognitive trait.

Because humans think about what other humans are thinking, we have been able to develop our environment (think, skyscrapers) and our cognitive capabilities (think, calculus) with astonishing rapidity.

Each generation can hang onto the ideas developed by previous generations, and so progress beyond them.

Here’s a very basic example:

I might say to you: “A platypus is in the elevator.”

Or I might say: “The platypus is in the elevator.”

This tiny linguistic difference (“a” vs. “the”) shows that I’m considering what you already know. In the first sentence, you don’t know about the platypus — even though I do. In the second sentence, we both know about it.

Tomasello connects theory of mind to human culture and development with remarkable dexterity and clarity; I highly recommend his book. (He’s also a lively speaker, if you ever have the opportunity to hear him.)

Uniquely Human: Candidate #2

Only recently I stumbled across another possibility: the ability to remember sequences.

Stefano Ghirlanda and colleagues looked at research considering the ability to learn sequences among a variety of species: various birds, macaques, even dolphins.

It turns out that humans can pick up complex sequences quite quickly.

In one study, for example, humans listened to a sequence of sounds, and were able to remember them with 90+% accuracy after 6-8 trials. Zebra finches, however, took between 300 and 800 trials to achieve the same level of accuracy — even though the sounds were zebra finch song syllables.

In another study, rats could learn what to do after individual signals with relative ease. To learn a series of signals, however, took on the order of 10,000 trials. You read that right: ten thousand.

(Imagine being the graduate student whose job it was to do all 10,000 trials.)

Ghirlanda and colleagues argue that sequence processing underlies all sorts of complex human cognition: episodic memory (this happened before that), planning (step one, then step two, then step three), even music (this series of notes isn’t that series of notes).

Without our ability to process those sequences, we would hardly be human.

Limitations

Like all studies, this one has limitations.

First, Ghirlanda and colleagues note that other species are good at remembering sequences that have to do with evolutionarily important processes: the steps required to capture food, for instance, or to attract a mate.

However, in addition, humans are good at remembering arbitrary sequences. Music helps in finding a mate, but it isn’t required. So too: math might be sexy, but it isn’t required for wooing.

Second, although Ghilranda did find research with other mammals, they did not find research with apes. It’s possible that they have the ability to learn arbitrary sequences.

Perhaps, in other words, this ability helps make us human, but isn’t uniquely human. Until we study more species, we can’t know for sure.

[For other thoughts on evolution and learning, click here.]

Does Forest-Bathing Benefit Your Anxious Amygdala?
Andrew Watson
Andrew Watson

AdobeStock_94176737

You have perhaps heard of “forest-bathing,” the Japanese practice of taking in the forest atmosphere to boost health.

For many, the idea has intrinsic appeal. (I work at a summer camp in leafy Vermont, and so am immediately drawn to ideas like these.)

Do we see any neural changes as a result of time spent in the forest?

The short answer: living near forests helps

According to a recent study looking at residents of Berlin, the answer is “yes.”

Those who live in or near forests demonstrate more “amygdala integrity” than those who don’t. In fact, forest-living promotes healthy amygdala development even more than living near parks or other green spaces.

The study itself is quite technical, but the headline message is clear: the place where you live can influence brain development.

A Longer Answer: are we sure?

As is always true, we have many reasons to pause before we make dramatic changes in response to this study.

First, the authors conclude that living near forest promote “amygdala integrity,” but they don’t say what “amygdala integrity” means. It’s hard to be opposed to “integrity,” but I wish I knew more about this part of the finding.

Second, we should be cautious when evaluating research that supports our own biases. If you–like me–LOVE spending time in the forest, then you’ll be tempted to wave this study about to support your long-held convictions.

“See!” you might cry, “I’ve always told you that forests were good for you and [**whispering**] your amygdala integrity!”

Research that supports our own pet causes can often take advantage of our blindspots. We should be especially careful in promoting it.

Third, there’s an unfortunate history of people getting excited about “nature is really good for your brain” research.

The New York Times got very excited about a study trumpeting the benefits of walking through a forest, despite real concerns about methodology in that study.

And yet…

…despite these three reservations, I’m inclined to think that the researchers are on to something here. Living in an environment that mirrors our evolutionary heritage might very well be good for our brains’ development.

Can Our Evolutionary Past Help Shape Our Classrooms’ Future?
Ashle Bailey-Gilreath
Ashle Bailey-Gilreath


AdobeStock_95617477 CaptionHumans are genetically adapted for learning. The transmission of information, skills, culture, and knowledge from generation to generation has helped us survive and become who we are today. Our journey to becoming modern humans has been shaped primarily because of the change in our environments.

The trouble is, our modern learning (and teaching) environments are not anything like those of our ancestors. Recent research is beginning to present some compelling evidence for implementing evolutionary-influenced practices and policies into our modern education system. In fact, the non-profit think tank I work for has done extensive work in this field, including publishing a textbook, hosting workshops for researchers and educators. We have also helped implement some of these practices in schools in both Florida and New York with great results. In order to design and implement an effective educational environment, we need to understand our evolved abilities to acquire skills and knowledge.

And importantly, some of these ideas have not only been touted by other research fields, but have also been put into practice by some educators. Here are six points that I believe everyone should consider about how our current educational system would look from the perspective of evolutionary theory:

  1. Learning should be child motivated

One way many evolutionary scientists can get a glimpse of our ancestral past is by looking at hunter-gatherer societies. What they’ve found is that adults do not control children’s learning, but rather help children learn as they grow – answering their questions and showing them the skills they need to succeed, when they need them. Within these traditional societies, children (and even teenagers) learn through their own self-direction through play and exploration, making it essential for there to be free time for these activities.1, 2

  1. Children are prepared to learn from birth  

Relative to our lifespans, humans have a longer period of childhood than any other species on the planet. While this prolonged maturing process has its downsides (greater parental investment), it also has its upsides: intelligence.

Our big, complex brains take a lot of time to develop, most of which happens after birth. While I won’t go into the driving factors of this development(which will be featured in a later essay), one thing is for certain: in ancient environments, children would have been very vulnerable because of this prolonged period. Children’s curiosity, playfulness, socialness, and their ability to imitate and learn new skills were extremely valuable for surviving these environments. 3, 4 Children’s prolonged development and innate drive to learn not only helped them survive, but also allowed them to flourish in society, allowing them to learn how to be social, learn and participate in their culture, become innovative, and learn language. This pattern is still evident in hunter-gatherer societies today. 2

  1. Learning should be immediately reinforced

While we all know the long term benefits of learning, young people often have a hard time understanding this. Research has shown that a number of species (from pigeons 5 to monkeys 6, and humans 7) find delayed gratification extremely difficult to hold out for. A great example of this is a very fun study that involved children and marshmallows.

Young children were put a room, one at a time, with nothing but a table, chair, and a big, fluffy marshmallow on a plate. The kids were told that they could eat the marshmallow now if they’d like or–if they could wait until the researcher came back (approximately 15 minutes)– they would be given two marshmallows. Needless to say, quite a few kids ate the single marshmallow.  

One way to address this struggle with self-control is by allowing children to play and explore more. When children participate in self-motivated play and explorations, the benefits often lie in the discoveries made, the excitement of the activity itself, feedback from others participating, and the immediate gratification of learning something new, while having fun doing it.  While sitting quietly in a classroom and listening to a conventional teaching lesson may allow children to learn the same things, they don’t realize that their good behavior and full attention will result in a better education.

  1. Learning is best in mixed-age settings

Before “grade” defined schools, children rarely were segregated by age. In modern hunter-gatherer and traditional societies, learning occurs in mixed age groups. In fact, this was an active model of learning environments as recently as the 19th century.

Children can learn from those older and younger than themselves, whether by imitating an older child or by participating in play and pretend with younger children. When helping younger children, older children begin to learn how to explain and teach their skills, while at the same time younger children are given the opportunity to engage with and learn from older children.

As every teacher knows, we often learn more by teaching than by being taught, especially when our students challenge us.  And research within the social sciences backs up this claim.8 While mixed-aged classrooms may be quite challenging to implement within our current school systems, not only because of the strain on the teachers but also because of constraining curriculum standards, they are something to consider for the future and for other less restrictive situations, like after school programs.  

  1. Learning environments should mimic ancestral conditions

Species are adapted to their long-term past environments, and so prior adaptations sometimes go awry. In other words: humans function in today’s world with evolutionary adaptations better fitted to habitats that are thousands of years old. Many of the problems that schools and children experience today may be unintended consequences of educational environments that are significantly different from ancestral conditions.

One example is physical activity. Physical activity and movement were a central part of the ancestral environment; however, in current learning environments, children are forced to sit still for extended periods of time. In fact, this deprivation of movement, along with other things like physical touch, greatly hamper children’s development. 9, 2

  1. Learning should be democratic

One of the main things that sets humans apart from many other species is our ability to cooperate and be egalitarian.10 People of all ages and cultures cherish having their voices be heard. Children are no different – they are often the first to resist being told what to do.

While this doesn’t mean that children should be allowed to rule the roost, it does suggest that they should be actively involved in the decision-making process, especially in the environment where they spend a significant amount of their time: school.

One popular real-life example of this is the Sudbury Valley School, in which adults do not control children’s education; rather the children make democratic decisions to educate themselves. The administrative body consists of students and staff members who make decisions together on rules, purchases, staff, and learning courses. The school and model have been working for over 40 years, with graduates going on to pursue careers in everything from science and social work to music.

So, how do we implement this knowledge in (and out of) the classroom?

By understanding our evolved abilities to acquire skills and knowledge, we can design and implement more effective learning environments. While some of the points discussed here may be impossible given the constraints of our current education system, there are some things we can do (or maybe you already do!) that can maximize children’s learning potential. One thing you can do is to teach in ways that maximizes immediate gratification! The most successful teachers are those that make their lessons enjoyable and engaging. Allow kids to interact with each other: be playful, curious, and social.

This suggestion ties into a second important point: let kids move, play, and explore with everyone, at all ages. While this strategy may be trickier depending on your school, collaborating with other teachers in other grades may provide a wonderful learning environment for your children to learn in (and learn from). These points don’t have to just take place inside of the classroom; rather they can be applied to all kinds of environments: be they playgrounds, neighborhoods, youth centers, or daycares.

Viewing the learning environment through an evolutionary lens provides us with a deeper understanding of how individuals learn and teach, especially in educational settings. Given what we’ve learned about our brain’s evolution and children’s development, it seems that educational practices need to evolve as well.

References

  1. Gosso, Y., Otta, E., de Lima, M., Moralis, S., Ribeiro, F., & Bussab, V. (2005). “Play in Hunter-Gatherer Societies,” in A. D. Pellegrini & P. K. Smith (Eds.), The Nature of Play: Great Apes and Humans, Guildford Press. [link]
  2. Gray, P. (2009). Play as a Foundation for Hunter-Gatherer Social Existence, American Journal of Play, 4, p. 476-522. [pdf]
  3. Bjorklund, D. (2007) Why Youth Is NotWasted on the Young: Immaturity in Human Development. Blackwell Publishing. [link]
  4. Bjorklund, D. (1997) The Role of Immaturity in Human Development, Psychological Bulletin, 122, p. 153-169. [pdf]
  5. Laude, et al. (2014) Impulsivity Affects Suboptimal Gambling-Like Choice by Pigeons. Journal of Experimental Psychology: Animal Learning and Cognition, 40, p. 2-11. [pdf]
  6. Addessi, et al. (2013) Delay Choice Versus Delay Maintenance: Different Measures of Delayed Gratification in Capuchin Monkeys. Journal of Comparative Psychology, 127, p. 392-398. [link]
  7. Mischel, W., Shoda, Y., & Rodriguez, M. I. (1989). Delay of gratification in children. 
    Science244(4907), 933-938. [pdf]
  8. Nestojko, J.F., Bui, D.C., Kornell, N., & Bjork, E.L. (2014). Expecting to teach enhances learning and organization of knowledge in free recall of text passages. Memory & cognition, 42(7), 1038-48. [pdf]
  9.  Cooper, D., Nemet, D., and Galassetti, P. (2004) Exercise, stress, and inflammation in the growing child: from the bench to the playground. Current Opinion in Pediatrics, 16(3), p. 286-292. [link]
  10. Burkart, J. M. et al (2014). The evolutionary origin of human hyper-cooperation. Nature communications5, p. [link]