According to Wikipedia:

John Maxwell Cohn (born February 9, 1959) is an IBM Fellow and chief scientist of design automation at IBM. Cohn has been an innovator in the area of design automation for both analog and digital custom integrated circuits. Cohn has 60 patents issued or pending in the field of design automation, methodology, and circuits.

In this TEDx Talk, he riffs on the importance of play in the success he has had over his life as an engineer. I could not agree more.

The neuroscientist Jaak Panksepp has identified play as one of the seven primary affective circuits in the human brain. From an interview with Panksepp in Discover Magazine:

Panksepp has charted seven networks of emotion in the brain: SEEKING, RAGE, FEAR, LUST, CARE, PANIC/GRIEF, and PLAY. He spells them in all caps because they are so fundamental, he says, that they have similar functions across species, from people to cats to, yes, rats.

There is more on the topic of play below the video, also from the Discover Magazine interview.

The importance of play: John Cohn at TEDxDelft

Published on Dec 19, 2013

Dr John Cohn (@johncohnvt) is a self-confessed nerd. He already knew he wanted to be an engineer at the age of eight, found himself a nerdy college, a nerdy job and even a nerdy wife, or at least a fellow-engineer. As a nerd he breaks the mould though. Because onstage, with his rainbow-coloured lab coat, his Einstein-inspired hairdo and his party light headband, he is most of all entertaining and fun. That ties in with his motto: keep things playful. Bring a playful spirit into your work.

John says he is at his most creative, influential, productive and happy when he is playful at his work. With playful he means being in a state of childlike innocence. So playfulness is not just about enjoying your work, you are even more creative, as studies show. You can also reclaim that childlike state, by imagining you are still seven years old.

Life however, has a way of taking play away from us. The harder life gets, the more we have to work at staying playful. If work is not playful anymore, than it is just work. Which is why they call it work, incidentally. Six years ago, life became very difficult for John, when his son Sam died in a car crash. Sam was an organ donor, and when his life ended he saved the life of four other people. Needless to say, John's life changed forever. And trying to get his life back on track involved a playful element, although he didn't think of it like that at the time. John and his family started making SamStones, small stones with Sam's name on it. Now, over six years later, some 40,000 SamStones have travelled all over the world, and each stone tells a story. One of them even went to space and back.

Life will give you reasons not to play, and you have to fight back!

* * * * *

Here are a few of the questions and answers from that interview on the topic of play:

Then you made a U-turn: Instead of studying separation anxiety, you started 
to study play and laughter. Why?

It was the classic masks of theater, sadness and happiness. We had essentially done the work on the sadness mask. I wanted to move to the joy mask. Joy is social, so you’re looking at play. Play is a brain process that feels good, that allows the animal to engage fully with another animal. And if you understand the joy of play, I think you have the foundation of the nature of joy in general. Part of its benefit is simply taking away the psychological pain of separation. Play is engaging in an attachment-like way with strangers, which you have to do later in life.

Time for another animal experiment, right?

To study attachment, we couldn’t use rats or mice. They’re laboratory animals bred inadvertently to live by themselves. But I noticed that rats in the lab are wonderful for play. Psychic pain reduces the inclination to play—but since rats don’t feel it, they can be separated without panic and then when you put them together, bang! They play.

And the rats played with you, too?

After the experiments we’d dim the lights to make the rats more comfortable. That was our time to have fun. You see me sitting there and saying, come on, guys, come on—it’s okay. I knew that if I could tickle them, they would get jazzed up more, and that’s what happened, right in front of the camera.

How did you turn that kind of playing around into a rigorous experiment?

I thought about the hunger research I’d done in the past. If I wanted animals to eat, then the best way was to make sure they hadn’t eaten for a while. If I want animals to play, I’d have to make them hungry for play. So I put them in a cage alone, apart from their family, first for 4 hours, then 8 hours, then 12 hours, and finally 24 hours. I was looking for a behavior that I could use to measure play, like jumping on each other. How often do they bounce and touch each other? Then they run around—it’s too complex to follow unless you do slow-motion movies—and they end up wrestling. These behaviors were very easy to measure. We collected a lot of data on the response to social hunger.

Is play embedded deeply in the brain, the way attachment is?

Many experiments over the years suggested it was, but to be sure I removed the upper brain of the animals at three days of age. Amazingly, the rats still played in a fundamentally normal way. That meant play was a primitive process. We saw, too, that play helped the animals become socially sophisticated in the cortex. That’s why it’s so important to give our kids opportunities for play.

And yet it seems that childhood play has become much more controlled than it was when I was young. 
I have gone to ADHD meetings to consider this childhood problem. But the doctors do not want to hear the possibility that these kids are hyper-playful because they’re starved for real play—because they are giving them anti-play medicines. Teachers are promoting the pipeline of prescription controls as much as any other group, because their lives are hard. They are supposed to be teaching kids at the cortical level of reading, writing, and arithmetic, but if they’ve got kids who are still hungry for play, it’s gonna be classroom chaos. And you can sympathize with them, because they should be getting kids that are sufficiently well regulated to sit and use their upper brains. But the kids’ lower brains are still demanding attention.

What happens to animals if they are deprived of play over 
the long term?

They look normal and they eat normally, they’re just not as socially sophisticated. Animals deprived of play are more liable to get into a serious fight. Play teaches them what they can do to other animals and still remain within the zone of positive relationships. If you have play you become sociosexually more sophisticated. Let’s say you have the classic triangle: two males and one female, because males are competitive for sex. So if you’ve got one animal that’s had lots of play and the other animal hasn’t, guess who is successful? The animal that’s had play knows how to stay between the female and the other male. The other guy’s a klutz.

Did you ever find a way to track and measure the play response in rats?

Yes. I had a postdoctoral student, Brian Knutson, who asked me whether there was a play vocalization. I said, we know they don’t make any audible sounds but maybe there’s ultrasonics. We wound up buying the equipment so his study could be done. Brian came in the first day after it was set up and said, Jaak, there is a sound when the animals are playing. That was the 50-kilohertz chirp [at a pitch far above the range of human hearing].