I was not at the Cincinnati Zoo when that 4-year old bolted from his mom into the enclosure. I am not an expert on gorillas or on zoo design. I don’t know the child in question or his parents (some reports state dad was there, too, although he’s not come under fire like mom has). We do know that it was a tragedy — a child (and his family and the bystanders) were traumatized, a 17-year old gorilla lost his life.

Preschoolers are developing their impulse control; they don’t already have it. You might have heard about the Stanford Marshmallow Experiment. That’s the test where researchers sat down with children 4 to 6 years old and gave them a marshmallow. The researcher tells the child something like, I need to leave and you can eat that marshmallow or you can wait and then you’ll get a second marshmallow when I get back. Then the researcher leaves the room and observes what the child does through a one-way mirror. And what they found is that the younger a child is the more likely they are to eat the marshmallow.

Young preschoolers, they are bird (marshmallow) in hand type people.

And then there are those children who have a harder time with impulse control. Those kids tend to be more active, less scared, more persistent (the ones who will nag nag nag you) and less concerned about punishment and reward. They are kids who live in the RIGHT NOW. These are the ones who eat the marshmallow before the door finishes closing behind the researcher. That’s a temperament thing; some kids just have more impulsive personalities than other kids and will need more support, understanding and opportunity to develop their self-control.

Back to that marshmallow test. They’ve looked at it a lot over the years and one of the things they’ve found is that children are able to delay gratification (be less impulsive) when their environment is “reliable,” i.e., when their environment is more predictable.

Here’s a video that explains that:

Now I want you to think about this when we think about young children in public spaces, where reliability is generally lower. If you’re at home or at your daycare or at your babysitter’s, you pretty much know when you’ll eat and what you eat. You know where the bathroom is. You know when your little sister goes down for her nap. You count on this consistency.

Then there’s the zoo that — with all it’s fun and excitement — is extremely unreliable. You will likely have to wait for the potty, It may be one of those scary self-flushing potties. Your juice might be warmer than you like it or be the wrong juice or the wrong straw. Your dad promises you that you’ll see the snakes but when you get there the exhibit is closed. Children have finite resources to draw on so even a child with pretty good impulse control might hit their limit at places that lack reliability.

I’ve been to the zoo with a slew of 4-year olds (my own and other people’s including some pretty hectic trips with a whole preschool class) and I know that at a certain point everyone is tired, grouchy and done-in. For any child — not just one who’s struggling with impulse control — this is the point where the lousy behavior comes out. Stand at the exit of a zoo sometime and watch how many kids are carried (or dragged) out sobbing. Notice how many wrench free of their parents’ hand or let go of the stroller or their parents’ back pocket to run to the cotton candy stand or souvenir store with their parents hollering at them to “Get back here!”

This time it was something far more dangerous with tragic results. On another day it might have just meant a lecture or a time-out.

Like I said, I wasn’t there and I didn’t see it. I don’t know that child or his parents and I’ve never been to the Cincinnati zoo so I can’t speak to the efficacy of the barriers around its exhibits. But I do know 4-year olds. Events like these are blessedly rare but impulsive behavior by preschoolers is not.