Your Toddler's Possessive Phase, Explained

This possessive phase may be challenging, but it can give you insight into your toddler’s growing mind.

Since it was Father’s Day, the card and the chocolate orange technically belonged to Lance Concannon. But William, his 18-month-old son, had another idea. “He didn’t even know what it was,” recalls the London based dad. “All he saw was this shiny thing in a box, and he was damned if he was going to let me have it.” William seized the candy and scurried away, screaming, “It’s mine! It’s mine!” 

“Do you even know what it is?” Concannon asked him after a few moments of this. “What is it, William? What are you holding?”

“William’s,” answered William. That answers that. 

William was in the everything-is-mine stage, which classically kicks in at around 18 months. “My and mine are some of the first words children use,” explains Peter Blake, Ed.D., a developmental psychologist at Boston University. Although they’ll say Mama and Dada first, they quickly realize that they can claim an object simply by using language: my ball, my dog, my cup, and so on. What a cool trick!

As we get older, we get better at managing our wants and needs in a more socially acceptable manner, but face it: We never outgrow our desire for possessions. We always define ourselves, at least in part, by what we own. 

What the Research Reveals

Though your kid’s grabby meltdown doesn’t seem like her finest moment, it actually reflects how smart she’s becoming. “It suggests that she is grasping the abstract concept of a person’s invisible tie to a thing,” says Susan Gelman, Ph.D., a developmental psychologist at the University of Michigan in Ann Arbor. Toddlers are little, so their reasoning is simple: Research has found that children between ages 2 and 4 tend to believe that the person who possesses an object first is the rightful owner, even if someone else gets hold of it later. The argument “I had it first!” would carry serious legal weight in a toddler-led court of law. 

But something important is happening at this stage of your child’s life: Her sense of self is becoming more sophisticated. When a baby sees herself in the mirror, she assumes she’s looking at an oddly two-dimensional new friend. However, a toddler can look at her reflection and understand that she’s seeing herself. In essence, a child’s sense of me emerges alongside her sense of mine. And she may be vocal about what is hers because she is focused on figuring out who she is. 

As it happens, decades’ worth of other research in the social sciences has also proposed a link between our stuff and ourselves. In the 1980s, behavioral economists coined the term “endowment effect,” which suggests that we consider our possessions to be more valuable simply because they are ours. Most of the research on this has involved adults, but some studies have found that the endowment effect shows up in toddlers too. 

While it’s true that they get confused about what is theirs and what isn’t, if you explicitly tell them what is theirs, they will file that information carefully away. Dr. Gelman, along with Nicholaus Noles, Ph.D., a developmental psychologist at the University of Louisville, in Kentucky, designed experiments in which 2- and 3-year-olds were shown identical toys and told that one was theirs and the other was not. When the toys were shuffled, the kids weren’t fooled; they kept careful watch and they could identify which one was theirs. In another study, the researchers added an additional question after all of the shuffling: “Which toy do you like best? The kids almost always said they liked theirs the best. Once, the kids were shown toys and a block of wood, and told that the block of wood was theirs; a surprisingly large number of kids claimed to love the wood best. “That’s just the way we’re wired,” says Dr. Noles.

Helping Him Learn

All of this is fascinating in theory, but your toddler’s iron grip on objects can still be frustrating in daily life. The psychologists who have studied this phase have these two pieces of advice for finessing a surge of possessiveness.  

1. Explain the rules.

Toddlers aren’t being selfish or antisocial. “They’re trying to figure out what’s right and what’s wrong, and what the rules are,” says Chuck Kalish, Ph.D., principal investigator at the Study of Children’s Thinking Lab at the University of Wisconsin Madison. 

One way to approach a tussle over toys is to clearly say to your child, “This truck is yours and that car isn’t.” Remember the shuffled-around-toys study? He can keep track, even at this young age, of what belongs to whom. Fortunately, as kids get a little older, they also discover that it feels good to make someone else happy by handing him a toy.

2. Then again: You don’t always have to insist on sharing.

You’ve probably learned that it makes sense to put away any very special toys or stuffed animals before another child comes over for a playdate. “After all, if a stranger picked up your purse or your phone, you’d be pretty upset,” says Ori Friedman, Ph.D., a developmental psychologist at the University of Waterloo, in Canada. You’d stick up for yourself, so why do we expect little kids to behave any differently? “When someone else yanks away a toy that your child is attached to, of course, he’s going to be a bit aggressive,” Dr. Friedman says. 

If you consider the fact that your child relies on her things to help her work out who she is, it becomes easier to see why sharing can be such an explosive concept. Through this lens, the “mine” stage is an exaggerated version of something most of us struggle with on occasion, no matter how old we are. Toddlers just tend to work through these frustrations a little more loudly than grown-ups do.

By Melissa Dahl