These days I research cognitive development in toddlers and preschoolers, but most of my graduate training involved grade-school kids, young adults, and beyond. This has left a few disconcerting gaps in my knowledge of the field. Not until last weekend, for instance, did I learn of the existence of scale errors in typically developing children.

Remember how Alice feels when she finds herself unable to squeeze through a miniature garden door? It isn’t necessary to tumble down a rabbit hole to experience this acute frustration: plenty of normal two-year-olds do so all the time. University of Virginia psychologist Judy DeLoache and her Northwestern University colleagues David Uttal and Karl Rosengren first addressed the phenomenon in 2004.

They invited 54 children between 18 and 30 months into a lab. One at a time, the children were invited to play with three large toys: a slide tall enough to scooch down, a car big enough to crawl inside, and a chair capable of supporting a toddler-sized bottom. Then the kids were led out of the room while all of the large objects were replaced with miniature replicas: a teeny slide, a tiny car, and a chair better suited for a Barbie doll. When the children returned, they were encouraged to play with the new objects. Twenty-five toddlers attempted to scooch down, crawl inside, and sit atop the replicas, to absurd effect.

In a follow-up study with colleague Elizabeth Ware, now at Viterbo University, the researchers found that children’s scale errors aren’t limited to instances in which their own bodies are too large to interact with other objects; children make similar errors with dolls. Note that in both studies the children weren’t simply fooling around, or playing make-believe: they were genuinely trying to engage with the small objects just as they had with the larger ones, and when this didn’t go as they’d hoped, they often became frustrated.

What’s going on? When a child sees a slide, she wants very urgently to slide down it—that’s what slides are for, after all—and so she develops a motor plan (i.e., a sequence of movements) for doing so. If she sees that a slide is too small, she must inhibit this plan—the point at which the trouble starts, researchers believe. Her two-year-old inhibition skills aren’t always up to the task, so she may stick with her original plan. She understands that the slide is small and bends down to reach it accordingly, but she is unable to abandon the plan she’s developed for interacting with it.

Both of these studies have their flaws, as do most early attempts at researching any phenomenon. For one, experimenters had no qualms about prompting children in ways that almost certainly encouraged scale errors. In the follow-up study described above, for instance, experimenters gave leading suggestions: “Does the baby want to go night-night in the bed? Does the baby want to go for a ride in the wagon?” (Thankfully, a third study confirms that scale errors occur in the absence of such prodding: more than 15 percent of parents reported having observed their child spontaneously make a scale error in daily life.)

A control condition from the original study—intended to demonstrate that two-year-olds understand which object size is most appropriate for a given action—was also less than ideal. Children were presented with both the miniature and larger versions of a toy and instructed to “ride,” “sit,” or “slide down.” Unsurprisingly, they chose to engage with the larger object. But this object was also—by about a factor of 10—the more prominent of the two, and two-year-olds aren’t known for their subtlety. Would the child have selected the appropriately sized object if the alternative had been very large instead of very small? Most likely yes, but we can’t know for certain.

Finally (just because at least some of you were thinking it), none of the existing work on scale effects in young children has even attempted to explain how Maru the cat fits into all this.