Categories and Inductive Inferences

Recruit healthy 5-, 7-, and 9-year-old children with normal hearing and vision and no history of developmental disorders. For the purposes of this demonstration, only one child is tested. Larger sample sizes (as in Frank Keil's transformation study¹) are recommended when conducting any experiments.

1. Data collection

1. Gather the necessary materials.
   1. Design eight vignettes describing the transformation of animals from one kind to another via surgery.
      1. Natural kind vignette example: "The doctors took a raccoon and shaved away some of its fur. They dyed the rest of the fur black. Then, they bleached a single white stripe down the center of its back. They surgically added a sack of super smelly stuff into its body, just like a skunk has. When they were all done, the animal looked like this. After the operation, was this a skunk or a raccoon?"
   2. Design eight vignettes describing the transformation of artifacts from one kind to another via physical alteration.
      1. Artifact vignette example: "The doctors took a coffeepot that looked like this. They sawed off the handle, sealed the top, took off the top knob, sealed the spout, and sawed it off. They also sawed off the base and attached a flat piece of metal. They attached a little stick, cut a window in it, and filled the metal container with bird food. When they were done, it looked like this. After the operation, was this a coffeepot or a birdfeeder?"
   3. Create cards with images of each item before and after transformation.
2. Preamble
   1. Present the child with a preamble introducing doctors and describing operations and surgery.
3. Test
   1. Present the child with each of the 16 vignettes in a random order.
   2. If the child tries to give an ambiguous response (e.g., "It's both" or "It's a skuncoon"), ask them to pick one of the two highlighted responses.
   3. Question the child in a free-form manner in order to understand what aspects of the vignette guided their responses. For example, the experimenter might ask questions like: "Why is it a birdfeeder?" or "If the animal looks like a skunk and smells like a skunk, why did you say it was a raccoon?" This questioning helps to determine what features or principles the child uses to guide their intuitions.
   4. Record the child's responses, and then transcribe them for future analysis.

2. Analysis

1. Two independent coders read the child's transcriptions and code them on a scale from 1 to 3 for each item. This score is an index of the child's resistance to categorical change.
   1. A score of 1 on an item means a child shifts their intuitions to follow the transformation operation. These responses focus on characteristic features.
      1. Example: "It's stinky and stripy like a skunk, so it's a skunk."
   2. A score of 2 on an item means a child's responses are indecisive, indicating that they are unsure if the transformation results in a change in the item's kind.
      1. Example: "It's a rac-unk or a skoon. I don't know."
   3. A score of 3 on an item means that a child resists shifting their intuitions following transformation operations. These responses contrast with observed features.
      1. Example: "It doesn't matter what it looks like on the outside; it's still a raccoon."
2. Use an analysis of variance to determine if there are differences between the three age groups and two types of items presented to the children.