The world is made up of many different kinds of things, and in order to get around the world successfully, we have to learn both about the individual items we encounter and we also need to learn information that will help us to deal with new things. So, when you learn that a particular object in your world is a chair, you need to know what to do with it, but you also need to pick up bits of knowledge that will be of value when you learn about other objects, like tables, lamps, or ovens.
When you look at what adults know about the world, there is a big difference in the way they think about artifacts and animals. Artifacts are human-made objects that are designed for some purpose, while animals are the result of an evolutionary process.
Generally speaking, the artifacts of a particular type vary a lot more than animals of a type. Any given chair might have legs, or it might have a pedestal. It may be made of many different kinds of materials. It may have many different colors. The fact that something is a chair tells us a little about it (like it was made for sitting on), but not much else.
In contrast, different animals of a type are all fairly similar. Cats, for example, have four legs, are furry, have similar internal organs, and behave in similar ways.
Adults recognize that animals and artifacts differ in this way.
At what age do people learn about this difference between animals and artifacts?
The difficulty with answering this question definitively is that young kids often have trouble telling us what they know. As a result, it is useful to have more indirect ways of teasing apart what they know.
A clever study by Amanda Brandone and Susan Gelman in the January 2013 issue of Cognitive Development examined the way kids talk about animals and artifacts as a way of assessing what they know about these kinds of things. In particular, they focused on generic language. A generic statement is one that is meant to apply to (nearly) all of the objects being described. If someone says, “Chairs are made for sitting in,” she means this sentence to apply to (nearly) all chairs. If she says “Cats meow,” then she means to describe (nearly) all cats. If children know that animals generally have more in common than objects, then we would expect children to use generic language more often when talking about animals than when talking about objects.
In this study, five-year-olds were shown a set of drawings of things that they were told came from an alien planet. Some children were shown the pictures and were told that they were kinds of artifacts (like machines, vehicles, and tools). Other children were shown the same pictures and were told that they were alien animals. Each object was given a novel category name. So, a child might be told that a particular object was a “dax.” The novel category name was used so that children could only use general knowledge about things to understand the new object.
At the start of the study, children were introduced to a puppet that they were told was blind. After seeing each picture, they were asked to tell the puppet about the object. A group of adults were shown the same objects and were also asked to describe them.
The experimenters analyzed the language that the children and adults used to describe the objects. In particular, they were interested in how often children and adults used generic statements to describe artifacts and animals.
Both the adults and the children used generic statements more often when describing animals than when describing artifacts. That means that even pre-school children know that animals of a particular kind have more in common with each other than artifacts of a particular kind. When adults and children used non-generic language, they used it about equally often for the artifacts and the animals. So, it is not just that people wanted to talk more about the animals than about the artifacts.
These expectations about objects and animals guide the way children learn about new things. Because children expect animals of a particular type to have lots of similarities, they look for those similarities when they encounter a new animal. When children encounter an artifact, though, they spend more time exploring the function of the artifact than the properties.