Four stages of mirror use

1. Animals react to their mirror image as if to an unfamiliar conspecific.

2. They inspect the mirror in various ways, including (usually) looking behind it. [Elephant example.]

3. They engage in "repetitive mirror-testing behavior," things like systematically moving back and forth while studying the image in the mirror.

4. They exhibit various kinds of "self-directed behaviors," such as inspecting their teeth or other areas of their bodies that they could not see without using the mirror. [Elephant example.]

5. They pass the Gallup spot test. [Elephant example.]