Is it a uniquely human ability?
Sometimes we are planning to do something and are about to start, when we are interrupted and have to do something else first. Most of us have heard requests like “Before you take your shoes off, could you please take out the garbage?”
Or we may even interrupt ourselves, by deciding that some action that we are planning necessitates our doing something else first. We might plan to paint a room in our house and be preparing to do so, when we notice that the walls of the room have some holes that need to be patched. Then, preparing to patch a hole, we may notice that there is a mouse inside it. After making the hole larger to remove the mouse, we may see that a whole family of mice has made a home inside the wall, and worse, we may see that the framing of the house inside the wall is rotten. Only after undertaking major renovations to the house do we finally return to painting the (same?) wall that we started with.
Such cases of “indefinite regression” are common in human behavior, but I doubt that many other animals are capable of them — that is, of holding one or more intentions in suspension (“keeping them in mind”) until we have accomplished other goals that we thought of later but must act on earlier.
Recursive problem solving is a special case of such thinking. It involves taking a problem and…
