A frame is a sort of skeleton, somewhat like an application form with many blanks or slots to be filled. We'll call these blanks its terminals; we use them as connection points to which we can attach other kinds of information. For example, a frame that represents a chair might have some terminals to represent a seat, a back, and legs, while a frame to represent a person would have some terminals for a body and head and arms and legs. To represent a particular chair or person, we simply fill in the terminals of the corresponding frame with structures that represent, in more detail, particular features of the back, seat, and legs of that particular person or chair. As we'll see, virtually any kind of agent can be attached to a frame-terminal. It can be a K-line, polyneme, isonome, memory-control script, or, best of all, another frame.
In principle, we could use frames without attaching their terminals to anything. Normally, though, the terminals come with other agents already attached — and these are what we called default assignments when we first talked about level-bands. If one of your person-frames is active, and you actually see some arms and legs, their descriptions will be assigned to the proper terminals. However, if certain parts cannot be seen, perhaps because they're out of view, the missing information will be filled in by default. We use default assumptions all the time: that's how, when you see someone wearing shoes, you know that there are feet in them. From where do those assumptions come? I'll argue that
Default assumptions fill our frames to represent what's typical.
As soon as you hear a word like person, frog, or chair, you assume the details of some typical sort of person, frog, or chair. You do this not only with language, but with vision, too. For example, when someone is seated across the table from you, you may be unable to see any part of that person's chair. Still, this situation will probably activate a sitting-frame. But a sitting-frame will surely have a terminal for what to sit upon, and that will be assigned, by default, to some stereotypical chair. Then, though there is no chair in sight, a chair-frame will be supplied by default. Default assignments are of huge significance because they help us represent our previous experience. We use them for reasoning, recognizing, generalizing, predicting what may happen next, and knowing what we ought to try when expectations aren't met. Our frames affect our every thought and everything we do.
Frames are drawn from past experience and rarely fit new situations perfectly. We therefore have to learn how to adapt our frames to each particular experience. What if a given situation closely matches several different frames at once? Some such conflicts could be resolved by the locking-in negotiations we described earlier; then only the frames that manage to suppress their competitors can influence one's other agencies. But the other frames could lurk offstage, awaiting opportunities to intervene.