How Do We Measure Interactivity?

What, precisely, do we mean when we talk about "high" interactivity and "low" interactivity? Is an intense, fast-paced action game more interactive than a complex, slow-moving strategy game? I don't think so. We need merely hearken back to my standard example of interactivity: a conversation. What makes a conversation more or less interactive? Certainly it's not the speed with which the interlocutors speak. To achieve high conversational interactivity, each person must perform high-quality listening, high-quality thinking, and high-quality speaking. For an intense conversation, you must really listen to the other person, really hear what they're saying. You must think carefully about what they said, gauging their true meaning. And finally, you must choose your words carefully to state your thoughts with perfect clarity. When all these goals are met smoothly, the conversation is intense.

Thus, a highly interactive game would listen very well to its player, think well about the player's inputs, and produce clear, expressive outputs. We have done a good job with the third step in this process, but what about the first two? Do you really believe that players can say everything that they might want to say during a game? Does the input structure permit them to make the full range of reasonable moves? And does the thinking structure of the game permit the computer to challenge the player as an equal?

So there is our way of measuring interactivity. You can estimate the interactivity level of any game by asking three questions:

• How much of what the player might desire to say does the game permit the player to actually say?

• How well does the game think about the player's inputs?

• How well does the game express its reactions?

Let's apply this metric to some games. We'll start with the generic fast-paced action game. This game permits the player to say only a limited range of words: move up, down, left, right, and so forth. It does permit the player to say them quickly. It's processing of the player's input is rather simplistic: All it does is move the player around on a map. Its expressiveness is quite complete, within the limited purview of the game. We can conclude that such a game supports a small amount of interaction at a very fast pace; the end result is certainly highly interactive, but the bulk of its interactivity is derived from its speed rather than the brilliance of its design.

So let's jump to the other end of the scale with a ponderous strategy game like Civilization. The pace is much slower, but the player has a much wider range of things to say, and the game executes a much more complex set of algorithms. In other words, the listening and thinking are much deeper in this game. Of course, the expressiveness of the game is certainly up to snuff. We conclude that Civilization is also a highly interactive game, even though it operates at a slower pace. The slow pace of the game is compensated for by the richer listening and thinking.

Thus, you can achieve a high interactivity game in a variety of ways. A fast pace can certainly help, although it is no guarantee of high interactivity. The important thing is to keep the players active. They can either do a few things rapidly or a great many things slowly but they must be mentally active at every step.