Benevolent habituation, important though it is, is only half of the picture. The other half, as we noted in the Premises chapter, is supporting flow states.
A person in flow state has elevated alpha-wave levels in the brain, not unlike those of a Zen monk in meditation. When in this alpha-wave-intensive state of flow, we can retain cognitive consciousness for far longer than the few seconds of duration characteristic of normal (beta-wave) consciousness. This extended consciousness equips us to solve complex problems, follow extended chains of reasoning, and take on tasks that we simply cannot fit into the transient episodes of normal beta-wave arousal.
Flow states also seem to be more conducive than normal consciousness to activation of the right superior temporal gyrus, a region of the brain associated with intuitive leaps and sudden insight. Why this is so is not yet clearly understood, but thousands of years of anecdotal evidence suggest that that the chatter of beta-wave activity in normal consciousness somehow competes with our “aha!” circuitry. Or, as a Zen master would put it, the mind is a noisy drunken monkey, and our Buddha-self can only whisper. The monkey has to be soothed into a flow state before we can hear.
Computer programmers are not unfamiliar with flow state; it appears in our folklore as “hack mode” and many of our behavioral quirks (such as programming into the still hours of early morning) are patently designed to maintain it. But flow is just as characteristic of many categories of computer users as it is of programmers. Flow-seeking behavior is obvious in writers, artists, musicians, scientists, and engineers of all sorts. On examination it turns out to be no less important to businessmen, military officers and even athletes. Human beings of all kinds rely on flow states to reach peak creative performance at what they do.
People who are practiced at maintaining flow can remain effectively conscious and creative for hours at a time, with tremendous gains ind productivity and inner satisfaction. In fact, it seems almost certain that no human being can function competitively (at least in creative or professional work), without routinely entering flow. This makes it a continuing mystery why we tolerate work environments full of loud noises and other kinds of interruptions that are disruptive of flow states.
We learn from [DeMarco&Lister] that it takes about fifteen minutes to establish flow, or re-establish it after it has been interrupted. In a normal working day, as few as seven randomly-spaced disruptions can completely destroy any possibility of maintaining flow long enough to get any real work done. There are a few exceptions (like, say, software controlling the alarm sirens in a missile-defense system) — but in general, one of the most important goals of any user-interface designer must be to make sure that his product is never, ever one of those disruptions.
Thus, our Rule of Distractions and Rule of Silence. Eschew popups and animations, avoid visual and auditory noise. Make messages clear but unobtrusive. When in doubt, quiet down.