Cognetics and the Locus of Attention
In short Jef Raskin argues that people can consciously attend to only one thing at a time, and that habits form automatically whether we want them or not. Two practical consequences for requirements: important messages must not vanish, and confirmation dialogs don’t protect against mistakes.
Based on: J. Raskin, The Humane Interface (2000), ch. 2.
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Key ideas#
Cognetics#
Raskin uses the word cognetics for the ergonomics of the mind: the study of human mental limits applied to interface design, just as classic ergonomics studies hand size and reach. His claim is that most difficulty with computers comes not from hard tasks or careless users, but from interfaces designed without regard for well-established cognitive limits.
Conscious and unconscious processing#
Raskin separates the cognitive conscious from the cognitive unconscious. He treats this as a practical, testable distinction, not a philosophical one. (You weren’t thinking about the last letter of your name until this sentence; the question moved it into consciousness.) In brief:
- The conscious mind handles new, unusual or dangerous situations and makes decisions. It works on one thing at a time, under deliberate control, with small capacity.
- The unconscious handles familiar, repeated, safe activity. It runs many processes in parallel, through habit, with huge capacity.
One locus of attention#
At any moment you can consciously hold only one locus of attention. Raskin prefers “locus” to “focus” because attention can also be pulled involuntarily, for example by a sudden noise. Everything else is either not noticed at all or held very briefly in perceptual memory. Visual impressions fade in a fraction of a second and are lost unless they become the locus and move into short-term memory.
Consequence: a message that appears and quickly disappears will probably not be remembered. It should stay until it is no longer relevant, or demand handling while it is still fresh.
Habits can’t be prevented by willpower#
Repetition forms habits automatically, and no amount of conscious effort stops it. Raskin’s thought experiment: swap a car’s brake and accelerator pedals and add a warning light. When a child runs into the road, the driver will still press the habitual pedal. The warning fails because the reaction never passes through the locus of attention.
Consequence for UI: “Are you sure?” dialogs before irreversible actions are a weak defense. Because they are routine, users learn to answer “yes” automatically, so the dialog fails exactly when the action was a mistake. Raskin’s preferred safeguard, developed elsewhere in the book, is undo. It works after the fact, once the user has noticed the error.
Multitasking only through automation#
People can do several things “at once” only when all but one of them are automatic. Two tasks that both need attention interfere and slow each other down. What looks like doing two things at once is really fast switching.
How to apply it#
- Keep critical information out of disappearing messages. Require errors and warnings to stay until they are resolved or acknowledged. Auto-dismissing notifications are acceptable only for information the user can afford to miss.
- Prefer undo to confirmation. For destructive actions, write acceptance criteria for undo or recoverable deletion rather than for a confirmation dialog.
- Don’t rely on warnings to change habits. If users must behave differently, change the design so that the habitual action becomes safe.
- Protect habits across screens and versions. Keep the position and shortcut of frequent actions stable. A moved button will be pressed where it used to be.
- Know where the user’s attention is. At a counter or in a workshop, attention is on the customer, the bike or the machine, not on the screen. Design for quick glances.
Review checklist#
- Errors and warnings stay visible until resolved.
- Destructive actions can be undone.
- Confirmation dialogs are rare and justified.
- Frequent controls keep their position and shortcut across screens and releases.
- Screens used alongside other activities can be read at a glance.
Example#
At The Workshop, a fictional chain of bike-repair workshops, a mechanic marks a job “waiting for part” on a tablet. The parts order fails, and a notification says so for three seconds while the mechanic is looking at the bike. Nobody notices for two days. The analyst changes the requirement: a failed order shows a persistent banner on the job and alerts the workshop manager.
Meanwhile, front-desk staff confirm every booking cancellation with “Yes” by reflex and now and then cancel the wrong booking. The new requirement: a cancellation takes effect immediately, an “Undo” option stays available on the booking for the rest of the day, and the confirmation dialog is removed.
Sources and further reading#
- J. Raskin. The Humane Interface: New Directions for Designing Interactive Systems. Addison-Wesley, 2000, ch. 2.