princípio
Occam’s razor
The best solution is the one that presents the fewest possible assumptions.
Remove everything that does not change the decision of whoever is using it.
Between two solutions that solve the same problem, the one that requires fewer parts is usually the better. In interfaces, the practical question is what each element on the screen is doing there and what would happen if it left. Apple took this to the extreme for decades: the iPod had a wheel, the iPhone had a button, and each thing removed was one thing fewer to explain. The limit showed up the day the button went away for good, and the same company needed a video to teach people how to close an app.
Why there is no neuroscience here
The biological mechanism behind the effect, and how much of it was actually measured.
The razor is a principle about how to choose between competing explanations, a rule of method and not a fact about the brain. There is no biological mechanism to present because there is no phenomenon: nobody measures someone’s parsimony. What gets measured is the cost of each extra element on a screen, and that cost is in the William Edmund HickMeasured decision time as a function of the number of alternatives, and found the logarithmic relation that bears his name.One reference in this work:1952On the rate of gain of informationSee on Wikipedia ↗See in the bibliography →–HymanRefined Hick’s measurement the following year, which is why the law carries both names.One reference in this work:1953Stimulus information as a determinant of reaction timeSee in the bibliography → law and George Armitage MillerWrote, in 1956, the magical number seven paper, which the field itself later corrected to about four.One reference in this work:1956The magical number seven, plus or minus twoSee on Wikipedia ↗See in the bibliography →’s law, where it has a number. Applying the razor to design is good reasoning practice, and it does not get any better with anatomy.
Why this law presumes no body at all
Who it was measured on, and what changes when the body on the other side is another.
Cutting what does not change the decision is a rule for whoever designs, and it holds the same on any screen for any person. The care is in what gets cut. Simplifying the presentation is not simplifying the decision, and removing a field that changes someone’s choice is not economy, it is omission.
How design translates it
What to do with it on a screen, without turning a finding into a rule.
How to measure this in your product
In a sign-up form, ask of each field what changes in the system if it does not come. The “how did you hear about us” changes nothing of what the sign-up needs to decide, and so it leaves the screen and the database. The field that changes something stays, even if the screen looks fuller with it. Splitting the same question into two steps is something else, and it is not the razor: there nothing was cut, only postponed.
Where it breaks
Where the law does not hold, holds less, or holds in reverse.
The razor works in reverse when what leaves the screen is precisely what the person needed in order to decide. A sign-up that pushes the mandatory field to a later step looks cleaner on the first screen and sends the person back to the start of the order when they discover what was missing.
Related neuromyths
What gets said about this concept out there, and what the evidence actually shows.
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Less is always more: the cleaner the interface, the better.
The razor says to choose the explanation with the fewest assumptions, not the screen with the fewest elements. Removing what changes the decision of whoever uses it is not economy, it is omission, and hiding complexity does not eliminate it, it only transfers it to whoever did not ask for it.
Um caso
A real product where this showed up, with what happened and where to check it.
The form that lost half its questions
In 2014 the UK government’s digital service relaunched the Carer’s Allowance application, the benefit for those who care for someone. After researching with the people who apply and questioning how the policy had been interpreted on paper, the team removed 170 questions from the form, 49% of the total, until only what the application actually needs was left. One research participant said it was much better than she expected and that she could do it on her own. The post gives neither completion rate nor time, and that is the number that would be most missed. Even so, it is the razor applied. Half the questions did not change the outcome of the application, and they left without removing anything the decision required. Before asking for a piece of information, it is worth knowing what changes if it does not come. If nothing changes, it did not need to be there.
Experimente
A piece to check in your own body what the text has just claimed.
Remove fields until the sign-up stops working
This is the sign-up form for any old service. Remove the fields you consider dispensable, one by one. The scoreboard says how many are left, whether the account can still be created and — when that is the case — where the work that field was doing went.
- Email without it there is nowhere to send the confirmation
- Password without it there is no way to sign in again
- Confirmar senha a “show password” button solves the same problem with half the work
- Name it can be asked for later, when it makes a difference to the person
- Sobrenome splitting the name into two fields serves the database, not whoever fills it in
- Telefone it is not needed to create the account, and it is the field that makes the most people give up
- Date of birth it is only mandatory when there is a legal requirement — and then it should say so
- How you heard about us it is a marketing question charged as a toll
- Aceite dos termos it is consent, and it cannot be presumed
9 campos. A conta pode ser criada.
The floor is three fields: email, password and consent. Everything above that is a choice, not a requirement, and each choice has a cost that whoever fills it in pays alone. Two things are usually said together and are not the same. Occam is about not adding what is not needed, and what is not needed really does vanish when it goes. A field that was doing some work, though, does not disappear when cut — its work reappears in an email with no name, in a more fragile account recovery, in a second screen later on. That part is Tesler’s law, and the two live side by side in the same form.
Who actually said this
The name the law carries, who actually wrote it, and why the mix-up stuck.
The formula is not Ockham’s. It is John Punch’s, 1639.
The sentence everyone quotes — entia non sunt multiplicanda praeter necessitatem, “entities are not to be multiplied beyond necessity” — appears in no surviving work by William of Ockham. It was written by the Irish Franciscan John Punch in 1639, in a commentary on Duns Scotus, almost three hundred years after his death. The attribution stuck because it is not unfair: Ockham used the argument all the time, in other words, and the razor does describe his way of thinking. It just describes nothing he wrote. The one who took this apart was W. M. ThorburnShowed, in 1918, that the formula of Occam’s razor appears in none of his works and was written 300 years later.One reference in this work:1918The myth of Occam’s razorSee in the bibliography →, in 1918, in an article with the best possible title, “The Myth of Occam’s Razor”.
THORBURN, W. M. The myth of Occam’s razor. Mind, v. 27, n. 107, p. 345-353, 1918. DOI
Fontes
Enunciado attributed to William of Ockham, 14th century, but the formula is not his.
Leitura complementar: Occam’s Razor Laws of UX em inglês