Forcing functions are a super way to help make things foolproof, or better, errorproof — as all of us make mistakes with designed things without being fools. You may have used your own forcing function when, in an attempt to make sure you remember your passport or tickets before a flight, you put them directly in front of the door so you couldn’t open it without noticing them. That little dialogue that asks you if you want to save your changes before closing your work, that’s a forcing function too.

My first memory of understanding a forcing function was when working with a giant machine capable of cutting through 100 pieces of paper at a time. The two buttons to operate it were on opposite sides of the machine. I couldn’t start the machine without spreading my arms out wide. There was then no way to also accidentally have your fingers in with the paper and near the blades when it started. Smart.

I learned this sense of forcing function from Don Norman’s classic The Design of Everyday Things. Also from Don, see Mapping.

The other sense of forcing functions for productivity is also really useful: helping kick ourselves into action.

Forcing function — design

Basics to consider for your photo and drawing composition. It has a long history.

Compose with the rule of thirds

Refers to a poem about a cart that worked perfectly for years and then collapses without warning. Useful parallels in engineering and design. For example, torch lights would generally benefit from being more like the one-hoss shay. A bike light gets progressively worse as the batteries get weak, and cycling gets increasingly dangerous until you decide you can’t take it any more. Much better to have a light that stayed full power, then warned you before it died.

Have you heard of the wonderful one-hoss shay,

And then, of a sudden, it — ah, but stay,

I’ll tell you what happened without delay,

Frightening people out of their wits, —

That the Deacon finished the one-hoss shay.

Now in building of chaises, I tell you what,

There is always somewhere a weakest spot, —

In hub, tire, felloe, in spring or thill,

In panel, or crossbar, or floor, or sill,

In screw, bolt, thoroughbrace, — lurking still,

Above or below, or within or without, —

A chaise breaks down, but doesn’t wear out.

With an “I dew vum,” or an “I tell yeou”)

He would build one shay to beat the taown

‘N’ the keounty 'n’ all the kentry raoun’;

It should be so built that it couldn’ break daown:

“Fur,” said the Deacon, “’t’s mighty plain

Thut the weakes’ place mus’ stan’ the strain;

'N’ the way t’ fix it, uz I maintain,

T’ make that place uz strong uz the rest.”

So the Deacon inquired of the village folk

That couldn’t be split nor bent nor broke, —

He sent for lancewood to make the thills;

The crossbars were ash, from the straightest trees,

The panels of white-wood, that cuts like cheese,

But lasts like iron for things like these;

The hubs of logs from the “Settler’s ellum,” —

Last of its timber, — they couldn’t sell 'em,

And the wedges flew from between their lips,

Their blunt ends frizzled like celery-tips;

Thoroughbrace bison-skin, thick and wide;

That was the way he “put her through.”

“There!” said the Deacon, “naow she’ll dew!”

Children and grandchildren — where were they?

But there stood the stout old one-hoss shay

The Deacon’s masterpiece strong and sound.

“Hahnsum kerridge” they called it then.

In fact, there’s nothing that keeps its youth,

Take it. — You’re welcome. — No extra charge.)

FIRST OF NOVEMBER, — the Earthquake-day, —

There are traces of age in the one-hoss shay,

There couldn’t be, — for the Deacon’s art

That there wasn’t a chance for one to start.

For the wheels were just as strong as the thills,

And the floor was just as strong as the sills,

The one-hoss shay

The standard reference for this is The Design of Everyday Things by Don Norman where he discusses stovetops and their controls in some detail(!). In this case it should be clear, unlike for our stove, which burner each control controls. Same goes for light switches. Same goes, as much as possible, for controls in a nuclear power plant.

Sketchplanations tagged with design-principle