Home-made instant poka-yokes

Everyday poka-yoke

Update: Also known as Useful Landmines in the 43 Folders world - thanks Pantufla!

Mistake-proofing - poka-yoke - can be as simple as encouraging/forcing yourself to do things in a sequence, to avoid forgetting or avoiding intermediate steps. If you’re the sort of person who hangs a jacket or bag on the door handle, so it can’t be forgotten on the way out, puts things in front of the door so you can’t forget them when you’re going out, or at the top or bottom of the stairs so you’ll remember to carry them to their intended destination next time you’re using the stairs, you’re engaged in mistake-proofing. You’re introducing a behaviour-shaping constraint to assist your own effectiveness.

In the above photo, putting the mobile phone (on-charge) inside a shoe makes it more likely that it will be remembered when going out: the act of putting the shoes on requires the user to pick up the phone, which could otherwise be easily forgotten. Similarly, Mark Hurst (of Good Experience and ‘Broken’ fame) regularly features two very simple poka-yoke procedures in his Uncle Mark’s Gift Guide & Almanac:

How to remember if the batteries aren’t in your camera

Summary: If the batteries are dead, or aren’t in the camera, keep the battery compartment open.

Description: When you’re charging your camera batteries (in a wall charger, say), keep the camera’s battery compartment open. That way, if you pick up your camera to put it in your pocket or purse, you’ll see that the battery compartment is open and will remember that the batteries aren’t in it.

Leaving the camera battery door open

There’s also this:

How to make sure they see the papers you dropped off

Summary: Put the papers on their chair.

Description: Here’s a tip I learned years ago and have used ever since. If you want to make sure that someone sees the papers you dropped off at their desk, put the papers on their chair. The natural inclination is to drop the files on the keyboard, or beside the mousepad. What’s the first thing the person does when they get back to their desk? They shove the papers aside, onto a nearby pile. They want to check their e-mail immediately, and those papers are in the way!

But put the papers on their chair, and watch what happens: the person refuses to sit on them! They take a second to pick them up, and while they’re in-hand, the person takes a look at the files while they get comfortable in the chair. Bingo: you guarantee attention to your drop-off.

Papers on chair

Of course the papers-on-chair method can also be used to remind (or discipline) yourself about dealing with important papers.

This kind of very simple sequencing poka-yoke comes almost naturally in our everyday lives, at least with certain tasks. Sometimes it’s simply reminding ourselves to do something (e.g. putting a Post-It note somewhere we can see it); other times it’s trying to prevent us proceeding until some action has been taken (e.g. putting a Post-It note right in the middle of the computer screen so we can’t ignore it). Donald Norman’s Things That Make Us Smart has some interesting discussion of the power of Post-It notes and their importance as “information in the world”, disburdening some of our mental load - also part of the whole Getting Things Done phenomenon.

Sometimes we even (consciously or otherwise) try to ‘trick’ ourselves into behaving how we want to (or know we should) - the random offset alarm clock (patent; Halfbakery discussion) and Gauri Nanda’s “runaway success” Clocky being examples that spring to mind. (I once had a bedside clock radio where the button to set the minutes no longer worked, which meant that I could only set it either on-the-hour, or, because I forgot to do it at the right moment, set it maybe between 5 and 30 minutes fast. That meant that there was an uncertainty built into every time I glanced at the display, and indeed every time the alarm went off. I was rarely late, as a result.)

I have a hunch that almost trivially simple sequencing poka-yokes (in particular) could be important in designing for sustainable behaviour, such as reducing energy use and waste generation. For example, if your rubbish bin had a recycling box built into the top, so that you had to lift it out of the way (hinged, perhaps, to make it hassle to remove entirely) before putting anything into the main bin, it would be difficult to ignore the recycling box. Hence, learning as much as possible about different methods people use to mistake-proof themselves, or shape their own everyday behaviour, is likely to be useful in exapnding this line of research.

So, what are the everyday home-spun (or otherwise) tricks you use to help mistake-proof yourself?

Chute the messenger

Rubbish chute
Rubbish chute

This is a communal rubbish chute serving a block of flats. The cross-sectional area of the aperture revealed by opening the hatch should be smaller than the cross-sectional area of the chute itself, so there’s less chance of rubbish bags getting stuck, even when someone crams one in.

That aperture dimension is important. It (to a large extent) determines the volume of rubbish that can be thrown away in one go. That in turn determines the size of the bins that users of this chute will (probably) have in their houses or flats, and thus how often the bin will have to be emptied. Taking the rubbish out can be a chore; halving the bin size doubles the number of trips to the chute, doubles the inconvenience.

It is, therefore, more desirable not to throw too much away. At the very least, having a smaller bin will make users aware more often of just how much waste they’re generating.

But does that have any measurable effect on purchasing decisions in the first place, assuming that more minimally packaged products are available as an alternative to those with excess packaging? How strongly coupled are the (limited) affordance of a smaller bin, and, at a couple of removes, in-store decisions? Is that rubbish bin, or indeed the chute aperture itself a social actor, a messenger, capable of persuading people to change their behaviour purely by existing with one set of dimensions rather than another?

Effectively, do people with smaller rubbish bins in their houses consciously buy items with less packaging?

Where else is this modified affordance -> inconvenience -> behaviour change pattern used as a strategy? As with making parking spaces deliberately smaller to make owning a large vehicle less convenient, the strategy may have some potential.

A lengthy debate

Norwich City Council is introducing a system of parking permit charges determined by the length of the vehicle:

The move away from flat-fee permits will penalise drivers who own vehicles more than 4.45 metres (14½ft) in length, such as the Vauxhall Vectra.

Brian Morrey, vice-chairman of the Norwich Highways Agency Committee, a joint initiative between the city council and Norfolk County Council, said: “We want to encourage more people to drive smaller cars. It is far more environmentally friendly and would also generate more parking space on the roads.”

(Quote from the Times; image from the Daily Mail)

From the Daily Mail - the parking permit charge bands for some common cars

Media reactions have largely been negative, with the measure being seen as a stealth tax, penalising larger families with larger vehicles, and so on; even the Green Party’s Siân Berry (London mayoral candidate and anti-4 × 4 activist) criticised the measure on the BBC News this morning for not being linked to the cars’ CO2 emissions.

Nevertheless, from a ‘design with intent’ point of view, this is an interesting strategy. The Council is clearly addressing the problem which it perceives - too many large cars in a city with “narrow, mediaeval” streets, rather than the ‘wider’ problem of CO2, and it’s addressing it directly, by making it less desirable to own a larger vehicle in Norwich if you’re going to park it on the street. Whether that’s ethical, sensible, or anything else is another matter: there are always unexpected consequences, and if, for example, more people decided to lay tarmac over their front gardens to avoid having to pay to park on the road outside, the impact of the permit costs might be felt long after the price had been forgotten (much like the window tax). While legal/economic/policy mechanisms for changing user behaviour, such as fines and permits, are perhaps outside the usual purview of ‘design with intent’, the idea here is still relevant: it’s a rather rare example of a direct response to a problem, and it - potentially - has that ‘trimtab‘ characteristic that is so fascinating about certain solutions.

An obvious physical-psychological mechanism analogous to the permit pricing structure might be to construct city car parks and parking spaces so that there were only a few spaces long/wide enough to take larger vehicles (making this very obvious), thus adding a little extra inconvenience every time a driver of a larger vehicle wants to park. Over time, that thin end of the inconvenience wedge might have an effect, even if it simply means that when the owner comes to replace the car, he or she thinks “Driving a big car’s so inconvenient nowadays; I’ll get something smaller.” On a large scale, those small decisions can have a significant impact. Has this been done anywhere?

I believe in mirror-queues

Meagan Call has written a very interesting piece examining the technique used in some (women’s) public restrooms* of moving the mirrors to the wall near the entrance/exit, rather than behind the sinks as might be expected (and is usually found in mens’ facilities), to lessen queueing and speed up throughflow:

No mirrors behind the sinks: photo by Meagan CallMirrors by exit instead: photo by Meagan Call

Women often linger, using the excess water from their recently scrubbed hands to squish, flatten, and fluff their hair. I’ve seen women who don’t bother to wash their hands bend over the sinks to play with their hair or re-touch makeup. And of course, some women go into the restroom for the sole purpose of looking into the mirror. No mirror equals less congestion, people washing their hands can get to the sinks more easily, and will leave more quickly.

Moving the mirror near the doors is actually an intelligent solution… by moving the mirrors away from the water, primping is less desirable. In addition, by placing it in the pathway of the door, people are more likely to feel foolish and in the way, and are therefore more likely to pass by quickly. The open space does not invite people to stay and look in the mirror.

Meagan’s analysis is spot-on - this is a clever technique which is subtle enough not to be noticed by the majority of users, but which nevertheless shapes their behaviour. The agenda is one of social benefit (for the greater good of the other users, reducing congestion) rather than explicitly commercial (in the context of the service area where the facilities are located), but it presumably has the effect of reducing complaints, hence increasing customer satisfaction even if only marginally.

We’ve looked before at some of the issues around mirrors in a retail environment, but in a confirmation/corollary of Meagan’s thoughts, I’ll end with two pertinent quotes:

Stand and watch what happens at any reflective surface - we preen like chimps, men and women alike… Mirrors slow shoppers in their tracks, a very good idea for whatever merchandise happens to be in the vicinity.

Paco Underhill, Why We Buy.

A large hotel in an American city received many complaints about the slowness of its elevators. It installed mirrors next to the elevator doors. The complaints ended.

Lawrence Lessig, Code and Other Laws of Cyberspace

………..

*/bathrooms/toilets/conveniences/other

Photos from Meagan Call.

Full, tilt

Balancing bowls. Image from Royal VKB websiteJan Hoekstra’s Balancing Bowls for Royal VKB (via Boing Boing) are an interesting ‘portion control/guidance’ solution - as Cory Doctorow puts it:

The tilt is tiny, all of 3 degrees, and the net effect is very satisfying — you gradually add snacks to the “light” side until it makes a soft and very definite *click* as it falls.

This kind of ‘very mild persuasion’ example is a great demonstration of how a simple physical property can be used to inform the user - the conventional modern solution in this area might be to monitor users’ behaviour, e.g. by weighing the amount of food put into the bowl, and then display it electronically, with an indication of whether a pre-set portion size has been exceeded. But these bowls simply tilt, with no electronics or moving parts (other than the bowl itself) necessary. It’s an elegant poka-yoke style solution.

Portion perception (and unit bias) is a fascinating area - we’ve looked briefly at it a few times - but I hope to explore it in more detail in due course, along with a review of Dr Brian Wansink’s Mindless Eating - in a post about how cognitive biases could be used in designing behavioural change.