But first, a Unix Koan:

A novice was trying to fix a broken Lisp machine by turning the power off and on. Knight, seeing what the student was doing spoke sternly:

"You can not fix a machine by just power-cycling it with no understanding of what is going wrong."

Knight turned the machine off and on.

The machine worked.

I hope that you’ll see what this has to do with anything by the time you read through.

As we were going away on holiday, mom asked me if i could show her that super-cheap store where I get stocked on cat food. My mom really loves to save! She’d do anything to get a good deal.

Intuition, as always, was right, but not followed upon. I did tell her she’d have trouble with it, so better not. But mom was adamant and I gave in, taking her to the NOWPET emporium, the future’s little foothold in south TLV.

To anyone who doesn’t know NOWPET - it’s all about cutting costs through automation. And what better place to start cutting than at a pet store by getting rid of those pesky sacks of flesh and getting truly efficient in serving our feline overlords?

So the end result is a store-like hi-tech vending machine - one that you step into by authenticating via your index finger print, take what you need, and go on about your business.

In theory, at least.

We illegally parked on the curb (my mom loves to do that, good luck finding that vacant evening parking space in Florentin) and I brought mom to the registration terminal, where one registers by entering a name, phone number, swipes a credit card to input a payment method, and then registers the fingerprint.

As I never had any trouble with the process, I assumed that since I’m there, it’d all be fairly straightforward.

And that’s where theory got to meet practice.

Registration was not hassle free, as the act of repeatedly placing the index finger on the scanner required an implicit aptitude that mom didn’t have; It didn’t seem to provide the feedback necessary for her to understand when to put it down, how long to hold it still and when to raise it.

But that was not all! Having beat registration after numerous attempts we finally entered the store, authenticating her freshly registered print (that took five tries) - and proceeded to locate the shelf that we needed with our 10kg sack of superb quality cat food. The shelf’s glass door was to be our doom.

No matter how many times did we try to put her index finger on the scanner - the door wouldn’t nudge!

Maybe you’ve not registered well, I said - let’s try that again? We re-registrered thrice, but ran into the same glass wall every time. At least the store was kind enough to let us out after every try (need your print for that, too).

“Ok”, she finally gave up. “Just buy it for me. I’ll wire you the money”.

And so I did - we came out, and to her great frustration I effortlessly performed the same process that she’s failed to complete for the previous 20 minutes.

As I was bringing the sack back to her car, mom was clearly unhappy about my success, sticking out her failure to operate the store. She was certainly hoping that I’d run into the same trouble so that she could regain some of her dignity before that soulless, cruel machine.

As we were driving back, I told her the koan about Knight and the LISP machine, which I recall from my Slackware distro of teenage years. Slackware had a quote like this displayed upon every shell login - it greatly enriched me.

“So why do you think he could turn the machine on, while the student couldn’t?”

I rubbed it in. “I don’t know” mom replied tiredly.

“By understanding how the device functions, Knight made subtle nuances in how he turned it on and off.”

And this is precisely why I could operate the pet store - and mom couldn’t.

What can we draw from this, other than the observation of my troubled relationship with mom?

Users vary wildly. 

What works flawlessly for me, a generation Y techie, is completely inoperable by a humanistically inclined baby boomer. Worth to keep that in mind when one builds UI/UX.

As an engineer, I end up in this fallacy way too often, making presumptions regarding users’ abilities when designing user flows & implementing UIs. Actually watching them interact with them is pretty eye opening.