I went to Home Depot and used their ACM (? automated cashier machine) as
1. I walked up to it and scanned my merchandise. (I noticed it was in the
proper initial state. I ignored the prompt to choose a language.)
2. I put in adequate cash (ignoring the button that prompted me to tell it
"Finish and Pay").
3. It (she, if you care, at least voicewise) gave me change and a receipt,
which I took along with my merchandise as I walked away.
I call that the primary interface. If there's a better name, just say so.
The next day I went to the grocery market, and being some sort of a caveman,
I expected to use their ACM with exactly the same mental model. Seriously...
it wasn't an experiment... I actually thought I could. Maybe someone
replaced our office coffee with decaf. In retrospect, it's inexplicable.
Anyway, as you might guess, I didn't get very far. It has unavoidable
prompts to start, finish, defer coupons, choose payment method, and a paper
cheat sheet posted to the monitor with produce/salad bar codes for those who
can't figure out how to look them up.
Do users have a right to expect the primary interface to work at all
Will the the primary interface eventually work at all ACMs, or should I go
back to drawing on my walls with mastadon blood?