On a recent trip to Helsinki I needed to stop at the cash machine to aquire the local currency. I wandered about the terminal and found the ATM.  Now to me, ATMs are one of those universal devices which follow a standard operating process.  Insert card into card slot, mash your PIN into the keypad, and bank gods permitting, cash will magically appear from cash slot.  Simple. Well, they do it a little different way up north. [caption id="" align="alignnone" width="480" caption="eeny meeny miny mo"] [/caption] As you can see from the above, I was offered two choices.  Straight away I went for the yellow, familiar looking card slot - the one with the arrows showing you the way.  Seconds later, my card was returned to me with an error message advising cards with a chip should be inserted into the blue slot.  WTF?!  Don't make me think.  OK, forgetting the technical reasons, why doesn't this machine (and the others scattered throughout Helsinki) simply have the one slot, and let the machine determine the type of card, and respond accordingly? Donald Norman coined the term affordance in his book The Design of Everyday Things, where he states:

... the term affordance refers to the perceived and actual properties of the thing, primarily those fundamental properties that determine just how the thing could possibly be used. [...] Affordances provide strong clues to the operations of things. Plates are for pushing. Knobs are for turning. Slots are for inserting things into. Balls are for throwing or bouncing. When affordances are taken advantage of, the user knows what to do just by looking: no picture, label, or instruction needed." (Norman 1988, p.9)

I like the last sentence.