Ticket vending machines

The other day I had to buy a ticket from a vending machine similar to this one here:

German Ticket Vending Machine (Photo Credit: flickrhivemind.net/Tags/fahrscheine)

German Ticket Vending Machine (Photo Credit: flickrhivemind.net/Tags/fahrscheine)

The ticket costed 2.50 € and I didn’t want to put in a 50 € bill so I used my bank card.  I entered my PIN, took the ticket and boarded the train calmly. Some time later I got a feeling I might have forgotten something and checked my wallet – I’d left the card in the ticket machine :D. Well the card was recovered (by a friend who was fortunately near) and so the story ends.

Now let’s see why slips like these occur. They are called Premature Conclusion Errors – forgetting to complete the action sequence because the main part of the goal is accomplished (getting my ticket). They are common for activities which people do over and over again.

To those who think “well it’s your fault, because you weren’t paying attention” I’ll say – “of course it isn’t”. The vending machine is clearly poorly designed – it deals with money and allows you to make such an error. What’s the solution? Every single ATM does the following: forces you to pull out the card and only then gives you the cash, thus avoiding precisely this kind of slips. Couldn’t the ticket machine ask me to get the card before spitting out the ticket?

P.S.: I didn’t use the 50 € bill because of fear: what if it gave me 47.50 € in coins. This points out another problem – I don’t understand how it works, so I’m scared to use it.