Observation - Vending Machines

For my observation, I chose a bank of three vending machines in a building on campus. Each machine was slightly different which made for a different kind of interaction for each interface. The first machine was Poland Spring machine that had individual buttons for each drink. This was the simplest interface of the three. The other two machines were of the keypad variety. One was for snacks and the other for beverages.

My first thought was that the Poland Spring interface was the simplest and thus, quickest to use. Each interaction was essentially three parts. First, the person inserted their money. Next, they selected an item by either pushing the button that corresponded with their selection or punching the two digit code on the keypad for their selection. Lastly, they removed the item from the bottom of the machine. I would say each person spent 30 seconds with the machine on average. Some subjects that didn't know what they wanted took longer and some subjects ended up walking away from the machine empty handed after juggling their change around a bit.

On the whole, I was surprised by the efficiency of all of the interactions. Having had my fare share of awkward vending episodes, I thought that at least one person would have trouble getting money into the machine, figuring out what the item key code was, or getting the item out but nobody had this trouble. The time differences for using the two different interfaces was negligable contrary to what I originally thought. I still think that having a seperate button for each item is a more user friendly interface but it didn't seem to be a factor during my observations.