Pick a piece of interactive technology in public, used by multiple people. Write down your assumptions as to how it’s used, and describe the context in which it’s being used. Watch people use it, preferably without them knowing they’re being observed. Take notes on how they use it, what they do differently, what appear to be the difficulties, what appear to be the easiest parts. Record what takes the longest, what takes the least amount of time, and how long the whole transaction takes. Consider how the readings from Norman and Crawford reflect on what you see.
I observed the self check-out counter at CVS in my neighborhood. I never generally notice the self checkout counter. Only in times when the queue for regular check-out is really long, do I consider going to a self check out. My logic has been that, a person doing this all day long will definitely be more efficient than a person who does it for the first time (or occasionally). I feel that this is the sentiment shared by most shoppers. As far as the human element is concerned, I don't think people go to a manned check out just to interact with someone, though some say it is personal.
I am not going into the specificity of the interface of CVS self check out, but the check out process in general. First thing I noticed was that there was not enough table space to place the items first and scan them all at once. Instead, it required picking up from the cart, scanning and then dropping them into shopping bags. This involved quite a bit of moving around and repetitive motions.The thing that took the most amount of time was reorienting to find the barcode and then scan it successfully. The payment part was pretty quick and efficient. I will attribute this to the fact that people are used to doing that every time they shop and pay a cashier.