PComp: Interaction observations

Blog assignment:
Observation. 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.

Handheld barcode scanner:
This at first appears to be a dangerous device, perhaps a weapon used to protect shopkeepers. Its primary powered attribute is a red laser. It is held by cashiers at the payment gateway blocking the exit. It has a handle about the size of an Altoids container, with another container bent and stacked on top. The whole piece is attached by a cord to the cashier station, and is never touched by customers. This implies that it serves a special function reserved by cashiers.
Simple construction consists of an opaque plastic shell, with a slight angle about one inch from the top. At the top, there is a slight inset. Inside is a translucent viewing window (about 1” x 3”) housing a bright red laser which seems to refract inside a mirrored chamber. It is always on, but not always in the cashier’s hand. It may be connected to the cashier station computer, since that is the other interactive item in use.
Since cashiers do not generally point the item directly at customers, and customers do not display fear or hesitation near the device, I rescind my prior interpretation. Cashiers generally direct this device at items passed to them by consumers, then bag the items. There is a beep when it passes over the items – if there is no beep, they continue moving it around the item. If there is still no beep, generally they turn to the computer and appear to reference something written on the items, then touch several buttons. Then they place the item in a bag and continue on.
As I approached, I was able to see the computer screen. The beeps correlated with text appearing in rows on the screen. Each row ended in a number,, and the numbers had an updated total at the bottom of the screen. On closer inspection I noted that these numbers matched those written below the items in their original storage location. I surmise that something on the items links them back to these numbered tags, allowing the computer to retrieve the item’s information.
With much closer inspection, I noticed that cashiers generally oriented items so that a rectangle full of lines, printed on the item wrapper, passed under the red laser. These at first appeared identical, however upon holding different items next to each other it was clear they possessed subtle variations. Somehow the variations in these bars must correspond to the numbers on the screen. Is there a small computer inside the laser device which can interpret these lines? Or does software on the computer read the input as variations of dark and light from a sensor, like a photoresistor? Perhaps the entire image is compared to a stored picture?

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