Where do you start with a brand new product category? Prototype, test, iterate.
There was no precedent for a supermarket personal shopping scanner (PSS), so all form factors were on the table. Was a large screen necessary to organise your shop? Was a handle needed to grip the product securely? How many buttons are needed?
Most importantly, we had to prove to some upper management decision makers that one should not use a mobile phone-like device with a miniature 12 character display in a rack as the solution.
"We know what the people want" will always stick in the back of my head, as clearly the exec was proven wrong (he wanted to push his existing OEM phone!). In those days Nokia still ruled, but a mobile phone did neither provide intuitive scanning, nor was the display large enough, not were they build to rugged specs.
The functional prototype designs shown here were tested with focus groups in staged shopping setups, while we observed behind mirror screens. What people do and what they tell you (what they think they did) are two different stories. While we as designers might have been biased towards a favourite, the tests were conducted by independent research inststiutes, hence objectivity of the results was guaranteed.