Video recorders and photocopiers, even ticket machines on the railway, often seem unnecessarily difficult to use. Last December I bought myself a video cassette recorder (VCR) described as "simple to use". In the first three weeks I failed repeatedly to program the machine to record from the TV, and after months of practice I still made mistakes. I am not a lone. According to a survey last year by Ferguson, the British manufacturer, more than in four VCR owners never use the timer on their machines to record a programme: they don’t use it because they' ve found it far too hard to operate.
So why do manufacturers keep on designing and producing VCRs that are awkward to use if the problems are so obvious？ First, the problems are not obvious to technically minded designers with years of experience and trained to understand how appliances work. Secondly, designers tend to add one or two features at a time to each model, whereas you or I face all a machine’s features at once. Thirdly, although finding problems in a finished product is easy, it is too late by then to do anything about the design. Finally, if manufacturers can get away with selling products that are difficult to use, it is not worth the effort of any one of them to make improvements.
Some manufacturers say they concentrate on proving a wide range of features rather than on making the machines easy to use. But that gives rise to the question, "Why can't you have features that are easy to use？" The answer is you can.
Good design practice is a mixture of specific procedures and general principles. For a start, designers should build an original model of the machine and try it out on typical members of the public -- not on colleagues in the development laboratory. Simple public trials would quickly reveal many design mistakes. In an ideal world, there would be some ways of controlling quality such as that the VCR must be redesigned repeatedly until, say, 90 per cent of users can work 90 per cent of the features correctly 90 per cent of the time.
According to the passage, before a VCR is sold on the market its original model should be tried out ______.

A. among ordinary consumers who are not technically minded
B. among people who are technically minded
C. among experienced technicians and potential users
D. among people who are in charge of public relations