MAKING plans by domestic videophone could take longer and lead to more confusion than discussing them over an ordinary phone, psychologists suggest. Using one to map out a route for a holiday trip, for example, is actually less effective than using a standard phone, Claire O鈥橫alley of the University of Nottingham told a meeting of the British Psychological Society last month.
The research may be discouraging for anyone thinking of buying one of BT鈥檚 home videophones, which the company says it has sold in 鈥渢housands鈥�. The problem arises because videophones have to squeeze so much data down a single line. The compression process leads to delays in voice and video reception. Videophones such as BT鈥檚 Relate 2000 update the picture only every couple of seconds. This jerkiness and interrupted flow can also be confusing, says O鈥橫alley.
She and her colleague Steve Langton, and Vicki Bruce of Stirling University, gave their volunteers a test in which they had to work out a common route using maps which had been secretly altered so that they differed in subtle but significant details. This meant that each pair had to 鈥渘egotiate鈥� about the route.
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With an experimental delay on the videophone system of roughly 500 milliseconds 鈥� 鈥渁bout the same as on an old transatlantic call,鈥� says O鈥橫alley 鈥� people were much worse at solving the map-reading exercise than when using either speech alone or a high-speed video link, which had no perceptible delay.
鈥淲e鈥檙e not trying to knock any particular product. It鈥檚 just that with current technology these links can鈥檛 work over domestic phone lines,鈥� says O鈥橫alley.
Conventional phone lines have a bandwidth of about 4 kilohertz, but an uncompressed video signal requires 1000 times more. The BT Relate 2000, made by GEC Marconi, went on sale early last year at a price of 拢399, and transmits up to five pictures a second.
The source of the difficulty is predominantly the delay, rather than the video quality: parallel experiments showed that people using a phone with a delay also had trouble solving problems. 鈥淚deally the delay should be less than 40 milliseconds,鈥� says O鈥橫alley. 鈥淏T is aware of our research, though we haven鈥檛 talked to them about the results.鈥�
The researchers used the 鈥渁ltered maps鈥� method because there are plenty of data from face-to-face experiments solving the same problem, says O鈥橫alley. 鈥淲e don鈥檛 know how this finding translates to business 鈥� for example, if you need to persuade somebody about something.鈥�
This is the sort of problem that might crop up at sales meetings, for example. 鈥淏ut we鈥檙e working on designing experiments which have those negotiating elements. We do know from other work that it makes a positive difference in such work if you can see somebody.鈥�
