Web page designers are missing an important trick by failing to recognise that signficant numbers of Internet browsers surf in packs, according to the advertising agency J Walter Thompson, which has just published the findings of its new Net research study, Project Iris.

Understanding how people are surfing the Net, rather than how many individual "hits" at particular sites are logged, is essential to identifying what turns browsers on and off, the agency claims. It is a strategy already pioneered by the agency's qualitative research system, InSitu, to research other consumer habits such as how people shop or watch TV. Participants are filmed and asked to describe what they are doing and why. This is then logged against a number of factors, such as how a product was displayed, or the length of a commercial break.

Now, JWT has joined forces with London's Cyberia Cafe to survey surfing habits. Phase one involved filming and interviewing 96 people as they surfed the Net. Initial findings will be supplemented by wider research involving 2,000 people over the next 12 months.

Project Iris found that many people browse for fun in groups, a fact ignored by Web page designers. JWT's head of behavioural research, Simack Salari, says: "People may go online alone at work, but an insignificant proportion do so with others for leisure and at home. It's very much a social activity."

As a result, attention levels vary: sole surfers have a lower level of involvement than groups, the research found. "Groups are more interactive: there are disagreements and questions," he says. The downside is the structure and design of many sites. "None cater for group access or response. Scrolling through text turns people off, and doesn't use the medium to best effect."

Ms Salari's findings are endorsed by the director of Cyberia and cognitive psychologist, Eva Pascoe. "The time people give a new homepage before giving up is just 12 to 15 seconds," she says. "It is essential to capture attention fast and hold on to it." Group use for leisure is not an exception, she adds: "It has implications: we must start retraining designers."